Absolutely. XD. Anyway, if you've got 100,000 subscribers, you're not exactly an unknown are you? ... Anyone notice the references on the Ben Heck show recently by the way? Quite amusing really...
The bottom side has solder mask because it needed to go through wave soldering. There is really no need for top side solder mask, but yes it does look a lot better with it.
Memories of my childhood have come flooding back (along with memories of waiting several minutes for games to load and dreading the "R tape loading error"!)
I was sending emails with my spectrum back in1983. How? Well with the aid of cb radio, mic and ear connected up to spectrum ear and mic at each end ! My group of friends were "connected". We also sent games to each other to load. A couple of lads were intercepting our data and. Messages so I had to devise a basic encryption program ! The spectrum taught a lot of kids SO much about electronics and programming. A lost art amongst children ( and adults ) these days who seem to be just phone morons now !..
Nick Clark That's very true man. I was able to write full games for myself and hack my way into purchased ones back when i was a kid witha 48k spectrum, then later a 128k one. I moved onto an 'Amiga' in the early nineties and could do a few things with it, then the whole console era began and until I grew up a bit more and started looking at retro stuff on TH-cam and remembered I actually used to be able to do stuff like that. Kids are definitely missing out on some stuff nowadays, but hey - progress! lol
Nick Clark I spend most of my time in school being completely brain AFK because it takes these morons ages to understand basic things, and I really can't be bother listening to exactly the same shit lesson after lesson, why the fuck can't i just stay home until we start a new topic.
If you want to see the full story/drama of how Sir Clive almost by accident ended up in the computer industry as the main player, watch "Micro Men" a BBC documentary-drama which tells the story of his rise and fall. There's a funny scene on it, which shows how obsessive and hands-on Sinclair was with every aspect of his product development and design...one of his engineers brings 3 keyboards to his desk for the new XZ Spectrum and sets them out in line, one a proper tactile resistance keyboard, one another version of the ZX80/81 flat, and the rubber keys..he tried them all and tapped the rubber one signaling his choice. The spectrum was initially the fastest and biggest selling home computer in the UK (and even in some overseas markets, in the US even it was licensed as Timex Spectrum but didn't make as much impact there), and it came down to 2 factors unrelated to the machine itself really or its capability (there were faaar better and more powerful machines, like the Acorn, Commodore, and BBC Micro). The Spectrum was a) very cheap and attractively priced b) first to market as a "games ready" computer with colour graphics and sound c) but the real clincher was, Sinclair had already established his name in the home computer market and so there were hundreds, if not thousands of programmers writing games for the ZX81 which soon began writing for the Spectrum. Pretty soon you had 1,000s upon 1,000s of games for the Spectrum and people exchanging games on cassette tapes lol. So having a Spectrum was a must-have, if you wanted the best games and/or access to good games free off your mates. You only had to walk into a shop that sold home computers and you could see row after row of Spectrum games, and just 1 bottom shelf for "other" computers. It's ironic that Sir Clive was totally against going into the computer industry AT ALL and he was very dismissive of computers (still is today!) and even dismissive of the games industry..he just failed to appreciate the value in software or the huge business potential which would eventually overshadow the hardware industry (something Microsoft DID realise). Now we have come full circle...Sir Clive has launched (indirectly, someone else is doing it, but he has lent his name and has a stake in the venture) to a crowfunded product called "Vega" which is like a modernised retro speccy..the original design proposal (done on a 3D printer looked very much like an original ZX Spectrum except it has only 4 rubber buttons and a joystick lol. They've now done a much more modern looking design. The Vega is claimed to have 14,000 speccy games (and more you can download freely) it plugs into modern TV's (oddly via composite tho, not HDMI, probably due to the limitations of spectrum graphics in those games) and is like a games console and is retailing for £100.
Pity there are so many emulators available that do run on hardware with support for HDMI. I'm not sure the Vega is going to have any staying power really. Load up an emulator on my raspberry pi zero plus a couple of quids worth of adapters from eBay and it's sorted for a lot less money.
Pity there are so many emulators available that do run on hardware with support for HDMI. I'm not sure the Vega is going to have any staying power really. Load up an emulator on my raspberry pi zero plus a couple of quids worth of adapters from eBay and it's sorted for a lot less money.
I had a Commodore, but my best friend had a Spectrum back in the day. He also had ZX81, the first computer on our street! Loved _all_ of these old comps. Another friend had an Amstrad with a tape deck built in. It wasn't like everyone wanted the same thing back then and we were actually happier to each have different computers. Great days! Have you seen the recent BBC film based on Sinclair those early days, called Micro Men? Well worth a look.
When i was 7 year old I got ZX81. 5 years later I got Zx Spectrum. This computers, retyping listings and learning basic decieded my profession. Becouse this I choised technical education, digital electronic, and now 30 year later of my first Zx81 I am professional programmer. Sir Sinclaire was changed the World!
Love this tear-down, though the vid under-estimates the impact of the Spectrum in the UK. It was huge (rather than quite popular) and for its day it did a lot more than the bare basics. I still have and use one. :) Love it! and thanks for this vid.
Went thru the keyboard membrame in a couple of years typing. Learned digital electronics with it, built shadow ROM, DAC/ADC, a PWM on the NMI to slow down hard to play games and even built an interface for a XT-PC keyboard using an eprom to map key codes. Learned Z80 assembly on it as well. Also had the joystick interface, and Interface 1 for the printer and micro-drives. Build my first adventure game with those... Ah, it was a good friend.
Nice one Dave. I LOVE vintage computers from the 70's and 80's, and from what I've seen in the comments on past videos I'm not the only one! Any teardowns of classic computers are always much appreciated, but if I ever see the words 'Acorn BBC Micro' in the title of an EEVblog video I will literally wet myself with joy :)
Get to see a speccy. It's just sooo iconic of the 80's and brings back memories. I remember seeing them on sale new in WHSmiths for £49.99 the year they came out. It didn't seem like a lot of money for a computer which could play 1,000s of games and had colour graphics..yet to a 10 year old, it may as well have been £5,000. My brother got one for xmas some years after they came out, and I was well miffed!! I sooo badly wanted one and was sure we'd both get one. My mother didn't realise you could actually program them and thought it was purely for playing games on, and my brother wouldn't let me it to play games even, let alone program on it! I ended up with a Tandy TRS-80 (a horrible computer, but also running BASIC). Years and years later, I bought a speccy for sentimental value and it's in my vintage computer collection now which has grown considerably large!
The original price of the ZX Spectrum in 1982 was £125 for the 16K RAM version and £175 for the 48K version. Prices were reduced to £99 and £129 within a year as competitors started reducing prices and producing cheaper models. I believe it was the 1K ZX81 that sold for £49.95 in kit form or £69.95 fully assembled (only £20 more!), back in March 1981. Now kits are rare and cost £300 - which is probably about the same as £50 in today's money! (Prices corrected.)
derekjc777 Thanks for correcting me, it was indeed the ZX81 I saw for £49.99 and the Speccy was £99.99! I remember both in WHSmiths. I now have both in my retro computer collection!
The reason the solder mask is wrinkled is not that it was applied over wrinkled solder, but rather that it was applied over solder, and then subjected to wave soldering to solder all the through hole components. The solder itself would have been a tin lead plated layer that was used as an initial etch mask, and then IR, or hot oil reflowed. The reason that there is no solder mask at the the top is that there was no soldering done at the top, so it was deemed as not necessary. A cost saving measure, but one that leaves the upper surface of the board at risk from shorts caused by any loose conductive particulate matter. I remember my own spectrum with some fondness, I applied the 128 upgrade which added not only more memory, but also a grown up sized keyboard, and an all important reset switch. My first attempt at soldering :)
This is the machine where I first learned the BASIC programming language when I was about 11 or 12. We had a few of those keyboard membranes and those cassette tape connectors at the back were always dodgy - kept having to weigh down the connectors so that they would bend at an angle to make contact inside the connector! Memories! Oh yes, and Daley Thompson's super test used to take 12 minutes to load then "R TAPE LOADING ERROR" at the end hehe (oh, that was on the 128k version not the rubber keyed 48k)
If this is the Rich Lowe I'm thinking of, do you still have any of that old adventure game we were writing? Also, I still have that Assembler I swapped for The Quill with you.
I did like the rubber keyboard along with some other Speccy-using friends of mine. It was quite fast to type basic when you memorized the keyword placings. The only bad part was the membrane key contacts. After a few years of hard use some keys would go bad. Somehow the white contact material would corrode on one or two of the most used keys (at least one friend had the same problem). I remember I did a DIY repair on the symbol shift key in my Speccy by inserting a copper wire in place of the top membrane and surprisingly it worked for a long time. Then I actually made a full replacement with a PCB with soldered separate momentary switches for each key, and the rubber mat would go on top of that. I still have it.
The keyboard and membrane look in good nick, the socket on the modulator is for a PAL TV into which the composite video signal goes into the side of which can be routed directly to the socket to convert it to CV with a bit of simple DIY soldering. The edge connector is not for cartridges, but is a universal type interface for printers, joystick controllers, I/O boards, games cartridge interface, the controversial long awaited Sinclair microdrives, RS232, floppy drives etc. By the way, have you heard of Timmy Mallet?
RE the voltage regulator - there would have been a large aluminium heatsink bolted to it originally, looks like you weren't the first person to take this thing to bits!
I converted mine to the Spectrum+ keyboard which was ok but you still couldn't type quickly. It was a bit like go faster stripes on slow car. Very versatile and far exceeded the limitiations it was originally designed for. There was a lot you could squeeze out of that 48k of memory !
This bring memories I remember breaking traces in one of keyboard flat connections cables while investigating what's in my computer - I fixed it by by taping litlle pieces of wire over the crack - but I spended week in fear of my computer will not work again - I was something like age 12 with no equipment, experience or money for new membrane (new membrane cost was like 25% of my moms income :D)
The voltage regulator definitely had a heatsink originally. The Issue 1 ran very hot and it was increased in size for later versions. It was through-hole wave soldered, so no need for resist on the top layer, typical Clive! No need for a socketed ROM, by Issue 3 it wasn't going to change.
Expensive boards would be lead coated and pulled up out of solder and be blasted by hot air jets to keep holes clear and solder level. The machine was called soler leveler
The regulator had a heatsink screwed to it, it wouldn't last 2 minutes without it! The shape of the heatsink varied depending on the issue. These computers were AWESOME. I spend most of my early teenage life literally glued to my one.
Fun fact: Richard Altwasser and one of his Sinclair colleagues went on to design the Jupiter Ace, which was one of only a handful of microcomputers to use Forth as its default programming language. The Ace was heavily influenced by the ZX81 with its form factor and overall design. Ofc the Ace was a commercial flop, but as you pointed out, Richard went to work for Amstrad in 1986. If you've still got that Speccy lying around, you should try rebuilding it. There are now reproduction ULAs available, and the other missing components are all off-the-shelf items. Heck, it'd make a fun school holiday project for the kids.
Hello! Dave, I'm your fan and I admire the work you do. I learned a lot from your videos and had a ton of fun along the way! Just keep up the good work. I just wanted to correct and add to a few statements you made, Dave, since I'm a big fan of Sir Clive Sinclair and ZX Spectrum too. First thing: The 7805 DC regulator was mounted on a large aluminum sheet heat sink, because the current drain was over 1A. So, the the sink was missing in that one. Second one: The membrane keyboard. You were right when You said that it was probably unreliable and it was. But in the later issues of Spectrums, issue 4 and 5, there was a much better membrane type keyboard that could last a life time, i guess. It was much more transparent, almost like glass. Third one: The TV modulator was a RF video-only modulator. But it can be a composite out by just cutting a few wires and adding one for composite bypass to the RCA connector. Or, to keep it retro, with a few touches of a soldering iron and a few passive parts it could output sound through RF modulator too, since the LM1889N has a sound input too.
My personal teardown Christmas Present :) A big TY from Scotland (where a lot of these were made by Timex in Dundee)! A mere 30 years to the almost day ('the day' actually being December 25th 1983) since I first got my hands on a ZX Spectrum and a tape recorder for the software. I used a 5 inch black and white tv initially, then I borrowed a 12 inch Sony B&W TV from the kitchen. On rare occasions (and 'cos my mum was as interested in computers as I was - Hungry Horace was my mums favorite) I got to plug it into the family 21 inch Sony Trinitron. I remember my mum reading out programs from the magazines and I typed them in. In 1984 I got a 14 inch colour TV for my bedroom and a copy of Elite. Several years later I emerged.... :D Currently working in IT. But the memories...:)
The 7805 regulator was screwed to the board by Sinclair, and had a heatsink (which was very necessary along with some thermal paste). Some of the boards did have solder mask both sides (the Issue 4S board, fabricated by Samsung for example). The issue 1 board is the most interesting - it has hand drawn traces! Issue 1 machines are quite valuable and hard to get hold of though. The rubber key mat was made in a condom factory (I've met Rick Dickinson, who did the industrial design for Sinclair back in the day). If you want to know more about the ULA, get Chris Smith's ULA book. There's some interesting little anecdotes too - the ULA was designed in only 6 weeks by Richard Altwasser. A Ferranti engineer made an error when making up the masks for the metallisation layer and the upper and lower clocks weren't connected, but a spec of dust (in a clean room!) landed in just the right place to fix the problem on just one single die, so they could use this to verify that the ULA was correct. (I believe Chris also subscribes to this TH-cam channel so give him a shout out :-)) See www dot zxdesign dot info/book (damn TH-cam not taking URLs)
Note the BASIC keywords on the key tops. They reflect the ingenious internal workings of spectrum basic. Every basic keyword was represented by one byte code from the unused upper half of the ASCII character set. Displaying the keyword was taken care of by the character generator if I remember right. This greatly simplified the interpreter and made program storage very compact.
I tell you what Dave. Comments on retro computers bring out the flame wars. I loved my Spectrums (all 6 of 'em) and took a joystick apart to make a five zone sensor for my bedroom as a kid. The screen had a very crude graphical representation of my room and bits would start flashing if any of the contacts had been made. Ahh, memories! Without computers I wouldn't have gotten into electronics.
My TI-85 calculator was when I got interested in coding. It had basic on it. It also had Z80 assembly, but you had to hack the thing to unlock that capability.
Fantastic. You can tell it's a later version. The first issue didn't have the 4.43MHz crystal. Instead, it used a simple tuned circuit with a trim capacitor. There was a hole in the bottom of the casing so you could put a screw driver in there and adjust it (or I drilled a hole - I can't remember!) As the unit warmed up, the frequency would drift and you'd see the chroma "shimmering" on the screen. I really f**ked up one day (I was just a lad of 16) and damaged it. I found a local repair shop who sent it off to Sinclair and they sent me a replacement for free!
Modified my Spectrums back in the day with 27128 eproms to replace the ROM and via a home built eprom programmer / serial-parallel interface. I didn't mind the rubber keys.
Fantastic memories, a great step up from the ZX81!. I had both, and it was my intro into the world of IT. I have made a Lot of money over my lfe thanks to starting out on these affordable early computers. It's also amazing to see how far computers have come in 30 years. Wonder what the next 30 years will bring...
I loved my speccy(s) - it's the machine that began my career. Spent so much time at that rubber keyboard learning BASIC, then assembler as a kid. I've recently read "The ZX Spectrum ULA: How to design a microcomputer" - which dissects every part of it. The thought that went into the design by Altwasser was fascinating (for me anyway). I now know why the video memory seemed so weird, and was horrible to work with as a programmer, but was designed specifically to be efficient to read by the ULA. So yeah, I'd recommend it.
if didn't class yourself as a celebrity when you made this video, you bloody well are now mate! (2017) Thanks for your enthusiastic and totally compelling videos.
When I was around 9 or 10 I remember being on holiday in the uk at my nans and I bought a 128 with tape drive and around 50 original games for 5 quid at the carboot !! my nan had to drag me out in to the sunshine that summer ! loved it to bits.
I am very familiar with these. RF output, often on UHF 36, but some territories used VHF. At least 9 issues of PCB - 1, 2, 3, 3B, 4A, 4B, 4S, 5 and 6A. It's not high DRAMs it's missing but two 74LS157 that interface the low memory. The 7805 should have a heatsink, attached with a bolt. The Issue 3 was the first with no adjustment for the colour encoder, but also "corrected" the poor heatsink position of earlier versions - that degraded the keyboard membrane on issues 1 and 2. Issue 4S had solder mask on top of the board, but issue 6A didn't. I've never seen a 4A or 4B, or for that matter a 5 (known to be UK only). The Spectrum+ had a "plastic keys over a rubber layer" keyboard - it was rattly! 4116s failing often took out the ZTX213 and 650 in the power section. If the transistors failed they sometimes took out the 4116s too. Most big fault conditions on these were caused by failures of that kind, often induced by interference with the edge connector when the power was connected.
My first computer was a ZX Spectrum+ that my parents bought me and my brother around 1983/4 and 30 years on i'm still into and working with computers (Gaming PCs now). Loved the simplicity, we also had the 'metal' printer and handheld TV too. In fact I did my lines in school on the printer and was let off for being creative!! lol
We had the Timex Sinclair in the US and Canada, we never got the Spectrum. It was a 4 or 16K? (not sure), monochrome with a flat membrane keyboard. The cool thing was you could order it as a kit and build it yourself. A lost art.
Timex Sinclair TS1000 was a 2K ZX81 machine. The States also had a Timex Sinclair TS1500: a 16K ZX81 in a silver Spectrum case with a grey rubber keyboard: I know because I bought one recently and got it repatriated to Blighty! Sinclair Spectrum (Timex Sinclair TS2048) was never released due to low sales of the black & white, silent TS1500, however a version with a built-in microdrive - the TS2068 - was sold but didn't take off due to the dominance of Commodore.
That's overpriced for 1983, I believe they were about 99 pounds in the UK by then. Factoring in the approx. 1 to 2 exchange rate, that's the good old 50% Aussie markup on imported electronic goods, a tradition that continues to this day.
Anybody else here hand build a ZX80 kit? That expansion port on the back of the Spectrum was a real nightmare. Put the RAM expansion pack on there and you'd be lucky to get through entering a program without it freezing. When from this to a QL then gave up after that debacle and spent quality time with the BBC Micro model B. Good times. Up till 4AM coding. The rush was huge.
Yes, built the ZX80, bought a ZX81, ended up with 7 ZX Spectrums before jumping ship and going 6502 with the BBC Micro. And yes, spent the rest of my life as a software engineer working on CP/M, DRDOS etc! What a wasted life!
To all the North Americans... The Sinclair ZX81 was rebadged in the US as the Timex/Sinclair 1000 (TS1000) and there was also a TS 1500 that looked a lot like a spectrum, but was a ZX81 with the Ram expansion built in. The Spectrum was actually a generation on from that. The TS 2068 was the model that is based on its design, though Timex messed with the base design of the hardware and the ROMs making it software incompatible. The Spectrum+ was released about 1984 and had a better plastic keyboard, the Spectrum 128 was a model with a new "128KB" mode and better sound chip (same as TS2068, incompatible with the TS models design though), and after Amstrad bought out Sinclair the +2 (built in cassette) and +3 (3" floppy) were released. Spectrum out sold everything in the UK at the time.
Thought I saw it and went back to check... Nobody else seemed to catch it and certainly don't see any mention in the comments... During the closeups at about 6:41 looks like one of the pads has a solder crack on it... Bottom left, last pin on the trace from the bottom... Just south west of the pin directly west connected to the ground mask of the hole in the board.
Yeh fantastic units in the day, used to repair these at my computer shop, still have lots of parts for these and the original service manuals in the loft, may even have a few ULA's left.......
It sure brings memories, I had a PC called "Juku" with a floppy disk games in ANSI code that had also this unmasked PCB. If I remember correctly it was made in eastern part of Estonia, Jõhvi or Narva, I don't remember exactly, but it was a dumpster salvage. Oh how I hate it, any time it showed "-" in a row of 8 +-ses, it simply didn't load a disk correctly and crashed. But it had far more DIL packaged chips than this, but the main processor was also a DIL-40 as here. I don't have that any longer, as an active electronics kiddie, I took it apart long time ago, lost all the components during next years of failed attempts to build something and it's gone into memories now.
The rubber keyboard man, that's one of the unique selling points :) I seem to remember my power connection on it getting dodgy over time, could be wrong though, long time ago and I don't have it anymore.
I distinctly remember the power connection on one of the in-store demo ZXs (not sure if ZX81 or ZX Spectrum) being so dodgy it rebooted at the slightest push, making me decide not to buy one anyway. Ended up with a more expensive home computer which was unfortunately dead ended by the company before gaining any traction. Learned a lot from working with it and understanding the silly compromises that ruined its performance though.
Yeah that's pretty much what happened to to mine. I remember I used to stick tops off of pens and such to try and keep it wedged in place. Slightest touch would cut it off. Got years of great gaming out of it though so can't complain too much.
Last year I built a variant of a russian clone of the ZX Spectrum (Pentagon 128) - lovely machine. It's basically a spectrum completely made in 74-logic with a disc drive and sound chip.
The regulator would have had an aluminium heatsink that ran the width of the back. I dimly recall it being about 3cm wide, maybe 2mm thick and was formed such that it used the raised space in the cover and ran all the way over to above the UHF modulator.
It was also very popular here in Portugal, most kids that had a computer, had a ZX Spectrum. my 48k died long ago, but i still have the 128k (that comes with the casette loader).
The crinkly solder mask is caused by the flow solder process, when the board is virgin from the supplier it is flat and smooth. I f you look you can see where it flowed from i.e.which component pad.
There was a long heat sink attached to the 7805, it rose up and along the top of the Issue 3.... it's been pinched at some point in the past from yours.
Dave... it seems the Regulator was originally bolted down. You can see the marks that the lockwasher left on the regulator tab. Too bad so many parts are missing.
Loved this video, brings back memories... 😄. I remember the keyboard, feeling linke 'dead flesh' to the touch.. I actually owned one of the very first issue 1 spectrums, It was a 16 kb version, which I sold to get a 48 kb Spectrum +... Wish I didn't do that, they're collector's items nowadays......
It could take a beating. I've slammed my hand into mine quite a few times, when dying in games. I wish I still had mine, but curious as I was, once I move to newer computers, I took it apart.
Hmmm... I know this is from 2013, but I'm just watching it... I guess the main reason they did have to use solder mask on the bottom is because everything was wave soldered. You wouldn't want to wave-solder such a PCB without solder mask on... Solder bridges would have been a nightmare...
I've got one of these lying around somewhere. It should still be working as well. I think I got it in a box full of computer crap at a flea market. Had some Amiga's in it too.
+Lee Mindel All Spectrum 48K had a heatsink. That computer has been canibalized. ULA, heasink, a couple of logic chips, keyboard connectors and maybe some passive components are missing
+zxprojects I agree. All these came with a heatsink. I used to repair them and if whilst testing you forgot to replace the heatsink it wouldn't last 5 mins without the regulator going bang.
It's a 5V voltage regulator. Ideally you want to be supplying it with a little bit more than 5V. The original power supply was 9V but I think it was so weak and the spectrum was power hungry so that 9V was pulled down quite low the regulator/heatsink would still get quite hot as it just burns up the difference in voltage between power supply voltage and 5V as heat. This has apparently caused problems for many in the retro crowd as they will often use beefier power supplies as replacements. Because they can supply more current, the regulator has to burn the whole 4V drop through the heatsink. This extra heat often ends up damaging the spectrum. One option if you don't mind spending a bit of money is to swap out the regulator with a TSR 1-2450. This is a regulator with clever circuitry which means it regulates the 5V out without having to burn the difference as heat. This has the potential to extend the life of your spectrum even if you are using the original power supply. I guess one other option would be to drop the regulator altogether and use 5V directly from a regulated power supply like a PC PSU. This is a little more expensive than the TSR 1-2450 though.
I don't think any Spectrums had the heat sink removed, certainly that was the case for all rubber key Spectrum 16/48Ks Issues 1 to 6, Spectrum+s (which were the same motherboard in a bigger box) and Spectrum+ 128Ks. I believe it's true of the +2s and +3s too: the grey original +2 had the same type of linear PSU as the previous Spectrum versions so it had an on board regulator to convert the 12v to 14v input voltage to 5v for logic circuits and +/-12v for video and the tape deck. The +2A/B and +3 PSUs included voltage regulators to supply 5v, +12v and -12v to the computers but I believe they still have a heat sink inside! The heat sink is present to remove heat from the 2805 voltage regulator when reducing the input voltage from 12-14v to 5v (+12v at-5v are also generated for the lower 16K 4116 RAM chips), which is essentially a linear device. The only way I know of removing the heat sink is replacing the 2805 with a switch mode device: either a eBay power circuit or a Tracopower device
My cousin had one of them, That's why he ended up in IT. Have you looked into electric bike conversion parts for the C5. Decent Batterys and controllers??
Hi Dave the Heat sink is missing from the regulator it stretches across over the edge connector almost all the way to the RF Modulator, I had a 48k Speccy (still do) I was 10 years old ,and used the heat sink to hold a reset button I fitted, also using my soldering iron to melt a hole for the button. On Later Spectrums i fitted a 555 to make the Power LED flash I’m not sure why i did that, but i seemed to think it was cool at the time :-)
The Sinclair computers were made to be bought and used by people who wanted a working computer, but couldn't afford one. They cut every corner imaginable(whilst still having a fully functional computer) in order to make sure that their computer was at most half the price of their nearest competitor and it worked. Until the Raspberry Pi, the Spectrum was the biggest selling British computer of all time. When put next to a C64 it looked like absolute shite in build and output, but sold on the fact it cost about 1/3 of the price and kids could play video games on it.
Hilarious. I have a working ZX81 at home (with 32k memory expansion). Fought hard to get it as an assemby kit at the age of 12. Still remember the days. I learned BASIC and Assembler (thanks, Rodney Zaks) on that thing. Thinking about reactivating it :-)
A real piece of computing history back from the day when you could acttually learn how to program on it. Happy Days. Never seen it without any clothes on.
I don't know if you will reply but I was wondering whether you ever received a working ZX Spectrum? I'm a Spectrum collector and have a number that I am (slowly) repairing. Once I've got them working I should have a spare one to send you, probably an Issue 2 so colour balance may be a bit dodgy, but I may have a spare Issue 4.
Don't sell yourself short, Dave. You are certainly a celebrity to all us geeks who watch your show.
Absolutely. XD. Anyway, if you've got 100,000 subscribers, you're not exactly an unknown are you? ... Anyone notice the references on the Ben Heck show recently by the way? Quite amusing really...
The bottom side has solder mask because it needed to go through wave soldering. There is really no need for top side solder mask, but yes it does look a lot better with it.
Memories of my childhood have come flooding back (along with memories of waiting several minutes for games to load and dreading the "R tape loading error"!)
I was sending emails with my spectrum back in1983. How? Well with the aid of cb radio, mic and ear connected up to spectrum ear and mic at each end ! My group of friends were "connected". We also sent games to each other to load. A couple of lads were intercepting our data and. Messages so I had to devise a basic encryption program ! The spectrum taught a lot of kids SO much about electronics and programming. A lost art amongst children ( and adults ) these days who seem to be just phone morons now !..
Nick Clark That's awesome, didn't know that was even possible
Nick Clark That's very true man. I was able to write full games for myself and hack my way into purchased ones back when i was a kid witha 48k spectrum, then later a 128k one. I moved onto an 'Amiga' in the early nineties and could do a few things with it, then the whole console era began and until I grew up a bit more and started looking at retro stuff on TH-cam and remembered I actually used to be able to do stuff like that.
Kids are definitely missing out on some stuff nowadays, but hey - progress! lol
Nick Clark I spend most of my time in school being completely brain AFK because it takes these morons ages to understand basic things, and I really can't be bother listening to exactly the same shit lesson after lesson, why the fuck can't i just stay home until we start a new topic.
Nick Clark programming should be included in school. ( id pay more attention if they did)
Graydon Treude Pay attention anyway man, it's got to be worth it!
If you want to see the full story/drama of how Sir Clive almost by accident ended up in the computer industry as the main player, watch "Micro Men" a BBC documentary-drama which tells the story of his rise and fall.
There's a funny scene on it, which shows how obsessive and hands-on Sinclair was with every aspect of his product development and design...one of his engineers brings 3 keyboards to his desk for the new XZ Spectrum and sets them out in line, one a proper tactile resistance keyboard, one another version of the ZX80/81 flat, and the rubber keys..he tried them all and tapped the rubber one signaling his choice.
The spectrum was initially the fastest and biggest selling home computer in the UK (and even in some overseas markets, in the US even it was licensed as Timex Spectrum but didn't make as much impact there), and it came down to 2 factors unrelated to the machine itself really or its capability (there were faaar better and more powerful machines, like the Acorn, Commodore, and BBC Micro). The Spectrum was a) very cheap and attractively priced b) first to market as a "games ready" computer with colour graphics and sound c) but the real clincher was, Sinclair had already established his name in the home computer market and so there were hundreds, if not thousands of programmers writing games for the ZX81 which soon began writing for the Spectrum. Pretty soon you had 1,000s upon 1,000s of games for the Spectrum and people exchanging games on cassette tapes lol. So having a Spectrum was a must-have, if you wanted the best games and/or access to good games free off your mates. You only had to walk into a shop that sold home computers and you could see row after row of Spectrum games, and just 1 bottom shelf for "other" computers.
It's ironic that Sir Clive was totally against going into the computer industry AT ALL and he was very dismissive of computers (still is today!) and even dismissive of the games industry..he just failed to appreciate the value in software or the huge business potential which would eventually overshadow the hardware industry (something Microsoft DID realise).
Now we have come full circle...Sir Clive has launched (indirectly, someone else is doing it, but he has lent his name and has a stake in the venture) to a crowfunded product called "Vega" which is like a modernised retro speccy..the original design proposal (done on a 3D printer looked very much like an original ZX Spectrum except it has only 4 rubber buttons and a joystick lol. They've now done a much more modern looking design.
The Vega is claimed to have 14,000 speccy games (and more you can download freely) it plugs into modern TV's (oddly via composite tho, not HDMI, probably due to the limitations of spectrum graphics in those games) and is like a games console and is retailing for £100.
Pity there are so many emulators available that do run on hardware with support for HDMI. I'm not sure the Vega is going to have any staying power really. Load up an emulator on my raspberry pi zero plus a couple of quids worth of adapters from eBay and it's sorted for a lot less money.
Pity there are so many emulators available that do run on hardware with support for HDMI. I'm not sure the Vega is going to have any staying power really. Load up an emulator on my raspberry pi zero plus a couple of quids worth of adapters from eBay and it's sorted for a lot less money.
I had a Commodore, but my best friend had a Spectrum back in the day. He also had ZX81, the first computer on our street! Loved _all_ of these old comps. Another friend had an Amstrad with a tape deck built in. It wasn't like everyone wanted the same thing back then and we were actually happier to each have different computers. Great days! Have you seen the recent BBC film based on Sinclair those early days, called Micro Men? Well worth a look.
When i was 7 year old I got ZX81. 5 years later I got Zx Spectrum. This computers, retyping listings and learning basic decieded my profession. Becouse this I choised technical education, digital electronic, and now 30 year later of my first Zx81 I am professional programmer. Sir Sinclaire was changed the World!
Love this tear-down, though the vid under-estimates the impact of the Spectrum in the UK. It was huge (rather than quite popular) and for its day it did a lot more than the bare basics. I still have and use one. :) Love it! and thanks for this vid.
Went thru the keyboard membrame in a couple of years typing. Learned digital electronics with it, built shadow ROM, DAC/ADC, a PWM on the NMI to slow down hard to play games and even built an interface for a XT-PC keyboard using an eprom to map key codes. Learned Z80 assembly on it as well. Also had the joystick interface, and Interface 1 for the printer and micro-drives. Build my first adventure game with those... Ah, it was a good friend.
Nice one Dave. I LOVE vintage computers from the 70's and 80's, and from what I've seen in the comments on past videos I'm not the only one! Any teardowns of classic computers are always much appreciated, but if I ever see the words 'Acorn BBC Micro' in the title of an EEVblog video I will literally wet myself with joy :)
Get to see a speccy. It's just sooo iconic of the 80's and brings back memories. I remember seeing them on sale new in WHSmiths for £49.99 the year they came out. It didn't seem like a lot of money for a computer which could play 1,000s of games and had colour graphics..yet to a 10 year old, it may as well have been £5,000.
My brother got one for xmas some years after they came out, and I was well miffed!! I sooo badly wanted one and was sure we'd both get one. My mother didn't realise you could actually program them and thought it was purely for playing games on, and my brother wouldn't let me it to play games even, let alone program on it! I ended up with a Tandy TRS-80 (a horrible computer, but also running BASIC). Years and years later, I bought a speccy for sentimental value and it's in my vintage computer collection now which has grown considerably large!
I think you missed a £100 off that price.
The original price of the ZX Spectrum in 1982 was £125 for the 16K RAM version and £175 for the 48K version. Prices were reduced to £99 and £129 within a year as competitors started reducing prices and producing cheaper models. I believe it was the 1K ZX81 that sold for £49.95 in kit form or £69.95 fully assembled (only £20 more!), back in March 1981. Now kits are rare and cost £300 - which is probably about the same as £50 in today's money! (Prices corrected.)
derekjc777
Thanks for correcting me, it was indeed the ZX81 I saw for £49.99 and the Speccy was £99.99! I remember both in WHSmiths. I now have both in my retro computer collection!
I've also corrected the prices: the Spectrum was actually £125 and £175 when first released and the ZX81 assembled was less than £70!
derekjc777
Now you're coming across as super-geek! Even I'm not that obsessive ;-P
The reason the solder mask is wrinkled is not that it was applied over wrinkled solder, but rather that it was applied over solder, and then subjected to wave soldering to solder all the through hole components. The solder itself would have been a tin lead plated layer that was used as an initial etch mask, and then IR, or hot oil reflowed. The reason that there is no solder mask at the the top is that there was no soldering done at the top, so it was deemed as not necessary. A cost saving measure, but one that leaves the upper surface of the board at risk from shorts caused by any loose conductive particulate matter.
I remember my own spectrum with some fondness, I applied the 128 upgrade which added not only more memory, but also a grown up sized keyboard, and an all important reset switch. My first attempt at soldering :)
Nice to see one again. I owned one back in it early 80's and used to repair them as part of my job. Good machine for the era.
The regulator isn't floating - there is a missing piece of bent aluminium sheet heatsink.
yep correct, and these computers used to get stupidly hot then start to cause artifacts on the screen, used to put mine in the fridge to cool down lol
This episode has lots of errors in it. Expansion not cart slot, RF not composite, 8/16 colors not 6 (half a dozen) and more...
I mean, it is floating *now*
This is the machine where I first learned the BASIC programming language when I was about 11 or 12. We had a few of those keyboard membranes and those cassette tape connectors at the back were always dodgy - kept having to weigh down the connectors so that they would bend at an angle to make contact inside the connector! Memories! Oh yes, and Daley Thompson's super test used to take 12 minutes to load then "R TAPE LOADING ERROR" at the end hehe (oh, that was on the 128k version not the rubber keyed 48k)
A very detailed book about the Spectrum is 'The ZX Spectrum ULA: How To Design A Microcomputer' by Chris Smith.
Love it. I have a working Spectrum and Commodore 64 at home - learnt to program on them and have been in IT all my life
If this is the Rich Lowe I'm thinking of, do you still have any of that old adventure game we were writing? Also, I still have that Assembler I swapped for The Quill with you.
I did like the rubber keyboard along with some other Speccy-using friends of mine. It was quite fast to type basic when you memorized the keyword placings. The only bad part was the membrane key contacts. After a few years of hard use some keys would go bad. Somehow the white contact material would corrode on one or two of the most used keys (at least one friend had the same problem). I remember I did a DIY repair on the symbol shift key in my Speccy by inserting a copper wire in place of the top membrane and surprisingly it worked for a long time. Then I actually made a full replacement with a PCB with soldered separate momentary switches for each key, and the rubber mat would go on top of that. I still have it.
The keyboard and membrane look in good nick, the socket on the modulator is for a PAL TV into which the composite video signal goes into the side of which can be routed directly to the socket to convert it to CV with a bit of simple DIY soldering. The edge connector is not for cartridges, but is a universal type interface for printers, joystick controllers, I/O boards, games cartridge interface, the controversial long awaited Sinclair microdrives, RS232, floppy drives etc. By the way, have you heard of Timmy Mallet?
RE the voltage regulator - there would have been a large aluminium heatsink bolted to it originally, looks like you weren't the first person to take this thing to bits!
I converted mine to the Spectrum+ keyboard which was ok but you still couldn't type quickly. It was a bit like go faster stripes on slow car.
Very versatile and far exceeded the limitiations it was originally designed for. There was a lot you could squeeze out of that 48k of memory !
This bring memories
I remember breaking traces in one of keyboard flat connections cables while investigating what's in my computer - I fixed it by by taping litlle pieces of wire over the crack - but I spended week in fear of my computer will not work again - I was something like age 12 with no equipment, experience or money for new membrane (new membrane cost was like 25% of my moms income :D)
You can *still* get brand new membranes LOL!!! Still expensive though...
I had to cut them shorter and shorter. What a thrill
The voltage regulator definitely had a heatsink originally. The Issue 1 ran very hot and it was increased in size for later versions. It was through-hole wave soldered, so no need for resist on the top layer, typical Clive! No need for a socketed ROM, by Issue 3 it wasn't going to change.
But they always socketed the ULA. I guess they knew they were the Achilles heel of their products.
Expensive boards would be lead coated and pulled up out of solder and be blasted by hot air jets to keep holes clear and solder level. The machine was called soler leveler
The regulator had a heatsink screwed to it, it wouldn't last 2 minutes without it! The shape of the heatsink varied depending on the issue. These computers were AWESOME. I spend most of my early teenage life literally glued to my one.
Fun fact: Richard Altwasser and one of his Sinclair colleagues went on to design the Jupiter Ace, which was one of only a handful of microcomputers to use Forth as its default programming language. The Ace was heavily influenced by the ZX81 with its form factor and overall design. Ofc the Ace was a commercial flop, but as you pointed out, Richard went to work for Amstrad in 1986.
If you've still got that Speccy lying around, you should try rebuilding it. There are now reproduction ULAs available, and the other missing components are all off-the-shelf items. Heck, it'd make a fun school holiday project for the kids.
Hello!
Dave, I'm your fan and I admire the work you do. I learned a lot from your videos and had a ton of fun along the way! Just keep up the good work.
I just wanted to correct and add to a few statements you made, Dave, since I'm a big fan of Sir Clive Sinclair and ZX Spectrum too.
First thing: The 7805 DC regulator was mounted on a large aluminum sheet heat sink, because the current drain was over 1A. So, the the sink was missing in that one.
Second one: The membrane keyboard. You were right when You said that it was probably unreliable and it was. But in the later issues of Spectrums, issue 4 and 5, there was a much better membrane type keyboard that could last a life time, i guess. It was much more transparent, almost like glass.
Third one: The TV modulator was a RF video-only modulator. But it can be a composite out by just cutting a few wires and adding one for composite bypass to the RCA connector. Or, to keep it retro, with a few touches of a soldering iron and a few passive parts it could output sound through RF modulator too, since the LM1889N has a sound input too.
7805 was actually screwed to a big heat sink which is missing in this one.
My personal teardown Christmas Present :) A big TY from Scotland (where a lot of these were made by Timex in Dundee)! A mere 30 years to the almost day ('the day' actually being December 25th 1983) since I first got my hands on a ZX Spectrum and a tape recorder for the software. I used a 5 inch black and white tv initially, then I borrowed a 12 inch Sony B&W TV from the kitchen. On rare occasions (and 'cos my mum was as interested in computers as I was - Hungry Horace was my mums favorite) I got to plug it into the family 21 inch Sony Trinitron. I remember my mum reading out programs from the magazines and I typed them in. In 1984 I got a 14 inch colour TV for my bedroom and a copy of Elite. Several years later I emerged.... :D Currently working in IT. But the memories...:)
The 7805 regulator was screwed to the board by Sinclair, and had a heatsink (which was very necessary along with some thermal paste). Some of the boards did have solder mask both sides (the Issue 4S board, fabricated by Samsung for example). The issue 1 board is the most interesting - it has hand drawn traces! Issue 1 machines are quite valuable and hard to get hold of though. The rubber key mat was made in a condom factory (I've met Rick Dickinson, who did the industrial design for Sinclair back in the day).
If you want to know more about the ULA, get Chris Smith's ULA book. There's some interesting little anecdotes too - the ULA was designed in only 6 weeks by Richard Altwasser. A Ferranti engineer made an error when making up the masks for the metallisation layer and the upper and lower clocks weren't connected, but a spec of dust (in a clean room!) landed in just the right place to fix the problem on just one single die, so they could use this to verify that the ULA was correct. (I believe Chris also subscribes to this TH-cam channel so give him a shout out :-)) See www dot zxdesign dot info/book (damn TH-cam not taking URLs)
Note the BASIC keywords on the key tops. They reflect the ingenious internal workings of spectrum basic. Every basic keyword was represented by one byte code from the unused upper half of the ASCII character set. Displaying the keyword was taken care of by the character generator if I remember right. This greatly simplified the interpreter and made program storage very compact.
I tell you what Dave. Comments on retro computers bring out the flame wars. I loved my Spectrums (all 6 of 'em) and took a joystick apart to make a five zone sensor for my bedroom as a kid. The screen had a very crude graphical representation of my room and bits would start flashing if any of the contacts had been made.
Ahh, memories!
Without computers I wouldn't have gotten into electronics.
My first computer, why ended up a programmer
My TI-85 calculator was when I got interested in coding. It had basic on it. It also had Z80 assembly, but you had to hack the thing to unlock that capability.
Fantastic. You can tell it's a later version. The first issue didn't have the 4.43MHz crystal. Instead, it used a simple tuned circuit with a trim capacitor. There was a hole in the bottom of the casing so you could put a screw driver in there and adjust it (or I drilled a hole - I can't remember!) As the unit warmed up, the frequency would drift and you'd see the chroma "shimmering" on the screen. I really f**ked up one day (I was just a lad of 16) and damaged it. I found a local repair shop who sent it off to Sinclair and they sent me a replacement for free!
Modified my Spectrums back in the day with 27128 eproms to replace the ROM and via a home built eprom programmer / serial-parallel interface. I didn't mind the rubber keys.
On my speccy i have a 27512 eprom with two toggle switches.
To choose from four different rom versions.
Fantastic memories, a great step up from the ZX81!. I had both, and it was my intro into the world of IT. I have made a Lot of money over my lfe thanks to starting out on these affordable early computers.
It's also amazing to see how far computers have come in 30 years. Wonder what the next 30 years will bring...
I loved my speccy(s) - it's the machine that began my career. Spent so much time at that rubber keyboard learning BASIC, then assembler as a kid. I've recently read "The ZX Spectrum ULA: How to design a microcomputer" - which dissects every part of it. The thought that went into the design by Altwasser was fascinating (for me anyway). I now know why the video memory seemed so weird, and was horrible to work with as a programmer, but was designed specifically to be efficient to read by the ULA. So yeah, I'd recommend it.
if didn't class yourself as a celebrity when you made this video, you bloody well are now mate! (2017) Thanks for your enthusiastic and totally compelling videos.
The tin plating was flat when the solder mask was applied. The wrinkling occurs when the board is wave-soldered after the components are inserted.
Margaret Thatcher took one of these to Japan, as an example of the UK's technological superiority. Oh the irony.
When I was around 9 or 10 I remember being on holiday in the uk at my nans and I bought a 128 with tape drive and around 50 original games for 5 quid at the carboot !! my nan had to drag me out in to the sunshine that summer ! loved it to bits.
Build something like a raspberry pi into it. :D
I am very familiar with these. RF output, often on UHF 36, but some territories used VHF. At least 9 issues of PCB - 1, 2, 3, 3B, 4A, 4B, 4S, 5 and 6A. It's not high DRAMs it's missing but two 74LS157 that interface the low memory. The 7805 should have a heatsink, attached with a bolt. The Issue 3 was the first with no adjustment for the colour encoder, but also "corrected" the poor heatsink position of earlier versions - that degraded the keyboard membrane on issues 1 and 2. Issue 4S had solder mask on top of the board, but issue 6A didn't. I've never seen a 4A or 4B, or for that matter a 5 (known to be UK only). The Spectrum+ had a "plastic keys over a rubber layer" keyboard - it was rattly! 4116s failing often took out the ZTX213 and 650 in the power section. If the transistors failed they sometimes took out the 4116s too. Most big fault conditions on these were caused by failures of that kind, often induced by interference with the edge connector when the power was connected.
My first computer was a ZX Spectrum+ that my parents bought me and my brother around 1983/4 and 30 years on i'm still into and working with computers (Gaming PCs now). Loved the simplicity, we also had the 'metal' printer and handheld TV too. In fact I did my lines in school on the printer and was let off for being creative!! lol
We had the Timex Sinclair in the US and Canada, we never got the Spectrum. It was a 4 or 16K? (not sure), monochrome with a flat membrane keyboard. The cool thing was you could order it as a kit and build it yourself. A lost art.
Timex Sinclair TS1000 was a 2K ZX81 machine. The States also had a Timex Sinclair TS1500: a 16K ZX81 in a silver Spectrum case with a grey rubber keyboard: I know because I bought one recently and got it repatriated to Blighty! Sinclair Spectrum (Timex Sinclair TS2048) was never released due to low sales of the black & white, silent TS1500, however a version with a built-in microdrive - the TS2068 - was sold but didn't take off due to the dominance of Commodore.
Yes memories. The Sinclair Spectrum was fantastic.
That linear regulator wouldn't normally float like that, there was a giant aluminium heatsink it would normally be screwed into.
1983 - I was 14 and found a 16k ZX Spectrum at Chandler's on the Sunshine Coast. Paid $299 for it from memory!
That's overpriced for 1983, I believe they were about 99 pounds in the UK by then. Factoring in the approx. 1 to 2 exchange rate, that's the good old 50% Aussie markup on imported electronic goods, a tradition that continues to this day.
Anybody else here hand build a ZX80 kit? That expansion port on the back of the Spectrum was a real nightmare. Put the RAM expansion pack on there and you'd be lucky to get through entering a program without it freezing. When from this to a QL then gave up after that debacle and spent quality time with the BBC Micro model B. Good times. Up till 4AM coding. The rush was huge.
Yes, built the ZX80, bought a ZX81, ended up with 7 ZX Spectrums before jumping ship and going 6502 with the BBC Micro. And yes, spent the rest of my life as a software engineer working on CP/M, DRDOS etc! What a wasted life!
To all the North Americans... The Sinclair ZX81 was rebadged in the US as the Timex/Sinclair 1000 (TS1000) and there was also a TS 1500 that looked a lot like a spectrum, but was a ZX81 with the Ram expansion built in. The Spectrum was actually a generation on from that. The TS 2068 was the model that is based on its design, though Timex messed with the base design of the hardware and the ROMs making it software incompatible.
The Spectrum+ was released about 1984 and had a better plastic keyboard, the Spectrum 128 was a model with a new "128KB" mode and better sound chip (same as TS2068, incompatible with the TS models design though), and after Amstrad bought out Sinclair the +2 (built in cassette) and +3 (3" floppy) were released.
Spectrum out sold everything in the UK at the time.
The 7805 wouldnt normally be floating, there is normally a small aliminium heatsink that would fit between the pcb and device.
That 7805 would have been screwed to the board with a heatsink behind it. They weren't floating like that.
Thought I saw it and went back to check... Nobody else seemed to catch it and certainly don't see any mention in the comments... During the closeups at about 6:41 looks like one of the pads has a solder crack on it... Bottom left, last pin on the trace from the bottom... Just south west of the pin directly west connected to the ground mask of the hole in the board.
Yeh fantastic units in the day, used to repair these at my computer shop, still have lots of parts for these and the original service manuals in the loft, may even have a few ULA's left.......
It sure brings memories, I had a PC called "Juku" with a floppy disk games in ANSI code that had also this unmasked PCB. If I remember correctly it was made in eastern part of Estonia, Jõhvi or Narva, I don't remember exactly, but it was a dumpster salvage. Oh how I hate it, any time it showed "-" in a row of 8 +-ses, it simply didn't load a disk correctly and crashed. But it had far more DIL packaged chips than this, but the main processor was also a DIL-40 as here. I don't have that any longer, as an active electronics kiddie, I took it apart long time ago, lost all the components during next years of failed attempts to build something and it's gone into memories now.
The rubber keyboard man, that's one of the unique selling points :) I seem to remember my power connection on it getting dodgy over time, could be wrong though, long time ago and I don't have it anymore.
I distinctly remember the power connection on one of the in-store demo ZXs (not sure if ZX81 or ZX Spectrum) being so dodgy it rebooted at the slightest push, making me decide not to buy one anyway. Ended up with a more expensive home computer which was unfortunately dead ended by the company before gaining any traction. Learned a lot from working with it and understanding the silly compromises that ruined its performance though.
Yeah that's pretty much what happened to to mine. I remember I used to stick tops off of pens and such to try and keep it wedged in place. Slightest touch would cut it off. Got years of great gaming out of it though so can't complain too much.
My dad bought me one in 1984! I have two now, if I manage to find them I'll send you a working one.
My first pc was the ZX Spectrum +2A, ah the 30 min waiting for the tape drive to load a game.I still have my Amiga 1200 still works.
Last year I built a variant of a russian clone of the ZX Spectrum (Pentagon 128) - lovely machine. It's basically a spectrum completely made in 74-logic with a disc drive and sound chip.
Was going to bed, but saw this in my subs, and said FUCK SLEEP!!
Not much of a fan then if your stayin up to watch how great the competition was :P
In the UK, there was one of those Spectrums in almost every direction that I could look.
That 7805 was not normally like that! It was definitely attached to some kind of heat sink in the two of these that I had.
I had the zx81. Didn't even know what a computer was but wanted one for some reason.
It was one of it's kind, even the microdrives, an endless tape drive, that was sold for this computer.
I call those buttons:glob of snot.
The regulator would have had an aluminium heatsink that ran the width of the back. I dimly recall it being about 3cm wide, maybe 2mm thick and was formed such that it used the raised space in the cover and ran all the way over to above the UHF modulator.
It was also very popular here in Portugal, most kids that had a computer, had a ZX Spectrum. my 48k died long ago, but i still have the 128k (that comes with the casette loader).
The crinkly solder mask is caused by the flow solder process, when the board is virgin from the supplier it is flat and smooth. I f you look you can see where it flowed from i.e.which component pad.
There was a long heat sink attached to the 7805, it rose up and along the top of the Issue 3.... it's been pinched at some point in the past from yours.
Dave... it seems the Regulator was originally bolted down. You can see the marks that the lockwasher left on the regulator tab. Too bad so many parts are missing.
Awesome! I would've loved to see it repaired...
The rubber keys were better than the version we had with the flat keyboard. It was a nightmare to type on.
Now you tell me! ;) There is a company who do a replacement layer with micro switches that supposedly changes it considerable.
+eLJaybud *considerably
Heehee, I just watched your video of the C5 last night. :P
I got an old magazine from the 80's guiding you on how to build this think on your own.
Alan Sugar's Amstrad CPC464 was light years ahead of the Spectrum!...and in a much nicer package too!
Loved this video, brings back memories... 😄. I remember the keyboard, feeling linke 'dead flesh' to the touch.. I actually owned one of the very first issue 1 spectrums, It was a 16 kb version, which I sold to get a 48 kb Spectrum +... Wish I didn't do that, they're collector's items nowadays......
Trust me, the rubber keyboards are better than the one we had that had the flat keyboard.
It could take a beating. I've slammed my hand into mine quite a few times, when dying in games. I wish I still had mine, but curious as I was, once I move to newer computers, I took it apart.
wow that was a fast teardown
My 2 are still working, the keyboard is dead flesh but I enjoy using it and one of mine really does have composite out, the previous owner modded it!
My first puter was a ZX81 with a whole 1 k of ram though i upgraded it to 16K
Hmmm... I know this is from 2013, but I'm just watching it... I guess the main reason they did have to use solder mask on the bottom is because everything was wave soldered. You wouldn't want to wave-solder such a PCB without solder mask on... Solder bridges would have been a nightmare...
I've got one of these lying around somewhere. It should still be working as well. I think I got it in a box full of computer crap at a flea market. Had some Amiga's in it too.
Sinclair Spectrum!!! good old memories!
It came with quite a bit more than what you got it with! it most certainly did have a heatsink on the voltage regulator!
Lee Mindel I prefer the issue 3 heatsink, although I don't like how loose it is compared to the issue 2
+Lee Mindel All Spectrum 48K had a heatsink. That computer has been canibalized. ULA, heasink, a couple of logic chips, keyboard connectors and maybe some passive components are missing
+zxprojects I agree. All these came with a heatsink. I used to repair them and if whilst testing you forgot to replace the heatsink it wouldn't last 5 mins without the regulator going bang.
It's a 5V voltage regulator. Ideally you want to be supplying it with a little bit more than 5V. The original power supply was 9V but I think it was so weak and the spectrum was power hungry so that 9V was pulled down quite low the regulator/heatsink would still get quite hot as it just burns up the difference in voltage between power supply voltage and 5V as heat.
This has apparently caused problems for many in the retro crowd as they will often use beefier power supplies as replacements. Because they can supply more current, the regulator has to burn the whole 4V drop through the heatsink. This extra heat often ends up damaging the spectrum.
One option if you don't mind spending a bit of money is to swap out the regulator with a TSR 1-2450. This is a regulator with clever circuitry which means it regulates the 5V out without having to burn the difference as heat. This has the potential to extend the life of your spectrum even if you are using the original power supply.
I guess one other option would be to drop the regulator altogether and use 5V directly from a regulated power supply like a PC PSU. This is a little more expensive than the TSR 1-2450 though.
I don't think any Spectrums had the heat sink removed, certainly that was the case for all rubber key Spectrum 16/48Ks Issues 1 to 6, Spectrum+s (which were the same motherboard in a bigger box) and Spectrum+ 128Ks. I believe it's true of the +2s and +3s too: the grey original +2 had the same type of linear PSU as the previous Spectrum versions so it had an on board regulator to convert the 12v to 14v input voltage to 5v for logic circuits and +/-12v for video and the tape deck. The +2A/B and +3 PSUs included voltage regulators to supply 5v, +12v and -12v to the computers but I believe they still have a heat sink inside!
The heat sink is present to remove heat from the 2805 voltage regulator when reducing the input voltage from 12-14v to 5v (+12v at-5v are also generated for the lower 16K 4116 RAM chips), which is essentially a linear device. The only way I know of removing the heat sink is replacing the 2805 with a switch mode device: either a eBay power circuit or a Tracopower device
4:45 ... anyone who has seen the inside of a Spectrum would know that the large metal heatsink that attaches to said transistor is missing ....
There was no need to ever upgrade the firmware on the rom chip because it worked perfectly well in the first instance.
I also remember the wrinkly bit on the board was in there even during the time of when they were all the rage.
My cousin had one of them, That's why he ended up in IT.
Have you looked into electric bike conversion parts for the C5. Decent Batterys and controllers??
I always kind of wondered about the crinkly parts on older electronics.
Hi Dave the Heat sink is missing from the regulator it stretches across over the edge connector almost all the way to the RF Modulator, I had a 48k Speccy (still do) I was 10 years old ,and used the heat sink to hold a reset button I fitted, also using my soldering iron to melt a hole for the button.
On Later Spectrums i fitted a 555 to make the Power LED flash
I’m not sure why i did that, but i seemed to think it was cool at the time :-)
The Sinclair computers were made to be bought and used by people who wanted a working computer, but couldn't afford one. They cut every corner imaginable(whilst still having a fully functional computer) in order to make sure that their computer was at most half the price of their nearest competitor and it worked. Until the Raspberry Pi, the Spectrum was the biggest selling British computer of all time.
When put next to a C64 it looked like absolute shite in build and output, but sold on the fact it cost about 1/3 of the price and kids could play video games on it.
Lovely stuff
This was posted on my Birthday!
Hilarious. I have a working ZX81 at home (with 32k memory expansion). Fought hard to get it as an assemby kit at the age of 12. Still remember the days. I learned BASIC and Assembler (thanks, Rodney Zaks) on that thing. Thinking about reactivating it :-)
A real piece of computing history back from the day when you could acttually learn how to program on it. Happy Days. Never seen it without any clothes on.
The ULA is the Ucommited Logic Array.
The wrinkly underside traces was normal all the original Spectrum 48ks had it.
I don't know if you will reply but I was wondering whether you ever received a working ZX Spectrum? I'm a Spectrum collector and have a number that I am (slowly) repairing. Once I've got them working I should have a spare one to send you, probably an Issue 2 so colour balance may be a bit dodgy, but I may have a spare Issue 4.
Decent little computer for its time.