I respected you before I saw this video but after seeing that you've taught your daughter to solder and you play MInecraft with her, I think you're freaking awesome.
It is easy to see that Noel is a fantastic father. Additionally, I think that Noel got the better of the deal in the "You solder the IC sockets and I will play Minecraft with you". Noel I am so impressed with your teaching your daughter how to solder. You are something else! A high-quality human being. God bless you sir. Fred
It is so very authentic and traditional to let children solder some of the part of the Amstrad boards. Fathers and Mothers in Hong Kong all put their children to work, although mine craft was considered inhuman.
Love that you got your daughter doing some hands on learning. Kids need more early introduction to skilled trades. Even if they never pursue it as a career, they will always have the knowledge.
in the 80's I had a summer job while at Uni fixing avionics boards for GEC, and one way we found shorts on PCB's was to connect a current limited supply to the traces in question, and use an accurate voltmeter to measure the voltage at various points. As you get closer to the short the voltage gets lower, as you get further away it goes up. If you use a low enough voltage you can often avoid activating semiconductor junctions and thus cut out that source of errors - I traced one fault using a quarter of a volt and a (very expensive!) accurate voltmeter. I suspect that nowadays a relatively cheap multimeter with decent probes would probably be stable enough to work. The very low voltage power supply might be more of a problem!
I've seen people use milli ohm meters to do similar, basically check the resistance at each location and then check/rework the area with the lowest reading.
@Rob Taylor, Hats off to you with the board! I can't believe you copied the actual traces, sooooooo much patience. I contemplated doing the same thing for a CoCo 2 and CoCo 3 board but I ended up hand routing just the power and a few other lines and then used an auto router.... You've inspired me and I might go back and copy the traces.
I’d love to see a post mortem on that transistor. Why you thought it was equivalent, how it wasn’t, and hopefully a new modern equivalent. Great video!
The ZTX312 is a high speed switching transistor, with on/off/storage delays barely over 10ns. By contrast, the BC547 datasheet doesn't even hint at its switching speeds (none that I could find anyway), so it's very likely very slow, and not suitable for MHz operation.
The circuit looks strange. There is no base resistor. Bipolar transistors must have a current limit for the base current. I bet a base resistor around 1k to 10k would have totally fixed the problem. The BC547 has a gain bandwidth of 300, which means it can do 1 MHz at a gain of 300 or 300 MHz at unity gain, or anything in between. It is plenty fast enough.
An equivalent would be 2N2369 to the ZTX312 as mentioned in datasheet for the original transistor. The 2N2369 is still available. The other equivalent being the BSV25 by the same original manufacturer is not.
Looking at the circuit diagram rather than which transistor is most similar to a ZTX312L, a 2N7000 MOSFET would fit perfectly and I would expect it to result in a proper clock signal.
This took me back to 1984 when the CPC464 was my first computer. I was still using it and my second machine the CPC6128 on release, right up to 1995. It was here I bought my third computer a Packard Bell with Windows 95. I had a great collection of the cassette tape games, along with the not so Floppy, floppy discettes. The monitor to tv converter and digital clock, Primary and secondary disc drives, the Romantic Robot from STS and disc. I even had the Eprom boards for blowing my own chips. Though the best mod I ever did on my CPC6128 was to fit the 464 chip, piggy backing the 6128 chip with one pin bent outward from each chip. Then with a toggle switch wired to those pins that when thrown it connected to the pin hole on the PCB. This in turn when the switch was thrown one way or the other before start up, would then boot the Amstrad into either CPC464 or CPC 6128 mode. That gave me two Amstrads for the price of one. I can't remember now about the mod, but I am sure if you don't know it, someone out there will know how it was done. It is a neat little mod to do if you are interested in both Amstrad models. Going back to the cassette tapes, I had all the Amstrad Action magazines and cover tapes. After purchasing the Romantic Robot from STS, I ran the game Chips Challenge, pressed the Button on the RR and up popped the code. During the game each level had a 4 character code to by pass levels you all ready played and continued from the higher level if the correct code was inputted. After having about 12 or so levels completed, I looked for the codes in the lines of the game programme code lines. These where broken up into four blocks and each block equalled a letter of the code as 1st, 2nd, 3rd and 4th if spread sheeted into columns. I found them all and a few bonus levels too and wrote to Amstrag Action with the results and had them printed in the next available issue. For the life of me I can't remember the issue number, but I am sure there is a copy of the magazine out there somewhere. Sorry for the long comment (excuse my grammer etc), but I thought you and the other readers would be interested in reading my experience with my Amstrad CPC machines etc.
I cut traces normally with a sharp blade knife or scalpel, cutting at a slight inward angle from both sides, essentially cutting out a shallow V underneath the trace.
I came to comment just that, usually I do it a bit over-wide and remove the copper in the center, to be REAL sure it's cut and won't bite me in the future. Ask me why ... :P
Two cuts and then the island of copper in between is thermally isolated from the rest of the track, so a soldering iron can easily soften the glue enough that the piece of copper just slides off. Much easier and cleaner than trying to scrape enough away mechanically!
A good way to remove unwanted traces is to use an X-Acto knife. The X-Acto knife works really well and looks really clean when you’re done. This looks like a fun project but finding the shorts on your own would’ve just driven you nuts, glad you found the shorts and were able to take care of them.
Just a couple of mistakes and an omission on a big board he hasn't yet tested? That's actually very impressive. Rob did a terrific job with that and kudos to you for building and testing it. Now Rob can get a perfect working replica board out there thanks to you.
As a woman in electronics tech I just want to tell you how much I love that you involve your daughter in your projects and teach her the trade. Thank you for your wonderful content and your great parenting. :)
Maybe I'm weird... I like to solder IC sockets!. When you get a VCC - ground short it's time to get out the €4,000,000,000 precision resistance meter... No, I don't have one either. The picture-in-picture of the 'scope probe on the schematic is excellent... liked that a lot.
This is so encouraging to see. I dusted off my CPC664 this evening, cleaned it up and inspected it... I won't be risking plugging in the monitor until it's had a thorough recapping so I can't power it up... I need to sort out an alternative PSU and some kind of video lead in the meantime. I spent so many hours in front of it as a teenager and really loved the machine, I was involved in the fanzine scene running a small CPC fanzine for a period of time - we were featured once in Amstrad Action. I also have a dead CPC464 I picked up about 20 years ago which I know doesn't work but it's in great cosmetic condition and has the proper retro GT65 green screen monitor. Some of your diagnostics on this new board will surely help me to diagnose it and I'm really pleased it seems most components or alternatives can still be purchased (apart from the ULA obviously). I'll be certain to watch more of your vids and have subscribed -- thankyou for producing this content!
Excellent work. Rob is doing a great service, creating these beautiful boards. Getting a replacement board from Rob is my next step if I can't locate the broken trace or solder bridge on my C64.
I forgot to say this in my last post..... I've never used and Amstrad CPC but your video is so good that you've inspired me to one day build one. Thanks for this video!
@@NoelsRetroLab I will definitely build one. I owned a CPC464 back in late 80s. Do you know when the these board will be available? ...and any good source for the gate array? Thanks.
I LOVE these retro-forensics videos! And YES, using the original hardware is always the prefered way. Just like vintage cars, we don't put anything "modern" that will look out of place, unless we have to. That's the whole point, to keep it as close to the original as possible.
Problem with current fpga’s is that they are 3V3, so as well as the fpga, logic converter chips are also required. The low end Tang Nano and Lattice MachX02 can easily replicate the digital functions contained in the gate array chip for those 8-bit computers. So if I designed a replacement solution , it would be a small board containing a few chips to plug-in where the gate array chip goes.
That's sweet that your daughter helps you like that. My daughter helps me build guitar pedals that we sell but she's a teenager now so offering to play Minecraft wont cut it, they want cash. lol
The CPC464 was my first computer. My parents were toy retailers in the 80s with several big successful stores and good connections, and managed to get a fully functioning promotional unit towards the end of '83 - earlier than the official release date (it even had the full colour RGB screen, not the green screen or the TV module). It was supposed to be a demo model to go on display in their main store but it never made it there. They gave it to me as my birthday present that year and I've been glued to a computer ever since. 😂 Awesome to see that they can be built at home relatively easily now. I might have to give it a try!
Noel, the issues you experienced with the board you showed in this video were actually fairly common back in the early days of computing. It's why many "retail-ready" production computers and electronics have bodge and patch wires, resistors and capacitors soldered in post assembly. I have a do use a razor blade to keep cuts more precise, but can't fault the use of a flat-head screw driver. Love your channel! Cheers!
Really great job building and debugging this first revision board Noel! You have some seriously sharp troubleshooting skills sir!!! Thank you for sharing your voyage down "Amstrad Lane" with us Noel. Fred
Thank you for this video and for all your efforts. It makes me remember my beloved Amstrad CPC 6128. I also had the Sinclair ZX81 and Sinclair spectrum 48 ....the Vic 20...Commodore 64..Amiga......this was a fantastic era
Another great video from yourself and board from Rob. Definitely going to get one of these once it goes on sale. The 40007 version of the gate array always comes heatsinked from the factory in all the CPCs I've ever seen, so would likely be worth adding one to your board rather than risk another one dying prematurely.
This channel is a real inspiration for most of us. Your content, edition and explanations are on the best of TH-cam. Thanks, Noel, for these videos!!! Keep up the good work!!!
Just dropping a line to say a fair amount of this went over my head, but I couldn't stop watching. (The hardcore, old-tech-loving, nerd in me...) In fact. I'm halfway through my life and considering an engineering degree. The interesting things that happen when you figure out you are on the ASD spectrum super late in life, you stop giving ***ks about everyone else and what they think and go after what makes you happy. Watching these videos is among those things. :)
Glad to hear that. And I don't think that has anything to do with the ASD spectrum and all about just getting older since the same thing happens to me 😃
I am actually surprised that only 3 board errors were present from photo-copy/tracing the original board. At the same time, I'm also surprised that this was never tested, not even once, before shipping it. In my humble opinion that I greatly respect, the best replica of an Amstrad CPC (64K, 128K, with tape or with floppy) would be a modern redesign of the board, with as many quality of life features as possible, while still being "layout compatible" with original cases. I would not mind if it included a R-Pi-0 GPIO header to sandwich a Pi-0 on the board for WiFi, ROM-loading/dumping, etc., maybe even HDMI video and sound. This would be something like the ultimate sleeper Amstrad CPC fully upgraded and not emulated/FPGAtiated. Running SymbOS Z80 (in addition to original and modern software) on such a machine would be a treat.
Nice video, hope to see more with repair part of old CPC like Kay board ribbon or floppy disk. For the extension question, I agree with a pizero solution connected directly on the Z80 or the expansion connector. Think about the pistorm for the amiga, what about a similar solution for the amstrad with a pi connected that offer storage, wifi, hdmi, emulated hardware like playcity or what you want. This will be awesome.
i think you maybe looking for something like the USIFAc II ... pic micro connected to expansion port, runnin FDC emu, USB, TTL serial port, esp32 wifi addon..and a whole bunch of other features.. and IMO pi-zero is too powerful for retro!
15:40 at least with the C64, we have good replacements with GALs, but the CPC is a whole other story! So much of its logic was in what was almost a CPLD. (As a C64 kid, I'm obviously biased, but the CPCs were nice machines only held back by their clock speed. And I really appreciate the plus series.)
Great job! I am an electronics diagnostician. I have found bridges on tracks, just like the ones you had. A very sharp craft knife or scalpel, lightly scoring the part to remove before teasing up the edges will look much better. I have used this method to modify boards. I recommend a good magnification device. It’s more important to take take and score lightly several times rather than deep score just once as the board and any interleaved foils can be damaged.
Excellent video as ever! Great to see these boards exist, and if there are new 40007 coming, even better. I see this as a great repair item for a CPC that has had serious board damage, use the case and keyboard etc from that to save it from the rubbish bin!
That's awesome to see Rob making more of these boards available. I'm currently building up one of his C64 boards. The great thing about the C64 boards is that new cases are available too.
Hi Noel, this is kind of a love letter comment to your channel. I am in awe. I am not really familiar with these devices and generally anything from their era but I've always been fascinated. I think you're by far (even though this could be personal opinion) the most interesting channel about this stuff. I absolutely love your personality, your editing, and your skillset. I hope to be able to learn something from how you run your channel. You're one of my inspirations, I don't think it means much right now, but maybe someday it will :) Absolutely loved this video. I was even a little sad when it ended.
Noel, I really enjoy your channel. It's given this American a greater appreciation of the "other" 8-bit machines of the world that influenced the history of computing as much (or more, like the BBC Micro that eventually gave birth to ARM etc) than the stuff that was popular/invented in the US around the same time. 👍
Instead of scraping the track away with a screwdriver, you should have used a scalpel to slice through the unwanted track. Much quicker, more precise, and neater. A trick I learned from my years in the Air Force.
From a guy who worked with circuit level repairs on Supercomputers: It's easier to break traces by using a very sharp utility or hobby knife, then either use the knife to lift a section of the trace, or once cut, use a blunt pick (like a dental pick) to gently widen the gap. It looks much better too. Even supercomputer engineers make design mistakes and boards have to be modified.
Hi! There is a good way to save some time and alcohol while cleaning PCB after soldering done. Just use regular paper towel soaked with alcohol. Sure, towel will be destroyed, but paper will accumulate all the residues. Just use some brush to clean all the paper scraps.
Always good to know people out there are making sure the legacy of some of these old machines are being kept alive. My guess is a CPLD would be more than enough to handle that Gate Array chip. Of course some of those single board computers might be an alternative using an adapter to pop into the socket. Nice troubleshooting also!
Thanks! The GA is beefy enough that apparently it's a tight fit in a CPLD, but that's the solution I'll be testing soon. Really looking forward to that.
This is wonderful. Also, this lovely replica board is based, i believe, off a RevA board i stripped from my original CPC, gave to a friend who in turn gave it to Rob. I'm pretty sure this is the case.
I thought that I loved my amstrad cpc... but your job,... that's really true love !!! (and technical and resolution capacity, of course) You're a monster dude
There is a technique for locating a short like the ones you had. Set your power supply to something like 1 volt, and set the current limit to maybe 100 mA. This will prevent damaging any traces on the board. Now apply 1V to wherever it would normally come from, either a voltage regulator if there was one, or a power connector. The voltage will drop down to a low value because of the current limit. Maybe 0.1V or less at the source. Now using the mV scale on your DMM, measure the voltage between VCC and Gnd at various points on the board. The voltage difference at points between the short and the power feed will be very small, but not 0 due to the trace resistance. It may only be a few mV at some points. As you get closer to the short, the voltage will drop. If you measure between VCC and Gnd on the "other side" of the short from the power feed, there will be no voltage, so that would also tell you that a short is between where you are measuring and the power feed.
And again a 5 stars video. I enjoyed both the pcb design and the fixing process. And yes it would be great to understand what happenned with that transistor.
@@NoelsRetroLab I would really love to see a new case. Maybe I'll get to design one some say. Some cross between the classic 464/6128 case and the plus series with space for more ram, a Dandanator and some other stuff. .. or even cooler: a Desktop CPC with an external keyboard (using the OG keyboard)!
Great vid - may I suggest the use of a scalpel to cut tracks rather than a screwdriver? It's more precise and reduces the risk of accidental track damage.
I don't care the make or model of these old PCs. What I DO care about is that there is such a strong community bringing ALL these old PCs back. That means we all win in the vintage PC scene... That being said, I always wanted a CPC. Those things were just gorgeous.
Amazing video. And your Amstrad test code works perfectly with the new board too (it couldn't be any other way, but it works). Thank you Noel for another excellent video !!!
You mentioned that the gate array is the only IC on the board that is not being manufactured today. That makes me wonder: What is being used for sound? I think it is marked as AY-3-8912 on the board - is that currently in production?
The Harlequin, (a Spectrum 128K clone), uses off the shelf logic chips to replace the ULA. Larger modern RAM chips, a surface mount chip for the video and a PCB that fits into a rubber key case or a 48K+ case. It also has Svideo out. It was fun to build, but yes, all those IC sockets were the boring part of it.The only original IC I had to use was the AY chip.
Yeah, that's definitely an option, although I suspect there's more logic than in the Spectrum ULA. You can actually see it in the prototype Gate Array boards that are floating around.
@@NoelsRetroLab It has 55 IC's. A Z80A, an AY-8912, a 32K EPROM, and 2 64K Memory chips and an AD742JR video chip, the other 49 are just the logic. LOL.
I've put whole ZX to some scrap Altera CPLD. Also implemented some scandoubler to convert output to VGA. Even made independant clock for z80- turbo mode up to 8MHz CPU clock and no wait states for computer. Total 5 chips: CPU, RAM, ROM, VRAM, CPLD. So, replacement of antique gate array must be easy task. Two GAL chips replace C64 chip...
I went the first path with recreating an Apple //e board to learn more about circuits back in highschool years ago. My favorite machine of that era is the Apple IIGS, thankfully my Woz Edition I got in the late 90s loaded with the best expansions and accelerator of the time still works great. I fear when it breaks with the GS not exactly being very popular compared Macintoshes and //e's of the period. I have had to repair a //e titanium that had the GS upgrade kit installed but thankfully it was a simple fix.
Great video!!! Having done the same thing for CoCo 2 and the CoCo 3 replica boards, I can totally relate to the snags you experienced. I'm currently in the process of searching for a handful of equivalent modern replacements for some diodes and transistors.
sooo cool... im gonna have to grab one of these boards, can you post a reminder when they are released please Noel... cool to hear about a 6128 board being worked on, i may even just wait for that, and drop my 464 bits into it...(with a 40007 mod or replacement CPLD/FPGA)
16:14 - Wow, that was a long time ago now. lol I did that Verilog translation after some other clever peeps like Gerald did the hard part (the decapping, and die analysis) to make an internal schematic. I don't know if anyone actually tested the old Verilog yet, but I tried to make it as close as possible to the schematic.
I couldn't figure out why PCB software would allow a short between a power pin and ground at first on the CPC recreation. But it was a mammoth effort by Rob to do a "full" recreation like that, tracing out every track. So this issue is actually quite small in the scheme of things. hehe tbh, I personally think it makes a video more interesting when there are faults or issues to fix. I realize this was a beta board, and I think people enjoy seeing the whole building and testing process.
A small CPLD should be enough to fit the ULA logic. The main issue with most retro projects is the 3V3 to 5V translation thing. You can still buy some of the older Altera or Xilinx CPLDs that run on 5V (or run on 3V3, but have 5V-tolerant IO pins). People have of course made repro "chips" for things like arcade PCBs, using small voltage translators / buffers, it just takes longer to do the layout for that.
I should say, btw - my Verilog translation of the ULA was only a starting point. Others have discovered errors in the schematic and other issues since then, and a lot has been fixed. It's interesting looking back at the cpcwiki posts again, and the newer posts. I haven't visited that forum in quite a while.
never tried to sodder anything before, but between watching this and watching a rival of yours do the same thing with an Apple I replica board makes me want to give it a try, maybe this or the Commodore 64 Replica on the same page. Here's hoping Rob eventually makes a replica Dragon 32 board someday in the far future :)
19:42 the reason for the shape is that your scope probe's GND is not connected here (or doesnt seem to be). If you were checking for signal integrity you would want a really short ground to your PCB's ground - often the ground lead is too long and creates ringing. Thats why they have those little springs that go on the tip of your scope probe :)
Could be a gain issue on the transistor - those old Ferranti e-Line transistors had a typical hFE of about 80 and you had to drive them pretty hard - by the standards of the time, they were pretty fast (ft ~= 400MHz), but were low gain. For comparison, even the really old BC109C had a hFE of 400-800. Since it looks like the primary intent was to square up the clock coming out of the gate array, the resistors would probably have been selected to drive it quite hard - you might find that if using a higher gain part then a higher value resistor would work better.
Really liked this episode. I had the 464 and the 6128 back in the days. I learned assembler on these machines. Sadly I don't have the computers anymore but I do have some Compact Floppy Disks that I didn't throw away for the 6128. So... it would be cool to maybe "build" a 6128 myself.
Looking forward to Marchimedes. Would be cool if it were slightly updated with VGA ports and flash memory, pure for modernization. Awesome built regardless. Keep 'em alive!
Excellent news. We will have to wait however, to have a cpc6128 version and perhaps more refined as we are not all capable of identifying issues on a board! But i could give myself a try and do the soldering part if there is no option to order the board with the components already soldered. Now if we had a reconstruction of the excellent and beautiful, full of character, case of CPC6128 . . .
I still have my original 6128, and it worked the last time I tried (except the rubber drive band of course). But that's 20+ years ago, so the knowledge I gain by watching efforts like this may come in handy one day!
Hi Noel.. you seems to have the best project every time.. this time it gives people like me who never get to see the real amstrad cpc when we were kids simply because it never reaches our shores a new hope.. well this is because the shipping cost to own one is too high and maybe building a new one with modern component is cheaper.. at least that is what I think.. anyway this is another great video and stay safe always..
So glad to hear that! I didn't think of it from that point of view, but it's true that it makes Amstrads much more accessible to people everywhere. I guess this makes it even more important to be able to hook it up to a modern USB keyboard so it can be used without an original case.
I respected you before I saw this video but after seeing that you've taught your daughter to solder and you play MInecraft with her, I think you're freaking awesome.
It is easy to see that Noel is a fantastic father. Additionally, I think that Noel got the better of the deal in the "You solder the IC sockets and I will play Minecraft with you". Noel I am so impressed with your teaching your daughter how to solder. You are something else! A high-quality human being. God bless you sir. Fred
It is so very authentic and traditional to let children solder some of the part of the Amstrad boards. Fathers and Mothers in Hong Kong all put their children to work, although mine craft was considered inhuman.
Sounds like an Iron Maiden parody: "Bring your daughter, bring your daughter to the solder!" 🤘
Also I taught my daughter to solder. But she teaches Minecraft to ME.
Love that you got your daughter doing some hands on learning. Kids need more early introduction to skilled trades. Even if they never pursue it as a career, they will always have the knowledge.
AN easy way to find PCB shorts is to run a couple of amps through it and use either a thermal camera, or film of alcohol to look for hotspots.
in the 80's I had a summer job while at Uni fixing avionics boards for GEC, and one way we found shorts on PCB's was to connect a current limited supply to the traces in question, and use an accurate voltmeter to measure the voltage at various points. As you get closer to the short the voltage gets lower, as you get further away it goes up. If you use a low enough voltage you can often avoid activating semiconductor junctions and thus cut out that source of errors - I traced one fault using a quarter of a volt and a (very expensive!) accurate voltmeter. I suspect that nowadays a relatively cheap multimeter with decent probes would probably be stable enough to work. The very low voltage power supply might be more of a problem!
I've seen people use milli ohm meters to do similar, basically check the resistance at each location and then check/rework the area with the lowest reading.
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So glad you got it going. And sorry you had to be the guinea pig tester! Thanks for your effort and patience and keep up the great work.
No worries. That was the fun part! Thank you for the wonderful board you created!
Hi Rob.. I love your work on the commodore as well.. great work indeed..👍🏻👍🏻👍🏻👍🏻👍🏻
Can't think of a better beta tester.
@Rob Taylor, Hats off to you with the board! I can't believe you copied the actual traces, sooooooo much patience. I contemplated doing the same thing for a CoCo 2 and CoCo 3 board but I ended up hand routing just the power and a few other lines and then used an auto router.... You've inspired me and I might go back and copy the traces.
thanks for your efforts too Rob!.. i will be getting one for sure!
5:13 so cute, so sweet.
i m a great fan of Amstrad CPC... my brain exploded watching this video! I want make a new Amstrad CPC in 2022! Marvelous!
I’d love to see a post mortem on that transistor. Why you thought it was equivalent, how it wasn’t, and hopefully a new modern equivalent. Great video!
Yeah agreed. I never get bored of Noel going down the rabbit hole :)
The ZTX312 is a high speed switching transistor, with on/off/storage delays barely over 10ns.
By contrast, the BC547 datasheet doesn't even hint at its switching speeds (none that I could find anyway), so it's very likely very slow, and not suitable for MHz operation.
The circuit looks strange. There is no base resistor. Bipolar transistors must have a current limit for the base current. I bet a base resistor around 1k to 10k would have totally fixed the problem. The BC547 has a gain bandwidth of 300, which means it can do 1 MHz at a gain of 300 or 300 MHz at unity gain, or anything in between. It is plenty fast enough.
An equivalent would be 2N2369 to the ZTX312 as mentioned in datasheet for the original transistor. The 2N2369 is still available. The other equivalent being the BSV25 by the same original manufacturer is not.
Looking at the circuit diagram rather than which transistor is most similar to a ZTX312L, a 2N7000 MOSFET would fit perfectly and I would expect it to result in a proper clock signal.
This took me back to 1984 when the CPC464 was my first computer. I was still using it and my second machine the CPC6128 on release, right up to 1995. It was here I bought my third computer a Packard Bell with Windows 95. I had a great collection of the cassette tape games, along with the not so Floppy, floppy discettes. The monitor to tv converter and digital clock, Primary and secondary disc drives, the Romantic Robot from STS and disc. I even had the Eprom boards for blowing my own chips. Though the best mod I ever did on my CPC6128 was to fit the 464 chip, piggy backing the 6128 chip with one pin bent outward from each chip. Then with a toggle switch wired to those pins that when thrown it connected to the pin hole on the PCB. This in turn when the switch was thrown one way or the other before start up, would then boot the Amstrad into either CPC464 or CPC 6128 mode. That gave me two Amstrads for the price of one. I can't remember now about the mod, but I am sure if you don't know it, someone out there will know how it was done. It is a neat little mod to do if you are interested in both Amstrad models. Going back to the cassette tapes, I had all the Amstrad Action magazines and cover tapes. After purchasing the Romantic Robot from STS, I ran the game Chips Challenge, pressed the Button on the RR and up popped the code. During the game each level had a 4 character code to by pass levels you all ready played and continued from the higher level if the correct code was inputted. After having about 12 or so levels completed, I looked for the codes in the lines of the game programme code lines. These where broken up into four blocks and each block equalled a letter of the code as 1st, 2nd, 3rd and 4th if spread sheeted into columns. I found them all and a few bonus levels too and wrote to Amstrag Action with the results and had them printed in the next available issue. For the life of me I can't remember the issue number, but I am sure there is a copy of the magazine out there somewhere. Sorry for the long comment (excuse my grammer etc), but I thought you and the other readers would be interested in reading my experience with my Amstrad CPC machines etc.
Wonderful =D Nice fault diagnosis there on the VCC to ground, and with the CPU clock! Rob did a great job on that PCB re-creation!
Thanks! Yes, he did a fantastic job.
I cut traces normally with a sharp blade knife or scalpel, cutting at a slight inward angle from both sides, essentially cutting out a shallow V underneath the trace.
I came to comment just that, usually I do it a bit over-wide and remove the copper in the center, to be REAL sure it's cut and won't bite me in the future. Ask me why ... :P
Two cuts and then the island of copper in between is thermally isolated from the rest of the track, so a soldering iron can easily soften the glue enough that the piece of copper just slides off. Much easier and cleaner than trying to scrape enough away mechanically!
@@charlesdorval394 Know the feeling! I had dendrites growing past a non-insulated cut once, have lacquered them since as well! :D
A good way to remove unwanted traces is to use an X-Acto knife. The X-Acto knife works really well and looks really clean when you’re done. This looks like a fun project but finding the shorts on your own would’ve just driven you nuts, glad you found the shorts and were able to take care of them.
Just a couple of mistakes and an omission on a big board he hasn't yet tested? That's actually very impressive. Rob did a terrific job with that and kudos to you for building and testing it. Now Rob can get a perfect working replica board out there thanks to you.
As a woman in electronics tech I just want to tell you how much I love that you involve your daughter in your projects and teach her the trade.
Thank you for your wonderful content and your great parenting. :)
sехism again
Very cool Noel, and you have perfectly outsourced the soldering part to your compagnon :-D Great works!!!!
Maybe I'm weird... I like to solder IC sockets!.
When you get a VCC - ground short it's time to get out the €4,000,000,000 precision resistance meter... No, I don't have one either.
The picture-in-picture of the 'scope probe on the schematic is excellent... liked that a lot.
This is so encouraging to see. I dusted off my CPC664 this evening, cleaned it up and inspected it... I won't be risking plugging in the monitor until it's had a thorough recapping so I can't power it up... I need to sort out an alternative PSU and some kind of video lead in the meantime. I spent so many hours in front of it as a teenager and really loved the machine, I was involved in the fanzine scene running a small CPC fanzine for a period of time - we were featured once in Amstrad Action. I also have a dead CPC464 I picked up about 20 years ago which I know doesn't work but it's in great cosmetic condition and has the proper retro GT65 green screen monitor. Some of your diagnostics on this new board will surely help me to diagnose it and I'm really pleased it seems most components or alternatives can still be purchased (apart from the ULA obviously). I'll be certain to watch more of your vids and have subscribed -- thankyou for producing this content!
Excellent work. Rob is doing a great service, creating these beautiful boards. Getting a replacement board from Rob is my next step if I can't locate the broken trace or solder bridge on my C64.
I forgot to say this in my last post.....
I've never used and Amstrad CPC but your video is so good that you've inspired me to one day build one. Thanks for this video!
I'm so glad!
@@NoelsRetroLab I will definitely build one. I owned a CPC464 back in late 80s. Do you know when the these board will be available? ...and any good source for the gate array? Thanks.
I LOVE these retro-forensics videos! And YES, using the original hardware is always the prefered way.
Just like vintage cars, we don't put anything "modern" that will look out of place, unless we have to.
That's the whole point, to keep it as close to the original as possible.
Very nice teamwork between Noel and Rob! Great video, as always.
Problem with current fpga’s is that they are 3V3, so as well as the fpga, logic converter chips are also required. The low end Tang Nano and Lattice MachX02 can easily replicate the digital functions contained in the gate array chip for those 8-bit computers. So if I designed a replacement solution , it would be a small board containing a few chips to plug-in where the gate array chip goes.
That's sweet that your daughter helps you like that. My daughter helps me build guitar pedals that we sell but she's a teenager now so offering to play Minecraft wont cut it, they want cash. lol
The CPC464 was my first computer. My parents were toy retailers in the 80s with several big successful stores and good connections, and managed to get a fully functioning promotional unit towards the end of '83 - earlier than the official release date (it even had the full colour RGB screen, not the green screen or the TV module). It was supposed to be a demo model to go on display in their main store but it never made it there. They gave it to me as my birthday present that year and I've been glued to a computer ever since. 😂 Awesome to see that they can be built at home relatively easily now. I might have to give it a try!
Noel, the issues you experienced with the board you showed in this video were actually fairly common back in the early days of computing. It's why many "retail-ready" production computers and electronics have bodge and patch wires, resistors and capacitors soldered in post assembly. I have a do use a razor blade to keep cuts more precise, but can't fault the use of a flat-head screw driver. Love your channel! Cheers!
Really great job building and debugging this first revision board Noel! You have some seriously sharp troubleshooting skills sir!!! Thank you for sharing your voyage down "Amstrad Lane" with us Noel. Fred
Thanks. Glad you enjoyed it! 😃
Thank you for this video and for all your efforts. It makes me remember my beloved Amstrad CPC 6128. I also had the Sinclair ZX81 and Sinclair spectrum 48 ....the Vic 20...Commodore 64..Amiga......this was a fantastic era
Another great video from yourself and board from Rob. Definitely going to get one of these once it goes on sale. The 40007 version of the gate array always comes heatsinked from the factory in all the CPCs I've ever seen, so would likely be worth adding one to your board rather than risk another one dying prematurely.
This channel is a real inspiration for most of us. Your content, edition and explanations are on the best of TH-cam. Thanks, Noel, for these videos!!! Keep up the good work!!!
Just dropping a line to say a fair amount of this went over my head, but I couldn't stop watching. (The hardcore, old-tech-loving, nerd in me...) In fact. I'm halfway through my life and considering an engineering degree. The interesting things that happen when you figure out you are on the ASD spectrum super late in life, you stop giving ***ks about everyone else and what they think and go after what makes you happy. Watching these videos is among those things. :)
Glad to hear that. And I don't think that has anything to do with the ASD spectrum and all about just getting older since the same thing happens to me 😃
I am actually surprised that only 3 board errors were present from photo-copy/tracing the original board. At the same time, I'm also surprised that this was never tested, not even once, before shipping it. In my humble opinion that I greatly respect, the best replica of an Amstrad CPC (64K, 128K, with tape or with floppy) would be a modern redesign of the board, with as many quality of life features as possible, while still being "layout compatible" with original cases. I would not mind if it included a R-Pi-0 GPIO header to sandwich a Pi-0 on the board for WiFi, ROM-loading/dumping, etc., maybe even HDMI video and sound. This would be something like the ultimate sleeper Amstrad CPC fully upgraded and not emulated/FPGAtiated. Running SymbOS Z80 (in addition to original and modern software) on such a machine would be a treat.
Apparently, this _was_ the testing: Noel was simply selected as a tester for the project.
Like Jared said, I *was* the beta tester for the board. I probably didn't make that clear enough in the video, so don't blame Rob! 😃
Nice video, hope to see more with repair part of old CPC like Kay board ribbon or floppy disk.
For the extension question, I agree with a pizero solution connected directly on the Z80 or the expansion connector.
Think about the pistorm for the amiga, what about a similar solution for the amstrad with a pi connected that offer storage, wifi, hdmi, emulated hardware like playcity or what you want.
This will be awesome.
Some people want super sized retro, others wanted authentic.
Theres room for both. Modern CAD allow easy version control and design.
i think you maybe looking for something like the USIFAc II ... pic micro connected to expansion port, runnin FDC emu, USB, TTL serial port, esp32 wifi addon..and a whole bunch of other features.. and IMO pi-zero is too powerful for retro!
15:40 at least with the C64, we have good replacements with GALs, but the CPC is a whole other story! So much of its logic was in what was almost a CPLD.
(As a C64 kid, I'm obviously biased, but the CPCs were nice machines only held back by their clock speed. And I really appreciate the plus series.)
Great job!
I am an electronics diagnostician.
I have found bridges on tracks, just like the ones you had.
A very sharp craft knife or scalpel, lightly scoring the part to remove before teasing up the edges will look much better.
I have used this method to modify boards. I recommend a good magnification device.
It’s more important to take take and score lightly several times rather than deep score just once as the board and any interleaved foils can be damaged.
Excellent video as ever! Great to see these boards exist, and if there are new 40007 coming, even better. I see this as a great repair item for a CPC that has had serious board damage, use the case and keyboard etc from that to save it from the rubbish bin!
That's awesome to see Rob making more of these boards available. I'm currently building up one of his C64 boards. The great thing about the C64 boards is that new cases are available too.
Hi Noel, this is kind of a love letter comment to your channel.
I am in awe. I am not really familiar with these devices and generally anything from their era but I've always been fascinated. I think you're by far (even though this could be personal opinion) the most interesting channel about this stuff. I absolutely love your personality, your editing, and your skillset.
I hope to be able to learn something from how you run your channel. You're one of my inspirations, I don't think it means much right now, but maybe someday it will :)
Absolutely loved this video. I was even a little sad when it ended.
Thank you! I'm really glad to hear that! 👍
Noel, I really enjoy your channel. It's given this American a greater appreciation of the "other" 8-bit machines of the world that influenced the history of computing as much (or more, like the BBC Micro that eventually gave birth to ARM etc) than the stuff that was popular/invented in the US around the same time. 👍
Really glad to hear that! Thanks!
Instead of scraping the track away with a screwdriver, you should have used a scalpel to slice through the unwanted track. Much quicker, more precise, and neater. A trick I learned from my years in the Air Force.
I'll try that next time. Thanks for the tip!
From a guy who worked with circuit level repairs on Supercomputers: It's easier to break traces by using a very sharp utility or hobby knife, then either use the knife to lift a section of the trace, or once cut, use a blunt pick (like a dental pick) to gently widen the gap. It looks much better too. Even supercomputer engineers make design mistakes and boards have to be modified.
Hi! There is a good way to save some time and alcohol while cleaning PCB after soldering done. Just use regular paper towel soaked with alcohol. Sure, towel will be destroyed, but paper will accumulate all the residues. Just use some brush to clean all the paper scraps.
Always good to know people out there are making sure the legacy of some of these old machines are being kept alive. My guess is a CPLD would be more than enough to handle that Gate Array chip. Of course some of those single board computers might be an alternative using an adapter to pop into the socket. Nice troubleshooting also!
Thanks! The GA is beefy enough that apparently it's a tight fit in a CPLD, but that's the solution I'll be testing soon. Really looking forward to that.
@@NoelsRetroLab There are probably some out there that can handle it. With the right optimizations I bet you can fit it.
This is wonderful. Also, this lovely replica board is based, i believe, off a RevA board i stripped from my original CPC, gave to a friend who in turn gave it to Rob. I'm pretty sure this is the case.
I had a CPC464 as my first computer. This video gave me major nostalgia
I thought that I loved my amstrad cpc... but your job,... that's really true love !!! (and technical and resolution capacity, of course) You're a monster dude
Nice. I have fond memories of using a CPC464 back in the day.
With a pretty helper like that who can resist building a CPC from scratch !!!
Good catch on the shorts on that board. Thanks for the links. Now all we need is 3D printed Amstrad replica case plastics..
17:49 not every hero wears a cape. That's why opensource projects are growing rapidluy - thanks to volunteers ^_^
There is a technique for locating a short like the ones you had. Set your power supply to something like 1 volt, and set the current limit to maybe 100 mA. This will prevent damaging any traces on the board. Now apply 1V to wherever it would normally come from, either a voltage regulator if there was one, or a power connector. The voltage will drop down to a low value because of the current limit. Maybe 0.1V or less at the source. Now using the mV scale on your DMM, measure the voltage between VCC and Gnd at various points on the board. The voltage difference at points between the short and the power feed will be very small, but not 0 due to the trace resistance. It may only be a few mV at some points. As you get closer to the short, the voltage will drop. If you measure between VCC and Gnd on the "other side" of the short from the power feed, there will be no voltage, so that would also tell you that a short is between where you are measuring and the power feed.
And again a 5 stars video. I enjoyed both the pcb design and the fixing process. And yes it would be great to understand what happenned with that transistor.
GENIAL ! Mon premier ordinateur, que de bons souvenirs. Merci. Thank you.
Great video! ... and great that there is a new board for the CPC464.
Thanks! Yes, I'm super happy we're almost there with CPC hardware. Just one more chip... and that one is about to happen too.
@@NoelsRetroLab I would really love to see a new case. Maybe I'll get to design one some say. Some cross between the classic 464/6128 case and the plus series with space for more ram, a Dandanator and some other stuff. .. or even cooler: a Desktop CPC with an external keyboard (using the OG keyboard)!
Great vid - may I suggest the use of a scalpel to cut tracks rather than a screwdriver? It's more precise and reduces the risk of accidental track damage.
I don't care the make or model of these old PCs. What I DO care about is that there is such a strong community bringing ALL these old PCs back. That means we all win in the vintage PC scene... That being said, I always wanted a CPC. Those things were just gorgeous.
Amazing video. And your Amstrad test code works perfectly with the new board too (it couldn't be any other way, but it works). Thank you Noel for another excellent video !!!
You mentioned that the gate array is the only IC on the board that is not being manufactured today. That makes me wonder: What is being used for sound? I think it is marked as AY-3-8912 on the board - is that currently in production?
This is some hard core stuff right here well done sir
The Harlequin, (a Spectrum 128K clone), uses off the shelf logic chips to replace the ULA. Larger modern RAM chips, a surface mount chip for the video and a PCB that fits into a rubber key case or a 48K+ case. It also has Svideo out. It was fun to build, but yes, all those IC sockets were the boring part of it.The only original IC I had to use was the AY chip.
Yeah, that's definitely an option, although I suspect there's more logic than in the Spectrum ULA. You can actually see it in the prototype Gate Array boards that are floating around.
@@NoelsRetroLab It has 55 IC's. A Z80A, an AY-8912, a 32K EPROM, and 2 64K Memory chips and an AD742JR video chip, the other 49 are just the logic. LOL.
I've put whole ZX to some scrap Altera CPLD. Also implemented some scandoubler to convert output to VGA. Even made independant clock for z80- turbo mode up to 8MHz CPU clock and no wait states for computer. Total 5 chips: CPU, RAM, ROM, VRAM, CPLD. So, replacement of antique gate array must be easy task. Two GAL chips replace C64 chip...
@@kaunomedis7926 Cool.
Great work. Good to see it's possible to increase the stock of actual hardware through a mixture of new and replica components 👍
Really nice adventure building this computer, thanks!!
I went the first path with recreating an Apple //e board to learn more about circuits back in highschool years ago. My favorite machine of that era is the Apple IIGS, thankfully my Woz Edition I got in the late 90s loaded with the best expansions and accelerator of the time still works great. I fear when it breaks with the GS not exactly being very popular compared Macintoshes and //e's of the period. I have had to repair a //e titanium that had the GS upgrade kit installed but thankfully it was a simple fix.
This was based on a board that I sent to Rob. I like to think of that board as Jango Fett and now there's all the clones.
Brilliant Noel! I really enjoyed the video.
My Daughter loves playing games on my 40 year old Speccy. She loves the retro aspect.
Me and my daughter also solder and play minecraft together. Seeing that really made me smile
Really great video and awesome support from the creator 2 tiny issues is a really great sign hopefully that's all you can find
Nice troubleshooting! I was thinking "test for a short before doing anything to the board!"
Yeah, lesson learned! 😃
Great video!!!
Having done the same thing for CoCo 2 and the CoCo 3 replica boards, I can totally relate to the snags you experienced. I'm currently in the process of searching for a handful of equivalent modern replacements for some diodes and transistors.
That wholesome Minecraft moment made my day :) hope you two have a great day too!
ah Noel my very first computer ever. tell me, is there any progress on the replacement gate array chip?
Oh yes! There are replacements already. I need to make a video about that.
Genius.. At last... Very well done.
My first computer was a CPC464 - good memories
Applause, Applause! Mostly for your little helper, but you also did fine ;)
sooo cool... im gonna have to grab one of these boards, can you post a reminder when they are released please Noel...
cool to hear about a 6128 board being worked on, i may even just wait for that, and drop my 464 bits into it...(with a 40007 mod or replacement CPLD/FPGA)
16:14 - Wow, that was a long time ago now. lol
I did that Verilog translation after some other clever peeps like Gerald did the hard part (the decapping, and die analysis) to make an internal schematic.
I don't know if anyone actually tested the old Verilog yet, but I tried to make it as close as possible to the schematic.
I couldn't figure out why PCB software would allow a short between a power pin and ground at first on the CPC recreation.
But it was a mammoth effort by Rob to do a "full" recreation like that, tracing out every track.
So this issue is actually quite small in the scheme of things. hehe
tbh, I personally think it makes a video more interesting when there are faults or issues to fix. I realize this was a beta board, and I think people enjoy seeing the whole building and testing process.
A small CPLD should be enough to fit the ULA logic. The main issue with most retro projects is the 3V3 to 5V translation thing.
You can still buy some of the older Altera or Xilinx CPLDs that run on 5V (or run on 3V3, but have 5V-tolerant IO pins).
People have of course made repro "chips" for things like arcade PCBs, using small voltage translators / buffers, it just takes longer to do the layout for that.
I should say, btw - my Verilog translation of the ULA was only a starting point.
Others have discovered errors in the schematic and other issues since then, and a lot has been fixed.
It's interesting looking back at the cpcwiki posts again, and the newer posts. I haven't visited that forum in quite a while.
never tried to sodder anything before, but between watching this and watching a rival of yours do the same thing with an Apple I replica board makes me want to give it a try, maybe this or the Commodore 64 Replica on the same page.
Here's hoping Rob eventually makes a replica Dragon 32 board someday in the far future :)
I have a hard time deciding if I want to build a cpc or a msx. As always wonderful video!
Nice work! I wish I had your soldering skills.
Superb Noel. Great video.
Glad you enjoyed it
I love the daddy daughter thing,I love it when my little one wants to help ,they grow up to quickly
19:42 the reason for the shape is that your scope probe's GND is not connected here (or doesnt seem to be). If you were checking for signal integrity you would want a really short ground to your PCB's ground - often the ground lead is too long and creates ringing. Thats why they have those little springs that go on the tip of your scope probe :)
19:52 I spotted the ground connection :) OK, the ringing is probably what I said above - the ground lead is causing it...
rebuild with more memories more and more will be better
4:20 I haven't heard that chiptune since back in the days when I was playing the cracked version of Worms 2
That one is an AY version of that cracked tune. You can see the link in the description for that track (and a bunch other awesome ones).
Could be a gain issue on the transistor - those old Ferranti e-Line transistors had a typical hFE of about 80 and you had to drive them pretty hard - by the standards of the time, they were pretty fast (ft ~= 400MHz), but were low gain. For comparison, even the really old BC109C had a hFE of 400-800. Since it looks like the primary intent was to square up the clock coming out of the gate array, the resistors would probably have been selected to drive it quite hard - you might find that if using a higher gain part then a higher value resistor would work better.
Great video. At last the cpc gets some love. Thank you.
Really liked this episode. I had the 464 and the 6128 back in the days. I learned assembler on these machines. Sadly I don't have the computers anymore but I do have some Compact Floppy Disks that I didn't throw away for the 6128. So... it would be cool to maybe "build" a 6128 myself.
Nice replica project! 👍
Great video and new board diagnostic!
Thank you! Cheers!
Very skilled and entertaining. I enjoyed very much, and learned at the same time. Thanks !
Oeh, so nice you show where you're measuring synced to the video. :) It's the little things...
This is where using a real pcb layout program comes in handy. DRC (Design rule checking) has saved many of designs
Looking forward to Marchimedes. Would be cool if it were slightly updated with VGA ports and flash memory, pure for modernization. Awesome built regardless. Keep 'em alive!
Is the 2022 the year of exotic Brit homecomputers?
Excellent news. We will have to wait however, to have a cpc6128 version and perhaps more refined as we are not all capable of identifying issues on a board! But i could give myself a try and do the soldering part if there is no option to order the board with the components already soldered. Now if we had a reconstruction of the excellent and beautiful, full of character, case of CPC6128 . . .
Amazing! Thanks for this great video. Really nice your daughter's part. Good humor sense!
Nice video. But what's about the CPC6128? The would be a gem! 😀
I still have my original 6128, and it worked the last time I tried (except the rubber drive band of course). But that's 20+ years ago, so the knowledge I gain by watching efforts like this may come in handy one day!
Coming soon! 😃
Enjoyable episode... always love the troubleshooting.
That was fascinating to watch thank you so much
Hi Noel.. you seems to have the best project every time.. this time it gives people like me who never get to see the real amstrad cpc when we were kids simply because it never reaches our shores a new hope.. well this is because the shipping cost to own one is too high and maybe building a new one with modern component is cheaper.. at least that is what I think.. anyway this is another great video and stay safe always..
So glad to hear that! I didn't think of it from that point of view, but it's true that it makes Amstrads much more accessible to people everywhere. I guess this makes it even more important to be able to hook it up to a modern USB keyboard so it can be used without an original case.
@@NoelsRetroLab yes that would great too…👍🏻👍🏻👍🏻👍🏻👍🏻
Whaou ! Amstrad is back. 😉
BTW, you can cleanly break traces open using a Dremel with a tiny ball-head drill bit (part of the set that comes with it).
Right. Someone else mentioned that. I don't think my set came with the tiny one, but I'll have to check. Thanks!
To break tracks I use a Dremel with an engraving bit as this gives a bit more control than "chopping" with a screwdriver or knife.