OK so first the horrible bend there must have happened in the mail, I've never actually removed it from the case until it was actually shipped. I am actually surprised it still works after someone played basketball with the package... The fuses I used were the same 1.5A 240V and they would blow the moment I flipped the switch. I didn't think of it until you said it and since you ruled everything else out I'd guess it was something with the power supply. Machine never had any luck with those and IIRC this was the 4th power supply for it. They were overheating like crazy all of them. I do not know all the history of the machine sadly. My father bought it back in the late 80s early 90s used so it might have had some work done on it before we actually got it. The machine did die on us twice when it was heavily used there up to mid/late 90s and was repaired by local garage repair guys that dad found somehow. One of them actually installed a reset switch for it. But after we got the first x86 box, a shiny new P166, it barely got even looked at much less powered on with the exception of a retro gaming night now and again.
Huh, that's very interesting, too bad that you had power supply issues, I would just get a new power supply, as they are more efficient anyways, and should never have a problem with overheating, as the old powersupplies were just horrible with that- good thing it only affected the PAL chip and nothing else. Otherwise a voltage spike likes to kill ram chips especially, or other chips that aren't removable.
'shouldnt' be possible for the 9v ac to go severe overvolts as its ac direct from a transformer winding , or was it a 220v mains psu being run on 240? that'd make it high?
@@andygozzo72 Yes it is possible because whenever you turn on a load, it makes a peak voltage, sometimes twice the normal voltage. Multiply by, 1.414 and you'll get the peak voltage of 9v. Voltage regulator converts to dc.
My best bet is: The RF shield got dislodged somehow and shorted the pins on the cassette port. Since first thing you did was rip off the RF shield, that's your short gone!
Next time you want to check a potentially shorted board, PLEASE consider using the “dim bulb” tester method using a incandescent bulb instead of the fuse. If it’s a dead short, the lamp will be at full brightness. The bulb serves as a current limiter.
Oh my God this brings back memories. At the beginning of my career I worked for a school board reparing c64s Apple TVs pets IBM PC XT AT. I'm happily retired now but it brings back a lot of memories I used to have a big tin I would throw all the bad commodore 64 chips into It weighed 2 lb eventually after a few years. I remember ordering certain ICs from commodore 50 to 100 at a time and that would last a couple months. The build quality on those things were terrible. I can still smell the tobacco scented solder we bought and the sound the plastic solder sucker made. I must have replaced thousands of chips in those things. Also repaired 1702 monitors 1541 floppy drives wow what a flood of memories. Thanks for the vid. It made me smile. The hardest short circuit on a c64 was the easiest and it was a solder splash from the grounding for the RF shield onto a scratch Vcc trace.
FWIW I used to work on telegraph systems with +/- 80v signalling current. It was not uncommon to short either to ground or to the opposite polarity. If it was a fused supply we would have been constantly changing fuses. Instead we used a ballast lamp whose resistance would increase with current. It also glowed to show a fault, much like your suggestion.
My VIC-20 blew fuses one after another when pressing play on the tape drive. I got tired of bringing it back to the store for fuse replacement, so I just drilled a hole in the tape drive and powered the motor with a wall transformer through a toggle switch. It worked great. I was 12.
When I'm dealing with something that keeps blowing a fuse, I hook up a circuit breaker (you can get at DigiKey, Mouser, etc...) and that provides the additional protection plus you don't burn through fuses :) I use Alligator clips like you have, but I have friends who used an old fuse and just soldered the legs of the circuit breaker to the fuse body so it plugs in just like the fuse does. That works fine if there is a lot of room. I keep values 1A, 2A, 4A, 7A, and 10A. So if it's a 1.5A fuse, I can use a 1A or a 2A depending on how much risk I want to take.
Could be the use of fast-blow fuses (Denoted by an "F" before the amp rating) versus slow-blow (Denoted by a "T" before the amp rating), as some fast-blow fuses will pop on powerup if the inrush current is too much, which is where there ought to be slow-blow fuses fitted...
Yes, indeed. The smoothing capacitors will initially draw a hefty current as they are fully discharged, and the current will drop once they are charged up and the only thing drawing any current is the circuit; and this initial surge can be enough to blow a fast-blow fuse rated for the current drawn in normal operation. For the best protection you really need a slow-blow (T) fuse upstream of the rectifier (to protect the power supply in case one of the diodes fails short-circuit) and a second, fast-blow (F or FF) fuse downstream of the smoothing capacitor. But on a complex board, you can run into the same problem again with the combined charging current of all the little decoupling capacitors; so you either have to split up the power rails and use separate fast fuses for different sections of the board, or just rely on the fact that in the event of a fault, just by conservation of energy, all that current will necessarily be flowing through the slow fuse and it will eventually blow. The question of whether or not the slow-blow fuse provides sufficient protection on its own is then a matter of whether or not the (non-faulty) rest of the circuitry can withstand the upset on the power rails caused by the fault for longer than the fuse takes to blow, without permanent damage. I've worked in a job where we more or less used to have to do exactly that; we were making safety-critical controls for gas appliances, and they had to be constructed in such a way that no matter what fault occurred, there was no way to create a dangerous condition, even if a second fault were also present. You could rule out certain combinations that would be impossible (such as one set of contacts in a double-pole relay changing over completely but not the other; although you _do_ have to consider the normally-closed contacts opening but the normally-open contacts never making, because that definitely happens in real life if a relay is faulty or some power supply problem prevents the coil magnetising fully), but the type-approval rests on your proof, and you can get into a whole lot of trouble if something goes boom after you swore it wouldn't.
I’m reminded of a fuse problem I had. When I was in my mid teens, back in the early eighties, I managed to buy a second hand VIC=20. It was often blowing its fuse (and I think I did jump it for some time - blush) I did eventually (maybe a year or two?) find the cause - a DIP switch in its 8K RAM pack had ended up centred (neither properly on nor off). Seeing this mail call brought back memories - although obviously not the same cause 😊 Really gained most of my practical early 1st-steps BASIC programming experience on that VIC and I loved it.
@@christianlarsen1070 In the 8K RAM Pack rather than the VIC itself - presumably to configure where it appeared in the memory map. I assume with some kind of expansion bus it’d be possible to have more than one. First computer, MK14 with 256 bytes RAM… 2nd, VIC=20 with 5K RAM + 8K RAM Pack… current machine have gigabytes - unthinkable back then!
Oh hey! I know that printer model! Inside out one might say 😸 - the blue part is actually one part of the guide inside the printer, so you can "thread" it without getting your fingers dirty. You can see that the cartridge is much smaller than the actual loop it needs to make.
Pretty funny to see a windows error box pop up when the 64 booted 22:26. BTW, you always scare me by removing and adding chips with the power and monitor cables plugged in. Even with switch off it's a dangerous practice.
Interesting that you mention the ceramic capacitors. I had a similar fault on a C64 I was working on. Generally my OCD will cause me to straighten the ceramic capacitors on any board I work on. Looking at all those 104 caps laying on their sides triggers me. Finding shorted capacitor leads somewhat justified my obsession about "fixing" them! :-)
I'm glad I'm not the only one that likes to line them all up nice and straight when I work on a board. The A500 motherboard has some great ones to line up in the back.
The problem is, those leads really cannot take being bent more than MAYBE once or twice. So there's a half-decent change they'll just break off when you go to straighten them back up! Unless it looks really bad or it might be causing an issue I try to move them as little as possible. Or just remove them and put new ones in.
Personally, I prefer the PAL version of the "8-Bit Dance Party". I think of it almost like comparing music recorded in 432 Hz vs 440 Hz that the music industry uses.
I recently got an old C64c (I wish I could remember what happened to the one I had that I got new when I was younger) and I am kind of glad it did not come with a power supply.
Printers are generally #4 & #5 on the IEC bus addressing. Always removed the SID on C64 boards when diagnosing issues. They are getting hard to replace with original parts. If you open the ink carts for the printer you'll find a small sponge, re-ink that and it will re-ink the cartridge.
@@MrHurricaneFloyd An old small business PC is cheaper at the moment and far more capable. Rpi4 is going for over $200 here in Canada in listings, then higher when you make an offer.
The spacing issue for USSR chips is the stuff of legend. According to the lore, the Soviets used 2.5 cm as their inch equivalent, making the spacing 2.5 mm instead of the correct 2.54 mm. This sort of works for 14 pin dips, but for chips with higher pin count which the Soviets bought in the west and smuggled into the USSR, they simply wouldn't fit on the Soviet made motherboards. Edit: To clarify chips produced in the west had a pin spacing of ten pins per inch, it was an American thing.😁
@@Colaholiker OH, the Soviets did buy up advanced chips in the "west" during the 80s and I'm fairly certain that some of those chips had export restrictions on them, so moving them to the USSR was de facto smuggling. I have no idea at what scale they illegally imported chips but from what I understand computers were rare in the Soviet Union.
@@OscarSommerbo But if the West had export restrictions, which I can imagine, why should the USSR, who wanted the forbidden fruit, want to use a different pin spacing? It's not like western countries wanted to steal Soviet technology. 😅 I think it was just too "American" to use 1/10 inch, but staying in the general scale was practical, so they went metric.
@@Colaholiker The way I heard it, again I have no idea of the truth of the story. In the 80s it was fairly common to convert one inch to 25 mm as it was "close enough". I think I learned the "real" length when I was 13 or 14. So the Soviets designing computer components used the inaccurate 25mm for inch, by mistake or out habit, rendering a lot of hardware unable to fit western chips. So the reason was most likely a common mistake.
As a temp fuse replacement you can clip in a 12v automotive lamp (1156/1157, any 12v single element, etc) across the fuse. If there's a short the lamp will just go to full brightness. If it's actually 9v you might be able to find a lamp that is closer in voltage.
yep, bulbs are good current limiters, i use them all the time, you can make simple 'constant' current nimh chargers with them , i once rigged up quick n dirty trickle charger using a 25w pygmy bulb, with BY127 in series off the mains, it was only me that'd be going anywhere near it and i knew what i was doing..
It could also be the wall voltage at his location. I've had several calls over the years from early HP Imagewriter (4, 5, 6) users whose printers didn't work. One office location had 85V coming outta the wall, and another user had the same thing in his house. Wouldn't work in his bedroom, but would work in his kitchen and livingroom. The fuser in the model is finicky and needs 120V.
My main C64 is equipped with an Ultimate 64 motherboard due to all of the repairs I've had to do to my other OG hardware. The Pi option is better with a Pi3 A or B than a Pi4.
Oh Adrian, you silly silly boy! You didn’t check for the short before trying to repair the bend in the PC board. It’s quite possible you (unintentionally) fixed it by bending it back into shape. Maybe there was an internal short on the ground/power plane due to the bend? 🤔 Or maybe the fuse WAS too small. I guess we’ll never know now.
My bet is on bad power supply. There are a few reports of that same behavior around and I had the very same happen to me, tested on 2 systems with multiple fuses, with a brand new Keelog supply. Poof! Every time.
@@espressomatic interesting, I'd have thought that when it comes to AC voltage can only be zero if the coil breaks - not higher. Do we know what voltage that faulty PSU was outputting?
For a moment we feared that the video would end without the reglamentary Adrian's *8-Bit Dance Party!* test 🕺🏻 (26:53) 😅 Nice job with the diagnosis and resurrection of that venerable board! 👍
That reworked socketed chip is not a ram chip. It is U8 by memory and is 74LS06 a buffered hex inverter (not gate) chip. It is hard to find on the schematic because the six inverters are used in different places all over the 64.
My guess is a 300mA (or so) fuse was used which wouldn’t blow on a ~250mA computer but did blow on this ~330mA example. But your 1.5A example is giving it plenty of room. Just like you said. Eager to see this patron’s comment for confirmation. (Algorithm engagement!)
Could also have been a fast blow fuse. The big capacitors on the C64 mainboard cause a lot of inrush current. Especially if you use an 1A fuse, it should be a slow blow fuse.
I made sure the fuse was the correct A. It wasn't the first time it blown it however I have no Idea if they were fast or slow blow ones. I also can't really check as they have been trashed moths ago (the package was sent out February).
@@krissy_h7854 fair enough! Thanks for replying here so I wouldn’t have to be checking back on the video! I totally understand how it is to not be sure of the details after this time, haha. Perhaps it was gremlins :)
IPA, at any concentration, shouldn't damage the plastic surface of an LCD. In my experience, it also won't clean it effectively. Your screen cleaner is probably 50-50 IPA and water. That's the long-recommended cleaning solution, and I've found it works well on most dirt that ends up on LCD displays.
My money was on a short (possibly a solder blob, the cassette transistor or one of the caps touching a lead they shouldn't) that got unbent either during the mashing it got in the post or while you were straigtening things before you straightened the board and started testing for shorts. A bad PSU would have to have been putting out a lot of voltage to blow the fuse, which I would have thought would have done damage elsewhere.
Interesting, I had a 1989 Commodore 64 C, which right after the warranty was expired, started blowing the power supply fuse. I don't remember anymore if it blew immediatly after connected to wall socket, or only when the computer was started. As the PSU is potted, there was no alternative, but to buy new PSU, and then the computer worked again. If I recall correctly, the fuse inside the computer did not blow.
I feel so lucky to have my original two-prong VIC20 (or VC 20 as it is called in germany) and my C64 breadbin still working. As for safety I recently bought some new PSU. Switching on these machines brings such good memories to me.
shouldnt be possible for the 9v to give trouble as its straight off a 50/60 hz transformer, 5v is a different matter, you could wire a 5watt 5v6 zener across the 5v line in the computer to clamp any overvoltage
I have a BMC64 running on a Raspberry Pi with a box with 2 joyports and a connector for my C128DCR keyboard attached to the GPIO of the Pi. I'm looking for an old C64 (breadbin preferably) with an intact keyboard but broken motherboard so I can fit the Raspberry Pi in it. Would love to see a development on the BMC64 to be able to use all of the keys of the keyboard in C128 mode.
The MPS - 803 printer was made by Brother. On seeing Made in Japan I thought of Seiko/Epson, but nope, it was Brother which had a similar model under their own brand.
While this is true, IPA may however damage surface coating on LCD screens. Some of the anti-glare stuff can suffer, but that is really down to the individual coating they used. In my experience, it is normally not a problem, but I wouldn't bet on it.
There's a device that looks like a regulator (maybe it is one) up by the cassette port. It's not anchored and you must NOT press it down or anchor it. If it gets pressed down, it shorts the board. Maybe the keyboard wire pushed it down. Could be the fuse value was not correct (been there - Thought I picked up the right one). Could be that the power supply was bad (in which case the fuse blowing was a good thing since it reduced the possible chip death count). PLA? Heck we've got lots of replacement options for it now.
One of my C64s has a PLA that developed a marginal fault about two years ago... it works perfectly fine, even with a 1541 Ultimate cart, but a few demos crash (always in the same place), even when running from disk. I put a heatsink on the PLA and now if I run the offending demo when the machine is cold, it works. The weird thing is that I'm expecting it to get worse, but it doesn't. The PLA is soldered in unfortunately.
Novice here. I see you testing the voltage regulators, but I can't see exactly how you are testing them, and what results you are expecting. I have a C64 that is blowing fuses, but I can't find out why. The bridge rectifier tested good, and no obvious issues are seen on the board traces. The previous owner had installed a Jiffy DOS modification with a reset switch that had a wire soldered to pin 3 on the user port. I removed all the mods and wires. But there is a small blob of solder left on pin 3 that I haven't removed since I'm concerned about how to do it and not damage the pin connector. I'd appreciate knowing how to test the VR's, and what I should expect to see in the positive and negative side of the results. Thank you for your great videos!
@@jeffsadowski I don't think that matters too much for diagnosis, if it's even really the case. First, current draw varies most with activity, so dependent on what is going on (is something trying to boot). Also if there's really a wider tolerance on older chips, it's still small compared to the difference in current drawn depending on activity. In this case, the current might have differed because the reference board didn't have a modulator or had some low power chips installed where the original used higher power versions.
Ooh, if I was gonna put a Raspberry Pi in a C64 case, it's not going to just run a C64 emulation. I'd have that sucker running several operating systems.
I have an avermedia pro gamer plus 2 capture and it is the same way. Occasionally just doesn't provide a pic and can't be seen. But it has a switch on the front to switch modes on it and I just usually have to flip the switch to self capture back to PC and that gets it working in OBS again.
Cool, 8-bit Yoda did his magic again 🙂 Adrian, could you tell me more about that pla on the Soviet chip? Never heard nothing about it, seems very interesting.
@@MrHurricaneFloyd Definitely got dropped or something got dropped onto it, but you need to pack your parcel to anticipate this. A couple of layers of bubble wrap to seperate a heavy 803 printer from a motherboard is not good enough. Cushioning completely around the printer in the form of packing peanuts, maybe double-box the motherboard. As a guide, pack your items so that they will survive a 2m drop or a 20kg item being dropped on top.
@@austfox2170 I have used thin plywood to box items for shipment. I was getting free 4' by 8' sheets from a truck repair company that had a few 1/4" holes drilled in them. Replacement roll up doors were shipped on them, to prevent shipping damage and they were under 1'4" thick so it was lighter than multiple layers of cardboard.
PAL machine on 60Hz likely has a single issue - the TOD clock (that you read from TI$ in Basic) is 20% fast. I don't think anything else syncs to the power grid but I may be wrong.
Maybe it's learned/instinctive response, but when you shorted the fuse, I could instinctively SMELL burning insulation. Even though nothing bad happened in the video, I guess it's a sign I've been in the trade too long😂😂😂😂
15:52 at this point i'd say that his trafo had a failure, sent too much volts, killed some parts (chips), now they're shorted, thas why it draws so much..
Someday I need to see if I can figure out what's wrong with my Commodore 64. It started acting flaky some 20 years ago so I stopped using it. I safely store mine in a closet, as my attic gets HOT.
They're not too hard to fix, as long as you have alot of socketed chips. Alot of times it's a pretty simple fix, even if you have to get a desoldering iron with electric pump, to desolder a chip.
That printer should be pretty easy to convert to 110/60. I’d be really surprised if it needs anything other than a transformer swap, unless there’s a motor which runs off of AC for some reason (which seems incredibly unlikely).
Calling those ports IEC connectors was a little confusing for me, I've always heard the circular ones called DIN, and the standard computer / appliance power cables called IEC cables. Not a critique, IEC also has a spec for round pin connectors I just thought it was a little strange.
Feed the board with a lower voltage, current limited and probe the board with a thermal camera ... that'll show the current consumer straight away! ... without releasing the magic smoke.
It's the 5V DC that goes out of whack. Especially if you use a newer VIC20 PSU on a C64, the 5V regulator can't take the extra load very long, but will burn out and then it can give anything between 6V and 12V which will cook especially the RAM chips quite fast. The 9V AC output can read a bit high or low depending your outlet voltage, but it is usually fine as it will be rectified and regulated for the parts that are picky. You CAN use a C64 PSU on a newer VIC 20 no problem as long as you have checked the 5V is in whack. Old VIC20 has just an 9V AC input and had all internal rectification and regulation, and required a roughly 30VA or higher transformer .
@@Ed64 Ah man, I should have known. I've got one of their little speaker things that look similar. Now I need to find all the Amiga Workbench graphics for mine.
The 9V AC getting rectified on the board? I didn't know that. Then why isn't it rectified inside the PSU just like the 5V? Does it have something to do with different voltages travelling from the brick to the machine itself close to each other? 22:24 - that got a really good laugh out of me, we're expecting a working or faulty machine, it starts up and right as it started it threw a little too modern error message, it seemed like :D
Yeah, on the early C64 boards, the 9V is used to create the +12 for the SID/VIC II but also a second 5v rail also used for those chips Supposedly a cleaner rail...So 9v is rectified, turned into higher voltage DC then run through a 7812 regulator for the 12v and a 7805 for the 5v. And yeah, it's funny when I'm running full screen to see a mouse cursor floating over the C64 image. (Or errors!)
The 9V AC is used for multiple purposes: One is that it is present on the user port for RS-232. RS-232 user port cables can use the 9V AC to generate the +12V and -12V for the RS-232 line drivers. The second application is the CIA clock, which counts AC phases. And indeed it is rectified to produce the internal 12V, 5V CAN and 6V tape power tails.
They are open source. The original EasyFlash uses 74 Logic ICs, an SRAM IC and 2 Flash Memory ICs all Through Hole stuff. The EasyFlash 3 uses mainly SMD components but also uses a CPLD and is much more powerful and feature rich.
Question: is it possible your use of hot air caused an unintentional reflow of solder in those areas of the board that may have cleared the short? I see William Squires has already asked this question as I look down through the comments. It is the most likely reason the board is no longer shorted out.
My guess is his PS had too-high AC line. I had 2 different rev c64s, both working with known good PS. BOTH would blow fuses when powered by a brand new Keelog PS. Unfortunately by the time I figured it out, I also lost 1 SID and on the same C64 the screen is corrupted at startup now - haven't yet been able to figure out what else died.
shouldnt be possible for a 9v ac transformer to overvolt more than usual tolerances, unless made wrong, too high, to start with, or a 220v type used on 240v mains,
that point me out psu is overvoltage and cause feedback kick fuse cause it to blew out that one reason i dont trust older psu because there no telling how much voltage is putting out it could ruined sin or pla chip
You can set this to music (I think you'll figure out what music on your own): _I'm too hungry for this fuse_ _Too hungry for this fuse_ _So hungry you lose_
![Adrian's Digital Basement ][](http://yt3.ggpht.com/ytc/AIdro_k7CrQRe71qN6c0Ua7A1P_I8KkxjqLa70u0zYeCvdvnKw=s48-c-k-c0x00ffffff-no-rj)
OK so first the horrible bend there must have happened in the mail, I've never actually removed it from the case until it was actually shipped. I am actually surprised it still works after someone played basketball with the package... The fuses I used were the same 1.5A 240V and they would blow the moment I flipped the switch. I didn't think of it until you said it and since you ruled everything else out I'd guess it was something with the power supply. Machine never had any luck with those and IIRC this was the 4th power supply for it. They were overheating like crazy all of them. I do not know all the history of the machine sadly. My father bought it back in the late 80s early 90s used so it might have had some work done on it before we actually got it. The machine did die on us twice when it was heavily used there up to mid/late 90s and was repaired by local garage repair guys that dad found somehow. One of them actually installed a reset switch for it. But after we got the first x86 box, a shiny new P166, it barely got even looked at much less powered on with the exception of a retro gaming night now and again.
Get a Ray Carlesn PSU and call it a day.
x86 is overrated anyway
Huh, that's very interesting, too bad that you had power supply issues, I would just get a new power supply, as they are more efficient anyways, and should never have a problem with overheating, as the old powersupplies were just horrible with that- good thing it only affected the PAL chip and nothing else.
Otherwise a voltage spike likes to kill ram chips especially, or other chips that aren't removable.
'shouldnt' be possible for the 9v ac to go severe overvolts as its ac direct from a transformer winding , or was it a 220v mains psu being run on 240? that'd make it high?
@@andygozzo72
Yes it is possible because whenever you turn on a load, it makes a peak voltage, sometimes twice the normal voltage.
Multiply by, 1.414 and you'll get the peak voltage of 9v.
Voltage regulator converts to dc.
My best bet is: The RF shield got dislodged somehow and shorted the pins on the cassette port. Since first thing you did was rip off the RF shield, that's your short gone!
Next time you want to check a potentially shorted board, PLEASE consider using the “dim bulb” tester method using a incandescent bulb instead of the fuse. If it’s a dead short, the lamp will be at full brightness. The bulb serves as a current limiter.
Oh my God this brings back memories. At the beginning of my career I worked for a school board reparing c64s Apple TVs pets IBM PC XT AT. I'm happily retired now but it brings back a lot of memories I used to have a big tin I would throw all the bad commodore 64 chips into It weighed 2 lb eventually after a few years. I remember ordering certain ICs from commodore 50 to 100 at a time and that would last a couple months. The build quality on those things were terrible. I can still smell the tobacco scented solder we bought and the sound the plastic solder sucker made. I must have replaced thousands of chips in those things. Also repaired 1702 monitors 1541 floppy drives wow what a flood of memories. Thanks for the vid. It made me smile. The hardest short circuit on a c64 was the easiest and it was a solder splash from the grounding for the RF shield onto a scratch Vcc trace.
New Patron Dave Plummer? Is that the Dave Plummer from Dave's Garage?!? If so, that's very cool to see him contributing to retro-youtubers.
Your ZIF 64 doesn't have an RF modulator, so that would explain its lower power draw.
It has my RF modulator replacement, woo
rf modulators shouldnt take much current, few tens of ma at the most, certainly with the UM1233 and UM1286
Strangest thing, each time Adrian said “bridge rectifier” I saw a white flash and hypnotic eyebrows moving around.
I kept hearing this Middle Eastern accent for some reason...
You could use a lamp instead of a fuse/wire, when shorted lamp will glow.
Right
I use a nail.
FWIW I used to work on telegraph systems with +/- 80v signalling current. It was not uncommon to short either to ground or to the opposite polarity. If it was a fused supply we would have been constantly changing fuses. Instead we used a ballast lamp whose resistance would increase with current. It also glowed to show a fault, much like your suggestion.
yep, its a very good idea when troubleshooting
Shango066 does this a lot when working on TVs
The instant I thought "be carefull buddy", you went ouch. Happens to us all.
"Super mini mailcall" - 30 minutes 😂 Everything as usual.
I like to see what a "mega mail call" would be like! 😁👍
This is golden
One might argue that it's because it's about one item or two, which normally is, but then the previous one had 6-7, so not always that either!
My VIC-20 blew fuses one after another when pressing play on the tape drive. I got tired of bringing it back to the store for fuse replacement, so I just drilled a hole in the tape drive and powered the motor with a wall transformer through a toggle switch. It worked great. I was 12.
When I'm dealing with something that keeps blowing a fuse, I hook up a circuit breaker (you can get at DigiKey, Mouser, etc...) and that provides the additional protection plus you don't burn through fuses :) I use Alligator clips like you have, but I have friends who used an old fuse and just soldered the legs of the circuit breaker to the fuse body so it plugs in just like the fuse does. That works fine if there is a lot of room. I keep values 1A, 2A, 4A, 7A, and 10A. So if it's a 1.5A fuse, I can use a 1A or a 2A depending on how much risk I want to take.
Dang good idea!
Brass rod.😁
Looks like you had some kind of metal clip on your bench you were putting the bare PCB on top of.. glad that didn't short anything out!
Could be the use of fast-blow fuses (Denoted by an "F" before the amp rating) versus slow-blow (Denoted by a "T" before the amp rating), as some fast-blow fuses will pop on powerup if the inrush current is too much, which is where there ought to be slow-blow fuses fitted...
Came here to say the same thing. Had a friend who kept blowing the fuse on a VIC-20, and it turned out to be this exact problem.
Yes, indeed. The smoothing capacitors will initially draw a hefty current as they are fully discharged, and the current will drop once they are charged up and the only thing drawing any current is the circuit; and this initial surge can be enough to blow a fast-blow fuse rated for the current drawn in normal operation. For the best protection you really need a slow-blow (T) fuse upstream of the rectifier (to protect the power supply in case one of the diodes fails short-circuit) and a second, fast-blow (F or FF) fuse downstream of the smoothing capacitor. But on a complex board, you can run into the same problem again with the combined charging current of all the little decoupling capacitors; so you either have to split up the power rails and use separate fast fuses for different sections of the board, or just rely on the fact that in the event of a fault, just by conservation of energy, all that current will necessarily be flowing through the slow fuse and it will eventually blow. The question of whether or not the slow-blow fuse provides sufficient protection on its own is then a matter of whether or not the (non-faulty) rest of the circuitry can withstand the upset on the power rails caused by the fault for longer than the fuse takes to blow, without permanent damage.
I've worked in a job where we more or less used to have to do exactly that; we were making safety-critical controls for gas appliances, and they had to be constructed in such a way that no matter what fault occurred, there was no way to create a dangerous condition, even if a second fault were also present. You could rule out certain combinations that would be impossible (such as one set of contacts in a double-pole relay changing over completely but not the other; although you _do_ have to consider the normally-closed contacts opening but the normally-open contacts never making, because that definitely happens in real life if a relay is faulty or some power supply problem prevents the coil magnetising fully), but the type-approval rests on your proof, and you can get into a whole lot of trouble if something goes boom after you swore it wouldn't.
I can't wait for you to do a video on that sweet little MPS-803 printer!
Or make music with it, that's always fun
If it's a Soviet PLA, it should be able to install you.
Install _us,_ comrade.
Install it in our air
I’m reminded of a fuse problem I had. When I was in my mid teens, back in the early eighties, I managed to buy a second hand VIC=20. It was often blowing its fuse (and I think I did jump it for some time - blush) I did eventually (maybe a year or two?) find the cause - a DIP switch in its 8K RAM pack had ended up centred (neither properly on nor off).
Seeing this mail call brought back memories - although obviously not the same cause 😊 Really gained most of my practical early 1st-steps BASIC programming experience on that VIC and I loved it.
A DIP switch in a VIC 20? 🤔
@@christianlarsen1070 In the selectable RAM expansion board and not the mobo.
@@christianlarsen1070 In the 8K RAM Pack rather than the VIC itself - presumably to configure where it appeared in the memory map. I assume with some kind of expansion bus it’d be possible to have more than one.
First computer, MK14 with 256 bytes RAM… 2nd, VIC=20 with 5K RAM + 8K RAM Pack… current machine have gigabytes - unthinkable back then!
Oh hey! I know that printer model! Inside out one might say 😸 - the blue part is actually one part of the guide inside the printer, so you can "thread" it without getting your fingers dirty. You can see that the cartridge is much smaller than the actual loop it needs to make.
Nice gift. Even if nothing else works the pal vic2 is awesome to have.
Pretty funny to see a windows error box pop up when the 64 booted 22:26.
BTW, you always scare me by removing and adding chips with the power and monitor cables plugged in. Even with switch off it's a dangerous practice.
Interesting that you mention the ceramic capacitors. I had a similar fault on a C64 I was working on.
Generally my OCD will cause me to straighten the ceramic capacitors on any board I work on. Looking at all those 104 caps laying on their sides triggers me. Finding shorted capacitor leads somewhat justified my obsession about "fixing" them! :-)
I'm glad I'm not the only one that likes to line them all up nice and straight when I work on a board. The A500 motherboard has some great ones to line up in the back.
The problem is, those leads really cannot take being bent more than MAYBE once or twice. So there's a half-decent change they'll just break off when you go to straighten them back up! Unless it looks really bad or it might be causing an issue I try to move them as little as possible. Or just remove them and put new ones in.
Personally, I prefer the PAL version of the "8-Bit Dance Party". I think of it almost like comparing music recorded in 432 Hz vs 440 Hz that the music industry uses.
I recently got an old C64c (I wish I could remember what happened to the one I had that I got new when I was younger) and I am kind of glad it did not come with a power supply.
Printers are generally #4 & #5 on the IEC bus addressing. Always removed the SID on C64 boards when diagnosing issues. They are getting hard to replace with original parts. If you open the ink carts for the printer you'll find a small sponge, re-ink that and it will re-ink the cartridge.
I think the 8023 could also print as #6 and #7.
Oh my goodness, I so enjoy your "filing cabinet wall of stickers," Adrian!!! I may steal that idea from you!
At this point, it's easier to find and buy a C64 with a working SID than being able to buy a RPI4 :)
Well, if you buy a starter kit you can find RPI4s all over the place... at least in Denmark. ;-)
The RPI3 still makes a decent Retropie machine.
@@bsvenss2 I haven't been able to buy any RPIs at msrp in Canada for over a year... Scalpers are selling RPI4 for $300+
@@bsvenss2 Availability is not the issue, pricetag is the issue.
@@MrHurricaneFloyd An old small business PC is cheaper at the moment and far more capable. Rpi4 is going for over $200 here in Canada in listings, then higher when you make an offer.
The spacing issue for USSR chips is the stuff of legend. According to the lore, the Soviets used 2.5 cm as their inch equivalent, making the spacing 2.5 mm instead of the correct 2.54 mm. This sort of works for 14 pin dips, but for chips with higher pin count which the Soviets bought in the west and smuggled into the USSR, they simply wouldn't fit on the Soviet made motherboards.
Edit: To clarify chips produced in the west had a pin spacing of ten pins per inch, it was an American thing.😁
Not sure if it has anything to do with smuggling, but the 2.5mm pin spacing is true.
@@Colaholiker OH, the Soviets did buy up advanced chips in the "west" during the 80s and I'm fairly certain that some of those chips had export restrictions on them, so moving them to the USSR was de facto smuggling. I have no idea at what scale they illegally imported chips but from what I understand computers were rare in the Soviet Union.
@@OscarSommerbo But if the West had export restrictions, which I can imagine, why should the USSR, who wanted the forbidden fruit, want to use a different pin spacing? It's not like western countries wanted to steal Soviet technology. 😅
I think it was just too "American" to use 1/10 inch, but staying in the general scale was practical, so they went metric.
@@Colaholiker The way I heard it, again I have no idea of the truth of the story. In the 80s it was fairly common to convert one inch to 25 mm as it was "close enough". I think I learned the "real" length when I was 13 or 14.
So the Soviets designing computer components used the inaccurate 25mm for inch, by mistake or out habit, rendering a lot of hardware unable to fit western chips.
So the reason was most likely a common mistake.
It was Metric vs Inch standard.
As a temp fuse replacement you can clip in a 12v automotive lamp (1156/1157, any 12v single element, etc) across the fuse. If there's a short the lamp will just go to full brightness. If it's actually 9v you might be able to find a lamp that is closer in voltage.
yep, bulbs are good current limiters, i use them all the time, you can make simple 'constant' current nimh chargers with them , i once rigged up quick n dirty trickle charger using a 25w pygmy bulb, with BY127 in series off the mains, it was only me that'd be going anywhere near it and i knew what i was doing..
I've used a small piece of solder as a temporary fuse in this scenario. Safer than a jumper wire, should blow before any component damage occurs.
a filament bulb is a good current limiter
The action starts at 8:50. I enjoy your diagnosis and repair!
It could also be the wall voltage at his location. I've had several calls over the years from early HP Imagewriter (4, 5, 6) users whose printers didn't work. One office location had 85V coming outta the wall, and another user had the same thing in his house. Wouldn't work in his bedroom, but would work in his kitchen and livingroom. The fuser in the model is finicky and needs 120V.
My main C64 is equipped with an Ultimate 64 motherboard due to all of the repairs I've had to do to my other OG hardware.
The Pi option is better with a Pi3 A or B than a Pi4.
Pi3 is still very capable even with just 1GB of RAM. That is probably why purchasing a used one costs near as much as a low RAM pi4.
Oh Adrian, you silly silly boy! You didn’t check for the short before trying to repair the bend in the PC board. It’s quite possible you (unintentionally) fixed it by bending it back into shape. Maybe there was an internal short on the ground/power plane due to the bend? 🤔 Or maybe the fuse WAS too small. I guess we’ll never know now.
My bet is on bad power supply. There are a few reports of that same behavior around and I had the very same happen to me, tested on 2 systems with multiple fuses, with a brand new Keelog supply. Poof! Every time.
He assumed the bend was due to the shipping and could therefore not have caused the shorting. Seems like a reasonable assumption.
@@espressomatic interesting, I'd have thought that when it comes to AC voltage can only be zero if the coil breaks - not higher. Do we know what voltage that faulty PSU was outputting?
It's just double layer board, so if there's short of the trace, there'll be actual visible crack on the surface
@@danny8376 yeah
That's what I was afraid of, was that he'd bend it in place and then Crack a trace open
For a moment we feared that the video would end without the reglamentary Adrian's *8-Bit Dance Party!* test 🕺🏻 (26:53) 😅
Nice job with the diagnosis and resurrection of that venerable board! 👍
That reworked socketed chip is not a ram chip. It is U8 by memory and is 74LS06 a buffered hex inverter (not gate) chip. It is hard to find on the schematic because the six inverters are used in different places all over the 64.
00:19 Great 90s song by Jennifer Paige "Just a Little Crushed" 🤣
Maybe the old RF-Shield (or its clamp) did short the mainboard before?
My guess is a 300mA (or so) fuse was used which wouldn’t blow on a ~250mA computer but did blow on this ~330mA example. But your 1.5A example is giving it plenty of room. Just like you said. Eager to see this patron’s comment for confirmation. (Algorithm engagement!)
Could also have been a fast blow fuse. The big capacitors on the C64 mainboard cause a lot of inrush current. Especially if you use an 1A fuse, it should be a slow blow fuse.
More likely to have been 150mA. At least the digits look similar. It happens.
I made sure the fuse was the correct A. It wasn't the first time it blown it however I have no Idea if they were fast or slow blow ones. I also can't really check as they have been trashed moths ago (the package was sent out February).
@@danielmantione oh, yes! I wasn’t thinking much about initial capacitor charge as an issue. That makes total sense
@@krissy_h7854 fair enough! Thanks for replying here so I wouldn’t have to be checking back on the video! I totally understand how it is to not be sure of the details after this time, haha. Perhaps it was gremlins :)
IPA, at any concentration, shouldn't damage the plastic surface of an LCD. In my experience, it also won't clean it effectively. Your screen cleaner is probably 50-50 IPA and water. That's the long-recommended cleaning solution, and I've found it works well on most dirt that ends up on LCD displays.
Wauw... that package got Aced (Ace Ventura'ed)
I remember doing a school assignment on my friend's C64 in GEOS and printing it out on one of those printers when I was around 12-13 (I think...)
That package has literally been ran over by a truck.
My money was on a short (possibly a solder blob, the cassette transistor or one of the caps touching a lead they shouldn't) that got unbent either during the mashing it got in the post or while you were straigtening things before you straightened the board and started testing for shorts. A bad PSU would have to have been putting out a lot of voltage to blow the fuse, which I would have thought would have done damage elsewhere.
Greetings from Slovenia to you too :)
Interesting, I had a 1989 Commodore 64 C, which right after the warranty was expired, started blowing the power supply fuse. I don't remember anymore if it blew immediatly after connected to wall socket, or only when the computer was started. As the PSU is potted, there was no alternative, but to buy new PSU, and then the computer worked again. If I recall correctly, the fuse inside the computer did not blow.
I feel so lucky to have my original two-prong VIC20 (or VC 20 as it is called in germany) and my C64 breadbin still working. As for safety I recently bought some new PSU. Switching on these machines brings such good memories to me.
shouldnt be possible for the 9v to give trouble as its straight off a 50/60 hz transformer, 5v is a different matter, you could wire a 5watt 5v6 zener across the 5v line in the computer to clamp any overvoltage
I have a BMC64 running on a Raspberry Pi with a box with 2 joyports and a connector for my C128DCR keyboard attached to the GPIO of the Pi. I'm looking for an old C64 (breadbin preferably) with an intact keyboard but broken motherboard so I can fit the Raspberry Pi in it. Would love to see a development on the BMC64 to be able to use all of the keys of the keyboard in C128 mode.
The MPS - 803 printer was made by Brother. On seeing Made in Japan I thought of Seiko/Epson, but nope, it was Brother which had a similar model under their own brand.
IPA containing cleaners wont damage plastics nor monitor but Acetone will melt most plastics
While this is true, IPA may however damage surface coating on LCD screens. Some of the anti-glare stuff can suffer, but that is really down to the individual coating they used. In my experience, it is normally not a problem, but I wouldn't bet on it.
@@Colaholiker delaminating MacBook coatings…
IPA 'may' affect some plastics making it crack/craze, i've had it happen
There's a device that looks like a regulator (maybe it is one) up by the cassette port. It's not anchored and you must NOT press it down or anchor it. If it gets pressed down, it shorts the board. Maybe the keyboard wire pushed it down. Could be the fuse value was not correct (been there - Thought I picked up the right one). Could be that the power supply was bad (in which case the fuse blowing was a good thing since it reduced the possible chip death count). PLA? Heck we've got lots of replacement options for it now.
It’s transistor
yep 2SD880 transistor, i think, metal tab is at a 'live' dc voltage
One of my C64s has a PLA that developed a marginal fault about two years ago... it works perfectly fine, even with a 1541 Ultimate cart, but a few demos crash (always in the same place), even when running from disk. I put a heatsink on the PLA and now if I run the offending demo when the machine is cold, it works. The weird thing is that I'm expecting it to get worse, but it doesn't. The PLA is soldered in unfortunately.
Novice here. I see you testing the voltage regulators, but I can't see exactly how you are testing them, and what results you are expecting. I have a C64 that is blowing fuses, but I can't find out why. The bridge rectifier tested good, and no obvious issues are seen on the board traces. The previous owner had installed a Jiffy DOS modification with a reset switch that had a wire soldered to pin 3 on the user port. I removed all the mods and wires. But there is a small blob of solder left on pin 3 that I haven't removed since I'm concerned about how to do it and not damage the pin connector. I'd appreciate knowing how to test the VR's, and what I should expect to see in the positive and negative side of the results. Thank you for your great videos!
Great show! Funny that Louis Rossman uses draw current for diagnosis as a standard tool, and you never had to use it.
Newer chips have a tighter tolerance for how much power they should draw.
@@jeffsadowski I don't think that matters too much for diagnosis, if it's even really the case. First, current draw varies most with activity, so dependent on what is going on (is something trying to boot). Also if there's really a wider tolerance on older chips, it's still small compared to the difference in current drawn depending on activity. In this case, the current might have differed because the reference board didn't have a modulator or had some low power chips installed where the original used higher power versions.
I wonder if there could have been a physical short that got cleared when you un-bent the board?
99% IPA on LCD's is fine. You're thinking about Acetone. You don't want Acetone on anything plastic because it will melt it.
yep, you can use acetone to 'melt weld' certain plastics ..
Do 64's take slo-blow fuses and it could have been that?
This C64 is a true survivor!
28:45 "I'll draw a P on there for partially dead" - "let me pop a quick H on this box, this way we all know it's filled with hornets"
Ooh, if I was gonna put a Raspberry Pi in a C64 case, it's not going to just run a C64 emulation. I'd have that sucker running several operating systems.
You don't have a thermal camera? 100% the best way to check for a short and heat in general. Fingers are a no go.
I pointed my thermal camera at my screen and saw right away where your problem was ;)
Where can I buy the raspberry pi add on for the c64 case? This sounds super cool!
hmm did heating the board to un-bend it, marginally re-flow anything that might have needed it? glad it's working!
god all the board bending had me biting my nails waiting for the snap
I have an avermedia pro gamer plus 2 capture and it is the same way. Occasionally just doesn't provide a pic and can't be seen. But it has a switch on the front to switch modes on it and I just usually have to flip the switch to self capture back to PC and that gets it working in OBS again.
Question for you - I saw you check the voltage regulators, what is the proper procedure to test them when there is no power?
Cool, 8-bit Yoda did his magic again 🙂 Adrian, could you tell me more about that pla on the Soviet chip? Never heard nothing about it, seems very interesting.
Adrian's Digital Basement ][ Where did you get your parts drawer organize in the back ground? I need to get more that are bigger like this one. Thanks
Guess I'll keep checking back for Christian's comment. I really wanna know that board's story.
Your ZIF64 doesn't have an RF modulator, it also consumes some.
not a lot, though
I had a citizen c120d dot matrix printer very similar if the ribbon is a bit dry give it a quick square of wd40 work well
I wonder if he was putting in a 0.5A fuse and the power spike on turn on blew it. (?)
Breaks my heart to see bad packaging with the potential of damaging vintage computer gear...
@@MrHurricaneFloyd Definitely got dropped or something got dropped onto it, but you need to pack your parcel to anticipate this. A couple of layers of bubble wrap to seperate a heavy 803 printer from a motherboard is not good enough. Cushioning completely around the printer in the form of packing peanuts, maybe double-box the motherboard. As a guide, pack your items so that they will survive a 2m drop or a 20kg item being dropped on top.
better to have bad packaging than to get thrown out!
@@austfox2170 I have used thin plywood to box items for shipment. I was getting free 4' by 8' sheets from a truck repair company that had a few 1/4" holes drilled in them. Replacement roll up doors were shipped on them, to prevent shipping damage and they were under 1'4" thick so it was lighter than multiple layers of cardboard.
PAL machine on 60Hz likely has a single issue - the TOD clock (that you read from TI$ in Basic) is 20% fast. I don't think anything else syncs to the power grid but I may be wrong.
Maybe it's learned/instinctive response, but when you shorted the fuse, I could instinctively SMELL burning insulation. Even though nothing bad happened in the video, I guess it's a sign I've been in the trade too long😂😂😂😂
If you shorted a fuse, it wouldn't blow.
15:52 at this point i'd say that his trafo had a failure, sent too much volts, killed some parts (chips), now they're shorted, thas why it draws so much..
It is going to be the regulator would be the first port of call and I will leave you too it.
Is there a reason not to use the bench PSU on current limit to power the 12V rail?
Someday I need to see if I can figure out what's wrong with my Commodore 64. It started acting flaky some 20 years ago so I stopped using it. I safely store mine in a closet, as my attic gets HOT.
They're not too hard to fix, as long as you have alot of socketed chips.
Alot of times it's a pretty simple fix, even if you have to get a desoldering iron with electric pump, to desolder a chip.
That printer should be pretty easy to convert to 110/60. I’d be really surprised if it needs anything other than a transformer swap, unless there’s a motor which runs off of AC for some reason (which seems incredibly unlikely).
If it's transformer based, it might even have an additional winding for 110V operation
@@gigigigiontis8 Oh, that's a good point too! Yeah you might just need to change which transformer taps are in use.
why does it keep blowing fuses... going out on a limb here... because it is sinking too much current?! Asked and Answered! :)
I just fixed a c64 that was blowing the fuse every time I turned it on. The only thing I did was remove the bottom RF shield.
I also learned how to test bridge rectifiers and voltage rrgulators. Thanks Adrian.
Calling those ports IEC connectors was a little confusing for me, I've always heard the circular ones called DIN, and the standard computer / appliance power cables called IEC cables. Not a critique, IEC also has a spec for round pin connectors I just thought it was a little strange.
Indeed. They’re DIN connectors.
3:29 - that is not a RAM chip. It's U8, LS 7406 logic chip. Always errors, no quality control.
I never had one blow a fuse; although I had a 1541 with a bad fuse....the old boards may be unreliable but nothing replaces the original
Feed the board with a lower voltage, current limited and probe the board with a thermal camera ... that'll show the current consumer straight away! ... without releasing the magic smoke.
Hi Adrian, COmmadore Vic 20 and C64 PSU give 5vdc and 9v AC as well. SOmetimes the 9v ac goes out of wack
It's the 5V DC that goes out of whack. Especially if you use a newer VIC20 PSU on a C64, the 5V regulator can't take the extra load very long, but will burn out and then it can give anything between 6V and 12V which will cook especially the RAM chips quite fast. The 9V AC output can read a bit high or low depending your outlet voltage, but it is usually fine as it will be rectified and regulated for the parts that are picky.
You CAN use a C64 PSU on a newer VIC 20 no problem as long as you have checked the 5V is in whack.
Old VIC20 has just an 9V AC input and had all internal rectification and regulation, and required a roughly 30VA or higher transformer .
4:57 Too bad Pi's (at the original, normal prices) are unavailable until well into next year! :(
Is that fuse Fast ( F ) or Timed ( T )? Current spikes on powerup can easily kill fast ones while timed are fine.
What is that little LED TV thing next to your monitor? It’s been bugging me because I want one!
It is a Divoom Tivoo or similar, they come in different shapes and sizes
@@Ed64 Ah man, I should have known. I've got one of their little speaker things that look similar. Now I need to find all the Amiga Workbench graphics for mine.
The 9V AC getting rectified on the board? I didn't know that. Then why isn't it rectified inside the PSU just like the 5V? Does it have something to do with different voltages travelling from the brick to the machine itself close to each other?
22:24 - that got a really good laugh out of me, we're expecting a working or faulty machine, it starts up and right as it started it threw a little too modern error message, it seemed like :D
Yeah, on the early C64 boards, the 9V is used to create the +12 for the SID/VIC II but also a second 5v rail also used for those chips Supposedly a cleaner rail...So 9v is rectified, turned into higher voltage DC then run through a 7812 regulator for the 12v and a 7805 for the 5v.
And yeah, it's funny when I'm running full screen to see a mouse cursor floating over the C64 image. (Or errors!)
@@adriansdigitalbasement2 Doesn't the CIA chips use the 60/50hz AC signal for timing?
Congratulations You are first
@@DaveMcAnulty yes they do.
The 9V AC is used for multiple purposes: One is that it is present on the user port for RS-232. RS-232 user port cables can use the 9V AC to generate the +12V and -12V for the RS-232 line drivers. The second application is the CIA clock, which counts AC phases. And indeed it is rectified to produce the internal 12V, 5V CAN and 6V tape power tails.
Hello from Serbia. ;)
Are you going to send it back to Chris?
The only thing I really don't like about the Easy-Flash is that it is proprietary. I wonder if it has an ASIC in it?
They are open source. The original EasyFlash uses 74 Logic ICs, an SRAM IC and 2 Flash Memory ICs all Through Hole stuff. The EasyFlash 3 uses mainly SMD components but also uses a CPLD and is much more powerful and feature rich.
@@RacerX- I thought the hardware was open but the software proprietary.
It really blows having an undersized fuse ;-)
Question: is it possible your use of hot air caused an unintentional reflow of solder in those areas of the board that may have cleared the short? I see William Squires has already asked this question as I look down through the comments. It is the most likely reason the board is no longer shorted out.
My guess is his PS had too-high AC line. I had 2 different rev c64s, both working with known good PS. BOTH would blow fuses when powered by a brand new Keelog PS. Unfortunately by the time I figured it out, I also lost 1 SID and on the same C64 the screen is corrupted at startup now - haven't yet been able to figure out what else died.
After seeing the video this is my guess as well. Unfortunately I can't test it as I no longer have it.
shouldnt be possible for a 9v ac transformer to overvolt more than usual tolerances, unless made wrong, too high, to start with, or a 220v type used on 240v mains,
there's a disc cap bent over behind the serial port...
With Keyrah you can also use an A600/Keyboard as a Keyboard for Windows 😉😀
Or in with a Pi for emulation inside the case. That's cool, I didn't know
Keyrah is unobtanium. Someone show me a link to buy one PLEASE!!!
that point me out psu is overvoltage and cause feedback kick fuse cause it to blew out
that one reason i dont trust older psu because there no telling how much voltage is putting out it could ruined sin or pla chip
You can set this to music (I think you'll figure out what music on your own):
_I'm too hungry for this fuse_
_Too hungry for this fuse_
_So hungry you lose_
Is it weird my brain went to white wedding before "I'm too sexy"? Maybe