Fun fact: You *can* use a new 5V VIC in older-revision C64s which expect 12V VICs. Bend away pin 13 (so it does not receive 12V from the socket, this would roast the chip) and feed 5V from the other supply pin via a short wire. I received a breadbin C64 with an old 250407 mainboard with that hack having been installed - apparently the old VIC was defective and only a new VIC was available for repair.
I just did that on my Breadbin, but I decided not to do any mods to the chip itself. Instead, I removed a ferrite bead that carries the 12V to the VIC-II, and tapped 5V from another ferrite bead that then is bodge wired to the VIC-II end of the removed bead. Et voila, a happy, untampered VIC-II 8565, and an easily reversible mod to the C64.
I actually threw a 5V VIC into a 12V machine once not realizing they were mismatched. Got a black and white picture. Eventually I figured out the problem and did what you said and surprisingly enough the chip worked just fine, not at all roasted :)
I didn't know that the vic2 chip had different voltages between revisions. Love the brown keyboard in the cream case . Your Phillips monitor looks brilliant 😋 nice vid Jan as always😋....Kim
Yes, I should have mentioned that indeed... It's kind of implied by the voltage difference I'm talking about but I definitely should have made it clearer to save some poor VICs...
Don't know the history of this machine, but the other day I saw an ad in a swedish magazine that advertized an upgrade to a 64C from an old breadbin. You could bring the machine to them, they would then replace the case for you. Given that it was a licensed vendor I assume they also could have added a new warranty sticker.
Really nice and informative video! As all your videos. Thanks to you and Periphrastic, I got back the wish to fix my old commodore and acorn machines :-)
Thanks! My theory is that someone repaired this C64 and used an old breadbin board for spares (the CPU also most likely came from that). Obviously whoever did it wasn't aware of the voltage differences.
www eigenwereld .nl its a dutch website about geek/nerd culture from games, comics, tv shows, music, etc etc and afcourse retro gaming and older systems As a old C64 and Amiga owner i realy enjoy showing people video's like yours and retro man cave to people who never had the privlage of growing up with them. I wish i had the space to buy them again and play with it. But i do have a raspberry pi i know not the same but a nice alternative i gues. Any way thank you for making this videos, and i am realy impressed of your knowledge of this older systems :)
Commodore did some strange things. I just bought a 1541C off a guy and it has a beige case with a brown drive and he said that's how it was when he bought it new.
just a little reminder for a request: to show the difference between earlier and later sid chips with the sampling playback differences they had, and a little bit about the workaround. as a c64 owner i remember reading this at the time, but i had an earlier 64 so i had no problems, so never knew the reality of it
Yes! It's still on my list (like a lot of other things). I will eventually get to it. Sorry it takes so long. Now that I have a working short board/new SID machine, I can try the SID fix soon.
Thanks! Yeah, they did a lot to cut costs. I don't think it was in production for long, though. It feels a lot flimsier compared to the "proper" C64C cases with screws and keyboard standoffs.
That's interesting. I've never seen a C64 (and I have 21 of them) that had a warranty sticker on it aside from the large square serial number sticker which mentions a warranty. And last night I found out that one of my C64Cs has a regular C64 motherboard in it, based on what the service manual says about board revisions. I never knew that.
Yes, the first C64Cs had 250425 boards, then 250466. Both "long" board revs. The ALDI C64 in mid 1987 was the first one to have a short board according to my research. I think the warranty stickers might be a German thing. I've seen a lot of warranty stickers from resellers, too.
fortunately you had a spare chip but it might be hard to acquire a new one for your spares collection since I think most C64 chips are not manufactured anymore. I hope people with dead and still half-populated C64 boards will think of you and send them to you.
I have a small collection of spare chips and two spares boards for C64s. They are getting rare indeed. I hope there's going to be more modern replacements in the future to keep the old machines alive. The original ICs won't last forever.
First time i tried a dead-test / diagnostic cartridge i was like "holy hell, everything is broken", then i learned about the harness. Ironically, the CIA chips that appeared broken in the computer i tested first - were actually both broken.
The Amiga had fortunately 2 CIA but I never had a C64. With Amiga it was simply swapping to know which one was bad. These chips are probably directly connected to the outside world. Like a printer or disk drive with the Amiga.
If you use a 656X VIC-II on C64c boards, there won't be a display. If you use a 856X VIC-II on the old boards then the 12V on pin 13 will destroy them.
How could possibly has this C64 ended with a wrong vic? somebody just throwed some random pieces together (keyboard, VIC, case, etc.) just to see what happens? :D Sometimes i'd love to know the history of some pieces of hardware that come to my hands, because once in a while a weird piece like this appears. I once found a casette tape in a garage sale where the tape itself had been removed and replaced by a circuit that, when put into a casette player, played a sinodal wave of a given frecuency. Who did that and the purpose of it remains a mistery to me.
My guess is somebody tried to repair it and only had an old board as the source for spares. Obviously whoever did it didn't think about the voltages. I kind of love these little obscurities. :)
that cassette is an alignment tool, you put it in and press play then adjust the tape head till it is spot on. of course since you dont have prior knowledge or instructions for it, you would have to run the output from the tape through either an oscilloscope or a spectrum analyzer using a tape player that was set correct, then take a snapshot of the correct sine, setting it up would be a "faff" maybe even a pain, but once you have your snapshot and a set of leads you could setup any tape drive.
Pretty interesting how frequently the RAM on the newer boards fails. I would have thought the newer ICs were a lot more reliable but it is a very common fault.
Ah, it's nice to have a simple fix once in a while. You were on-the-ball to spot the 6569 VIC-II on the board. Was @_Scoosie_ aware of the incorrect VIC-II version before sending this donation? What other goodies did he generously donate? *rubs hands eagerly*
Oh, there was a lot in there. Disk drives, another C64, Amiga peripherals, power supplies, etc. etc. Mostly bought as "untested" from ebay, I think and passed on to me because of the lack of time to go through it and repair. ;) I think @_Scoosie_ didn't know about the different VICs before.
Anyone else hear the high pitch CRT noise about 10:40 in? My other half says i'm deaf, but I can hear my old CRT monitor making that high pitched noise (and the buzz that some light bulbs/chargers make). I shouldn't be able to at my age apparently.
@@JanBeta haha yeah, I've not picked up my bass in a long time! I'm 32 tomorrow, so technically I shouldn't be able to hear it either at my age. Odd that I can anything as I loved loud music when I was younger. Black metal at that.
please help me i ahve a commodore c64c black screen , i opned it up and found a blown diode , i have replaced it but its still showing black screen please help
Yes! The VIC-II can easily be destroyed if you put it in the wrong way. There is a little notch on one side of the chip that you have to line up with the notch in the socket and the marking on the PCB.
I have a breadbin ASY# 250407 Rev B board, it seems fine when powered up, can type a little program and run. When I put a cartridge in it, it goes black or garbage screen. PLA has been replaced, VIC II and SID have been swapped in to working machine, all okay. Any ideas?
Mh, that's odd. Is the cartridge known to work? Did you clean the cartridge connector? I found that it's often just a bit of smudge on the edge connectors that prevents stuff from working properly.
Hi Jan, yes a good Cynthcart and a diagnostic cartridge. The Cynthcart comes up black, diagnostic comes up with garbage, blue border and all. I'll look at the edge-socket closer. But have a true dead-test cart on the way. Also removed SID and did these tests - great Channel!
The OCD person inside of me cringes to see that torn-off cardboard under the short board. Seems like you'd get better convention cooling by taking that out, right?
Actually it's useless, i remove pretty much all cardboard/metallic "shielding" from the computers i own (have a pile). Some say it's for cooling, but it have no noticeable effect, and the metalic pieces that descend down above processors are for airflow to be able to reach down. You're better off with modern silver paste and heatsinks. Metallic cases was to reduce the processors "spraying signals" around and for FCC compliance.
Well, since people have reverse engineered the SID chip (SwinSID) and the PLA's (PLAnkton amongst others), i'm sure there will be new VIC chips and others too.
Yes, I usually take them out. Their only purpose is to shield the outside world from the RF noise the machine produces. Which doesn't matter to most modern stuff (unless you want to listen to AM radio or something like that). Airflow should be a bit better without it (top part is more important for that, though obviously).
Jan Beta, I din’t now that the VIC-II use 5v on the pin where normally 12v is connected. So you can damage the IC if you put a VIC-II in a older C64 mainboard.
