I just started watching and I suspect after seeing the oscilloscope activity that you have a short between data line 7 and some other line on the system. Probably happened under one of those sockets when whoever owned this machine installed those sockets. I'm very curious to see what is the actual problem 😊
Nice, a disaster which managed to kill 2 CIA's, ROM IC's but the SID and the PLA survives, that's a first for me. And a quick question, what id that transistor looking mod on the ArmSID?
I have just finished watching the video in its entirety. I just want to thank you for the HUGE work you put into editing it and to clarify all the moments. I learned a lot from it.
I'm not surprised the ROMs failed with how poorly the system seems to have been treated. They are easily damaged if treated poorly. The PLA looks like it was already replaced with a more recent one so I expected that to work. The pin replacement on the 8701 clock IC looked dodgy, but the fact you had video means it likely was working. The other ICs being bad in weird ways was quite unexpected, but it seems like this system has been through the ringer... or washer and back? Fun to watch, but I'm sure it was quite the session of debugging.
Great video! What a conglomeration of faulty chips. Great job troubleshooting along the way. I'm pretty sure I don't want to know how much time you invested in that board. :D
Wow, a rev 425 board that doesn't have all the big IC's socketed from factory that's different. I thought commodore only went back to soldiering the IC's with the rev 466 they made after the 425 as a cost reduced long board model.
an actual useful testing mode for a test cart would actually be just toggling a selected address line every 500ms, same for a selected data line, so that you could "relaxedly" check the logic levels for each line with a oscilloscope... Maybe that would only be possible with some sort of test module that replaces the 6502...
Hi, nice work, could you possibly give me the link to a 250407 board? So I can test my traces. I forget the website. This board is driving me crazy. Dirty one flash, and kickman is garbled. All ram and logic chips replaced and tested. I must have lifted a trace somewhere. The only chips I have left to desolder and test are the cias, and basic and character roms.. 4 bad ram and 2 bad 257s.. everything else tested good. Any thoughts would be much appreciated:)
I just added a link to bwack's 250407 replica in the description. If all the traces check out ok, I'd suspect the ROMs next. Even though the dead test, and ultimax games like kickman do not use the ROMs, if one of them is messing up the data bus, then you will get flashes with the dead test. You could always cut the pin for that data bit on each of the ROMs and test again. Saves removing the entire chip, and you just reconnect the leg with a bit of solder. 1 flash would indicate data bit 7, so that would be pin 17 on each ROM.
Well... all roms are good, cias.. everything is socketed and tested a few times. Still one flash... well, I didn't try the 556 and the 2 4066 chips. Yet. Voltages are all good. I spent 3 hours yesterday testing all the traces.. maybe I missed something , idk. I'm loosing my mind is correct. Lol. The only bad chips that were originally on the board was 4 rams and both 257s. I've fixed a couple dozen of these in the past but this one definitely has me. (Happens to the best of us indeed) gunna leave it alone for a while. But if you have any thoughts would be greatly appreciated. Probably still a trace somewhere I'm guessing. I guess if I didn't do everything old school and I had an oscilloscope... lol. Anyways love all your videos.
@donaldblakley6796 hmm don't know where to go from here. Looking at bwack's interactive BOM, I can see D7 goes to the CIAs, ROMs, CPU, SID, VIC-II, and the ram at U12. Could be a broken trace between those somewhere, or one of them is still faulty.
Maybe someone's power supply brick failed and fried all those chips at once?
Definitely plausible
I just started watching and I suspect after seeing the oscilloscope activity that you have a short between data line 7 and some other line on the system. Probably happened under one of those sockets when whoever owned this machine installed those sockets. I'm very curious to see what is the actual problem 😊
Ah I was so wrong! That was a ton of bad chips, wow!!!
Nice, a disaster which managed to kill 2 CIA's, ROM IC's but the SID and the PLA survives, that's a first for me. And a quick question, what id that transistor looking mod on the ArmSID?
It's a 3.3V regulator, I managed to kill the original one on the armsid putting it in a pla socket.
I have just finished watching the video in its entirety. I just want to thank you for the HUGE work you put into editing it and to clarify all the moments. I learned a lot from it.
ooh... a missing ground will or course be the cause of a total random behavior!
Great work in repairing this c64! SiD sound drunk at 46:00 😁
Dang man. Great job.
Wow! What a lot of faulty chips. What is amazing is that the SID survived since the 6581 is so prone to failure. Nice Work!
Great work and result!
Are you a kiwi? I sense our ‘accint’ there 😊
ua-cam.com/video/6D5lEtKFC-M/v-deo.html Sounds like one of Kraftwerk's earlier, more challenging albums.
I'm not surprised the ROMs failed with how poorly the system seems to have been treated. They are easily damaged if treated poorly. The PLA looks like it was already replaced with a more recent one so I expected that to work. The pin replacement on the 8701 clock IC looked dodgy, but the fact you had video means it likely was working. The other ICs being bad in weird ways was quite unexpected, but it seems like this system has been through the ringer... or washer and back?
Fun to watch, but I'm sure it was quite the session of debugging.
😢😴🍪
🛌
Great video! What a conglomeration of faulty chips. Great job troubleshooting along the way. I'm pretty sure I don't want to know how much time you invested in that board. :D
Would Evapo-Rust do the job for this sort of thing? Derust and then wash? Seems like a better choice than a contact cleaner.
The character ROM is not completely bad, it has a single bad bit.
Wow, a rev 425 board that doesn't have all the big IC's socketed from factory that's different. I thought commodore only went back to soldiering the IC's with the rev 466 they made after the 425 as a cost reduced long board model.
Love the use of the F word, absolutely needed :)
1rd
That is one cursed C=64.
Hello is this the 8bit guy?
an actual useful testing mode for a test cart would actually be just toggling a selected address line every 500ms, same for a selected data line, so that you could "relaxedly" check the logic levels for each line with a oscilloscope...
Maybe that would only be possible with some sort of test module that replaces the 6502...
That would be nice, but yeah not sure if it's possible. You'd probably need to get the VIC-II to "agree" to such a thing
It's a haunted C64!!!
What a rollercoaster ride
"What the F....". Love it..
What a journey!
This is why we need chip replacement projects like ARMSID or Kawari.
I appreciate that you thoroughly explained your troubleshooting mental process
"Hardest, yet most satisfying..." > Don't say it, don't say it, don't say it...!!!!.
Very enjoyable and educational video, the use of F word is very funny too.
Very good fault diagnosis! Thank you for the very good insight into how far a repair really can go!
"ground, ground, that's not ground" would make for a good tshirt.
Great video mate. Tons of dead chips.
Back to the past🔥
Hi, nice work, could you possibly give me the link to a 250407 board? So I can test my traces. I forget the website. This board is driving me crazy. Dirty one flash, and kickman is garbled. All ram and logic chips replaced and tested. I must have lifted a trace somewhere. The only chips I have left to desolder and test are the cias, and basic and character roms.. 4 bad ram and 2 bad 257s.. everything else tested good. Any thoughts would be much appreciated:)
I just added a link to bwack's 250407 replica in the description. If all the traces check out ok, I'd suspect the ROMs next. Even though the dead test, and ultimax games like kickman do not use the ROMs, if one of them is messing up the data bus, then you will get flashes with the dead test. You could always cut the pin for that data bit on each of the ROMs and test again. Saves removing the entire chip, and you just reconnect the leg with a bit of solder. 1 flash would indicate data bit 7, so that would be pin 17 on each ROM.
Thanks buddy:) I appreciate the help. Cheers
Well... all roms are good, cias.. everything is socketed and tested a few times. Still one flash... well, I didn't try the 556 and the 2 4066 chips. Yet. Voltages are all good. I spent 3 hours yesterday testing all the traces.. maybe I missed something , idk. I'm loosing my mind is correct. Lol. The only bad chips that were originally on the board was 4 rams and both 257s. I've fixed a couple dozen of these in the past but this one definitely has me. (Happens to the best of us indeed) gunna leave it alone for a while. But if you have any thoughts would be greatly appreciated. Probably still a trace somewhere I'm guessing. I guess if I didn't do everything old school and I had an oscilloscope... lol. Anyways love all your videos.
@donaldblakley6796 hmm don't know where to go from here. Looking at bwack's interactive BOM, I can see D7 goes to the CIAs, ROMs, CPU, SID, VIC-II, and the ram at U12. Could be a broken trace between those somewhere, or one of them is still faulty.
@@TheRetroChannel I just found that pins 3 and 4 are connected with my continuity tester on every ram... wtf