Second time I'd watch. You are great engineer. Did'nt use death test cart just looking whats going on on the signals and deducate what is wrong. PROFESIONAL man !

@iz8dwf

4 жыл бұрын

Hi! Thank you for the very nice comment! I've used some tests in other repairs, but in this case the faults were too many for any test to run (data bus conflict prevents any possible code execution for the CPU).

great video earned my subscription thank you. Improved my repair skills and only 2 videos in. Never seen a current probe before... very handy!

@iz8dwf

4 жыл бұрын

Hi! I'm glad you liked it! I'm always trying to come up with more content as time permit. Yes the current probe is a great troubleshooting tool! Thanks.

that board looks pristine!

Interesting video, thanks.

that is the first time that i see a current tracer. that seems very handy.

@iz8dwf

4 жыл бұрын

Hi! Yes, I've found it very useful in the repairs. It's used on some other of my videos.

The same logic ICs that failed in two black screens I fixed as well, one also had a 7406 failed. All were MOS branded. What is the diagnostic cartridge used, looks different from the kind I have?

@iz8dwf

5 жыл бұрын

Hi Tor-Eirik, actually in this video I used a simple game cartridge as part of the troubleshooting. I have a dump of a diagnostic cart called " C64 burn-in" that I load from disk. It was dumped sometimes around 1986. I believe it can be turned back to a cartdridge using a 2764 ROM mapped to $E000-$FFFF.

Do you know of anyone in the US who repairs the C64? I also bave a very stubborn black screen, but I don't have the tools/ knowledge for desoldering IC chips. The SID chip gets quite hot, but I don't think that would stop it from working at all.

@iz8dwf

7 жыл бұрын

Hi, the absolute master of Commodore repairs in US is Ray Carlsen, see: personalpages.tds.net/~rcarlsen/ You can also try the usenet group comp.sys.cbm to locate someone near you (if any). The SID chip usually runs hot even if it's good, if it's socketed, you can remove it carefully (if you don't know exactly how to extract a chip from a socket, don't do it anyway). The C64 can work without the SID installed, but of course it won't produce any sound. And yes, there're SID failures that can cause a black screen too (mostly shorted data and/or address lines).

3:30 - The nice MOS-Chips? In my experience the MOS branded 74xx logic chip replacements are much mor notorius for failing then normal 74xx from other manufacturers. they must have made them during the warming up of the production machines before the process was working good enough to make the "real" MOS-Chips. The only logic chips that are more notorious for breaking in C64s are the russian made ones (their package looks brownish and ugly).

@iz8dwf

7 жыл бұрын

It was mostly an ironic comment. And "real" MOS chips can have a high rate of failure comparable with the "logic gates" one. I've repaired quite enough Commodore stuff to think that logic gates (74xx equivalents) and other chips (ROMs, Custom chips...) fail at about the same rate.

@elektro-peter1954

7 жыл бұрын

You might be right. But the bigger chips have much smaller structures inside than the measly logic gates, so I think especially the MOS 77xx chips are especially crappy. I have repaired lots of that stuff over the Years, too. I don't see many broken 6510s by the way. Mostly PLAs, SIDs, CIAs and VICs in that order. Of course also ROMs if they are MOS-brand. The 85xx chips on the new C64 seem to be more stable. I see mostly bad RAMs on those. Of course the occassional CIA.... Nice work repairing that board! Keep the old machines alive!

@iz8dwf

7 жыл бұрын

Hi, thanks, I've made other similar videos with all the Commodore stuff I repaired, but I was also doing repairs (with no help from oscilloscopes and such nice things) in the '80s. I've quite a few boards with MOS logic chips that still work fine, so I really don't know. Might be different batches had high failures, might be process variations at some point in time. I collect all MOS chips that I substituted, but it's still a too low sample to draw any meaningful conclusion. CIAs are the winners, but usually they suffer damage due to things hooked on the various external ports.

Ciao Video molto interessante il tuo :-) Sto cercando anche io di riparare il mio C64 con il medesimo sintomo di schermata nera. Il VIC II scalda veramente tanto ma il segnale video arriva (no boot) dunque penso sia ancora funzionale. Una domanda per le tue misure fatte sulle TTL usi due canali con l'oscilloscopio?

@iz8dwf

7 жыл бұрын

Ciao, grazie per il commento! Come avrai potuto vedere in questo video (ma anche in altri: kzread.info/dash/bejne/lp6nu7COfrLRXaQ.html e kzread.info/dash/bejne/rHaglq-bh8andpc.html ), le cause di un black screen possono essere le piu' disparate e a volte anche piu' di una in concomitanza. Senza un minimo di strumentazione elettronica, si rischia di cambiare componenti a caso e si rischia di peggiorare la situazione. Se vuoi scrivimi e ne riparliamo: iz8dwf@amsat.org

How do u fix a issue with a controller port

@iz8dwf

3 жыл бұрын

Depends on the actual issue. But it's likely to be a CIA problem, unless it's paddle related (then it's likely a SID problem). I'd try swapping the two 6526 if they're socketed, but the question is too generic anyway.