Commodore 64 Black Screen Triple Challenge (Part 2)
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- Опубліковано 5 жов 2024
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It turns out Commodore #2 had multiple faulty components, so I took longer than expected fixing it. It makes for an interesting investigation starting with unreliable socket on the VIC, a shorted kernal ROM, and a bad PLA. As a bonus I build a quick (and really tall) adapter to fit a 27C128 EPROM on the ROM slot.
Information on building ROM/EPROM adapters for the C64: ist.uwaterloo....
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some favorite mystery dramas of other people: CSI, House, Sherlock, etc - my favorite: Noel's Retro Lab. Noel is like a computer detective/surgeon . When he finds the culprit (or culprits) its always a victorious, "YES!!" moment!
Haha, thanks Fin! Glad you liked it! :-)
"It's not just a matter of swapping out chips until something works, I wanna know why" - exactly my attitude. I tend to find many people on forums just laughing at me because of that, I struggle to understand why. I love your videos, I like seeing the full troubleshooting without any major cuts. Well done!
I also believe we have the same eeprom programmer and it seems that you can get 12.7V eeprom after all - I was led to believe that those "windowed" chips were all 21V which the Xgecu won't support.
Nice that someone feels the exact same way I do about that. One of the good side effects of making videos is that it keeps me honest and really forces me to dig deep and get to the source of things.
As the years go by I'm finding that machines from the late 70s to mid 80s I fix tend to have multiple faults far more often. Our lives aren't going to get any easier the longer our patients sit in the attic:)
Great. Such a systematic and step-by-step approach. Very clarifying.
These are great videos
Thanks!
Love the schematic with the IC and probe point following the troubleshooting. Good work. Love it.
Long ago I repaired my C64 with together other 3 units (trying to learn a bit more about troubleshooting this things). This had no video, I took the VIC out and 2 or 3 pins on the socket were MELTED due to the intense heat from the VIC (we used the 64 to play games only). Just by removing the VIC and inserting it again I could get the system working I ended changing the socket and tried my best to source a better one. It was the same board as yours, with the copper finger on the cage that really does not help a lot. ALL the VIC I saw, are toasty as hell when working, even worse than the PLA. I recall reading articles in the arely 2000 about the VIC, it had a TDP of 2W and this package was not designed to make it. Firts ones were CERDIP ...... (I have one PAL C64 with CERAMIC VIC with the GOLD top) ... then COST REDUCTION was the name of the game.
Another great video with awesome skill in finding each issue!
Thanks again! Welcome to the Lab 😃
I only discovered your channel a few days ago but I already love the detective work, how you present things (the documentation inlays next to you testing things out). Subscribed, and looking forward to watching more from you !
Thank you so much! Glad you enjoyed it!
I Love your channel! You don't skip any step, go into every detail to find out what is going on and never give up, I like that!
You style and approach are spot-on, easy to follow even for a novice. I learned more on C64 troubleshooting, multimeter and scope use with this and the last video than countless hours spent reading troubleshooting guides on forums and am quite encouraged to tackle my own three black-screen C64s. Thank you!
Wow, thank you. That was my goal making these videos, so that's great to hear!
The step-by-step troubleshooting with excellent narration is really interesting. The text caption comments are great (and often entertaining 🙂).
Really glad to hear that! Thanks!
Your multimeter has a Hz setting that can be used to check your clock signal. While it is not perfect, it would give you a look at the frequency vice a voltage.
I forgot to mention in my comment on #1 video that I liked your idea of individual heat sinks on each of the important ICs.
Brilliant and really a pretty difficult one. Nice equipment in your Lab! Best regards.
Thanks! I actually try not to spend too much on equipment. Just enough to get the job done. The oscilloscope is by far the most expensive part, but even though it wasn't that bad.
Excellent repair
this second repair is much more complicated.
Excellent search for faults
Thank you. Yes, this second one was a doozy because so many things were wrong and inconsistent. Spoiler: The third one is actually much more straightforward :-b
At 8:54, you probably meant "oscillator" and not "oscilloscope".
It happens all of the time with me, too... :-)
Hahaha, yes, definitely! I didn't notice it before (and nobody else did apparently) 😃
Nice sanwich you made with the e-prom
Asi da gusto con videos como los tuyos sigue asi
That's how nice it is with videos like yours, keep it up
Awesome content!
Thank you! Glad you liked it!
Wow, that was a hard one! Great job!
well done again👍
Great videos! Keep 'em coming!
Another great video! Thanks for sharing. Would you be able to provide a link for the EPROM burner you used? Thanks!
Thanks! I use the TL866II. It works great! www.autoelectric.cn/en/tl866_main.html
@@NoelsRetroLab Thanks!!! Much appreciated.
Thanks a lot, very interesting
A good thing for begInners would be a small dso138 oscilloscope kit, they’re fairly cheap and can really help with diagnosing. Or even an old analog crt oscilloscope, my 80s East German Osciloscope is still awesome and working
That's right, although the analog ones have a definite learning curve that a beginner might be frustrated with. I sometimes recommend a "logic probe" of the kind that just tells you high, low, or activity. That in itself can be pretty useful.
Again nice job dude....
What brand of IC Sockets do you recommend? I have a bunch of older ones that just look cheap to me (and half the ones on ebay look terrible as well) and would rather pay a little more for something that is reliable. Thanks :-)
Some people swear by the sockets with rounded holes, but I'm not a fan. They're hard to fit for some ICs, especially if the legs still have a bit of solder in them. I find that cheap sockets from Ebay/Ali work well. Just make sure they have metal on both sides (I think all sockets do these days).
@@NoelsRetroLab I believe the metal parts are called wipes, so one with metal on one side only is "single wipe" and those with metal on both sides are called "dual wipe". I'm not a fan of the round sockets either and always use dual wipe.
Your comment that the board had not been messed with previously may have been incorrect because half of the ram was Fairchild and half was Hitachi. That seems a little odd to me. OTOH, I've noticed that Atari's 800XL often will have 7 Micron Technology chips and one Samsung. What's up with that?
Commodore is notorious for mixing ram, mine has half ti and half hitachi
Just been given a breadbin c64, fixed a short on the onboard power supply so now doesnt blow fuses. Getting black screen, and U9 ram chip gets hot. Hopefully thats all it will need!
Quality im learning loads il tackle one one of these days
I could tell from just looking that the pin 16 of that socket was bent way too far in.
Yeah, if you look closely you can definitely see that. Good eye!
@@NoelsRetroLab Not bad for someone with bad eyesight xD
Hi and good day
Like you recommend a link for spare parts of commodore or another 8bits computers, now i was repair a Amstrad CpC128 and 464, and two ZXspectrum 48K, but have two C64 with black screen and not found chips spare parts. Agree your videos great info,
Thanks, gracias
Great video Noel, one question since I have a faulty C64.... I measured 6 ohms in the 5 v rail... and proceeded to remove overheating chips when turning on a strong psu. Is is ok 6 ohms in the 5v line? Also is there other way to find the short circuiting one?
Nm, it was a ram chip
@@mlorenzati Glad you found it! I don't know the exact resistance between 5V and ground, but 6 ohms seems waaaaay too low :-) Did that RAM chip get really hot?
@@NoelsRetroLab Exactly, after removing the memories (2 were in short circuit, the line when to 20K plus ohms. On my way to get new memories!
nice channel. got my sub mate :)
Awesome, thank you!
I'm curious, I don't see you using any ESD protection at your workstation. Am I missing something?
No, I'm not very good with that. I've been told I should get an ESD mat with grounding, but never got around to it. At least I don't have a carpet or other static-generating elements. What kind of ESD protection do you use? Just a wrist-grounding bracelet?
@@NoelsRetroLab Until recently I too used nothing other than frequently grounding myself on a grounded screw in a nearby light switch. That is until I twice in quick succession fried two joystick control ICs in my ColecoVision. So, now I have a two layer grounded ESD mat with a grounded wrist strap. The main reason I asked is that I was surprised that you weren't using ESD protection compared to the professional equipment and setup that you have.
That's what you get when you learn things on the fly like I did (instead of it being a real job with real training) :-) I will look into that more seriously now. Thanks!
@@NoelsRetroLab Well, you know much more than I do. I have zero training and am learning on the fly like you. Anyway, kudos to you - your videos are superb and your step wise methodology a huge boon for those like me who are trying to learn. Thank You :)
Sorry to be picky but the volt meter you use is called a mult-tea meter not mult-eye meter....