Commodore 64 Black Screen Triple Challenge (Part 1)

[@bobingabout]

A dry joint, and a timer chip. I never would have guessed that.

[@PedroDelgadoWeb]

Excellent video - a step by step logical debug of the problem, excellent presentation, quality editing and lighting - this is what KZbin should be about :)

[@NoelsRetroLab]

Thanks so much!!

[@bradnelson3595]

This is an underrated channel. I've got an old, non-working 8-bit computer on the back shelf. I think if I watch a few more of these videos, I might be able to tackle it.

[@NoelsRetroLab]

That's my goal! If by watching some videos you're encouraged you try it out yourself, my job here is done 😃

[@charlybrown9024]

Great. Such a systematic and step-by-step approach. Very clarifying.

[@SobieRobie]

It's good idea to add Part 2 on the End Screen - this will help people to continue watching and will maximize the reach.

[@w4twa]

Hey thank you for this series. I’m troubleshooting my 64 now. I appreciate you showing the scope waveforms because it helps me know what I’m looking for with my scope. Also, the info you gave about the 556 and how it should operate along with cpu, helps immensely.

[@NoelsRetroLab]

Glad to help! Good luck with your repair.

[@brianp415]

I've watched a lot of c64 repair videos lately while trying to repair a few c64 I rescued. This has to be the best one I've seen!! I find the other 2 overlays Great support as what's going on the repair/test. Amazing!!!! hope to see more c64 repairs.

[@NoelsRetroLab]

Thank you! Glad you like them. There will be more C64s to come, don't worry. I have at least one sitting here waiting for its turn :-)

[@jasonmoore1051]

Love your clear systematic approach. Thanks for the great educational video. Looking forward to watching some more!

[@leesmithsworkshop]

I have to say this is one of the better black screen videos and it covers all the basics. It's a shame these do not have a lot more views.

[@NoelsRetroLab]

Thanks so much, Lee!

[@reset1974]

Nice video, Noel. I have two boards to review and i will check the 556 as you have shown here. Many thanks, very interesting. Buen video,Noel. Tengo dos placas para revisar y comprobaré el 556 como has mostrado. Muchas gracias, muy interesante.

[@NoelsRetroLab]

Pues si tienes cualquier pregunta cuando te los mires, avísame sin problema!

[@paulhewett6483]

Love watching these videos it inspired me to get my C64 out of the loft I've owned it since 1985 been up there since 1990 plugged it in and worked just as it did when I put it away..keep up the good work

[@datort]

I just found your channel a couple of days ago. Great video, in this I loved to see your forensic approach to solve these issues. Topped with your calm voice it's just interesting to follow you. Thanks for sharing and I'm looking forward to the other parts when I finished my work today. ;)

[@NoelsRetroLab]

Awesome, thank you! Glad you liked it!

[@tho_tho]

This is a great video, but the thing that stood out for me the most was that you've put small heatsinks on all the chips that tend to get hot on yours, really smart idea, can't believe I never thought of something like it sooner for my old devices with hot chips!

[@NoelsRetroLab]

Thanks! Although it's even better if you put one long heat sink instead of several smaller ones. I need to do a video about that running some tests actually.

[@tho_tho]

@@NoelsRetroLab Looking forwards to it, really curious to see how well these perform since they tend to only really cool chips after they hit ~35°C!

[@AlenMarkov]

Well done and very nice for watching - thanks for your effort!

[@NoelsRetroLab]

Thanks! Glad you enjoyed it.

[@tony359]

I love the "brushed rag" trick! I always struggle to clean alcohol, this sounds like a great idea!

[@NoelsRetroLab]

Thanks! Glad that was useful :-)

[@carnright]

Excellent video! The window within window was very helpful and how you went over the schematics was superb. I also had never seen the use of a rag to soak up the IPA after scrubbing, which is a great idea. First of your videos I have watched, now to binge watch the rest! Thank you :-)

[@NoelsRetroLab]

Glad you enjoyed it! The rag trick I saw it somewhere years ago and it's great. Otherwise all you do is smear the flux and leave a sticky board 😃

[@blackcathardware6238]

Thumbs up. I didn't expect the 556 to go faulty and had the capacitor (C25?) in mind. Good work.

[@NoelsRetroLab]

Thanks! Yeah, you never know what's going to fail, that's part of what makes this whole process so much fun! 😃

[@blackcathardware6238]

Atari 1040ST uses a similar/same circuit around a 556 in the reset circuit. I repair 68K Ataris and design HW for them but watching people working on other retro computers is very entertaining and you can always learn new techniques.

[@drtadjakaroghli6898]

Brutal como siempre esperando el resto......

[@doktor6495]

Done very nicely. Very systematic failure analysis! SUBSCRIBED!

[@mrkingston2001]

Great video! Thanks for sharing!

[@IDPhotoMan]

New Subscriber - great videos, i especially like your popup diagrams while testing.

[@svenpetersen1965]

Well done. Subscribed!

[@kamidphish]

I gotta get a vacuum desoldering station and scope. Oh look, it's almost Xmas. :-)

[@SocrateTheCat]

Hello, thx for these 3 serials. I have learned a lot on my C64. You are very educational. Regards.

[@NoelsRetroLab]

You're welcome! Glad you found them useful.

[@Ikrananka]

New subscriber here. Great video, like others I particularly like the overlaid schematics showing where you're probing. Hoping you'll do more C64 videos in the future.

[@NoelsRetroLab]

Thank you! Yes, the C64 is one of my favorite systems, so I'll definitely be doing more videos about it in the near future.

[@Ikrananka]

@@NoelsRetroLab Fantastic :)

[@pierrekressmann7629]

excellent!! Subscribed

[@KolliRail]

Very good video!

[@mortensteen]

Subscribed! Great video - love me some C64 fixing. :D

[@twretro]

When you unsoldered the chips I thought: Well... Thats just guessing... Why is he doing that? But: the cleaning procedure after soldering is much netter than Mine I have to say!

[@Brock_101]

thank you for the visual anotation... it really helps.. :) congrats on saving the c64.

[@NoelsRetroLab]

Thanks! My goal is to try to get as many people as possible comfortable doing this, so I'm glad to hear that it helped with the pinout diagrams.

[@brunoc.3669]

Great channel! I just don't understand how the multimeter wasn't showing continuity on the inductor at 4:13. You were testing the leads, surely the fact that one of them wasn't properly soldered in the PCB shouldn't have affected that measurement.

[@egumit]

Very nice video. Could you have piggyback another chip before replacing the chip or would that only work for ram?

[@NoelsRetroLab]

I'm not a fan of piggybacking at all. It only works if the failure is caused by the chip leaving one or more outputs in a floating state. Then the piggibacked chip can put the correct results. If the failure outputs some levels, they'll be conflicting with the piggybacked chip and who knows what comes out of that. Having said that, piggybacking *might* work for something simple like RAMs, but I doubt it would work at all for the CPU or the VIC (it may for the PLA?? I haven't tried that).

[@johnfosteriii5792]

On your 'good' 64, you should have most of the 'high-fail' IC in ZIF sockets so damage possibility is minimized. Almost all of mine are ZIF socketed. Great video and I look forward to #2 & #3.

[@NoelsRetroLab]

Yes, good idea. I probably should do that sometime. Adrian (Digital Basement) has one like that and it seems really handy.

[@ShadowD71]

That's a very nice walk througt Repair Video ... Thanx a lot ... Greetings from Germany

[@NoelsRetroLab]

Thanks! Glad you enjoyed it.

[@donaldblakley6796]

Nice work, and throural troubleshooting:) I have been working on these for a couple years. Silly me. Still no scope. This 407 board. Black screen and dead test won't work. Voltages are ok other than output of switch. 4.6v and cassette port pin 3 is over 6v like it's running all the time. I ruled out cpu, sid, vicII and the roms in another board. Cpu resets from low to high on pin 40 with logic probe. Oh and pla good. Is it the switch or 556 possibly? Any thoughts are much appreciated.

[@tenminutetokyo2643]

Dood that’s froogin’ nuts.

[@somosdeamstrad]

What are you going to do with 3 commodores? Interested in swaping it for a cpc 464?

[@NoelsRetroLab]

Haha, they're a friend's. He told me "I have 3 C64s that output black screen" and I told him to bring them to me so I can make a video :-)

[@somosdeamstrad]

@@NoelsRetroLab It is a pitty... :-)

[@ChrisCebelenski]

A person with one C64 knows what color it is. A person with three is unsure.

[@NoelsRetroLab]

No, no, you got it wrong. A person with one or two C64s doesn't know what color it is. A person with three does :-)

[@kke]

Hmm, why is there a 5V regulator when there is a 5V input?

[@NoelsRetroLab]

I'm not really sure, but the 5V from the regulator goes straight to the VIC chip. I suspect it needs a very steady 5V and the one from the external power supply wasn't good enough.

[@kke]

@@NoelsRetroLab So why bring in the 5V at all from the PSU :) For the power led?

[@NoelsRetroLab]

The rest of the board is all powered by the 5V of the power supply, it's just the video chip that has the 5V from the regulator. I agree it seems like a really odd choice. The ZX Spectrum for instance had a 9V DC input, and then it generated 3 different voltages internally (and to be fair, that's the part that always failed too :-) ).

[@ioannisnobelis9651]

God status. And, we love (and want) your t-shirt!

[@NoelsRetroLab]

Haha... I actually can't believe you're the first one to mention the t-shirt :-)

[@wizalex]

@@NoelsRetroLab we all jealous about your t-shirt....

[@markdjdeenix6846]

That’s unusual!an inductor became a resistor .Normally they go open circuit

[@Explore531]

I have a question I gotten a used commodore 64 keyboard from Ebay and when I hooking it up on my smart tv I have notice my screen showing black and white on the screen so is there something wrong with the keyboard or just the component cable ?? please reply

[@consiglioiannuzzi9314]

hi, i would like to make your own power protector, where can i find the wiring diagram? thank you

[@StevesRetroGaming]

Great video Noel - BUT what tool are you using to remove the keys from the keyboard?

[@NoelsRetroLab]

Thanks! It's just a "key puller". Pretty much a couple flexible wires that hook under just about any key and let you pull vertically. Something like this: www.ebay.co.uk/itm/Mechanical-Keyboard-Key-Keycap-Puller-Cap-Remover-Steel-Tool-For-Cleaning/114223979356

[@StevesRetroGaming]

@@NoelsRetroLab Thanks Noel - LOVE your videos

[@Magisktification]

I have an Amiga 500 with the same problem... Are they like the C64 that it could be almost anything?

[@bradhig]

how come your working c64 doesn't have a shield over the vic chip? Won't that cause RF interference?

[@mojoblues66]

Why does the board create 5V from 10V through a voltage regulator when the power supply already provides 5V?

[@awilliams1701]

lol I'm like you should check the reset line next!!! oh well.

[@michalsulko7402]

Hello, I have a C64G at home and I have a problem with it. Could you help me please? I don't have the original video cable, but I made my own and it works. The problem is that when I connect the video cable and power to the C64, I get a black screen, just like in your video. I followed your video to test the voltage and everything went fine. I pulled out and cleaned out all the chips that could be pulled out. The fuse is good, the power supply is good too. I cleaned the whole board of dust, I checked the board to see if everything was holding, if everything was in good condition and so on. I think everything is fine. When turned on, the light is on, so there should be no problem with the switch. I also removed the SID chip from the board, turned it on, tried it, but it didn't help. I don't have an oscilloscope, so I don't have any values measured like the ones you had in the video. The chips are probably warming up normally, no big differences. What could be the problem? Would a reset button help? Thank you !

[@NoelsRetroLab]

Hello Michal, not sure, sorry. It sounds like you did the right things. The PLA could very likely be bad. Also, check with a voltage meter to make sure the RESET pin on the 6510 is high. Beyond that, I would try a dead test cartridge and look at the small MOS chips.

[@michalsulko7402]

@@NoelsRetroLab Hi, I apologize for a later response, but now I have time for C64. So I checked the voltage as you said and got 4,83V. I don't have a dead test cartridge, is there any other way to test it? I don't know... Can I ask you for email to send you some pictures how it looks with the main board please? Thank you very much!!

[@EvilCensor]

@4:07 you check the inductor directly, why did you think that re-flowing what appeared to be poor solder joint would make any difference? I'm not trying to be funny, I'm just wondering.

[@NoelsRetroLab]

I'm not sure! I was initially going to replace the inductor when I saw that it was soldered really badly, so I figured I would reflow it. If my measurement really was from the leads of the inductor, then it makes no sense. The only thing I can think of is that I was probing the solder instead of the leads themselves.

[@EvilCensor]

@@NoelsRetroLab Thanks for the reply and the video. Always good to see a C64 brought back :)

[@scottlarson1548]

I thought they just tied the reset line to a big capacitor which would keep the line low long enough for the CPU to reset.

[@NoelsRetroLab]

That's what I've seen in other systems. No idea why they felt the need to get all fancy about that. I think the Apple II might be the same. Maybe it needs to stay active longer than a Z80 and a cap for that would be too big?

[@stefanweilhartner4415]

never thought that such a standard chip like the ne556 would die. at least it costs next to nothing. but you didn't test the Sid chip in detail.

[@NoelsRetroLab]

Yeah, I've seen plenty of simple chips die, like 74xx for example. You just never know what's going to fail :-) You're right I didn't do an in-depth test of the SID. Most of the time if they make sound during the Dead Test Cartridge and I play a game and it sound OK I call it good, but it wouldn't hurt to do more in-depth testing.

[@stefanweilhartner4415]

@@NoelsRetroLab i think because the SID is mixed signal the digital part sometimes still works fine but the filters are gone bad. that showes only in music where filters are being used extensible

[@NoelsRetroLab]

Right. That makes sense. Do you recommend any particular suite of tests for the SID?

[@FernandoelChachi]

I would like you to fix some Atari 400 ;). My problem is that I don't have the Memo Pad message till I press break. After that I can reset and it will show the Memo pad message. I've changed both Ram and CPU boards, so the only culprit must be in the main board. All caps changed. Keyboard runs fine and it doesn't matter if I unplug it, it won't show the memo pad till I press break. I believe that it thinks that something is connected and it won't stop till that process breaks with the key. I recently have put 48K memory and also changed it to use RGB (and modern voltage regulators in the kit) so it looks great, but that problem is still there.I forgot to tell that at first I was having a problem with some not working keys that was solved changing both 4051 chips. Could it be the Pokey instead causing my problem?. Should I try to resolder it?. Maybe you could point to some possible culprit here?

[@NoelsRetroLab]

I'm afraid I don't know. I'm reasonably familiar with Atari 8 bit, but I have actually never messed around with an Atari 400. I'd love to get my hands on one at some point. I doubt the Pokey chip could be causing that, but who knows! Check on AtariAge. Chances are someone there will be able to point you in the right direction.

[@FernandoelChachi]

@@NoelsRetroLab Thanks. I wonder what can make it to run perfect after a reset and not from a cold start.

[@FernandoelChachi]

@@NoelsRetroLab A Break I mean

[@NoelsRetroLab]

@@FernandoelChachi That can often be caused by bad electrolytic capacitors, especially around the power supply. Probably no harm in changing them and then seeing if that improves things.

[@FernandoelChachi]

@@NoelsRetroLab Thanks. I changed all of them

[@peteregan9750]

Oh I thought with 3x C64 you would have made a super C192 :P

[@NoelsRetroLab]

Haha, that's an idea for a super challenge! 😃

[@indcsion]

Im getting a black screen but with a cartridge I can hear sound. I only have rf to test with right now.

[@NoelsRetroLab]

That's good news! That means most of the C64 is working! :-) It could be the RF modulator, or maybe the way you tuned it to your TV? Ideally try to get an s-video or composite cable and check it that way. If it's still black, it's probably the VIC II chip that is not generating a correct video signal for some reason (the one in that protective metal cage).

[@indcsion]

@@NoelsRetroLab I'll try to get a video cable. Thanks

[@indcsion]

My 2nd c64 works but I cant get the left direction to work. It could be the controllerss but on both controllers left doesnt work

[@indcsion]

I got the controls working by switching out cia chips from the black screen one. Luckily most of the chips are already in sockets.

[@NoelsRetroLab]

@@indcsion Good find! So one of them isn't working correctly, but they shouldn't be too bad to replace. And yeah, isn't it great when most chips are socketed! The only thing to watch out for are for slightly corroded sockets not making good contact. Actually, I wonder if that was happening with the CIA chips. Try swapping them back again and if they work, then it was just a dirty socket.