The RF Modulator adds them. Replacing the modulator with a replacement circuit should fix it.

Thanks to you, another C64 has been saved!

My snack is KFC Ruffles and my drink is Coors Light. This is the first video I've seen of yours. I'm actually happy to see you have tough c64s to repair. Easy fixes don't educate us as much. Cheers!

Thanks for the video. I had a green screen CPC464 as a kid, my first computer. I just picked up a colour one with a few games for a good price and it needs some tlc for sound and cassette belt but I was looking for the best way to play all the games, this DDI 5 looks very interesting. Would you say this is the best way? I've seen some devices for the GX4000 with a GUI and you can scroll through the games on screen with a controller, is anything like that possible on the 464 or is this as good as it gets?

Thanks for the video. A more thorough initial process could contemplate opening the case before turning on the computer and checking voltages and doing visual inspections to see if is safe to turn it on. Great tip on the zener diode for the datassette; they were very common here in Europe compared to the floppy drives, which were awfully expensive

Excellent video and troubleshooting. That's awesome you saved the vicII :) that was definitely a hard one. But never in doubt.. I knew u would get it. The cassette problem u had happened to me once.. ( the zener diode) it drove me nuts for quite a while. Since then I have always used my tester to check the cassette motor pin on port to see if it's constantly running. ( a bad pla can also make it run all the time 6v +) anyways another great video.... this really excited me that I wasn't the only one who had that diode issue. Awesome. U take care, and can't wait for # 10:)

I also use the deadtest as first diagnostic. But the version i use is newer. Just google deadtest kinzi. It has some extra features and shows colors when doing the first mem test and if bad it shows the normal white flashes.

Lots of issues! I appreciate you stepping through the process of troubleshooting/fixing! Great job fixing that C64!

Great work! I learn a lot, thanks! I really like your combined (?) multimeter / oscilloscope. Would you mind share which one you use? Thanks in advance.

Excellent video and work! Thanks for sharing

Really love watching you going through c64 repairs. I also do this as a hobby. You know you can use the minipro to test the PLA!

Sorry to say, but I find your troubleshooting process not quite logical. Especially considering you have a second working unit to do testing. Good effort, extraordinarily complicated diagnosis process. I have observed that you normally start very well in your repairs, but then tend to drift away…….Thanks for sharing

This is again one of those cases where the cost of the repair does not (or barely) justifies doing it. BUT, 250425 is my favorite long board, if it were me, I wouldn't scrap it as a parts donor, which I think you won't do too. There is no logical explanation on why that replacement PLA died. I guess it was just bad luck. As you already found out, there wasn't an actual short on the PSU 5V rail, and yes the power switches do drop the voltage when there is oxidation on their contacts, this is also true with the power connector, you should take a look there and clean/replace if necessary. Check input voltage right at the power connector pins, and then on the switch pins. A healthy C64 PCU (original or aftermarket) should provide a decent 5V (even a little above it) and if it drops around 4.7-4.8V around the board, there must be a reason for it. I am glad you decided to follow a methodical approach, here is what I follow for C64s: 1) Open it before applying power. (If something to go bang or smoke, I would like to see it) 2) Remove the SID (Not needed for anything, and too valuable to risk it) 3) Connect video, power on. 4) Check voltages. 5) Check clock signals (Yes, plural. Includes the dot clock and color clock as well as the CPU clock, all measured first from the clock generator circuit, then on the CPU) 6) Check reset line. 7) Depending on what I see on the screen, attach Dead Test or Diagnostics. If none of them boots up, start probing, PLA pins first. I re-insert the SID only after I am sure that I have a fully working machine, I never poke around with the SID in circuit.

Big fan of you show.

Keep up the good work

Another one will keep on living! Although it may seem that you've replaced the sockets unnecessarily, it is a good practice, those old sockets are always prone to give you problems.

What about bbc basic and cpm you just need 16kb pageable into bottom of ram? what about rzx files?

For the Atari 2600 one, how does this handle games that don't run at the standard 262.5 NTSC/312.5 PAL line resolutions and refresh rates, or constantly change (Empire Strikes Back, Moon Patrol, and especially Buck Rogers are notorious examples)?

It's always the PLA. Even if it's not 😂😂😂

Congratulations! You found the "spell". Too bad it was in the possession of a creature that was hiding it's bad intent behind a "patsy" chip. As you said yourself, you got there in the end, and another C64 lives on!

Excellent work:) glad to see u back. Nice troubleshooting. But I noticed the clocks were off... at the end. Another bad vicii unfortunately:( very well prepped video though. Jumping everywhere, but also wanted to say that I hope everything is all good with u and your parents now❤ looking forward to next part. Wasn't a bad thing changing all the mt ram and mos logic chips anyways:)

Thanks for the video! I didn't know that the VIC II could be responsible for giving those random RAM flashes with the dead test, good to know

You got it done! Nice work! Thanks for sharing

When you ran the diagnostic test at the end of the video, the CIA timers were not the same. Anyway, thanks for the vid and keep up the good work.

FYI: I stated, incorrectly, when cleaning the user port, that most or all of the bottom pins were ground. I just discovered I was mistaken. Those pins have other purposes and should definitely be cleaned. Sorry for the confusion.

Sir, how time we chage files need

Had a good version of this on coco 1

Where are you passing the sound to? Does your monitor have sound or are you sending it to an external speaker?

It is bright, sharp and crisp, it has vivid colours as those colours were ment to be, it is brilliant. If I would search I would be able to find more words that would praise this Copperdragon thing. There is only one disadvantage and that is the low resolution of the original computer, big letters and cyphers fill the screen. With the original video output you could imagine some distortions were ment to be, under the vagueness was hidden a universe of things you had to fill in with your imagination. I will explain. A game has a walking man of 8 pixels high, two legs are two pixels high, the body also two pixels, the arms, two pixels, the head, with the ears and eyes and hairs and nose and lips and eyebrows, with a smile on his face is also two pixels high. You can't do that with just two pixels. Reality kills the fantasy. Now the screen is filled with abstract objects. One line can mean numerous things, like a road, a floor or a trajectory of a missile. The sharper the image is the harder the mind has to work to translate the abstract forms into imaginary friends.

Errare hunanum est, bro. Errare humanum est.

Great work bud 👍. We're only human mistakes happen. I have myself once mixed up the pla and sid, and once I had the basic and character roms switched when testing.. dead test no problem... but no basic screen or diag... took me a couple hours to find it and be like duh. ❤ man:)

Great job fixing these C64s!

Thanks for the video and don't worry: as we say here, the one who doesn't make mistakes is the one that does nothing. So, in the end it was a bad PLA and SID? I find your way of soldering/desoldering pins interesting, not going one by one in line, but going zig zag

Occam’s razor. Sometimes the best is stop, and come back the next morning to take a look at it again….

I am as careless as you are, and from one to another, here is my tip for not putting the ICs in wrong sockets; Before you start pulling them off, write on them what they are with that white marker. Very easy to confuse ICs with faded markings but believe me you won't put an IC marked with big white letters as CIA in a CPU socket.

I know a zif board is handy, and low hanging fruit is tempting, but for understanding how to spot a bad cpu or cia or pla using your oscilloscope is much more useful than a quick "this chip is bad cause it doesn't work in my other machine" video. I do enjoy your effort and the continued homage to Adrian Black by using his signature sound test.

It's good to see you "Finally" solved it and the C64 is singing & dancing again. But did you actually solve the Low +5Volt rail ? I'm seeing lately more of this board, with that very issue (among other issues). My solution to this so far has been to 'Shotgun' all the 10uf 25V Electro Caps (yes even the pair inside the Video / clock metal shield - where the supply is derived from the 9v AC). Why? Well not only to restore the +5V rail but also before removing these caps I'm seeing varying levels of tarnish/corrosion on the Solder joints below the caps (and nearby components) to corrosion on/under the soldermask & PCB surrounding the electrolytic caps. Now I'm not PRO , let's Shotgun everything (except for known boards with leaking Caps ... thanks Mac & Amiga) and then see what it's doing (that way of thinking if you are not careful will end up causing more issues (broken tracks / shorts , wrong value/ reverse polarity, etc.) and chasing your tail). Now previously I've heard people say Electrolytic Caps in a C64 won't stop your computer from booting up. Well I've seen over the years multiple Caps preventing the reset circuit from working and some caps in the RF Modulator preventing video out, But now am also seeing on the 250407 boards leaking caps. So be warned, and take appropriate action when needed before your C64 gets damaged.

What does it use for sound, is it all sample-based here?

Wow! Carnage indeed. In my mind, this is beyond a feasible repair. I would make it a donor board, all mechanical parts like the switch, ports, etc. may have a new life in an otherwise poorly board. You haven't tested the 8701 clock generator on camera, but most probably that will be fine too. RAM ICs and color RAM are worth desoldering and testing (most probably futile work) but the logics etc are not worth the effort.

NIce repair, maybe that clock generator was warking maybe :)

Thank you for this series, I love C64 repairathons. I also repaired a bunch of them in the past months, but I am not as kwoledgeable as you. I wonder where all those computers end up in your case, whether they stockpile in a closet like the ones I repaired. From time to time I could turn them on, checking if they are still operational and maybe hoping that I have to fix them again! 😄

Nice work bud 👍. Very sad to see the beloved 466 board be so bad:( awesome that the 6567R9 is good though. Enjoy the rest of your weekend. Cheers

The last time a certain Number 5 got hit by what you could call overvoltage, it had an unexpected, but rather nice effect...

That "Brick of Death" racked up the kills. I lost a 6581R4 to a faulty PS too. It was not a happy time.

I don't think Tramiel imagined the C64 lasting this long!

I enjoy watching someone who knows what they are doing, tracking down issues and resolving them like this. Thanks for making videos like this so we can learn as well. Much appreciated.

I wonder how that 250466 motherboard ended up inside that breadbin. It was good to see you working with one of those.

Machines which someone put some work on can be a pain. Untouched c64s usually are quite easy to fix. Very well done, sir! :-)