Commodore 64 help

[Retronick]

Hello! I recently acquired three Commodore 64s and the disk drive while I was traveling in Hawaii. Guy owned 'em since they were new and no longer had any use for 'em (it was me or the dump).

One of them works perfectly, but the other two and the drive are having some minor issues I was hoping I could get some insight on repairing.

• Floppy Drive: Not sure if this is talking to the Commodore or not because it started billowing smelly smoke and ozone 30 seconds after I powered it, leading me to unplug it and quickly take it outdoors. I'm guessing this is because some capacitors have popped. Wanted to see if anyone had other guesses and suggestions on where to find parts and /or suggestions on repair.

• C642: This one seemed to work perfectly when I first powered it on, but now the text on screen flashes different colors. Otherwise it accepts commands and seems to function normally, leading me to believe it's a video problem. Here's a video of the glitch in action:

https://www.youtube.com/watch?v=TAhJm3TcS_w

C643: This one is probably the worst out of the lot. Text appears scattered across the screen and it accepts keystrokes sporadically. Here's a snap of the glitch in action: http://www.retronick.com/wp-content/uploads/2015/06/IMG_6815.jpg

Any suggestions are welcome! I'm writing a series of posts on playing with these things because I've never messed with them in the past (we were an Apple IIc family).

Thanks!

Nick

[AdamAnt316]

I'm no expert, but I can at least take a crack at them. Here goes nothing:

*Floppy drive: Definitely could be bad filter capacitors, but hard to say for sure. Rather worrying that the line fuse didn't pop first. If it was the filter caps, check for collateral damage in the area. Rectifier bridge(s) and voltage regulator(s) are likely candidates; hopefully, none of the more major components (like the power transformer) let out its magic smoke...

*C=64#2: Sounds like a graphics issue, perhaps the VIC chip or one of the other graphics ICs. Check this list (http://personalpages.tds.net/~rcarlsen/cbm/c64/c64-ic.txt) against your symptoms.

*C=64#3: Again, sounds like a bad chip or two. Check the above-linked list against symptoms.

Fortunately, spare parts are fairly plentiful (apart from certain chips, like the 6581 SID, and even they can still be found). Check the following site for more repair info:

http://personalpages.tds.net/~rcarlsen/

Good luck!
-Adam

[Gamevet]

Did you actually hear a popping sound when you turned on the disk drive?


I'd suggest opening it up and looking for a cap that is leaking, or has the wrapping separating from the center of the cap at the top.


You might get lucky with the other 2 C64s. I'd suggest taking a pick, or the end of a mechanical pencil to flick the pins of the chips on the underside of the board. You may just have a loose solder joint that is causing the issues.

[Retronick]

I'm no expert, but I can at least take a crack at them. Here goes nothing:

*Floppy drive: Definitely could be bad filter capacitors, but hard to say for sure. Rather worrying that the line fuse didn't pop first. If it was the filter caps, check for collateral damage in the area. Rectifier bridge(s) and voltage regulator(s) are likely candidates; hopefully, none of the more major components (like the power transformer) let out its magic smoke...

*C=64#2: Sounds like a graphics issue, perhaps the VIC chip or one of the other graphics ICs. Check this list (http://personalpages.tds.net/~rcarlsen/cbm/c64/c64-ic.txt) against your symptoms.

*C=64#3: Again, sounds like a bad chip or two. Check the above-linked list against symptoms.

Fortunately, spare parts are fairly plentiful (apart from certain chips, like the 6581 SID, and even they can still be found). Check the following site for more repair info:

http://personalpages.tds.net/~rcarlsen/

Good luck!
-Adam

Thanks! Yeah, I'm being hopeful that it was just some bad caps and didn't have anything to do with the power transformer. I know the fluid in the caps dries up and they can become distended and pop over time. Not looking forward to whatever nightmare is resting just beneath that charming beige carapace. Thanks for the links! If nudging and reconnecting stuff doesn't do the trick I'm certain something there will.


Did you actually hear a popping sound when you turned on the disk drive?


I'd suggest opening it up and looking for a cap that is leaking, or has the wrapping separating from the center of the cap at the top.


You might get lucky with the other 2 C64s. I'd suggest taking a pick, or the end of a mechanical pencil to flick the pins of the chips on the underside of the board. You may just have a loose solder joint that is causing the issues.

That sounds pretty likely given the nature of both problems (the loose solder joint). If that doesn't do it it shoould be simple enough to pull the chips and replace 'em. Thanks!

[Retronick]

Did you actually hear a popping sound when you turned on the disk drive?


I'd suggest opening it up and looking for a cap that is leaking, or has the wrapping separating from the center of the cap at the top.


You might get lucky with the other 2 C64s. I'd suggest taking a pick, or the end of a mechanical pencil to flick the pins of the chips on the underside of the board. You may just have a loose solder joint that is causing the issues.

Oh! And I did not hear a pop. I heard a smooth whirring noise and saw that the green LED power indicator had lit up. Then it started pumping gross smoke out through the disk slot.

[Gamevet]

Oh! And I did not hear a pop. I heard a smooth whirring noise and saw that the green LED power indicator had lit up. Then it started pumping gross smoke out through the disk slot.

That was probably the belt getting stuck. You might have a spindle that needs a little lubricant. If that was all it was, I'd suggest taking a slightly damp (Isopropyl Alcohol) swab to the little white head within the drive. They tend to get quite dirty and will lead to disk read errors.

[AdamAnt316]

Capacitors don't always look bad on the outside when they crap out, though seeing smoke does narrow things down somewhat (but not entlrely). I had an early digital clock (http://www.electronixandmore.com/adam/temp/clock/nixieclock1_small.jpg) which suffered from one or more shorted filter capacitors; it worked for a few seconds when I first plugged it in, then the digits dimmed, and the fuse blew. Tried replacing the two filter capacitors (which looked perfectly normal from the outside), but the fuse kept blowing. Brought it to a friend of mine, and he discovered that some of the rectifier diodes had been taken out when the filter capacitor(s) had shorted. Once those were replaced, it no longer blew fuses (it still had issues, but that's another story).

As for belts, those generally don't cause copious amounts of smoke when they go bad, unless you're talking about a high-torque application like a vacuum cleaner. More often than not, if a belt in a disk drive or other electronic device goes bad, it either becomes too stretched out to allow for the device to work at the correct speed, or the rubber either breaks apart or turns into a nasty goo. I haven't had any belt issues so far with my numerous Commodore 1541 disk drives, though I suppose it's possible.
-Adam

[Gamevet]

As for belts, those generally don't cause copious amounts of smoke when they go bad, unless you're talking about a high-torque application like a vacuum cleaner. More often than not, if a belt in a disk drive or other electronic device goes bad, it either becomes too stretched out to allow for the device to work at the correct speed, or the rubber either breaks apart or turns into a nasty goo. I haven't had any belt issues so far with my numerous Commodore 1541 disk drives, though I suppose it's possible.
-Adam

I'm not saying that the belt went bad. I'm saying that the spindle on the other end of the belt might be stuck. The motor of the drive might be fine, but the spindle on the other end might not have enough lubrication to spin like it should, thus causing the belt to get stuck and smoke.

[AdamAnt316]

I'm not saying that the belt went bad. I'm saying that the spindle on the other end of the belt might be stuck. The motor of the drive might be fine, but the spindle on the other end might not have enough lubrication to spin like it should, thus causing the belt to get stuck and smoke.

I suppose it's possible, albeit unlikely (and if that were the case, the belt would be bad, in all likelihood). If the smoke was caused by something being stuck in the drive mechanism itself, I'd be worried about the source having been the motor, or something else hard to replace. According to another of Ray's articles (http://personalpages.tds.net/~rcarlsen/cbm/1541/fix1541.txt), a possible source of smoke in a 1541 is one or more of the tantalum capacitors, which is definitely a possibility. With any luck, the cause is something like that, rather than anything in the drive mechanism itself.
-Adam

[Niku-Sama]

Crack that floppy open, snap some pics

[Gamevet]

I suppose it's possible, albeit unlikely (and if that were the case, the belt would be bad, in all likelihood). If the smoke was caused by something being stuck in the drive mechanism itself, I'd be worried about the source having been the motor, or something else hard to replace. According to another of Ray's articles (http://personalpages.tds.net/~rcarlsen/cbm/1541/fix1541.txt), a possible source of smoke in a 1541 is one or more of the tantalum capacitors, which is definitely a possibility. With any luck, the cause is something like that, rather than anything in the drive mechanism itself.
-Adam

The motor is separate from the spindle that turns the floppy disk. The belt goes from the motor to the spindle that turns the disk. If the disk spindle is slightly sticking, it will cause a whirring sound, because the belt is slipping ever so slightly. You can hear a similar sound with a car's fan belt, if something like the AC pump, smog pump or water pump are starting to have lubrication/worn bearing issues. My Mustang GT was making that same kind of noise, until the smog pump finally stopped turning, the belt started smoking and finally snapped. I only brought that up, because he had said that he'd heard a whirring noise.

If it is a tantalum capacitor that gave out, it would definitely smoke like he described. He should see a burnt capacitor if that did happen.

https://www.reliabilityanalysislab.com/tl_hd_0303_tantalumCaps.html

[AdamAnt316]

The motor is separate from the spindle that turns the floppy disk. The belt goes from the motor to the spindle that turns the disk. If the disk spindle is slightly sticking, it will cause a whirring sound, because the belt is slipping ever so slightly. You can hear a similar sound with a car's fan belt, if something like the AC pump, smog pump or water pump are starting to have lubrication/worn bearing issues. My Mustang GT was making that same kind of noise, until the smog pump finally stopped turning, the belt started smoking and finally snapped. I only brought that up, because he had said that he'd heard a whirring noise.

If it is a tantalum capacitor that gave out, it would definitely smoke like he described. He should see a burnt capacitor if that did happen.

https://www.reliabilityanalysislab.com/tl_hd_0303_tantalumCaps.html

Most of the disk drives I've dealt with make audible whirring noises under normal conditions when accessing a disk. A belt used in a car would have a lot more torque behind it than the one used in a disk drive (plus, said belt would be made out of more than just rubber, in all likelihood), so it'd be more likely to smoke if something got stuck. Most of this is conjecture, of course, without knowing exactly what the whirring sounded like before the 'magic smoke' poured out. Any further reports, OP?
-Adam

[Gamevet]

Most of the disk drives I've dealt with make audible whirring noises under normal conditions when accessing a disk. A belt used in a car would have a lot more torque behind it than the one used in a disk drive (plus, said belt would be made out of more than just rubber, in all likelihood), so it'd be more likely to smoke if something got stuck. Most of this is conjecture, of course, without knowing exactly what the whirring sounded like before the 'magic smoke' poured out. Any further reports, OP?
-Adam

A vacuum cleaner's rubber belt will smoke when the brush spindle gets stuck.

I usually think of the sound being generated by the DD as more of a hum. When he said whirring noise, it led me to believe that it was possibly the belt slipping, and because the belt is so thin, it won't make a loud pitched whirring noise like a larger belt would.

Hopefully it is a cap. Those are a hell of a lot easier (less expensive) to replace than the disc assembly.