An absolute fool and his dead Vic

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SwissArmyTin
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An absolute fool and his dead Vic

Post by SwissArmyTin »

I'll start off by saying: I am not an expert on electronics. I'm familiar with the absolute bare-bones basics, and that's about it, so forgive my ineptitude.

I have an early model NTSC Vic-20 that's never worked and has definitely seen better days. I've had it for several years now; didn't pay much for it. Aesthetically, it looks fine. Open it up, though...yikes.

The original 4700uf capacitor seemed to have exploded on one side, leaving a nasty trail of electrolytic fluid on the board. The trace underneath and around the capacitor look absolutely screwed. I ended up replacing the capacitor with an identical one, cleaned the board, reflowed several broken solder joints, and it still didn't work. Turn it on, power led lights up, black screen; same as before. I gave up at the time 'cause I didn't (and still don't) know what to do.

Since I'm soul-crushingly broke, I can't just simply buy a working Vic, so I'm stuck with this one.
From my view, it would be an act of God to get this thing working again, but I'm determined to have at least one working Commodore machine, so pretty much any and all help would be immensely appreciated.

Here's an album of the naked board: http://imgur.com/a/emEyM Currently have it thoroughly disassembled for cleaning, thought it was a good chance to get some decent pics of the damage. All the missing ICs and metal shields are off-screen
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mrr19121970
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Re: An absolute fool and his dead Vic

Post by mrr19121970 »

I think you need 1 working machine to test the ICs in your non working machine. The most expensive IC will be your VIC-I to replace this for NOS or even a used version you can pick up another machine.

I bought recently 2 NTSC machines for 30 us$ both untested. Both naturally broken. One with a dead 6502 and the other with a broken char rom. I also managed to snap off a key peg during preparation for cleaning. Most people would be happy with 1 working machine, but not me. I ordered a rockwell 6502A, a char rom from elsapion and a key peg from retroleum.co.uk. cases are restored, keyboards stripped and cleaned. Just waiting for the parts to arrive now.

I didn't manage to get my main boards as clean as you have got yours. I only cleaned with a q-tip and ipa
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eslapion
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Re: An absolute fool and his dead Vic

Post by eslapion »

The damage to the board is centered around one specific large trace and you can apparently easily fix this by soldering one or more wire above it and through the vias.

If you have a black screen upon power-up then more than likely the 6560 is still good but its impossible to tell what's going on with the ROMs, CPU, VIAs and RAM.
Be normal.
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mrr19121970
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Re: An absolute fool and his dead Vic

Post by mrr19121970 »

One thread I saw has a better solution than wires
For anyone that is anal like me and won't be happy with a wire patch - Use self-adhesive copper tape from a hobby store. It's used for making stained glass panes.

You must first stick some of the copper tape to a clean glossy surface, then cut a replica of the trace (even complicated shapes and pads can be done) using a scalpel.

Lift the new trace from the cutting surface using a razor blade (careful - it's very fragile and will tear easily), then apply it to your damaged PCB - you did clean and prep it first, right?.

Stick the new trace down and flatten it well using some kind of tool (I used an embossing tool).

Solder both ends, then apply some translucent paint to match the rest of the board.

Now sit back and admire your fine repair!
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SwissArmyTin
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Re: An absolute fool and his dead Vic

Post by SwissArmyTin »

mrr19121970 wrote:One thread I saw has a better solution than wires
Only problem there is the OP lifted traces/pads, whereas mine are still on the board, albeit fairly destroyed. Guess I can ply off the worst of em. Hopefully I'll be out making a parts run today; I was planning on picking up that tape as the strips connecting the ground plane to the weird paper/foil shield on the bottom lost cohesion. Patience permitting, I might try this. If not, ghetto jumper wires everywhere.
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mrr19121970
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Re: An absolute fool and his dead Vic

Post by mrr19121970 »

get yourself a glass fiber pen and rub them off.
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eslapion
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Re: An absolute fool and his dead Vic

Post by eslapion »

I'd be tempted to tell you to send your board to Ray Carlsen, along with the chips you removed.

Since almost all important chips are socketed, I'm quite sure he'll fix your board for a small price.

BTW, this capacitor explosion in your VIC usually occurs when somebody is dumb enough to plug a 120V cable in the 9Vac input connector. Probably a nice initiative of a smart previous owner.
Be normal.
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SwissArmyTin
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Re: An absolute fool and his dead Vic

Post by SwissArmyTin »

mrr19121970 wrote:One thread I saw has a better solution than wires
Well, tried this method today. http://i.imgur.com/ED3ejoG.jpg
Is it a bad time to admit I may or may not know what I'm doing?
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mrr19121970
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Re: An absolute fool and his dead Vic

Post by mrr19121970 »

Looks fine to me. Get some green nail varnish after checking with your continuity meter.
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SwissArmyTin
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Re: An absolute fool and his dead Vic

Post by SwissArmyTin »

Don't exactly have a meter, but I take it this's a good sign
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mrr19121970
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Re: An absolute fool and his dead Vic

Post by mrr19121970 »

Well swap the led with a buzzer and its the same as the continuity meter I have. So yes. Fine....
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SwissArmyTin
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Re: An absolute fool and his dead Vic

Post by SwissArmyTin »

Well, re-assembled everything, hooked it up and...power light + blank screen. Bummer.
Oddly, this time there was a bit of static moving in several distinct patterns. I know for certain this wasn't present before, but I have no clue what it means. I'm still dead broke, so testing and replacing any faulty ICs (which is the probable remaining cause) is gonna be a problem.
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eslapion
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Re: An absolute fool and his dead Vic

Post by eslapion »

SwissArmyTin wrote:Don't exactly have a meter, but I take it this's a good sign
You're kidding, right?

If you have anything above 5.25 volts you'll damage the chips. If you have less than 4.75 volts then it's going to work unreliably.

This is not much of a sign of anything.
Be normal.
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SwissArmyTin
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Re: An absolute fool and his dead Vic

Post by SwissArmyTin »

You're kidding, right?

If you have anything above 5.25 volts you'll damage the chips. If you have less than 4.75 volts then it's going to work unreliably.

This is not much of a sign of anything.
That thing's a joke. Only use it ever gets is for leads and nothing else. I'd never use it on an IC or component. I may be stupid, but I'm not that stupid.
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joshuadenmark
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Re: An absolute fool and his dead Vic

Post by joshuadenmark »

I don't think your stupid at all, but shows a lot of initiatives with the skills you got, thumbs up :D
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