Denial

rhurst · Posted: Mon Apr 27, 2009 3:26 pm Post subject: C64 help?

I got these two C64, both not working:

1) powers-up, the screen does go black (TV and video monitor), nothing more.

2) powers-up, screen initializes 38911 bytes free, no blinking cursor. An Omega Race cartridge starts, but will randomly start (as if FIRE was pressed) and ship will thrust on its own. I can press RESTORE to reset the game, but I cannot invoke any options using the F-keys.

So I got it in my head that I might be able to "cannibalize" one for parts useful for the other... but given those symptoms, where should I focus on?
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saehn · Posted: Mon Apr 27, 2009 4:58 pm Post subject:

Check these, great documents:

http://personalpages.tds.net/~rcarlsen/cbm.html
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rhurst · Posted: Mon Apr 27, 2009 5:20 pm Post subject:

Excellent, thanks... I'll post if I am successful. This looks interesting to start with:

U1 906108-02 (6526) CIA
Startup screen normal, but no cursor. No keyboard or control port
access. Partial failure: some keys or joystick positions don't work, one
character appears ahead of startup cursor, screen fills at startup as if
keys are being held down. Cartridge works.
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shem · Posted: Mon Apr 27, 2009 5:31 pm Post subject:

is it a breadbin or a c64c

things to check 6526 ram and if it is a bredbin check U17 Pla probably the most common fault in the old c64
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6502dude · Posted: Mon Apr 27, 2009 5:40 pm Post subject:

If both 6526 chips are in sockets, you can try swapping them to see if trouble moves to disk I/O and keyboard starts working ok.
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Mega-Cart: the ultimate cartridge for your Commodore Vic-20

rhurst · Posted: Wed Apr 29, 2009 6:36 pm Post subject:

Unfortunately, they are both soldered ... where's a good outlet for sockets? I read it's a good idea to put sockets in if you are successful at de-soldering the chip in place.
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Bacon · Posted: Wed Apr 29, 2009 11:32 pm Post subject:

carlsson · Posted: Thu Apr 30, 2009 1:38 am Post subject:

The 6526 chips are 40 pin, right? Well, you can buy from whichever electronics reseller you like. In the US, Jameco and Digi-Key might be the two biggest. A little pricy but with a big inventory. If you want to go cheap, try Futurlec which ships their stuff from Thailand. I recently placed an order from them and didn't have reason to complain.

Of course it depends how many sockets you need. One, two, ten, fifty.. any other parts? Perhaps you even have a local dealer stocking from one of the resellers, at a slightly higher margin but without a minimum order value.
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Anders Carlsson

saehn · Posted: Thu Apr 30, 2009 12:14 pm Post subject:

Bacon · Posted: Fri May 01, 2009 1:15 am Post subject:

rhurst · Posted: Fri May 01, 2009 4:25 am Post subject:

Thanks for all the good input -- I have a local friend I could tap for the actual operation, as he used to be a Commodore reseller/technician from the 80's and 90's. But I do not want to use up any 'favors', heh.

Finding parts and taking the job on myself isn't enough to inspire me, when I consider the low success probability and the hit on my ego if I were to fail. Razz

So I found this repair shop that will replace the chip, with a socket, so it's worth the small investment to keep this machine working. Thanks again for the feedback!
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Any technology distinguishable from magic is insufficiently advanced. See also magic.

saehn · Posted: Fri May 01, 2009 9:55 am Post subject:

Thanks for the advice, bacon! I'll keep those tips in mind the next time I need to de-solder an IC.
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saehn/Style

rhurst · Posted: Wed Jun 17, 2009 5:36 pm Post subject:

In case you would like to know, here is the final disposition of that C64 unit. I hope you enjoy this as much as I did!! Razz

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Any technology distinguishable from magic is insufficiently advanced. See also magic.

channelmaniac · Posted: Thu Jun 18, 2009 8:11 am Post subject:

EEEEK!

What a scumbag.

$50 to repair a C64? It does NOT take very long to fix one! It's generally quick enough that I do it for $30 flat rate as long as it's not stuffed with bad chips by an unscrupulous customer.

I have had that happen before!!!!

(Have you thought about outing them on the forum?)
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Call me a cheap bastard... I learned to fix things to save money... even surface mount soldering...

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carlsson · Posted: Thu Jun 18, 2009 8:31 am Post subject:

I would have bought a known working C64 from a trusted seller, then kept the broken one for parts. Perhaps sold or donated it to someone who knows how to repair them. It kind of reminds me about an episode many years ago when I sent a C64 for repair and got a different chip replaced than what the invoice said they had swapped! Eventually it turned out not to be a fault in the computer, rather failing power supply.
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Anders Carlsson