Fixing a Commodore 64 Memory Error

After a few years put away, my beloved C64 gave me the ugly news: ?OUT OF MEMORY ERROR IN 0

This is not a difficult problem to fix. Here's how. (I'm no expert, just some kind of wizard)

(-- Images resized to 1280x765 (thread still says they're larger). --)

This error message means the cpu and some other components have already passed testing.
http://jlew.org/c64/IMAG0016.jpg



This problem is often caused by an unstable power supply. You really need to measure its' output, careful not to short on the ring, both the 9v and 5v rails both during warmup and after 30 minutes of being plugged in. In my case, the power supply was hosed.
http://jlew.org/c64/IMAG0017.jpg


Picked up this beautiful working VIC 20 locally for xxx to steal the power supply.
http://jlew.org/c64/IMAG0018.jpg

Time to open the C64 up.
http://jlew.org/c64/IMAG0020.jpg

http://jlew.org/c64/IMAG0021.jpg

These 8 ICs are the machine's 64K of memory, and at least one of them is a turd.
http://jlew.org/c64/IMAG0022.jpg

The board has shielding on the bottom that must be removed to get access to the solder joints.
http://jlew.org/c64/IMAG0035.jpg

The shielding may need to be desoldered from the edge of the board.
http://jlew.org/c64/IMAG0037.jpg

http://jlew.org/c64/IMAG0039.jpg

continued...

---------- Post added at 13:29 ---------- Previous post was at 13:13 ----------

Each memory IC needs to be desoldered (The corner ones may need to be coaxed out as the board seems to have solder built up there for the circuit).

Removing these chips can be destructive to the chips. Since you are ordering at least one new IC, you might as well order eight.
http://jlew.org/c64/IMAG0043.jpg

http://jlew.org/c64/IMAG0045.jpg

http://jlew.org/c64/IMAG0048.jpg


Centerfold.
http://jlew.org/c64/IMAG0049.jpg


Solder eight 16-pin sockets in place.
http://jlew.org/c64/IMAG0055.jpg

http://jlew.org/c64/IMAG0063.jpg

http://jlew.org/c64/IMAG0064.jpg

http://jlew.org/c64/IMAG0070.jpg

She has to put her clothes back on sometime.
http://jlew.org/c64/IMAG0076.jpg

http://jlew.org/c64/IMAG0077.jpg

I actually decided to reuse as many of the originals as possible (sockets make this practical).
http://jlew.org/c64/IMAG0081.jpg

http://jlew.org/c64/IMAG0091.jpg

http://jlew.org/c64/IMAG0092.jpg

http://jlew.org/c64/IMAG0093.jpg

http://jlew.org/c64/IMAG0094.jpg

http://jlew.org/c64/IMAG0095.jpg

http://jlew.org/c64/IMAG0097.jpg

http://jlew.org/c64/IMAG0111.jpg

Sockets are the way to go.

oi, price driving!!!

i paid xxx for my VIC20, i feel ripped off now >:P

:thumbsup:Good job

It looks very well done:thumbsup:

I have a few questions to check up my own pile of psu:

What does a bad psu gives as output voltage? Do you messure with C64 on or off? How much gives the 5 volt line if it is working?

Did us increase 110 v to 120 or not?

Sorry for the many questions.

Quote:

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Originally Posted by jvdbossc

It looks very well done:thumbsup:

What does a bad psu gives as output voltage? Do you messure with C64 on or off? How much gives the 5 volt line if it is working?

Did us increase 110 v to 120 or not?

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Measure the PSU output pins while the PSU is not connected to the C64.
The DC voltage needs to be exactly 5v or 9v (.01 maybe ok) with zero fluxuation. Also, there must be no AC current.

I don't know what you mean by 110 vs 120. Anything in between 110 and ~120 is fine for North American devices.

And thanks!

Quote:

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Originally Posted by SaviorX

oi, price driving!!!

i paid xxx for my VIC20, i feel ripped off now >:P

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Don't be surprised if your comments get muted. :whistle:

Also, VERY IMPORTANT:

Do NOT use a C64 PSU on a VIC-20! (C64-PSU + VIC20 = BAD)

The C64 PSU does not have enough juice to power a VIC-20 and will damage the mainboard (or so I have been told by a reliable nerd).

Great mod. Too bad I can't see the pictures because they are HUGE! You should use PostImage.org or AmiBay's built-in attachments to post your pictures. :(

Heather

@jlewsp4: very good job!

Quote:

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Originally Posted by SkydivinGirl

Great mod. Too bad I can't see the pictures because they are HUGE! You should use PostImage.org or AmiBay's built-in attachments to post your pictures. :(

Heather

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Oh! Sorry. I use a modern PC for web browsing so I didn't think:Doh:. I resized the source images a bit (though the thread still says they're larger as far as I can see).