c64 issues..

i have 2 c64's ...and one has issues.

As luck would have it I've fitted the sd2iec on my spare c64 which has now started playing up. It has done this once before but so long ago i forgot.

Anyway I've been using it all day and now the half the keys don't work, the screen flashed black but came back and occasionally random graphic chatectors appear..

i suspect the keyboard (i/o) chip has died? i have swapped the keyboard , it works fine on another and my good one fails on this c64 too..

PS

All ic's are soldered to the c64 pcb except about 3 small ones (logic?? not sure)

Hi,

I have an old C64 board that could maybe donate some chips for your machine. The SID chip has gone as that went to fix TC's machine, but as far as I recall the rest are there. I think it could be the CIA chip on it's way out, but I can't remember if I removed that for TC when he was troubleshooting his 1541.

Let me know what you need and I'll see if they are there on the board.

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i suspected heat...its been on all day , so I've left it outside for 45 mins, cool to the touch now and guess what - it all works perfectly!!!

?????????

---------- Post added at 21:10 ---------- Previous post was at 21:09 ----------

Thanks Merlin,

im puzzled as to what is wrong at the min - heat is an issue so i will have to check the temp of each chip to which one fails...

This sounds like a typical CIA (6526) failure.
Only one of them controls the keyboard, I usually switch between the two in order to check if its actually bad :)

On this Rev C board , they are soldered. oddly on my Rev A board (1983) they are socketed..

Typical Commodore cost reduction :lol:

Quote:

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Originally Posted by mjnurney

On this Rev C board , they are soldered. oddly on my Rev A board (1983) they are socketed..

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6526 and 6526A CIA Chip Information
Possible causes for game port, keyboard, user port, serial port and cassette port malfunction on the Commodore 64 and 128

The 6526 or 6526A CIA chip is the most commonly needed replacement chip for the Commodore 64 and 128. If you can't get any joystick to function properly on your Commodore 64 or 128 or if a certain pattern of keys (like every other key or a diagonal row of keys) doesn't seem to work or if the cursor just marches across the screen without any key being pressed then you probably need to replace the 6526 CIA chip (marked U1 on most Commodore 64 boards). Usually this chip gets blown out by accidently touching one of the pins on the joystick port when you have static electricity on your body (from walking across a carpet or from touching the TV or monitor screen).

This is also the same chip as the U2 chip (on most Commodore 64 boards) which may need to be replaced if the cassette drive, the user port and/or the serial port are having problems. Note: If the chip is not in a socket then you will need to get someone who knows how to desolder chips to remove it for you and install a 40 pin chip socket (available below). Important: Once you replace the chip make sure to keep static electricity away from the joystick ports of the computer or you might end up Zapping it again! We just got in a big shipment of these new 6526A CIA chips!

click here for pricing and more details

http://www.oldsoftware.com/6526.html

---------- Post added at 21:30 ---------- Previous post was at 21:21 ----------

it seems i need 1 or both of the i/o controller chips at some point...to be fair the c64 has been on almost all day which is very unusual but i will have to source some :-)

Cheapest way: buy a used C64, old type with sockets.

yep , i may just keep it for spares, i have another

Here I have a lot of bad experience with old brown types, the white seem to live longer here, or have more life left. No idea why, mileage seems to differ international but not locally.. The 5 volt line is really high these days with 240 volts in stead of 220 as well.. Might be good idea to hack c128 psu it has more stable output..