Filled fix (replace) c64 memory (Finland)

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Mendel

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I have a c64 with "out of memory in 0" error.

I need (probably) a new power supply, need new memory chips and I need someone to solder the new memory chips on it.

basically, an operation very similar to this: www.amibay.com/showthread.php?t=19196

This is beyond my soldering skills.

Would anyone like to do such a project for me?

Alternatively a cheap "new" c64 would do the trick I suppose.
 
If you are happy to send the board to the uk then I can replace the ram for you

TC :)
 
Thanks for the offer! I´ll keep on the lookout for any possible local offers for a bit and if there is nothing then I´ll ask you again (y)
 
I did this recently and it was easier than I thought. You can do it!

Just snip off all legs and remove each chip, then unsolder each pin and use needle nose pliers to pull it out of the hole. Then install a socket. :)

Tedious and a few hours of work for sure, but you will feel good that you did it yourself!

Alternatively an easy way to fix would be to piggy back a chip on each chip and see which one is bad, and do that one chip, or solder the new chip on the old one!
 
I did this recently and it was easier than I thought. You can do it!

Just snip off all legs and remove each chip, then unsolder each pin and use needle nose pliers to pull it out of the hole. Then install a socket. :)

Tedious and a few hours of work for sure, but you will feel good that you did it yourself!

Alternatively an easy way to fix would be to piggy back a chip on each chip and see which one is bad, and do that one chip, or solder the new chip on the old one!

Whoa, don't solder a new chip on the old one. At very least cut it out like you suggested before. It would be pretty bad to have the bad chip still giving off bad data after popping in a new one.;)
 
I have the soldering tools for this so I could help you out. Send a PM and we can discuss details :)
 
Thanks for the offer. pm sent

Now then, let´s first think about getting spare parts such as ram chips and power supply from somewhere. I dont really have any idea as to where to get those but maybe you have an idea or we´ll work something out (y)
 
let´s first think about getting spare parts such as ram chips and power supply from somewhere.
I strongly suggest you to find yourself a brand new custom-built one from reliable supplier or if you're going for original model get it at least tested before buying, those old bricks are prone to murder poor Commodores when they fail.
 
current plan is to ask for memory chips from bebek and power supply from partco with possible soldering help from ajk.

Wish me luck! :cool:
 
C64 sent to ajk for repairs. (y)

Condition before any fixes:

20130610143525.jpg

This happened right after booting the machine up.
 
Alright, I've got the machine here now and have tried it out. I started with the original power supply and the condition is the same:

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As discussed in PM, we decided to make a fresh power supply in any case. The C64 needs 5 volts of DC and 9 volts AC, which is a peculiar combination and you sure can't find a single power supply these days which provides both. You can find separate supplies of course.

The 9 volt line needs to provide over 1 amp of current, and I couldn't easily find a supply like that (only some with 0.3 amps or so). However, 12 volt linear DC power supplies are easy to find.

The way these work is there is a transformer to drop down the mains voltage and a rectifier and smoothing capacitor to make the output direct current. It just so happens that the AC output of the transformer is 9 volts, which is exactly what we need. So I simply took out the rectifier diodes and capacitor. The output voltage turned out to be a little bit higher than that of the original PSU, but this should not be a problem.

(The C64 motherboard in fact rectifies the AC to 12V DC - just like the PSU circuit did - it would be possible to bypass this and just feed in 12V DC, with some caveats, but this is a topic for another thread.)

The 5V power supply is a switch type device which means it doesn't need a bulky transformer and can be quite small, sort of like most mobile phone chargers are these days.

I combined both power supplies with a suitable Y-cable arrangement and a fresh 7 pin DIN plug, and it works well. Less elegant than a single brick but hey, at least it's brand new.

Will start replacing the old RAM with some sockets and new memory chips next.
 

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After quite a while of desoldering (damn ground planes) and a short while of soldering, I got the sockets installed for the RAM. You can see in the first photo that one RAM chip was already socketed, most likely an earlier fix.

Somehow I managed to install one socket backwards :Doh: This is essentially a cosmetic issue though, just have to remember to orient all the RAM chips the same way if this needs to be serviced in the future.

Anyway, after putting the RAM in, the C64 again boots beautifully:

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We'll discuss with Mendel if there is anything else that still needs to be done, and then I will ship the system back :)
 

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We agreed that I will also make an s-video cable for the C64. S-video should provide much better image quality than the RF or composite outputs, as the colour signal is kept separate from the luminance (brightness / "black and white"), so there is minimal colour bleed going on.

It's a bit fiddly trying to fit all the wires into the DIN plug, but I think I got one put together reasonably well. The difference is certainly noticeable:

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I also uploaded a short video clip to YouTube which demonstrates the difference well.

The improved image quality brings out the cross-hatching and banding artefacts of the VIC; essentially various clock signals from the motherboard make their way to the visible image. It is possible to filter these out also, but it requires a bit more extensive modification of the motherboard so we'll probably let it be for now.
 

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We agreed that I will also make an s-video cable for the C64. S-video should provide much better image quality than the RF or composite outputs, as the colour signal is kept separate from the luminance (brightness / "black and white"), so there is minimal colour bleed going on.

It's a bit fiddly trying to fit all the wires into the DIN plug, but I think I got one put together reasonably well. The difference is certainly noticeable:

attachment.php


I also uploaded a short video clip to YouTube which demonstrates the difference well.

The improved image quality brings out the cross-hatching and banding artefacts of the VIC; essentially various clock signals from the motherboard make their way to the visible image. It is possible to filter these out also, but it requires a bit more extensive modification of the motherboard so we'll probably let it be for now.

Oh yes. That looks better! Also, I think most of the artifacts you are speaking of are probably much more obvious on an lcd such as yours and I hope the image quality will be optimal on my crt tv (Sony Trinitron). Certainly better than with composite cable, I mean look at the difference with the colors!
 
We agreed that I will also make an s-video cable for the C64. S-video should provide much better image quality than the RF or composite outputs, as the colour signal is kept separate from the luminance (brightness / "black and white"), so there is minimal colour bleed going on.

It's a bit fiddly trying to fit all the wires into the DIN plug, but I think I got one put together reasonably well. The difference is certainly noticeable:

attachment.php


I also uploaded a short video clip to YouTube which demonstrates the difference well.

The improved image quality brings out the cross-hatching and banding artefacts of the VIC; essentially various clock signals from the motherboard make their way to the visible image. It is possible to filter these out also, but it requires a bit more extensive modification of the motherboard so we'll probably let it be for now.

Nice picture. I've tried making several S-Video cables but usually resulted in worse color bleeding than with composite.
 
I've tried making several S-Video cables but usually resulted in worse color bleeding than with composite.

This one is pretty simple, just one 330 ohm resistor in the chroma line to bring down the saturation, otherwise everything is directly connected to the C64 a/v pins. Perhaps the resistance could be even higher to tone down the saturation more.
 
I've tried making several S-Video cables but usually resulted in worse color bleeding than with composite.

This one is pretty simple, just one 330 ohm resistor in the chroma line to bring down the saturation, otherwise everything is directly connected to the C64 a/v pins. Perhaps the resistance could be even higher to tone down the saturation more.

Thanks! Have to get me a bunch of 330 ohm resistors and try this out. The S-video in my Atari XE behaves just the same.
 
@protek

You could also get something like a 1 or 2 kilo-ohm trimmer/potentiometer, connect that temporarily, and dial in a good value. Then replace it with the nearest value fixed resistor once you know what works best.
 
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