Faulty Sx-64 - Please Help.

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Faulty Sx-64 - Please Help.

Postby DomCoolNZ on Sat Sep 24, 2016 10:08 am

Hi All,

After watching various Tezza videos I started my classic computer collection. My aim is to get all of the classic computers that I used when I was a kid. One of the classic computers I used was a Commodore SX-64. I recently purchased one from TradeMe. The seller posted "Was working when last turned on" however as soon as I got it it was faulty. As I have only ever seen this one I didn't push for my money back.

The seller informs me that this is from the private collection of Graeme Duffy. I don't know if that name means anything to anyone here.

Anyway, on to the fault. When I turn it on it looks to work but very quickly develops vertical lines in the display. If I turn it off and then on again the screen no longer shows the OS but instead shows random colours all over the screen. If I give it time it will repeat the same symptoms.

The seller informs me that he spoke with his dad (Graeme Duffy) who suggests that it is either ram or the Power Supply.

Although I have done small repairs to my Apple IIe computers, given the rarity of this I do not want to "learn" on it. Therefore I am looking to find someone or a business that feels comfortable and skilled enough to repair it.

Does anyone know where I can take this to for a repair?


Dom H
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Re: Faulty Sx-64 - Please Help.

Postby tezza on Sat Sep 24, 2016 10:46 am

Yes, the old "was working when I last turned it on" seller comment... :)

If it is ok for the first few seconds, I would suspect a power supply issue (rising volts as it warms up) or maybe a capacitor problem. In my experience, if it's an IC it either works or it doesn't. Mind you a faulty PSU can soon blow up RAM and other chips.

Commodore power supplies are notorious for developing faults and blowing up chips...at least for the stand-alone PSUs on the C64s. I'm not sure about the SX-64 which has it's own built in PSU.

There are lots of diagnostics docs on the web for the C64s, if you can't find anyone to take a look at it.
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Re: Faulty Sx-64 - Please Help.

Postby mons2b on Tue Sep 27, 2016 9:33 pm

I recon first stop replace all the capacitors in it. Both the main board and the power supply board. I assume its intergrated in the SX unit?

Those are so rare now that no matter what you have to fix it! :) . It will prob take time and lead to a headache or two but I doubt it cant be done.

Try contacting the below guys. They supply nice premade cap kits for the more modest c64 units. Let them know you have an SX. :D

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