Re: Fixing the C900 power supply

From: Gerrit Heitsch <>
Date: Fri, 02 Jan 2015 19:30:22 +0100
Message-ID: <>
On 01/02/2015 04:33 PM, Michał Pleban wrote:
> Hello!
> As it turned out, my C900 is almost operational now. The only thing left
> is fixing its power supply. So far I have been using the PSU I stole
> from a 720 (they have even the same motherboard connector!).
> This is the power supply of the C900:
> Looks like it's a switching PSU like most of other Commodore stuff, but
> I have never repaired a PSU before so I am quite stuck on where to go
> first. None of the parts look obviously broken, but the PSU does not
> wotk - it just emits a high-pitch hissing sound and that's it, no
> voltage is coming out.
> I would be grateful for any pointers.

Well, there are a few things that would be good to know.

- What are they using as the primary switching transistor?
- What are the ICs on the vertical board?

Also, all capacitors with an 'ROE' logo should be regarded as suspect 
and at least checked if not replaced. They tend to mutate into a short 
circuit internally. I see a few of them on the righthand side.


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Received on 2015-01-02 19:01:42

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