Kaypro problems

From: Cliff Boyer <homeline_at_ezl.com>
Date: Tue May 12 22:39:45 1998

>3) The fuse is fine, but the PSU won't start up. This is suprisingly
>common (I've had it twice in the last month). Most small SMPSUs run the
>control circuitry off one of the transformer outputs, which leads to a
>bootstrap problem (the PSU can't run without the control circuit, but the
>control circuit can't work without the PSU running). The solution is a
>small circuit to give the control circuit enough power to start. In a lot
>of cases this takes the form of a high-value resistor chain from the HT+
>(400V DC) line to the chopper control circuitry. And for some reason this
>resistor open-circuits. It's worth checking all high-value resistors on
>the primary side.
>When you've inspected the fuse, get back to us and we'll attempt to talk
>you through the PSU...
Well, I checked the fuse on the P/S, and its OK. So what is the next step?
Is this something I can take to a repair shop. I know of a TV & stero shop
that has worked wonders on an old Pioneer amplifier of mine. A P/S should be
of no problem for them. I would like to attemp to fix my self, but I just
don't have that sort of time at the moment! Or can anybody recommend someone
I can send it (the power supply only) to for repair?

Cliff Boyer
Received on Tue May 12 1998 - 22:39:45 BST

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