On Sun, 2006-06-04 at 11:10 +0200, Christian von Wechmar wrote:
> Hi Everyone,
>
> I received a 9420 PSU two days ago. If my information is correct, it stems
> from a Halliburton operation in Gabon. I have been using the matching
> Hercules II amp (with batteries) for more than a year now, and am very
> happy. Had to wait for an opportunity to ship the PSU cheaply, as the usual
> freight charges were too hefty.
>
> Anyway, the 9420 does not work. When plugged into my Herc, and the amp is
> switched on, it (amp) powers up for about three seconds, and then shuts
> down. The meter stays lit however. I tested the PSU while unplugged from the
> amp. When shorting pins 3 and 6 on the 12-pin plug, the same happens.
> Shorting pins 1 and 2 on the 4-pin plug reveals the same issue. 14.5 Volts
> for about 3 seconds, and then nothing. I measured the V at the rectifiers,
> and it appears that they only have power for half a second or so. It is
> apparently long enough to charge the large caps with 14+V.
>
> It traveled by air from Gabon to London to Cape Town, and had two bent
> heat-sink fins. It definitely got bashed along the way, or in its previous
> life. I opened it, cleaned it, inspected it closely, but cannot find any
> obvious problem.
>
> I'll order the manual from TT on Monday, but experience has shown that it
> will take about 3 weeks to arrive here in ZS. It would be nice to use the
> PSU before then. Anyone have an idea/solution/recommendation for me to try
> in the meanwhile?
>
> TU ES 73
> Chris ZS1DX
>
Try a resistive load of a few amps. Many switching supplies have minimum
loads they will stay one with. Otherwise their minimum pulse width
causes the output to go high and when it goes out of regulation the
supply gets shut down.
--
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
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