Re: Help with Tektronixs 492 S.A. PSU fault.
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Have you posted this on the Textronics group.io?
On Friday, 15 January 2021, 18:55:32 GMT, Nick Gregory G0HIK via groups.io <nickg0hik@...> wrote:
I came to switching on one time and it light up, but nothing on the display.
The +15 v rail is 4.7v
The -15 v rail is -3.1v.
I think the minus rail uses the plus rail as a reference so it may well be just the + 15v rail faulty.
I've disconnected all cards and connectors and the volts are still low, so I dont think is a card fault and it's probably a PSU fault. The 0.3 ohm resistor in the +15v line says its has a draw of 1.0 amps with seems a lot at 4 volts though.
the +/- 17v rails that feed the +/- 15v are fine.
I would have suspected s/c Tants, but there does not seem to be any tants.
Any help welcomed please.
I've included a part of the circuit with some voltages on.
Thanks Nick G0HIK