Re: Help with Tektronixs 492 S.A. PSU fault.

geoffrey pike

Hi Nick.
Have you posted this on the Textronics
Good luck

On Friday, 15 January 2021, 18:55:32 GMT, Nick Gregory G0HIK via <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

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