SWR WorkingPro 12 not powering up, not blowing fuses

[JerkyPudding]

I have a SWR WorkingPro 12 on the bench. It doesn't seem to power up, no LED no signs of life, but it is receiving power at the rectifiers and filter caps. It's reading 60v at the + and - rails. It is not blowing fuses either. I am also having trouble finding a schematic. Any thoughts and suggestions?

I appreciate the help.

[olddawg]

Schematic? What is the source of the LED supply?

[Jazz P Bass]

Well if you have the HV rails, it is powering up.

Does the amp not work?

Check the IC power supplies next.

Note: I do not see an LED on the schematic.

Workingman 12-15.zip

[Enzo]

That is workingman series, Jazz, he has WorkingPro 12.

You have the main rails for the power amp, but I suspect your low voltages are all missing. There is a pair of fuses for them. They make +/-30v from which +/-15v regulated supplies are derived.

[JerkyPudding]

That is workingman series, Jazz, he has WorkingPro 12.

You have the main rails for the power amp, but I suspect your low voltages are all missing. There is a pair of fuses for them. They make +/-30v from which +/-15v regulated supplies are derived.

Wow, thank you all very much for the contributions! The service manual is great!

Sure enough, the fuses are both out (F2, F3). Next question: what would have caused them to blow?

[Jazz P Bass]

Sure enough, the fuses are both out (F2, F3). Next question: what would have caused them to blow?

Anything after them?

The load on the supply can be removed by disconnecting the preamp connector.(P4)
There is also the output board to consider. That is connector P203 & P204.

Then you can prove out that the + & - 15Vdc supplies are working.

If they don't come up, then you can track down the supply fault.

If the supply is at fault, that still leaves open your question of why it failed.

Get the supply up & running unloaded & take it from there.