I have a onkyo stereo that will not power on. Did the basic diagnostic items. Checked all caps, resistors, diodes and yes the fuse. Think I chased it down to a bad transformer. On the power supply board. 8.9ohms on the secondary side but 1.1k ohms on the primary side. Don't have a spec sheet but never seen one that high. The part number 8200280150620S seems to be obsolete. Any ideas on where I could find a replacement. I have some saved transformers but done know what the output needs to be. Any help would be great.

 

I have a onkyo stereo that will not power on. Did the basic diagnostic items. Checked all caps, resistors, diodes and yes the fuse. Think I chased it down to a bad transformer. On the power supply board. 8.9ohms on the secondary side but 1.1k ohms on the primary side. Don't have a spec sheet but never seen one that high. The part number 8200280150620S seems to be obsolete. Any ideas on where I could find a replacement. I have some saved transformers but done know what the output needs to be. Any help would be great.

That has the look of a standby mains transformer, does the amp have remote control?

If its what I think it looks like - there's probably a thermal fuse buried under the tape around the primary winding. Bypassing the thermal fuse would be a really bad idea - but just temporary to measure the secondary voltage could get you out of trouble.

You have to be dead careful to peel away the tape without damaging any of the very fine windings - if you're unlucky, the fuse could be under layers of winding.

They tend to be somewhere around 9 - 12V, but no telling what any particular manufacturer settled on. The voltage rating of the reservoir electrolytic will tell you what its not more than - but it could include a substantial safety margin.

 

It is a standby power supply. I tried to split the core but it looks like they put epoxy on it. The amp no longer has a remote. I am getting 10.2 volts out. I have been told that the system needs 12volts but have not been able to verify spec.

 

Your best option is to search for the service manual, or look at the pcb marking for voltages, look at the large smoothing capacitors for voltage rating, yours has 25V on it, which would give about 12-15V Ac out.

 

That was a replacement cap. The original was 16v but I'm getting 10.2vdc out.

 

That was a replacement cap. The original was 16v but I'm getting 10.2vdc out.

That doesn't sound silly - its probably about right.