Repair ZP120

Ok.... this is revealing. This would appear that your transformer is bad. The AC through the transformer should certainly give you output voltage on the secondary...

Just to verify... you are measuring the output of the transformer... NOT the board?

gruv2ths - What do you think?

Look at this:

https://www.wikihow.com/Test-a-Transformer

The shaper looks good since you have AC on the inputs. You show 0v outputs. From this doc, it appears you may have found your problem. Your transformer looks bad.

I'll add this in there as well: http://www.electronicrepairguide.com/testing-transformer.html

Under Number 1 - "Switch on the equipment and measure the input and output voltage of the transformer with either an analog or digital meter. If there are no voltage or lower voltage then it suppose to be, the transformer need replacement. I personally liked this method because you are testing the transformer under full operating voltage which is very accurate. "

Guys, this power supply is generating the proper voltages. He is getting his 3.3, 8ish and 15.
I suspect it’s a idiosyncrasie of the meter. I bet a scope will show you what is at the secondary leads better. When I am back at my bench I will get some scope plots and show them here.

The scope never lies 😉 Interestingly, I used a Fluke 87 and it got the voltages...

Nice scope....I have a Rigol DS1104Z. They are invaluable.

Mine doesn’t have the True RMS feature, and that may be why?

Ahhh yes, that would do it 🙂

Thanks gruv2ths. That makes me feel better about those voltages. I received the new STA508 last week and planning on replacing it this week. After I replace it, I will try powering on the amp again and cross my fingers.

Ando, did you get the voltages coming from the riser board to the logic board?