Hello guys,
I'm new to this forum but as many of you I'm very interested in the technical side of electronics, especially about audio equipment.
To enhance my knowledge I started to recover defective audio products and try to repair them.
I have a Marantz UD-5007 bluray/CD player that doesn't turn on.
When measuring the voltages I noticed the 5V standy voltage isn't there.
In fact it's only 3.7V. I replaced the ZD502 with a new specimen but that didn't help.
I also replaced all electrolytic capacitors, there no solution either.
Now I'm starting to wonder if the regulating IC U503 does work properly.
The resistor R552 measures just fine, R554 is difficult to measure. My multimeter swings from 6k to 10k, even if I measure exactly at the resistorlegs.
Could this be because one of the capacitors is throwing off my measurement?
Also the optocouplers are hard to measure because they both have resistors parallel over them.
So, in short terms, I don't know what to do next. My plan was to replace U503 but since I have 3.7V it seems to work, only not in the right voltage...
Thank you in advance