Yamaha A-S500 Amplifier - Repair Log (Dim light - won't turn on)

[sammy3]

This is a repair log of a Yamaha A-S500 Amplifier - perhaps it will help someone in the future with a similar issue
Symptoms
Dim power led like its in standby mode (but wont wake up)
No relays activate
No error codes/blinking lights
Wont enter diagnostic mode

Service manual
https://www.manualslib.com/manual/1074982/Yamaha-A-S500.html

Testing
Test fuse 1 on OPERATION (1) P.C.B. (the power led can still come on if this fuse is blown)
Fuse was found to be good.
(Images of boards attached to post)
Check voltages on CB2 connector coming of the same board.
Found:
PRY is 0v (should be 4.7v) - so power relay not activated
N_RST is .8v unstable (should be 5v)
PWR_DET is 3v unstable (should be 5.1v)
+5.5SUB and MG are correct

Issue:
After testing caps - c7 was found to be low (12nf instead of 47nf)
Part number MPE 473K 400 Q2 C.POL.MTL 0.047uF 400V +/- 10% 10mm lead pitch (Polypropylene metallised)
All other caps were healthy and after replacing this cap it now powers up fine.

[wasedadoc]

Yep. Another case of the capacitor in a capacitor dropper losing a lot of its capacitance.