Infinity 475a

[seankane]

This amp does not power up. The blue light on the cover and the protect light come on. I've read through a few old posts, seems the problem could be on the pwm board. Probing around with my meter I don't get any odd readings from any devices.


I have zero experience with these amps, anyone have this issue before?

 

[ultra]

If there is no DC output at any channel when the amp tries to power up, there should be an electrolytic cap close to the opto, replace it.

 

[Perry Babin]

If you can't find the problem, post the DC voltage on all terminals of the 494.

The 475 service manual is in the infinity folder.

 

[seankane]

I found the opto's U4 and U5 but don't see any caps around them. The only caps near are on the stand up pwm board. Looking at the schematic 2 caps on that board are tied to the protection circuit.