Memphis 16 MC250D

[warpedhifi]

I finally started working on this amp. The amp powers up fine, get a green led light, relay kicks in, and the pulls about 1.8 amps idle. But there is no sound. Did not see anything on the driver card that looks bad. It looks like the IRFZ540's were replaced.

Anybody know if the 540's are originally used in this amp?

Any idea's for no sound?

Here is a picture of the amp and driver board.





Thanks!

 

[Perry Babin]

Are you getting rail-rail oscillation on the output transistors?

 

[warpedhifi]

Ok, this is what I am getting on the 540's:

Q312:
G: 22.6vdc
D: 33.5vdc
S: 17.5vdc

Q313:
G: 4.7vdc
D: 17.5vdc
S: -.06vdc

Q311:
G: 4.6vdc
D: 17.5vdc
S: -.06vdc

Q310:
G: 22.5vdc
D: 0.0vdc
S: 17.5vdc