9090DB no sound

[big fudge2]

so when i turn it on it comes out of protection. but as soon as i play music it makes a loud "pop" and goes into protection for a few seconds and comes back out, but then wont play anything. I already replaced the 180ohm resistors on the driver board that were out of spec but cant seem to find anything else. Any ideas??

 

[LBPete]

Have you checked the DC offset? It's probably too high. There are many other fuse resistors on the driver board that could have drifted out of spec. There are many, many threads on this site that address the issue you are having. Use the forum search tools and start reading.

- Pete

 

[big fudge2]

I did and i measured .015v, i checked all other fuse resistors on the driver board and none of them are out of spec.

 

[LBPete]

If you measured the DC offset at the speaker terminals while it was in protection, the result is meaningless. The protection relay disconnects the amp output from the speaker terminals. Take the wood cover off, set it on it's side, transformer side down and remove the bottom cover. There is a blue and a gray wire coming off the power supply board that go to the protection board. Measure the DC voltage between each of those wires and the steel chassis.

On the driver board there are 4 150 ohm fuse resistors that frequently drift out of range. Be sure you check them.

Please use the forum search tools and read previous posts on this topic. All of these steps have been posted many, many times.

- Pete

 

[danrclem]

I put a driver board from another unit in mine and it did the same thing with a DBT hooked up. The 8080db that the driver board came out of would make a loud pop through the speakers ever so often. It had been sitting for about a year when I put it in the 9090db. I put all new resistors in place of the fused ones in the original board and the 9090db came out of protection and played but had a hum. I changed the fused resistors in the PSB and the hum was gone.

I'd change them all.