Behringer K900FX - no sound output

[MrBungle]

I have had this amp for a little over a year and has been great since a few days ago. I run 2 synths through it and never play over 3/4 volume. Yesterday while playing, the sound just cut out on all 3 channels. none of the inputs or outputs work. I took it apart and inspected everything, nothing looks burnt out or damaged. When I turn the volume all the way up you can still hear the speaker is on. I'm no expert with testing electronics but I have a good digital multimeter. What should I go about testing first? What could have possibly happened? Thank you for any help.

-Eric

[Enzo]

If the speakers make any sounds at all, then they are still operating and still connected. SO that rules out a wire coming off the crossover. Still it never hurts to try other speakers plugged into the amp.

Isolate the problem.

Without me looking, that amp has some patch jacks like preamp out, FX send and return, power amp in, doesn't it?

Plug a signal into the power amp in jack. ANything come out? if that works, try the FX return. Likewise, plug a cord from the FX send to the input of some other amp. Anythiong comeing out? How about from the preamp out?

[MrBungle]

mods/admins can delete this thread. I bought a PA and turned this into a monitor. thanks

[CraigW]

I currently have a K900FX with no sound, only an occassional click/snap which varies with master volume.

I have the + & - 15 volts at the regulators.

LEDs for EQ and effects light properly.

I was able to jumper in a signal on the shielded pair in the connector leading to the amplifier board and had injected signal output from speaker...so the output is working correctly.

Closely looked over the input and the preamp boards and knocked them around a bit checking for poor solder connections.

They said it made some pretty loud scratchy noises at first then went to what I have now.