amp issues

[zztunnell]

I have a couple problems with some of the amps ive acquired.

I have 3 QX 4150's I need to get running.

1 bought non working. It powers on,but with protect light lit up.No output from speakers and humms or buzzes at the toroids.
1 has 1 side working 1 side not.

And the final 4150 is in excellent cond except for a broken crossover switch on one side.

The rest of my amps work great,but a few have really glitchy crossover switches. When you wiggle them the sound goes in and out.

Can I manually bridge these switches in the off or full pass position or do away with them completely and bridge to fullpass on the board?

Anyone interested in helping me get these 4150's running?

[zztunnell]

Heres some pics of the guts of the 4150 that doesnt work(humms/buzzes)when powered up.

And a pic of one of the crossover switches. Does anyone know where i can find new 3 position switches like these?

Still looking for advice or someone willing to try their luck at fixing the 2 4150's.

Also wondering if there is a way to improve the performance of these amps(upgraded caps/transistors.....)

Thanks!


P.s. Dang it! I keep forgetting to add my pics backwards(last to first)sorry!

[zztunnell]

I got most of the parts to fix my amps. Do I need to replace the pink insulator strips that go under the fets? If so where can I find them? Thanks.

[trickyricky]

If they're not damage leave them, if they have nicks or cuts then replace them. I would use kapton or mica insulators available pretty much everywhere. Check mouser and digikey, you'll also need new thermal compound so don't forget that either.

[zztunnell]

Thermal compound? There wasnt any before.

I have some Artic Silver 5 high density polysynthetic silver thermal compound left over from a Xbox 360 repair will this work?

Im assuming you put a thin layer over the entire bottom surface of each fet,like you do when you replace a module on a HEI distributor?

The pads are intact and in good shape.

[trickyricky]

If the insulators are in good shape with no nicks or cuts then re-use them. As for the thermal compound, if it didn't have any then don't bother applying any, just make sure they're absolutely clean (no debris, hair, metal shavings, dirt).

[zztunnell]

Great thanks for the info.