Crate xt65r cooked

[tbernard]

I bought a Crate xt65r used today without testing it first, had no AC nearby and no inverter

After getting home, the amp hummed when I turned it on, and had a terrible burnt smell coming out of the back. The fuse in the holder was a 5A instead of a 2A, so I wasn't sure if that could have caused too much current somewhere on the board at some point enough to burn something.

I took the PC board off to look for any obvious burns or problems with tracks, but the back of the board looks fine.

I can use a multimeter and have done minor electronic repair on smaller items....so I believe I can do this with some guidance, I'm just new to digging this deep. I hate getting ripped off so I am determined to fix this thing so if anyone could point me in the right direction, or give me a good starting point that would be awesome!

I would appreciate any information,

TBernard

[mozwell]

check out Help repairing crate xt65r

power amp might be similar to GT65 or GX65 or TD70 etc, all seem to use the same power amp.

First, unplug the speaker, do not connect it until we fix the power amp.
Measure the ohms across the speaker terminals, 0 ohm, or something like 6 ohm......

Measure the DC volts across the speaker wires, more than + /- 100mV ? (Dont let the speaker wires short together)
Measure the voltages on the 3 legs of both the power transistors with multimeter red lead, multimeter black lead to 0V (speaker negative lead)
Meaure the voltage on pin 4 & pin 8 of op amps in the pre amp.
If power supplies are ok, we can go to the next step.

My guess is that the power transistors need to be replaced, and we should replace the large resistors in series with them as well.

Also, put a 2A fuse back in hte fuse holder.

[Enzo]

An oversize fuse doesn;t MAKe an amp draw too much current. It ALLOWS the amp to draw too much current when something fails. AN oversize fuse won't CAUSE failures, but it makes them worse when they occur.