Schematics for specifically the Crate GX900H Excalibur head power amp??? Please!!!

[Spencerltm]

I have only found the GX2200h and it looks nothing like mine.

[Spencerltm]

It's an older head.

[Jazz P Bass]

Here is what I have.

The preamp drawing is dated 1995, while the power amp & layouts are dated 1999.

crate GX900-2200.zip

[Spencerltm]

Basically it started with a loud hum. Blew a fuse, and that's all it will do when you cut it on now.
Every time I find the short. After a few seconds the meter reads the OL correct reading. It's really weird. I don't wanna just replace things until it works. Lol. I'm truly stumped.

[Jazz P Bass]

What exactly have you done to try to isolate the problem?

Is this schematic closer than the GX2200H that you have?

I would start by removing the load on the output section (ie: the speaker)

With the power supply off & drained, check the (4) output transistors for a short.

If they are o/k, then you need to check the power supply for shorts.

After you find the short(s), look up "lamp limiter" & build one.
It will help to limit any current to the amp when you do power it on.
The more times that you blow fuses, the more you are stressing out the components of the amp.