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Crate GX-212 on the bench (schematic?)

3/9/2006 12:41 AM
Erik MillerCrate GX-212 on the bench (schematic?)
Client says that it emitted an ozone smell; forever thereafter it has exhibited a constant crackling and the volume controls act as if they are always full on.  
 
Opened it up and first noticed that IC2's top was literally blown off. You could see the little chip inside and everything.  
 
Also the following resistors had crisped: R39 (4.7K?), R47 (10K), and R43 (2K2?). The question marks denote resistors that I measured, but were too roasted to read the color code.  
 
Q6 (J175) was physically cracked in two.  
 
Replaced all the resistors and IC2, to no effect. It's still cracklin'. Need to source a J175 or equivalent.  
 
Interrupting the preamp-power amp connection via the jack shows that the power amp section is fine; no crackle, and running my signal generator in gives a clean, strong output.  
 
So my gremlin is somewhere in the preamp.  
 
Problem is, no schematic, and it's a Crate. Little tiny PCB traces, and they'll probably want me to pay them 10% of replacement cost of the piece for a schematic.  
 
Anyone got a schematic for this?

 
Replies:
Enzo Those bad parts don't make sense. U... -- 3/9/2006 1:31 AM