Solid State Guitar Amp Forum | DIY Guitar Amplifiers
Solid State Amplifiers => The Newcomer's Forum => Topic started by: tortuga on June 26, 2011, 07:45:05 PM
I am trying to fix a Crate CR-IIR that I recently acquired. I have dug up quite a few schematics, but am not sure which one would be well suited since I have not found the one of the exact make and model.
As of now, the amplifier will not power up. The 2 amp fuse blew, and upon inspection, it looks like some of the diodes were burnt up, but most of the parts are not charred. I have gone through sections of the amp with my multi-meter and continuity tester. There are three perf boards. One looks like the preamp and tone stack to me. The The second is part of the power amp I believe. The third is the caps that go out? I'm not really sure.
I have experience with building kits and circuits, but have never really gone through troubleshooting a circuit, and have been doing a lot of reading on this as of lately.
Any help or advice would be greatly appreciated. I really happened to like the sound of this amp until it went up in smoke!
P.S. I don't know if pictures of the circuit board would be helpful, but I could post them as well since I don't have the original schematic.
Last time I had this happen the power amp chip had blow and took out with it the rectifying diodes and fuse. I replaced the TDA20XX chip, rectifying diodes and fuse and away I went.
So you were playing this amp when it died? Did you have the proper speaker hooked up to it? Did the speaker blow? Were you playing it loudly when it died?
The CR-IIR is way older than TDA20xx.
This thing is a very early Crate amp. 1979 or so. Discrete transistor output stage. STart checking those power transistors for shorted. Make sure the power supply rectifiers are not shorted.