Crate GFX30 Schematic

[raja]

Hi all,
I'm new to this forum and to SS amps in general.
I've built a couple of tube amps and have a friend whom wants me to look at his Crate.
The amp works but the volume is about 1/2 watt, very low. He had it repaired by a local tech but this repair only lasted about 8 months. It now is showing the same symptoms as before. I'm thinking it might be the Mosfet, on SS amps this is the device providing the power amplification isn't it? Not having the schematics makes it hard to troubleshoot.
Any help you all can provide is greatly appreciated.
Thanks
Raja

[J M Fahey]

Hi Raja.
Google for that schematic, it might even be here somewhere or search Ampix.
Anyway, take a couple internal pictures, and check what the output transistors are. If it were a 15W amp it would be easier, because almost everybody uses some TDA2030, 2050 or similar.
JMFahey.
PS: does it have an effects loop?

[raja]

Hi JM,
Thanks for the reply. I have searched for the schematic to no avail but was able to make contact with Loud Technology whom now own Crate. They will send me the schematic if they have it. The amp does have an effect loop. I'm pretty sure I know which part was replaced before and if not to pricey I pop another one in. I'll take some pic's tonight and post.
Again, Thanks for the help
Raja

[Brymus]

Hey could you PM that schematic to me if you get it?
I have the Crate GX20M and it uses the TDA2040 for the power section.
I recently ordered some of the TDA20XX series from Tayda Electronics for about a 1$
apiece - YES 1$ or so each.
It took almost a month to get em (from Bangkok I believe) but I saved a bundle over Mouser (3-4$ each) and the like.
They have amazing prices http://www.taydaelectronics.com/servlet/StoreFront
After my first order they sent me a 20% discount for the following month unfortunatly
I didnt have the funds to order again so soon.

[raja]

Hey Brymus,
I did receive the schematic from Loud Technologies, they were very helpful.
Just email them @ misupport@loudtechinc.com, along with the Model and Serial #. They will send you all of the schematics if they have them.
I'm sorry but I agreed not to post the schematics without permission.
The amp I'm repairing uses the TDA2050, which runs $1.79 at Mousers but I'm going to try it locally first.
Let me know if you have trouble getting the schematics from Loud.
Raja

[Brymus]

I wasn't asking you to post it > so anyone could download it.
I asked if you could PM it to me so I could further my knowledge,compare with my GX20M.
If you dont feel comfortable with that than I understand.
I dont own a GFX30,I was just looking to learn more by studying an existing design.
I love Crates,more for sentimental reasons than sound quality.
But I think they are excellent amps to learn with.

Good luck with your repairs
Bryan