Ampeg B200R

[mistercams]

Thanks a lot mozwell for the schematics!
My B200R got the classical issues, bad crossover wiring, jfet/fuse blown and bad solder joints. I am currently reparing it and hope to have some fun with this amp very soon!

[soundguruman]

Thanks a lot mozwell for the schematics!
My B200R got the classical issues, bad crossover wiring, jfet/fuse blown and bad solder joints. I am currently reparing it and hope to have some fun with this amp very soon!

Have a look at the underside of the power amp board.
The larger components, such as transistors with large unsecured heat sinks, tend to break off the solder tracks from vibrations during transport.
This has been the ongoing issue.
On some of these, the factory glued the parts down, some of them have no glue.

Power transformer: Check to see that the transformer is tightened down. Many of these amps have loose transformers.
The transformer can move around, and the wires can break off.

Ground wire, from AC power, green wire. Make sure this wire is attached tightly.
The screw that attaches the wire to the chassis may not have been tightened all the way, at the factory.

Jacks: I recommend that the jacks be changed to Cliff UK jacks.
The original jacks have metal (switch) contacts that oxidize very rapidly.
This causes intermittent audio, or may cause the audio to fail.
This problem occurs more when there is a lot of dust and dirt getting inside the chassis.

Soldering Overall: It might be the best idea to re-solder the connections, especially on the power amp board.

[J M Fahey]

Big issue is solder connections. The parts tend to vibrate and break their own solder joints.

Loud, not SLM...? what's the difference?
It's become pretty obvious to me that the two are related...

[J M Fahey]

Have a look at the underside of the power amp board.
The larger components, such as transistors with large unsecured heat sinks, tend to break off the solder tracks from vibrations during transport.
This has been the ongoing issue.
On some of these, the factory glued the parts down, some of them have no glue.

Power transformer: Check to see that the transformer is tightened down. Many of these amps have loose transformers.
The transformer can move around, and the wires can break off.

Ground wire, from AC power, green wire. Make sure this wire is attached tightly.
The screw that attaches the wire to the chassis may not have been tightened all the way, at the factory.

Jacks: I recommend that the jacks be changed to Cliff UK jacks.
The original jacks have metal (switch) contacts that oxidize very rapidly.
This causes intermittent audio, or may cause the audio to fail.
This problem occurs more when there is a lot of dust and dirt getting inside the chassis.

Soldering Overall: It might be the best idea to re-solder the connections, especially on the power amp board.

[Jazz P Bass]

Or better yet, compress them into a 'zip' file.

[jpfx88]

I am having issues with my b200r blowing fuses, it just buzzes for about 3 seconds and blows the fuse, the current limiter on the negative to wall has burnt too. Any ideas as to why it's doing this?

[Jazz P Bass]

It appears that something in the amp is shorted. That is what is blowing the fuse.

Stop putting fuses in it until you find the problem by probing in an unpowered state.

A few items to check are the output mosfets (for a short between terminals), and the power supply itself (shorted diodes).

As an aside, it would be best if you started a new thread, so as not to get all involved confused.

Schematic: http://music-electronics-forum.com/a...mpeg-b200r.zip