Ba-2000 problem

[Jacob_audio]

Hi everyone. I have my ba-2000 for a couple of years now, and it’s have been in 3/4 services and no one could even diagnose the problem. So the problem is that:
After some time of playing (probably when it warms up), the voltage suddenly jumps to maximum power (crackling/scratching at full power) regardless of potentiometers. Then it turn to standby mode, the red light comes on, and after a short time the green light comes on again, it plays for a while and the same thing happens again. As if this strange voltage bypassed everything and transported it directly to the speakers.
Maybe some of you had a similar problem or even heard about it, I would be very grateful for your help.

 

[CrSens]

You need someone specialized in vintage electronics repair. There are many knowledgeable techs in this forum, maybe you can connect with one of them, depending where you live.

 

[jefferylhenr]

I have a ba2000 and had to rebuild the protection board, specifically replace all the fuse resistors. They are noted on the schematic as FR. And that was after a fairly meticulous restoration. Unless you know how to troubleshoot. It will take finding someone who can go through it for you. Obviously your current shop isn’t set up to take the time to eliminate all the possibilities.

I also have a Yamaha ca1000 that would randomly do what you are describing. Went through it multiple times, before resoldering the entire connector board even though they looked perfect under a mag glass. After that resolder, zero issues. It was acting like crap being thrown off by the preamp, but it was just bad solder joints.

You may have multiple issues. Or it could be your preamp throwing off dc or random spikes. Might want to try another preamp for starters. Nice sounding amp.

 

[ivandezande]

Impossible to say when we don't know what has been done. I replace near half the components in a BA-2000 to make it reliable.