Why do you need a B3 service manual ?
What is the problem with your B3 ?
B3 was sold only in JAPAN
Power transistors are obsolete
Here is some very rare documents
View attachment 908376
View attachment 908377
Do you need anything else ?
I can help you and it is the best advice no matter what anyone else will tell youHi Mr. Clinic-audio,
My B-3 DC offset left chanel is 324mV, right chanel is 25mV. Please kindly help me if you have information of how to adjust DC offset?
Thank you very much in advance.
Dear rottalpha,View attachment 2527068
DC voltmeter on the red dots or speaker terminals
Adjust the pots with green dots
does this help?
Hi Mr. rattalpha,
I just finished the adjustment for both bias and DC offset as per above instructions from you and Mr. clinic-audio.
Left: Bias: 42.5—>41.3mV; DC: 323.8–>11.5mV
Right: Bias: 22.0—> 41.7mV; DC:135.0–>25.5mV
It is not perfect but anyhow better than before, I think.
I used 2 volt meters at the same time and adjusted, same way with what I did when diy the V-fet amp from Mr. N.Pass before. Is it correct?
Hi Mr. Wu and welcome to AK,Actually this amp is too old so sooner or later I must have it overhauled.
Hi Mr. Wu and welcome to AK,
I would comment to you that if you enjoy this amp and listen to it often, sooner would be much better than later since after 40+ years, later could easily become too late.