I acquired a BM1900 over a year ago and everything works correctly (almost!) . The only service I performed was to replace 3 lamps ..bass, treble and balance.

I use this receiver for FM listening and TV-DVD out (to Tape In). Recently, I was testing out different speakers to audition and there is a problem that I didn`t notice before. The Bass and Treble controls don`t work with the left channel... tested with speaker out pair 1 , tested with speaker out pair 2 , and with headphones. Prior to testing out the new speakers, I always used the tone controls in middle /flat position with LOUDNESS =OFF / this function works OK on both channels.

After reading several topics in this forum related to BM1900/2400, this problem was not detailed but other issues point to electrolytic caps.  I did open the unit earlier(rear back rail +alu lid) and the 6 electro caps in the tone control board are orange coloured with 1 mismatch > C200 = red vis-a-vis C300=orange nonetheless both are 1uf, 63v

On the tone control board, I measured voltage at various points listed in the SM and they all tally up within range-spec i.e. 5.75 vs 5.6 at base of TR200-300...

Am I looking in the right place ? Would replacing the electrolytic caps solve this problem ? I figure if the slider(s) are defective , what are the odds that both are isolated to 1 channel (left)? I must also add that none of the slider-controls are noisy.

Any help, expertise, and opinions would be greatly appreciated.

Thanx, Ihor