Hi everyone, new to the forum but longtime Ada user. so i picked up a B200s power amp broken for cheap. it is now mostly working after i replaced some burnt resistors and transistors and fixed a trace on the board that was broken. but here's the problem, CH A works fine but CH B is very low output and slightly distorted.
Hey t-rack, bummer, I'm quite fond of the B200s BTW. MJMP may have some ideas to help, (a geus that may help ??, re-flow/melt all the connections around the the power supply and also where it connects to the PCB, long shot but may work ? MJMP ??)
Cheers R
Check those 0.47 ohm/5W resistors for broken leads and also reflow the solder around them.These can create this sort of problem.
thanks but tried that , no change. heres what iv'e done so far replaced CH B only, both 8599 both 8099 ,2sc3858 ,2sa1494 ,2n5415 ,2n3440 ,c6,c8,c9,c13,and repaired 2 burnt traces
still at a loss on this one
Maybe vol pot ? or in/out jacks ? (@ MikeB what was the issue with yours recently ?)
Blown speaker! Or was there something else i've forgotten?... Oh, yeah there was a dodgy output jack. It made a big difference. If you are changing these, make sure you use jacks that don't earth against the chassis.
Hey Mike, did you ever have issues with the pots ?
Yeah. One of them is a bit crackly, but only when I'm actually adjusting it, so I've been able to put off doing anything about it.
I'd replace them to be on the safe side. Chances are a crackly pot can fail with no further warning ( had that on my 2:90 once, vol jumps and so on).
I used Bourns pots and never had any issues since.....
Did you check the 2 zener diodes D1 and D3?You should have 5.6V on the collector Q5 and -5.6V on the collector of Q2.
Quote from: rnolan on January 08, 2015, 01:31:56 AM
Hey Mike, did you ever have issues with the pots ?
what would be the best pots to use as a replacement?
when it comes to the back output jacks, is there a suggested best replacement part of those as well?
thanks!
Just saw this old thread, t-rack, did you get it sorted ?
darthphineas, did anyone get back to you about the pots and jacks ?