29-03-2013, 01:36 PM
(29-03-2013, 01:11 PM)tiv48 Wrote: AC series transistors do not suffer tin whiskers that is mostlt AF11x .
yours is a late model my circuit shows germinium transistors.
lock fit transistors tend to go open circuit (quit often)
to have 18 volts at the emiters of the output pair surgests that tr5 is short or turned hard on.
what voltage do you have on the base of tr5/6 when in the fault condition?
direct coupled amps are to me anyway a pain.
rob t
Rob, thanks for the suggestion. I didn't make a note of the voltages at the bases t5/t6, and, guess what, the amp. is working O.K. Maybe I'll replace T5 and t4(BC159) as a precaution, though I'd like to [undefined=undefined]prove which component(s) is/are faulty first!
