Doug,
What transistors are on the finals board? While you are looking at it,
look for any electrolytic caps with bulging ends, or bodies. There are
a number of places handling even discontinued transistors.
Such swollen electrolytics would need replacing, which you could easily
do. Same for any electrolytic with whiteish leakage.
Just use same or larger capacitance near the orginal value, and same or
slightly higher voltage rating.
If the transistors are all bipolars, you can use a diode test of many
DVMs, to check each base emitter and base collector junction, to find
any failed ones. Those junctions should test like a silicon diode does,
about 0.6 volt threshold.
Most failures are in the higher current or higher voltage parts first,
so the finals would be tested first, then moving to driver stages.
Rarely a ceramic cap might fail, or a mica. But about all there is left
are resistors that might change values, or cores and wire, that won't
fail unless something very unusual happened to your rig. It is probably
easier to troubleshoot a finals board than a receiver.
Good Luck and 73,
Stuart Rohre
K5KVH
|