Thanks for the suggestions to date.
I have made a little more progress
Using a good light source, the existing caps look fairly bad. The one with
the lead cut loose measures a dead short on the VOM, and two others look like
they are slightly deformed at the top end with swelling inside. Cant see the
diodes and resistors yet, but dont intend to take the boards out until I get
the new parts.
The good news is that the old Drake undersized (2 watt) glitch resistor didnt
blow, which I am reading as a sign that the immediate problem was upstream
in the power supply, and not on the amp rf deck (scraping load cap not
withstanding). I never did hear any "noise" from the rf deck, and the
initial power up reading on the plate meter shows that one leg of the voltage
doubler was not operating to begin with.
Looks like I can get some 105 degree computer grade caps from Mouser for
about $9 each if I buy more than 10, and they are about 1/4 the size of the
old ones.
I wonder if I should replace the two giant 50k 50 watt dropping resistors
which have the unusual mounting scheme at the top of the supply. They measure
ok, about 10% low, but there was at least one thread on this board that i
found which indicated that they sometimes give an arcing problem from the
mountings. Seems like drake could have simply put another winding on the
transformer instead of using these things to get 120 volts from 2500.
73 Randy
K8BUX
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