John,
I just went through that with mine.. Same kind of fault/overdrive shut down..
Max output about 220 watts and the inconsistant output..
What I found:
1. Bad solder joint at one end of R3 on the DC Distribution board.. Could be
any one of them,
R1-R4..
2. Bad solder joint at L3 on D amp Q3 base..
3. Bad solder joint at both ends of R15 on D amp Q3 base..
4. Replaced all 8 transistors with 2SC2879's..
5. I also had to replace both pass transistors on the A unit in my 9420..
My suggestion is to remove the bottom cover and go over every component on the
DC Distribution brd, and ampifier boards with a spudger, or your finger looking
for loose connections.. See if they seem to move easily.
then give a little tug on the wires.. They may pull out.. If you do find any
it's easy to remove the DC Dist brd and repair on the foil side.. On the amp
boards you'll have to fix on the top side,
"BIG JOB" to remove amp boards..
My Herc works better now than it ever did!!
GL,
Harry
Harry N. Coates
Comstock Park, MI
WA8HC@charter.net
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