TS430S.9

A recent bulletin, from WA2PAY, asked for help for a TS-430S which had 
intermittent power output; it would suddenly drop to ten watts, then
go back to full power on its own.  Interestingly enough I just recently
fixed a TS-430S which had precisely this symptom.  The intermittent
nature gave me fits, since there was nothing I could do to it to make
it come and go.  I tried heat (hair dryer and running the rig under
a towel on the bench), cold (overnight in the fridge), beating,
pounding, thumping, probing, all to no effect.  The problem finally
turned out to be bad feedthroughs in the base circuits of the final
amplifier.  The base leads of the finals are soldered onto PCB foils on
top of the board.  They go nowhere else on the top.  The signal is
carried through the board to the foils on the bottom sides by some
feedthrough rivets.  When I lifted out the final amp PCB, the
bad feedthroughs were immediately obviouI have been fixing bad rigs
for years and years, and solder joints are always a prime suspect).
There were some very obvious cracks in the solder around them, and
they were only making contact intermittently.  Soldering them with
sufficient heat and solder cleared the problem.  I also found a few
bad solder joints on other parts of the PCB, by the way, but the
ones on both final amp transistor bases was the main cause of the
trouble.  By the way, if I kept the key down continuously while the
rig was in the ten watt mode, one ofthe base resistors eventually
started to smoke.  If you have this problem, inspect all the resistors
in the base area of the final amp PCB for signs of overheating.  In
many cases, they will be burned.  Over the years I have cleared a lot
of problems in a wide variety of Kenwood rigs, both HF and VHF, by 
resoldering PCB connections.  It never hurts to give the evil eye
to the solder side of PCBs when you have problems.