[TenTec] CENTURY 21-FINALS

[WB9IOG]

Two weeks ago I blew something in my Century 21. Found the problem to be
one of the finals shorted to ground. Thought the problem was in the
power supply at first. In process of replacing both finals now.
My question has to do with setting the trip point and alignment of the
meter. So I don't blow it again. Someone else had replaced the older MRF
475's with the newer transistors (C1969). It is possible that the
silicone grease for seating was done with the old grease, and noticed
some dirt that may have preventing a good seat of both finals. 
The manual specifies an adjustable 2.5 ohm load resistor with a 10 A
meter in series with the 12 VDC output. This is aligned to 6A. No
problem, but where does one find a 2.5 ohm variable at 100WATTS! I can
put two 40 watt DALE  fixed resistors in parallel and get very close to
the 2.5 ohm load. Then adjust the DC load to the equivalent wattage.
Does that make sense?
Also noticed a meter shunt at is 390 ohms.The schematic shows none, but
the power supply shows a resistor Rsc (no value). Possibly that is the
390 ohm unit. What does Rsc mean?
Possibly "selected during production" as I've seen on a lot of BA
schematics?
Someone out there has done this before, as it seems the 21 was prone to
blowing a final.
I'ts my guess that setting the shut off point correctly is the primary
cause.
Any guidance appreciated.
BTW I sure enjoy the unit!

Mike
Le Claire, Ia
Tnx

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