I agree with voltage checks at the actual tube socket with a good, very good,
i.e. high impedance [FET or equiv], voltmeter. If voltages are within 5% of
correct values, then the resistors should be within spec. If voltages are 15%
off, then replace.

With the S-85 you can remove the tubes which opens one side of the tube bias
resistors. So, with the tube removed plate decoupling resistors, screen grid
resistors, cathode resistors can be checked in circuit.

Secondarily, typical A-B carbon composition resistors absorb water vapor and
swell/crack with time/age. This is easily found by an eyeball exam with a little
magnification for those of us over 60 years old :-).

Finally, use a good contact cleaner on the bandswitch wafers. You can use a
Q-tip for those hard to reach places.

/s/ DD, W1MCE

Bill Ogden wrote:

Really stupid question: When checking resistors while restoring an older
receiver, is it common to attempt to check the resistor while it is in the
circuit? That is, make a guesstimate of the parallel resistance (working
from the schematic). Or, should I disconnect one end of each resistor to
check it?

(Am working on an S-85. Have replaced most capacitors. No hum and the B+
voltages are OK, so the original power supply capacitors seem OK. General
sensitivity is still low, so resistor checks seem to be next on the list. IF
and RF alignment are OK. The last owner had the local osc above the signal
on band 4, which was the only serious problem. Tubes are OK, I think.)

Why an S-85? It was my first receiver, way back when (with a Heathkit Q
multiplier).

Bill - W2WO