"David Shrader" wrote in message
. ..
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

snipping here...

Check the instruction book to see if it specifies the
type of meter used to get the readings in the chart. Very
often older receiver voltages were measured with low
resistance meters, around 1000 oms per volt. If you use a
modern very high resistance meter the voltages will read
high. For example, nearly all the specified voltages for the
SP-600-JX were measured with a 1000 ohm/volt meter except a
few which specify a VTVM.


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Richard Knoppow
Los Angeles, CA, USA