Hello Jeff,
Have you tried measuring the voltage at the wiper terminal of R1 (Control
Board) or RP6 pins 4/5? These points are all connected together along with
U2 pin 5, so you should get the same voltage +- a couple of millivolts at
each of these points. The voltage at all these points should vary but remain
equal as you tweak R1 and be >>.002V, approx 3.8V downwards.
However your .002 volt reading makes me wonder whether or not the probe is
actually making contact with U2 pin 5 or is sitting on top of a layer of
gunge that has formed on the IC's pin e.g. corrosion.
73,
Geoff
GM4ESD
"jrb" <[EMAIL PROTECTED]> wrote on December 18, 2005 at 1128 PM
I've just completed the first alignment and test and everything checks
out except setting the AGC threshold.
When I put the probe of my DMM on pin 5 of U2 (a hellish place to get
consistent readings) and adjust R1
I get only .002 DC volts.
I've resoldered the pins on both U2 and R1. I've looked through
Troubleshooting and the Reflector and
haven't found anything relevant.
By the way I had no trouble with the S-Meter alignment which is dependent
on the AGC threshold.
Is there any place else I should look on the control board for a
possible source of trouble, or could U2 or
R1 be defective? (I know components are rarely defective).
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