Brightness pot question

[ChadTower]

I'm still working on this XM501... tried the rejuvinator, didn't do anything.  I was poking at the controls and noticed that the brightness pot seems to do nothing.  The rest all show a response.  I haven't found any spots where it is visibly removed from the circuit.

The schematic lists it as a 200k resistor, R21 as shown below.  When I turn it all the way down resistance reads as 5ohms.  All the way up - 132k.  I don't see how to tell from the schematic what the low reading should be but can I assume that 132k isn't enough at max and that this thing should be replaced?

FWIW, I can tone it to R22.

[Ken Layton]

You're getting false readings because of other components in the circuit.

You need to temporarily unsolder all wires going to that pot in order to test it accurately.

[ChadTower]

You need to temporarily unsolder all wires going to that pot in order to test it accurately.

I was afraid of that.

It was brought up in my project thread, and I have thought of this but didn't understand enough to consider it fully, but would the signal from a VCR be displayed as dim, and thus maybe I have a good monitor that I'm still trying to fix?  I have been considering that maybe the signal from the VCR isn't strong enough to be bright on the monitor. 


EDIT:  out of circuit it tests to 175k fully open.  Good enough or should I replace it?

[qrz]

since turning the ctl is producing no effect , also suggest verifing 150 v source ,  check r95, r22, then check c10 and q21 for  possible shorts ....

qrz