Re: 465B Horizontal Trace Issues - Help requested


@Sabrefencer
 

Tom,

Before my last post, I photographed (as a method of marking) the x1, and x10 pots and sprayed a small amount of Deoxit under the "dial" - the pot looks like it may be sealed, so I have no idea if it penetrated, but what the heck. I worked these pots back and forth many times with the power off, and even with scope operating, but no impact on collapsed trace. I have returned them to their original position. I tried to measure the resistance across the pot and nearby resistors, but this section of the circuit has parallel paths, with other resistors, so that may be difficult. I do not see a way to remove the pot without accessing the dark side of the A4 board, which requires disassembly. Is there a way to bypass or "jump out" the pot, either with a wire or a resistor (or even by resistor decade box - which is giant discrete pot)? In the meantime I am searching Mouser for a replacement pot.

You mention bias voltages in the stage, I do not know where to check that.

Thanks Gary

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