While you've got the box open....
Here's a writeup on a problem that I encountered recently and it was purely by accident that I found the two faults were related - the initial reported fault was 'drifting off frequency' but mine was ' distorted WFM and FMn audio".....
My problem was distorted WFM and FMN audio - hunting through the messages gave the same solution - change C135. However another solution entitled "Icom R7000 design error fix" showed what the real problem is/was - maybe it's the same 'defect' but with different symptoms.
However, IMHO the main cause of the defect is a dry atmosphere! If you look at the schematic around C135 you will see that the circuitry attached to pin 5 of IC6 has no DC return path to ground or negative - even the slightest bit of leakage through C135 will fix my problem but maybe not yours if C135 is excessively leaky. My problem was cured by adding a 2.2Mohm resistor across C135 and now all is good. When I think back to when the problem started, it was about four months ago, winter was coming and the heat pump/heat recovery system was working well, my humidity is about 35%rel where its's 65%rel outside - perhaps the very dry atmosphere has finally dried out the PC board and raised the input impedance so high that Pin 5 has no DC path to anywhere and just floats - usually high as the negative input sources current - driving the output low until distortion sets in. Turning off the power for a minute or so lets all the volts disappear and all is good for 30minutes or so, then the distortion creeps in.
C135 and it's associated components are on the IF board which is handily right on top behind the display. it's easy to pull all but one of the multi-pin connectors off, one is soldered into the board, a single wire and a coax connector, then six screws or so and the board can be hinged out. With the aid of the printed board layout you can easily solder a very small 1/8watt resistor across the traces by C135.
Cheers - Martin.
