[Greg Steinlicht]

Turning the wheel has no impact on the display.  No red volume lights appear nor does any green light appear, absolutely nothing happens.

Using the MCP, if I press FF the green “moving” light (indicating the tape is being fast forwarded) shows up on the MCP display.

If I adjust the bass, the MCP display first shows red lights at the far end of the left and right sides (of the adjustment spectrum) with a single green dot in the middle. This quickly goes away and then the display shows the bass level.

Do these symptoms possibly point toward a faulty opto coupler?

 

BTW – thank you for the very detailed explanation!

 

• This reply was modified 2 weeks ago by Greg Steinlicht.
• This reply was modified 2 weeks ago by Greg Steinlicht.

[Greg Steinlicht]

The opto coupler was the next potential issue I was going to look at after ruling out the micro switch. I guess at this point it makes sense to rule out the opto coupler.  Looks like a simple repair, unsolder and resolder three pins.

Any chance if you know if there is a certain polarity to the opto coupler pins? I want to avoid installing it incorrectly.

[Greg Steinlicht]

I tested the micro switch with a DMM. When the wheel is turned and the metal bar in the middle makes contact with either side contact, there is continuity.  So at least that part of the switch appears to function.

• This reply was modified 2 weeks, 4 days ago by Greg Steinlicht.

[Greg Steinlicht]

Guy, thanks for your response. I have already cleaned the microswitch, with contact cleaner, but it did not have any effect.

When you say “shorten the contacts”, does this mean squeeze in the contacts inward while turning the wheel or something else?

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