Question Solenoid self-activating on Pioneer ct-1040w cassette deck

Apr 17, 2021
Having just replaced the belts on a Pioneer ct-1040w, I'd greatly appreciate any advice/pointers on where I would be best investigating as a likely cause of the ff/rew solenoids activating on their own. On deck power-up, the flywheel assembly and idler gear start spinning and after 5-10 seconds, the rew solenoid engages. The behaviour is slightly intermittent, the solenoid will release again sometimes after several seconds and keep up the pattern of engaging/releasing. Holding down the stop button will cause it to release (but only as long as the button is held). Sometimes it alternates between ff/rew. The deck uses logic controls so I'm not sure where in the chain from button to solenoid I should be concentrating on to locate the source of the problem.

I checked the service manual and located the control circuitry. Testing the diodes gives an OL for the rew solenoid (D03) which if I'm understanding correctly means that the diode is bad. Testing the other diodes however, all gave readings in both directions, which again in my limited understanding I took to mean that they are shorted. I became suspicious that all 4 diodes would be bad though and felt that I'd reached the limit of my current understanding.

I'd really appreciate anyone with more knowledge of this than I have giving me some pointers on if I'm making the correct conclusions from my test.

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