Help requested: AIWA HS PL55 auto-reverse not working

I might need some help with this from someone who knows the Alpha-mechanism better than I do. This AIWA HS PL55 that I have here does not do auto-reverse. It will begin to switch correctly, make some noise and then give up and switch back.

I've run the mechanism through its paces manually and the cam gear seems to do its thing correctly. However, upon a reverse, the head bridge is not positioned correctly and the central clutch/idler assembly also does not swing to the correct position to drive the other reel.

I've done a quick clip – this is what the mechanism does: Watch clip

Note the captions: parts of the mechanism (idler/clutch assy and head bridge do not move to their correct positions.

Here are two other images showing the mechanism with center hub taken off in two positions, FWD and what should be REV.

This is FWD, idler and head bridge are in correct position:


This is what should be REV, but idler has not moved over to right to drive other reel and head bridge is in neutral, but not in REV play more (to far right).


Do you have an idea what is causing this and how it can be fixed?

 

FWD play can be engaged just by rotating the gears, but for REV play engagement you need to keep the solenoid engaged at a certain moment.

There are 2 potential issues:
- if the mechanism does not engage REV play at all (motor is freewheeling, not engaging the camgear), problem is mechanical caused by level beneath clutch not moving.
Usually this is caused by lack of lubrication and also fact clutch is not properly repaired and puts additional force on that lever.
- if the mechanism does engage in REV, but reverses back to FWD or stop (depending on autoreverse setting), problem is the FWD/REV switch.
The swtich has 2 switches inside, one to swtich the preamps and one for the microcontroller.

 

Thanks for this very valuable piece of information, @Valentin! I guessed as much from my testing the mechanism manually. Indeed, I managed to make it reverse successfully by holding the solenoid manually.

Since the solenoid is just an electromagnet, should I not be able to measure continuity through its two poles? I cannot on mine. This seems to suggest that the solenoid itself is defective, which would make absolute sense given what else the mechanism does.

I'm currently awaiting shipment of a PL303 for spaces which uses the same solenoid. I guess I will have an opportunity to test this out soon.

 

Yes, you should be able to measure the solenoid's coil resistance. If it's open circuit, solenoid is defective.
Let us know what happens with the replacement solenoid.