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.
So, it is only now that I have been able to pick this up again. I eventually changed the solenoid, but to no avail. I also replaced Q10, the transistor directly responsible for actuating the solenoid – also no dice. I am pretty much back to square one now. I have been able to pinpoint the fault to the take-up reel not switching from the one responsible to take up on side A to that one on side B. The head bridge is raising properly and the capstan in also switching, but the take-up reel is not. Since the solenoid is apparently responsible for just this, I still need to figure out why something is prohibiting the reel from switching to side B. Also, FFWD is not working, but REW ist. (Struggling, but not initiating.) Possibly related. By the way, I tested the FWD/REV-switch and that's not it. It's something mechanical for sure. I may have to disassemble the core mechanism, clean it and reassemble it. Any guesses as to the reason would be very welcome. Could it be the clutch? (Which was broken and has been restitched.)
Another thing I should mention is belt can be slipping on some of these Alpha-2 mechanisms. While the original belt is usually still good, sometimes it needs to be replaced. Note the belt needed is 56mm x 0.8mm, while all sellers out there seem to give you 56mm x 0.6mm instead which WILL SLIP especially when engaging REV PLAY. As far as the clutch goes, make sure the wire stiches are tight enough and there's no friction between the wires and the C clip below. Ideally a new retainer should be installed, they are available in China: https://www.goofish.com/item?spm=a2...ac2eJ7R5G&id=918176667983&categoryId=50025387
Thanks again, @Valentin. I replaced the 0.6mm belt that I indeed had with a 0.8mm one and even though torque is now noticeably improved, the issue is not gone. Something is audibly (and tangibly) blocking the reversing process. I need to keep looking. Goofing only seems to be available in Chinese. Are these retainers available elsewhere accessible to Europeans? Also, do you know a good source for packs of 0.8mm belts? I do not seem to be able to find one, not even on AliExpress.
Don't know if these retainers are available elsewhere. On that site you need a proxy to buy and a plugin to translate the descriptions in English. You can search on Aliexpress, they may be available there also. If you find them, please post a link here. As for the belt, I use this one: https://fixyouraudio.com/product/sq...8-for-cassette-players-and-cd-players-h65anm/ On Aliexpress this is available: https://www.aliexpress.com/item/1005003229619461.html Search other listings of this user, I think he has packs of 0.8mm. However there are few dimensions that you will need in this thickness.
Browsers such as Chrome can translate Chinese to English. Then you need a proxy service like Superbuy to complete the purchase. You drop the URL of the Goofish item you want into Superbuy. They arrange the purchase and charge you for it plus shipping to a Superbuy warehouse. Superbuy then advises you of the cost for their services and for shipping to you. You can also combine orders for final shipping. When you pay, the item is shipped to you. People over there are making all sorts of parts for Walkmen. Very cheap, while the costs to buy whole units add up to substantial amounts. However, recent changes to duty etc. for small imports into the US may make even small purchases uneconomic. This does not impact other countries such as Canada. Voting matters. This works the same as Buyee in Japan.
Thanks. I am a regular Jauce buyer, so I am familiar with the general system. I might try this out some time.
Thanks! That AliExpress ad is unavailable in my country (Germany). I am aware of the FixYourAudio-offer. Maybe I‘ll try that. By the way, I made a video showing what the mechanism does while it's seizing up. Not sure if that helps pinpoint the issue: view here. I am considering a full disassembly and cleaning of the Alpha-2 mechanism. Is the transport timed in any particular way, and, if so, is there a guide out there somewhere on how to retime it properly?
In the video it can be seen the belt is slipping at the motor. It's also visible it's too thin, looks like a 0.6mm belt, not 0.8mm. Mechanism is not timed. It's worth removing the camgear and the lever below the clutch gear and re-grese those 2 items. Add only a minimal amount of grease. And after that install a thicker belt.
Sorry for not mentioning this: I had already switched back to a thinner belt at this point. It‘s not that. With a 0,8mm belt, I can actually feel the mechanism shaking and even see the front lid move when it hits its „obstruction“, so high is the torque with the stronger belt. It just isn‘t moving any further. If its not timed, I‘ll definitely do a full cleaning and regrease at some point. Thanks!
Given this only thing I can recommend is remove that camgear and lever below clutch, clean them well and re-grease. Sometimes have seen the old grease on camgear to cause problems on these Alpha-2 mechanisms. However, as stated only use a very minimal amount of grease, as otherwise the levers won't slide properly due to grease surface tension.
