This tutorial covers the adjustment of middle pulley in WM-10/20/30/WM-W800 mechanism. In these mechanisms the middle pulley sits at an angle when the belt is tensioned, causing very little clearance between the gear attached to the pulley and small reel drive gears. This can cause all sorts of problems ranging from grinding noise while running to very high W&F figures and even gear wear. That's why it's highly recommended to adress this design flaw when this walkman is serviced. It's an even better opportunity if the walkman is going to be disassembled to replace the table reel gear(s). Procedure goes as follows: 1. Remove the back cover and belt. 2. Remove the capstan retainer and flywheel/capstan assy. Note there is a washer either stuck on the capstan or on the bushing. If it's stuck to the bushing, remove it and put on the castpan instead. 3. Remove the casptan bearing retainer (2 screws). 4. Remove the buttons assy (4 screws- 2 long, 2 short). 5. Remove the pulley assy from button assy (2 screws). 6. Remove the pulley from its bracket. Pay careful attention to the split washer, it's a very small one. 7. Cut the left post as show in the picture. 8. Bend the plate that holds the pulley in the vertical direction, opposite to the belt tension as shown in last picture. 9. Oil the pulley bushing and re-install the pulley back to its arm. If any of the table reel gears need to be replaced, now is the moment to do so. 10. Re-install the buttons assy, add grease to the pulley arm slider. 11. Oil the capstan bearings (there are 2) and re-install the capstan/flywheel assy. Bottom (main) bearing shouldn't be lubricated, rather oil the capstan instead to make less of a mess. 12. Clean the capstan with IPA while rotating the flywheel to remove any remaining oil. 13. Re-install belt and re-assembly the case.
I have this apart now while I'm waiting for my replacement uptake reel gear and was debating how to fix this: 1) Add washer on the belt side of the pulley, or 2) Trim the non belt side (what this post does). #1 is non destructive and also creates just the tiniest bit more clearance between the pulley and the back cover. #2 is probably easier to accomplish without having to source a small wash and possibly a longer screw? I had one of these back in 1983 and by 1984 this was already an issue. If you pressed on the back cover, the pulley would rub causing tape speed distortion. It has no doubt gotten worse with time. This and the shrinking uptake reel gear seems to be the two design flaws on this unit. Not sure why the rewind gear doesn't break as it's exactly the same.
Also, what oil should we use? I have this: https://www.amazon.com/dp/B00AZMJZUE Which is billed as safe for plastic gears.
For lubrication use watch oil, the one in the link is fine. And where grease is needed (like the pulley arm) Molykote EM-30L. Yes, this is a design flaw which is made worse by wear. That pulley arm is thin and plastic, so it flexes under belt tension. Also the arm itself has some play both in the buttons assy and in the table reel assy, which will naturally make it sit on an angle when belt is tensioned. Solution is the one presented in the thread (#2) because adding washers will raise the gear too much creating poor engagement with the other gears. #1 is something I tried before and doesn't really work as expected, especially in FF/REW.
Interesting. However, since, the gear assembly is attached underneath the arms, won't cutting part of the mounting post off raise the gear on that end, not lower it?
Yes it will raise the gear on that end, that's what we want in order to increase the clearance. In theory using a washer on opposite end should achieve a similar result if the thickness of the washer is adjusted correctly. However in practice it's hard to tune the thickness of the washer to exactly what is needed and such mod may also require a longer screw (as you already mentioned). From testing I've done this seems the simplest method to achieve the desired result. Ideal scenario would imply to machine the entire mounting post at a different angle (as the pulley angle is on 2 axis) , but that's easier said than done. So far, this is what worked best, that's why I posted it on the forum. If you find a better solution, please share it. I will update the thread myself if I find better ways of adressing this problem, especially a solution to the tilt on other axis.
When I was pulling the ribbon cable back, I think this solder point to the left of the pcb standoff was used to attach the ribbon cable to the chassis. It came off easily but it had that look underneath the cable that made it seem like it was soldered to the chassis at that point. I could be imagining it.
Yes that point needs to be connected to chassis. Also, as a sidenote, that part of the flex doesn't need to be removed to service the walkman.
