Excessive Wow & Flutter in Sony WM-2 (0.78% RMS with 8Hz Spike)

I bought the ferric chloride off of Amazon, MG Chemicals 415-1L Ferric Chloride. Norm

 

Thank you, Norm!

By the way, I meant to ask you if you sorted out the WM-2 Gen 1 missing-part mystery.

Alex

 

I did not Alex. I never figured out where that mystery part that fell out goes. You may recall that I bought a second one only to discover that it was of a different revision. I got distracted by restoring a WM-150. I got the take-up reel sorted by buying a compatible donor unit but still have not completed a clutch wheel swap. The WM-150 came missing a clutch wheel spring. I fashioned one by using a guitar B-string. I don't think I got the tension right, maybe the felt washer is just to glazed/compressed, I'm not sure. I've been sidelined by work and house chores. I have a Nakamichi CR-2a and a few other Walkman's in the queue. Just no time... Thanks for remembering and asking about the WM-2. Norm

 

Norm,

It really is a WM-2 mystery. After looking through Service Manual Supplement #2 and comparing the schematics against my two units, it’s clear Sony made several post-production modifications, several within the [FWD] and several within [PLAY] button versions. When you factor in those revisions alongside the center gear variations (the solid molded plastic version vs. the prone-to-cracking gear bonded to the metal core), it is a maze.

The WM-150 is a beautiful model—full metal body and the amorphous head! It's one of my favorite models from the early '90s. I used to own its little brother, the EX-48. That lineage had a perfect blend of design, sound quality, and overall functionality. Amazing value for the money - I bought it around the same time for $90 and absolutely loved it. It eventually kicked the bucket in 95/96 and went to a landfill —a decision I’ve regretted.

If you happen to know the exact specs or dimensions of that clutch wheel spring, let me know or post a photo. I have a large assortment of spare springs salvaged from various audio gear, so there might be a suitable candidate in the mix for you. I managed to find a better replacement spring in that pile to set the proper back tension on my Technics RS-B905, so hopefully we can find a match for your WM-150.

I’ve never owned a Nak. The CR-7A is definitely my favorite of the CR line, though the audio nerd in me is always drawn to the ZX-7. But... I can't service them, therefore trying to avoid.

Let me know.

Best,

Alex

 

Thank you, Alex, that is very kind of you. I bought a junker WM-AF604, it would seem they share a lot of the same components. I just need to find time to get back to the bench, if the junker doesn't work out, I'll keep your generous offer in mind.

I wanted to get another deck that would not be too difficult to work on, the CR-2a seems to fit that bill. My main deck [Yamaha KX-630] that I originally bought has only had the belt replaced. Both motors on the CR-2a will have to be disassembled and cleaned/lubed, it's a common problem. I got as far as removing the Sankyo transport mechanism but that's it. While it is an entry level NAK, it has a bias adjustment knob on it so I can manually adjust bias to my tapes though being a 2-head deck will be a little tedious. I really wanted a CR-3a, but didn't want to shell out the coins. This hobby can get expensive. I also have a Marantz PMD221 and a couple more WM-5 laying around that will need to be restored. It has become almost an obsession for me, but time to stop with the buying. I have enough to keep me busy for some time, perhaps, I'll find more time during the winter months.

If you can work on a Walkman, you can work on cassette deck. Don't be discouraged. Heck, it may be easier, the parts are bigger . Cheers! Norm

 

No worries, Norm! I’m always happy to help a fellow vintage audio enthusiast, so just let me know if you need that spring.

I definitely hear you on the costs—this hobby can get out of hand quickly, so I try to keep my own collection on a pretty short leash.

On your cassette decks: if I recall correctly, Yamaha actually used Sankyo transports in many of their models as well, so the CR-2A is a practical choice. I don't have hands-on experience with the Sankyo mechanism myself, but it sounds like a great project.

As for the Nakamichi CR-7A and ZX-7 I mentioned earlier, those auto-azimuth (and CR-7A auto-tuning) systems require rare, expensive alignment jigs to be properly calibrated. Good Nak techs these days could make a full-time living just servicing those TOTL decks, as they are harder to find in acceptable shape and even harder to maintain.

Best of luck with your projects. I will update you on my WM-2 after the capstan etching session. I hope it works!
Best,

Alex

 

Update:
Performed the capstan etching on the donor unit. An interesting (and slightly nerve-wracking) procedure. Unfortunately, it didn't resolve the issue—the W&F is still audibly present on playback.

I'll keep troubleshooting even though I am out of ideas at this point for what can cause this so persistently in two (?) units.

 

I'm also out of ideas, Alex. I've been following this thread since the beginning and I know you've done a lot of work with methodical thinking involved. Is it possible that when installing the belt, there may be contaminants/oil coming in contact with the belt? For example, when installing a belt it can sometimes slip off pulleys and wheels while routing the belt and come in contact with an oiled/greased part? I make it a habit of washing my hands before installing a belt and soaking a Q-Tip with alcohol and holding it to the belt while hand-spinning the motor a or large gear/wheel. The question is, how does it sound when playing a tape? If it sounds satisfying, despite not getting the W&F numbers you're after, I think I would call it good and just enjoy the music from it. I've had to take that approach a couple of times. Even guys who do this way better than I, don't always hit the factory numbers. There is a guy on YouTube [LT Tapeheads] who seems quite competent, sometimes end up with results that would make me cringe and writes it off as, '...well, that's as good as this one can get.' At any rate, I wish you good luck in getting it sorted, I know it's bugging the heck out of you. Cheers. Norm

 

Norm,

Thanks for the support and the tips. I’ll give your belt-cleaning method a try. Of course, the belt slipped off a couple of times while routing, so it’s very possible it picked up some residual oil along the way. I always check, but I could miss something.

I’ve also watched LT Tapeheads’ videos on this Sony lineage. He’s a good resource, but as you said, results vary. He has a trick where he preheats the capstan bushing with a temperature-controlled soldering iron. I am not sure what it does exactly. But since I don't have a temp-regulated unit yet, I’m holding off on that one for now.

As for the sound, it really depends on the music. Chicago WBMX radio mixes sound OK, but 70s rock or jazz with sustained notes makes the wobble a bit more obvious. Still, it’s borderline acceptable—if it weren't for those occasional long-note wobbles, it would sound fantastic: deep bass, great clarity, and a very balanced sound overall. The low-end frequency response on both units was surprisingly impressive: -22 dB at 30 Hz!

Ultimately, the effort wasn't wasted. Both units work reliably, and I've become remarkably fast at dismantling and reassembling them. I still have a shot at figuring out the problem. Plus, I got a valuable silver lining: I now know never to buy a player from this Sony lineage again.

P.S. I haven't checked the transistors Q601, and especially 602- 603 in the tape speed circuit. It's a long shot, but one of the "fellow tinkerers" found (after the exhaustive cleaning, etc.) that his Revox elevated W & F was caused by a weak transistor. Of course, these are different machines and different schematics, but I think it is worth checking at least their current voltages.

Thanks again for bouncing ideas around, Norm! I appreciate it.

Alex

 

Hi,

In my case, I've discovered a forgiven screw that improves the W&F. Never touched it before, it seems to adjust the tape's path guide. After a little try the W&F are now better. Have to be carefull, because and incorrect adjust may cause that don' t engage the head correctly when you press play button.

 

Can't upload the image, server error ocurred.

Anyway, you can see the screw if you take off the door, on the tape transport chassis, the only screw at the right side, if you put the unit on landscape position

 

@worlwide I'm working with my 2gen unit. I've received the belt, and can put everything together, with the correct wiring. It starts to work, but need some attention yet. But W&F seems not bad, hopefully soon can be upload a new post

 

@JUAN ANDRES MONTIEL DIEZ Thanks for sharing!

That screw adjusts the tape-guide height. The head height on both my units is already properly set, so I doubt it's the culprit for the elevated W&F.

I'll keep troubleshooting - not ready to give up yet.

 

Update: Checking the voltages didn't yield much—nothing matched the values listed in the Service Supplement (except for polarity), though both of my units read very closely to each other. It’s likely just another (?!) undocumented production revision.

With no other clear avenues, I disassembled the donor unit, gave it another thorough cleaning, and relubricated all possible friction points, incorporating the tips mentioned above. After reassembling and testing, there’s a noticeable improvement! The wow & flutter dropped by nearly half to 0.377% WRMS.

While still not close to ideal, it's a big step forward and makes this WM-2 donor listenable. I suppose the combination of minor tweaks finally paid off. Plus, count me sold on the capstan etching procedure—I had my reservations initially. The next step is doing the same to the main unit and wrapping this project up. There's only so much tinkering one can do!

Thanks to everyone for the input and support throughout this thread—it's been an incredible help.

Alex

 

Congrats, Alex! Always good to see progress. About the same numbers I'm getting on my recent WM-150 restore. Cheers! Norm

 

Norm,

Thanks for your help and support,

Similar w&f readings from your WM-150 and my WM-2 are interesting … not sure what to make of it, but the similarity is noted

Once again, thank you!

Alex