Hi all, I know there are several well-known issues with the mechanism on the Sony WM-150 Walkman machines, but I believe this is slightly different and I'm hoping someone can explain how the auto-reverse detection should work on these. The service manual gives no mechanical description other than an exploded diagram. I'll use the part numbers from that in my description. Bit of background, I have acquired a WM-150 that a previous owner has tried to repair but left in a bit of a state. The good news is the clutch gear is intact, as is the usual take-up drive gear (366), and the belt appears to be fine. Some odd things are apparent, such as the clutch assembly is missing the silver/black checkerboard pattern for the FF/REW end detection (I have replaced that) and the small spring (360) that acts on the auto-reverse pickup lever (321) driven by the clutch wheel was clearly bent at some point and needed straightening. The player plays fine both directions, FF and REW stop correctly and auto-reverse works 90% of the time when you press the green reverse button, but it doesn't work automatically at the end of each side: failing to turn the right hand spool when it is the supply side doesn't trigger reverse, and holding it when it is the takeup side just causes the big white gear to jump where it meshes with the clutch. I suspect the pickup lever (321) is meant to be influenced by the motion of the reel table attached to it, but it is too free-moving for this. So, my questions are: 1) Why would the gears jump when the takeup spool is stalled? The clutch can slip, but is very stiff. Is this the issue? 2) Should there be some viscous coupling between the supply reel (328) and the pickup lever (321)? 3) Should the green auto-reverse button make a sickly "twang" sound when pressed? Many thanks Jon
Ok, so first of all I will attach screenshots of the mechanism's diagrams as it will be easier to reference the parts mentioned this way. Then, the mentioned takeup reel drive gear (366) is not the only one that can fail. For reference both 366 and 321 can fail, but in most cases glueing them back to the reel shafts is enough. 321 seems to be used for both the gear and the detection lever. Yes, it definetely should be influenced as that detection lever is what triggers the auto-reverse. If that isn't working auto-reverse detection at the end of tape won't work. 1) Which takeup spool ? FWD or REV playback ? In REV playback the idler gear (big white gear between clutch and reel) is rotating in a direction that tends to disengage it from other gears. If the clutch is too stiff, indeed this might be the problem. Check the spring of the clutch, the felt pad (if it's sticky) and if the area where spring slides is lubricated. 2) There should be a small spring between the reel and pickup lever. If that's missing, the lever won't work properly. 3) When the button is pressed, the camgear is released, so I would say yes. However without a recording of the actual sound it makes it's hard to say for sure.
Hi Valentin, thanks for the detailed reply. I've made a fair bit of progress since I posted, and your input has helped confirm some of my ideas. What I've done so far is; 1) Yes, I found that small spring and put it in (I think) the right place inside the pickup lever, along with a split + stepped washer that acts as the lower seat, but which the previous owner had put inside the reel table (!). Neither of these are shown on the diagram - they are inside the pickup lever/gear assembly. 2) The pickup lever now correctly swings one way or the other depending on the direction of reel 328. 3) I see now that auto-reverse works when reel 328 is *not* pushing the lever to one end, and it gets bumped to the middle, which is where the peg is that pushes the pickup lever forward to change direction. So at least I understand the operation. 4) What I hadn't realized until I saw your excellent pictures on the "WM-150 lubrication guide" is that the tiny spring 360, which was badly bent, actually only pushes the pickup lever to one side when *not* in play mode, so that FF/RW do not continually trigger auto-reverse. In playback mode it swings down, away from the pickup level. This spring is now the correct shape and does the job, so thank you! 5) The clutch did have the friction disk stuck to the main gear, so it didn't slip properly. I've replaced that and it now works nicely. 6) I've attached an MP3 of the button noise. It's very quiet if you lightly press the button enough to trigger auto-reverse, but press it all the way in and it "twangs" like this. 7) I'm currently struggling with the reverse direction change. All the levers/cams/arms seems to line up correctly and the same for each direction, but for Reverse, the camgear seems to want to push the sliding direction arm too far over, which ends up jamming the camgear. The change to Forward play does not have this issue. Lastly, does anyone know where I could buy a replacement 329 reel table? After sorting out so many bad things with this player I managed to snap the spindle off the perfectly functional reel table! I am so angry with myself - it was pure ham-fistedness, but the result is I need a replacement. Since no-one else is so clumsy there does not seem to be a market for replacements :-( Best wishes Jon
When I initially looked at the diagrams realised there are quite a few parts that are not actually shown, so the diagrams are "block diagrams" showing only assemblies. In regard to the recording, it doesn't sound ok to me. Sounds like 2 gears not engaging properly for a brief second. So the answer is it shouldn't "twang". Think you need to re-examine the mechanism carefully and look for any bent metal parts given this and the other camgear jamming problem you mentioned. As for the table reel, a donor unit is the solution. Think any from the list here - post #18 (https://stereo2go.com/forums/threads/list-of-walkman-portable-recorders-common-problems.7535/) will work.
Thanks Valentin. I've now aquired a donor machine of the same mechanism type which should help provide a reference as well as spare parts. Interestingly the green auto-reverse button on this unit makes the same twang sound whenever pressed even when the unit is not powered. I'll report back anything that might be useful for others.
Maybe that's the sound of the camgear being released as suspected initially, in which case it's normal. From the recording it wasn't obvious how loud that twang really is.
To be clear, it's not related to any gears: even with the camgear and clutch removed it happens. In fact it's the vertical lever (354) which is responsible for releasing the camgear that makes the noise. The green A/R button pushes down on a small pivot (365) which goes past a certain point then pings back. This in turn releases the main lever (354) so that pings back under tension and that's where the noise is coming from. Basically it means that you can't hold down the A/R button and have it keep reversing back and forth, but it sounds very weird.
I just checked my WM-B603 walkman (which is the only I have handy with this mechanism) and can't really hear the twang, but only a click. Holding down the button does nothing, for another auto-reverse cycle I need to let it come back up and press it again. Have serviced a few walkmans with this mech in the past, but haven't noticed anything suspicious in regard to pressing the green button. Would be really curious what you find out in this regard.
I have repaired a WM-150 based Walkman with a similar issue. There was a spring missing near the supply reel. Looking in the parts list and going from memory, I believe it was maybe part of the 321 "Lever assembly", the part that's on the same shaft as the supply reel - so there should be 2 total springs on that reel, one in the tape compartment, and one by the auto-stop mechanism that is VERY thin. I also had the same spring bent. The spring was bent to keep pushing the auto-stop mechanism, and to keep it from engaging. That spring, if I remember right, should only engage with anything when pressing stop. When the VERY thin spring is in the supply reel correctly, there will be a very small amount of drag that keeps the auto-stop mechanism working as it should. My recommendation - find a parts Walkman. The WM-150 mechanism is in TONS of different models, and are easy to find for $50 or less, because they are broken and in need of re-caps. I'm thinking of models like the WM-F2095 or WM-2091, that have the bulge in the back because it can accept either a gumstick or AA battery. Just take auto-stop parts from that and put it in your WM-150.
