Hello, I am becoming a little desperate with a WM-DD1 which I have bought mid last year. When I got it, the sound was very quiet and the mechanics sounded a little bit odd. When I took it apart to change the capacitors, I saw that the rubber ring which the motor is pressed against to drive the capstan had broken (explaining the strange noise) so I've ordered a new one of those on eBay. The new capacitors and the new capstan "belt" didn't lead to clear sound sadly. Two weeks ago, I came back to it, confident that I could make it sound good again and decided to also order a new pinch roller. So I replaced the pinch roller and voilà, it sounded pretty decent. I then took of for vacation over the weekend. When I arrived at home a couple of days later, I tried if the Walkman was still working alright but I sounded awful again. I then recorded a 3 KHz signal onto a tape, put it in the Walkman, connected the Walkman to my oscilloscope and had a look at the measurements. The frequency has a variance of about ±0.15 KHz which seems to be quite a lot. The waveform does look pretty awful as well, no comparison to the perfect sine wave measured with my normal tape deck. I already tried all the adjustments mentioned in the service manual but they didn't seem to work. My assumption is that probably there is some old grease which gets more fluid after some operating time because the problems usually get less after playing for about 30 minutes. I hope someone of you has an idea on what I may have missed. Thank you very much in advance. Sincerely, lxndio
It sounds like you've done a good job covering the potential sources of problems! I don't own a DD1 but had to lightly sand the rubber capstan ring when I replaced it on my DC2 as it was not "perfect". I'd try the following in this order: Check if the new rubber capstan ring is seated/sealed properly with no gaps. Re-do flywheel thrust adjustment. When the machine is off, see how freely you can turn the capstan flywheel. Get some 1000 grit sandpaper and lightly sand the new rubber capstan ring in play mode until it feels as if it's running very smoothly. Compare takeup/supply reel tension just by turning with your hand. Remove motor and see how freely it spins, add a tiny amount of sewing machine oil to the shaft bearing. Finally, check if the wow/flutter is caused from the the rest of the reel mechanism driven by the flywheel and belt. On a normal DD mechanism this is usually caused by cracked gears but I think you may have a lead when it comes to dried lubricant, so look out for that. Try isolating the reel drive out of the equation if all else fails- remove the teel table belt, make an acceptable disposable copy of a 3khz tape, turn the takeup reel with a toothpick and see if you can hear a difference.
Thank you for answering that quickly. The new capstan ring is seated properly and glued into place so that it cannot move freely on the flywheel. I have set the flywheel so that the motor can run freely without touching the flywheel when pushing the motor down (as described in the service manual), distance between pushed down motor and rubber capstan ring <=0.1mm. I have used 1200 grit (I didn't have 1000 in the house) to sand the new capstan ring slighty, added some oil to the motor, to the flywheel shaft and the axis of the pinch roller. I also removed the belt that drives the spooling mechanism and spooled the tape manually to determine that the spooling mechanism is not causing the problems. All of that sadly didn't lead to a working player. However it is still noticeable that the problems become a bit better after playing for some time. Best Regards, lxndio Edit: After an hour of playback it does now sound pretty good. I'll see (or hear) how it is tomorrow after letting it sit at night.
It's good that you have isolated the problem from the reels, and the problem now lies around the capstan. Let's see if a few hours of playback "fixes" anything permanently. One check to rule out a dirty speed pot since you have a speed tape: add deoxit to the speed control pot(s) and then turn them all the way round to clean it, then set the speed again. I've once experienced flutter caused by a failing mylar cap in a 4th revision D6C's speed regulating circuit. Discovered it by chance: when I touched the cap, the flutter went away.
I'd also suggest deoxit in the speed pot and a good flush. Also, is the actual capstan shaft polished to the point where it's not getting any proper traction? If so, a light sanding may help. Regular use also helps greatly.
Hi, Have you tried lubricating the capstan where it runs in its bearing ? Just a tiny,tiny drop of thin clock oil Cheers Peter By the way looking for a manual or circuit for this deck as I have one which is distorting at high volume But only with the Dolby on or it might be off ( can't remember which ! ) All Elec chaps replaced
I've cleaned the speed pot because I have also thought it might cause the problem since there was a capacitor leaking next to it when I got the Walkman. Luckily neither the speed pot nor the PCB was damaged. I have now slightly sanded the capstan shaft with very fine sandpaper and put a drip of oil where the flywheel touches the bearing. The strange thing is that the playback becomes better the more the player runs. However, stopping it for just 30 minutes and everything is as bad as before.
Maybe the motor is a little claggy inside. There is a thread elsewhere about a well known issue with the wm-3 and TPSL2 motor and them eventually seizing up. But there is a simple remedy for it. I'd certainly defer to that thread but I may be right to summarise that the user removed it, soaked in Isopropyl and then when dry, gave it a good lube with sewing machine oil and restored it fully. But don't quote me. But given that it eases up with use, it sure sounds like the lube / grease in the motor eases up as it warms (as does all grease). I think that is worth investigating. A new motor either on its own or from a donor swapped out could also go some way to pinpointing the motor as your problem source.
I would say that if you can rule out mechanical issues, this is purely electrical at this point- it might be a failing mylar cap on the servo circuit like my D6C, or a bad solder joint somewhere. It can also be a bad Servo IC- diagnosing at this point won't be easy. Try getting a scope and test the power going to the motor and see if there are irregularities. I don't have the expertise to offer you further electrical advise- I discovered the failing mylar cap on my D6C by pure trial and error. I found that when I touched the leg of the failing cap, the flutter went away. I replaced that cap with a high tolerance one and that fixed it. Edit: Try doublecee's suggestion too! But if the motor is already free-spinning with no resistance, might be unlikely.
I have taken a look at the signal going to the motor on an oscilloscope and it was clear to see that instead of sending a clean DC voltage there was a signal fluctuating in a range of ~1V which obviously causes the motor to run at different speeds. I have then taken a look at the mylar capacitors and reflown the solder joints of those. The Walkman does sound very much better now but just to be save I am going to replace the two mylar caps with new ones. Seems that just a bad solder joint I've missed caused the problems... Thank you all very much for your help
Great job on finding the cause! If you do replace the mylar caps, make sure to get higher tolerance ones (I believe the original is 5%?) that equal or better the original spec, and of a "good" brand.
The only service manual I could find online was for the WM-DD11. You can find it when searching for "Sony WM-DD1 service manual" on Google. The DD11 is, if I am not wrong, nearly the same device just with another case. I have quite some experience with that model now, so if you have a specific problem you may just ask me if you like
Hi, Thanks for the info,found it now Problem I have is distortion at high volume with Dolby on ( or might be when off I'd in normal mode ) I have changed all Elecrolytic caps
Just checked it. Interesting it sounds fine with Dolby on but distorts when Dolby it turned off at high volume
Now I have the circuit I'll get the scope out ! I noticed the motor servo chip is the same as fitted in the wd6c !
Found the fault I'd replaced a 100uf cap with a 10uf !! 100 uf cap now fitted all is well Should have gone to spec savers !
