WM-EX1 showcases wow & flutter after belt/pinch roller replacement - help needed

Hey, all.

I picked up a WM-EX1 via eBay and was fully expecting for some repair work to take place once the unit arrived, so I ordered a replacement belt from FixYourAudio to get started.

However, after swapping out the belt, there is still a large amount of wow & flutter. I removed the belt and cleaned both it and the belt path with rubbing alcohol. No change.

I then went ahead and swapped out the forward-direction pinch-roller with a new one I also picked up from FYA. No change.

I’m a bit lost at what to do next. When hooked up to my scope, the 3150Hz test-tape I have flutters between 3.12-3.16 when playing. In many cases the entire tape will come to a halt and the auto-reverse mechanism will kick-in.

Playing with the speed adjustment provided no fix.

Other things I have done to the unit include testing it with both a gum-stick battery and AA battery. I’ve also demagnetized and cleaned the tape head, as well as cleaned the capstans.

Any help is appreciated.

Thanks, all.

 

Just noting that this only occurred due to an issue with the album I was testing. Disregard.

 

Runs the motor smooth and gently or screening sound from it is hear? Same wow & flutter on A and B side?

 

I would check the motor itself: does it have any lateral play when you try to tilt the rotor ? Some up and down play is normal, but it shouldn't have any lateral play. I have seen failed motors on these EX series.

Measuring the wow&flutter with your scope is not the most reliable way to draw conclusions. Adjust the tape speed to 3000Hz, then measure using WFGUI. First link in here: http://www.ant-audio.co.uk/index.php?cat=post&qry=library
Please share what wow&flutter figure you get, because "large amount" is relative.

 

Sorry for the delayed response; it's been a busy holiday season.

The motor itself doesn't appear to have any side-to-side play, but it can be moved up and down slightly.

I used the WFGUI tool via a microphone (I don't have a USB RCA/AUX input device sadly).

The speed set was 3150Hz as I have a test tape for that speed and WFGUI supports it.

The detected speed was approximately 3165Hz, so a bit fast.

The meter would dance slowly between .25-.75%.

 

Ok, so the fact that motor doesn't have any side-to-side play is a very good thing. There's obviously no problem in measuring with a microphone, as the wow&flutter of a digital system is practically zero.

Tape speed is indeed a bit fast, but not a concern at all, I would not even bother to adjust that, at least not at this point. The figure of 0.25% WRMS is ok, but the 0.75% WRMS is way out.
The fact that it "dances" slowly between 2 values indicate there is either some periodic friction occuring in the mechanism or the belt itself is not uniform (which is what I suspect).

Check the belt visually and see if the thickness is uniform all around or it has some high and low spots as it moves on the pulleys. By the way, have you checked wow&flutter in both directions ? Is it similar ?

 

i don’t know this special model (to new for me ) but it’s very important to make sure you got the right belt(s), it‘s not the lenght only, it‘s the shpe, too. many of those aftermarket-belts are that tiny bit different in diameter/too square/too flat/not oval etc.
as f.ex. on wm-20/40/7 the right size but wrong shape belt bring this effect. maybe a point to check…

 

Have you tried head and azimuth adjustment?

 

Alright, so I took everything apart and gave it a bit more cleaning time. I also cleaned the pot that controls the speed of the motor.

Using another laptop, I was able to connect the Walkman directly to a Line-In jack and rerun the Wow & Flutter tests.

Playing the tape in one direct resulted in an RMS of a semi-stable .28%. The other direction resulted in an RMS of .17-52%.

Here's the kicker, the side that plays worse is the side with the newly installed pinch-roller.

Ha. I don't know if you've ever had one of those projects where you didn't want to put in much effort to fix it, but I'm there now.

Debating whether to figure this out and keep playing around or just resell it and call it a day.

Thanks for everyone's help thus far.

Thinking I might just stick to home decks for the moment.

 

Ok, so the fact that on one side you got a decent figure and on the other not, to me indicates the belt itlself can be excluded as a potential problem.

It's probably either the newly installer roller that causes this fluctuations. Or it's something mechanical binding, like a tooth on one of the gear that is worn out/deformed.

I attached a picture from the WM-EX1 service manual: if the side problematic is one driven by left capstan (that will be forward play), then I suspect something in those gears.
Do you have some periodic mechanical noise when that variation of wow&flutter occurs ?
Now that I think about it, despite this model does not have the problematic magnetic clutch, there might still be a problem with the clutch on this unit (Gear C on the diagram)

If it's on the other side (right capstan, reverse play), it's either the new roller or it is possible that the capstan itself is bent.
A forum member sent me a private message with this phenomenon some time ago. Look if the flywheel on the problematic side has any wobble while it rotates (although I doubt it).

 

I remember years ago that problem, It was due I lost the washer that locks the capstan, I put another similar but the wow & fluttter was increased. There is a plastic cap covering the washer, you have to remove It to see the washer, check both washers holds firmly the capstan, and there is no an excess of movement up and down

 

I also recommend checking out this thread, as the mechanism of the EX1 seems similar to the EX508:
https://www.tapeheads.net/showthread.php?t=41384

 

Yáll are awesome — thanks for sharing!

I might take a look into the Walkman again and see if I can get it working.

Again, this was suppose to be a minimal-effort project, and I have other projects that are higher priority.

I’ll let everyone know if I decide to poke further into this device.

Otherwise, it might just be a nice treat for someone on eBay to tackle.

Thanks, all!