Advice needed: Startup sequence changed, slim metal EX808, won’t run.

I have run WF tests using recommended software WFGUI, it was difficult to get good screen shots as results for some (502&808) varied a lot.
Also a problem, i don't have an external microphone, so my laptop only used it's internal mic, which sometimes picked up my keystrokes!

I ran each one at least 2x to get variation captured
I normally had to use either the 1% or 4% scales if they behaved badly consistently
is there a way to take a snapshot or capture these graphically?

EX808: WF varied a lot, speed sounded like a cyclic increase? rotation of something?
it would sometimes show jump to 3500+ instntaneous, but i never could catch it!




EX502 also had a very cyclic speed change... went from very good, then once per "revolution" (whatever is causing) would jump a lot!
and you can see a big speed change too when it does this...




EX172 my cheapo held very steady:
I didn't think to change the scale, sorry... speed kept very steady, background noise consistent and low...

 

Excellent training on the measurement of the sound characteristics, thank you, will read the wiki article too.
I learned for this software I had to increase the sampling frequency to the max (FFT size) or the software would only show large measurement steps.
I am no expert on this software, it does help with setting to the 3khz tone, but it does have more features... I liked the graphic nature...
I did not think to adjust output volume to max, but i did learn to turn off AVLS and tried to place headphones close to microphone, but i know some of the mechanisms are noisy, so they are influencing the graph on my software.

using my laptop, i placed the walkman well away from microphones to keep mechanism noise out of the measurements.

I planned to dis-assemble the motor, though it is locked up and looks like either water or acid damage. I have some products i will use to try to remove the rust so hopefully we can learn.

Thank you, and take care.
mike in SC

 

Ok. So the 0.18% WRMS one is an excellent result. 0.22% WRMS one I would consider good to very good for what it is.

The 0.36% can be kind of acceptable depending on the type of music you listen to, but it really needs to be lower than that to be considered good/ok.
The 1.3% and 4.7% are well outside any reasonable limit and there's a very serious problem there. Check pinch rollers for indentation mark or shaved/worn out teeth on one of the gears. Worn motor can't be excluded, check the lateral play (up/down is normal).

A cyclic jump in speed can indicate there is a cyclic resistance in the mechanism, so you can rotate it manually and see if there is something strange you can feel. It can be a shaved off tooth on one of the gears, an indentation on one of the pinch rollers, etc.
Also, check the wow&flutter on both forward and reverse play. What is the difference between FWD and REV ? FWD is the one driving the gear train, so you can expect much lower W/F on REV.

Another thing to check is the tape speed trimpot. Rotate it a couple of times from one end to the other (to "clean" it), then make adjustment again. Observe if there are any imporvements. You can also use contact cleaner if battery acid has leaked on the board.
A very dirty/corroded speed trimpot can also cause an intermittent jump in speed, but that would be erratic, not cyclic as you mention.
The EX808 might have some shaved teeth on the FWD capstan, there's s thread on tapeheads where Marian mentions this on a walkman he repaired.

P.S.: As for measurements, the internal mic should be ok. Ideally, you want to connect the headphone out directly to the LINE IN of a sound card, but if you don't have that, a mic will do (even internal one, but avoid noises that are unrelated to the measurement).

 

Connection directly to PC input....

I can do that... sometimes I miss the obvious...

 

It's only obvious if there is one. Most laptops only have a combo jack (4 pole) for MIC input and headphone output. In fact, if you think about it, there are few situations nowadays where one would need a line in. I actually fail to see a single use scenario for the usual consumer.

Even the jack itself on laptops might become obsolete in the near future due to how ubiquitous wireless heaphones are.
I hope that won't be the case, but the reality is people just don't use that jack anymore.

Desktop motherboards have line in on the integrated sound card, but I don't think that many people own a desktop PC in 2022.

And then dedicated sound cards (USB or PCI) are not that common either. I mean most of the consumer audio stuff nowadays connects directly to Internet and streams music which you choose on a phone app.

That's why I have to assume it won't be that easy for most people to use WFGUI (or at least not with line in) because of this exact problem.


Want to add another point in regard to the jump in speed cause I noticed a detail that I have missed: you mentioned the speed jumps up.
In this case, a more likely scenario is the pinch roller does not apply enough pressure and in a certain position, the tape is pulled by the takeup reel instead of capstan (at much higher speed obviously).
If speed jumps down the the increased friction would hold true.

 

You were correct, my single jack on laptop doesn't recognize speaker input, only output...

I put completely new capstan pinch rollers on the EX808, easy except i keep losing keepers! new rollers from Marian...
The signal is not completely steady, but here is a snapshot now! you can easily see the improvement...


...and the reverse direction


EX808 this was a huge improvement... the signal still jumps around a lot during my recording, i just caught 2 that were pretty similar...
important thing i can listen to a cassette now and the music isn't crazy with wow and flutter

still hear noise coming from mechanism, noisy, i wonder if there is still something else dragging internally.

 

Indeed it is a significant improvement ! However almost 0.7% WRMS is extremely high and you won't be able to use the walkman with this kind of value, the wobble will be audible even with fast music.
You are on the right path with the repair, but the target should be at least half the value you are obtaining now. Even lower would be preffered.

The fact that noise is coming from the mechanism indicates where the problem is. Try to identify where the noise is exactly coming from and you will likely find your problem.

How about the capstans ? Are they clean ? Do they look super shiny (polished where the tape rides) ? I don't know if the capstans on this unit are the type wind sand-like surface from the factory or not.
How about the motor itself ? Does it have lateral play ?

 

EX808 mechanism still sounds "noisy", mechanical on the outside, i thought i felt a "bump" on the cassette door with a tape playing every 1/3-1/2 tape revolution; still mechanical noise even without a tape in the unit... music seems to sound good now, but I'm sure if I can quiet the mechanism it'll be what it's designed to do...

i will open it again to see if i can narrow down the source of noise, i need to adjust the speed slightly anyway!

I cleaned capstans and new pinch rollers (I oiled pivots and shafts, so had to clean up again), my big concern there is still drag somewhere that caused the original gear damage, which was serious damage...

I have opened that trashed motor, and I"m trying to get rid of more rust and completely open so we can see internals now, will post photos... have a feeling i will definitely break something! no problem, at least we'll know whats inside!

 

EX707 Donor Motor dis-assembly and parts:

I soaked this motor assembly in "Evaporust", which is a non-destructive chemical rust dissolving solution:
after about 4-5hr, i began to pry it apart
the unit appears to be tightly held together, no play (I reassembled after taking these pictures), and magnetic forces seem to hold it together (?)
the top most magnet acts as the top of the motor:


below are the motor parts , top view of each: the green electronic board has lost it's copper tracings but you can see contact points...


Below are the bottom of each part
Note the brass bearing part of the "flywheel" appears to have a steel central point of contact (like a turntable center ball bearing)


two of the plates are magnetic, which sandwich the green electronic card.
when i reassembled the parts, they are very difficult to get apart again.

I wonder how this motor could be lubricated safely?

 

Glad to see it disassembled. Given to top magnet is not part of the pulley, it can be disassembled safely.
I tried to remove that part before, but to me it seemed to not move at all. Now I realise I just did not apply enough force.

The design is different than WM-702 I shown: that only has a ring on top and has proper wound coils.
This one, in order to be thinner it has coils made of PCB traces. Given there are only so many turn you can make on PCB, you have to compensate for the weak magnetic field with very strong magnets, hence why they put 2 and not just 1.

Design is very similar to Panasonic so called "Twin Rotor Motor". Those also require a lot of force to remove the top magnet, but it can be done with a plastic tool without damaging that thin PCB containing the coils.

 

1) Regarding motor in EX series: I can't figure out what holds rotating assembly in the bottom pan: maybe the PC board snaps in? The WM702 appears to have one additional part, an actual "top plate" (top left in photo) to hold the motor assembly together


2) Changing capstan rubber pinch roller: that entire process was easier than anticipated, except removal/reinstallation of the tiny split "keeper": I
I saw a tool used online, it looks easier than my X-acto blade: do you know what tool this is?


The axle pin pushes out easily in one direction, I then used high quality synthetic watch oil on the shaft and pivots, not grease, correct?

 

About the tool used to remove those cut washers, I've saw it online before. Don't know what the name of the tool is, but would like to find out. I would like to buy myself such a tool.

As for the motor in EX series: it's it the same as the one you diasssembled already ? Can't you remove that top magnet first ? If you can, in theory you can take the whole assembly out (2 magnets - rotor - pulley and board) in order to lubricate the bearing.

 

Donor motor is EX707, Clean motor is my EX808: appear to be exactly same motor... i would like to lubricate if i wouldn't damage the motor, this is my fear.

Regarding tool; I am searching for something similar looking now, have seen "leather chisel" that are similar but "V" is too deep... will keep looking

 

I have the same suggestion I stated before in regard to the motor: try to use a plastic tool (spudger like those used to open mobile phones) to separate that top magnet (2 such tools on opposite sides of disc).
That is what I used in panasonic RQ-S/RQ-SX with twin rotor motor. Those are similarly very hard to pull apart as they are neodymium magnets.

Will try to disassemble such a motor myself in the near future, as I have at least 2 EX walkmans with bad motor that I do not care if I damage it further.
But it can be separated without damage for sure.

 

OK, I don't have any more Sony with damaged motors right now... I do have panasonic twin rotor i have planned to dis-assemble

This might be it... on Amazon here for $7.99

 

I did disassemble the motor on an EX walkman that I had handy. Created a thread about it: https://stereo2go.com/forums/threads/how-to-diassemble-and-lubricate-sony-wm-ex-fx-motor.7940/

The part that you need to pay the most attention to is removing the glue, not removing the top disc. I think I did damage a trace on my motor, cause I used a pair of tweezers to remove the glue, so I recommend using a plastic tool instead.
In my case it's irrelevant, as the motor is completely shot, it has a ton of play in the bushing.

EDIT: I soldered the board back together (as it was desolderd from all points) and tested the walkman for the sake of it.
The motor seems to work. I didn't put a belt in it, as the wobble in the shaft is just too much to be useable anyway, but I think I did not damage the PCB after all.

 

1) with the glue off the rim of the PC board, were you able to lift the motor without disassembling the two magnets and PC board? This would be great, you could get to the central bushing to lube!
2) will you anticipate re-glueing the PC board to the bottom pan? OK, guess i need to read the thread, sorry,

 

I did edit the thread in regard to re-glueing. As of any motor of this type, yes I think re-glueing will be necessary. But I don't think it is a problem, because if you use the right lubricants, it's likely you will never need to open it again.
Maybe not in 2 spots, as the PCB will be held in place by where it is soldered at the pins, but at least in one spot opposite to the connections I would glue it just to be sure.

As for removing the entire rotor-stator assembly, it is certainly possible if you remove the glue first. But there will be much less room to work on the glue if you don't remove the upper magnet. I would remove it, as I don't see such a big risk.
I even tried to remove it using one plastic tool and one flat blade screwdriver and no damage occured, so it's not as fragile as it looks. I an absolute worst case scenario you will scratch and remove some solder mask, but that won't affect functionality.

 

This writeup is very good! Can you put this on your "Walkman Repair Tutorials"? These writings are so helpful!
You suggest super glue on edge of PC board; does this hold the PC board horizontal in the outer cage?

Also, is there a tutorial on how to replace capstan pinch rollers on EX? It is easier than i thought... and now i will change all my old Walkmans...
Another thought, how to remove and replace plastic keeper/split washers... hopefully our new tool will help make it easier.
Maybe suggestion for any other special tools too?

 

I already put the thread in the walkman repair tutorials. I will create another one with the WM-702 motor as well, as that's a bit different and also has problems with being noisy and lack of lubrication.
In regard to glue, I used normal super glue in the one I disassembled. You can use gel-type if you want it to be softer and easier to remove, but gel-type take a much longer time to cure.
You just need to put the PCB horizontal in the cage and press it after putting the glue to make sure it remained horizontal. After that let it cure and that's it.

In regard to pinch rollers on EX there is no tutorial. I may do one in the future when I replace such rollers, but replacing pinch rollers on these is not always needed.
Pinch roller tutorials I only did on DD series and D6C, which are both very involved to replace. For DD it's also common for the pinch roller bracket to not be straight,
requiring some bending and some grinding with a dremel on the carriage to make it fit correctly after bending, so a lot of work on these which needs to be done regardless if one changes the roller or not.
Then on DD if the shaft of roller is not lubricated (it's not from the factory), it will squeel when FF/REW.
As for the tool suggested, I need to try it to see if it is indeed better than just a simple pair of tweezers. If it is, I'll recommend it. One will still need to keep a finger above the washer, otherwise it will fly regardless of tool used.