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

Installed new belt from Marian: belt appears to work, however doesn't play , but will rewind one direction: I notice there appears to be "reversing gear" that flops around, and it's not very clear from service manual, but i think a linkage has come apart... can someone with more experience confirm? I have taken off larger white gear and notice smaller reverse gear seems to have place to link, i marked with question mark on photo...


tries to run in REW and stops, but FF will keep running, but noisy... maybe this gear is "flopping?

 

..Also, I pushed in the solenoid and spun the left capstan pulley, which then changed the FF/REW position, but can't figure out how to get it back in the center position... advice appreciated here too...

 

What is depicted in the service manual is not useful, it only shows the parts without explaining how the mechanism works.
The floppying gear should have a spring, so that when it is initially rotated, the whole arm on which it sits rotates together with the gear. That gear is used for FF/REW. FF and REW are engaged just by rotating the motor clockwise/counterclockwise.
Then FWD and REV (forward and reverse play) are engaged by the cam gear, moving the head towards the tape, engaging one of the pinch rollers and moving one of the gears to drive the respective takeup reel.
You bring the mech back to middle position by turning the capstan pulley backwards.

First, you need to check the mechanical operation manually. If everything is working ok by hand, it means the problem is in the electronics.

 

Couldn't get mechaism to shift, so decided to remove capstan pulley and gear to see what's behind them:


also noticed some letters on the FWD/REV cam wheel, at 3 different stop points, just wonder what they mean...


when i flipped the large black gear behind the capstan over, to inspect that gear, here's what i see...


So this gear is no good... could i have damaged by continuing to rotate the same direction instead of reversing at proper time in sequence?
no other gear teeth show damage, just this one...
Ideas or spare gear availability would be appreciated...

 

The 3 positions on the cam gear can only be: STOP, FWD (forward play), REV (reverse play). FF and REW work just by rotating the motor with cam gear in STOP position.

About the gear, doing that kind of damage requires a significant amount of force, so I think it's unlikely you damaged it yourself (assuming you did not force it).
Given your initial problem, I'm tempted to believe the gear had some damage from the beginning, which was agrravated by using it.
If the grease inside the hole was sticky, that made the gear turn hard and amplified the issue even more. You did mention at least one of the gears had sticky grease, so that probably contributed.

A spare gear you will find in an EX model that uses a similar mechanism. I need to check, as I may have one walkman with this type of mech that has a bad motor.

 

Thanks Valentin... i tried to treat gently, did not force it, just gently turned CCW then CW, watching for movement... the mechanism has always made a "chatter" and when this first started, that was one of the original symptoms described, and yes i have found sticky lubrication on several parts in the mechanism... it is still curious how a mechanism like this can apply the force needed to "chew" the gear like this...

I will look for similar mechanisms... I notice in service manuals, many of the thin walkman tape transport mechanism end in -60, could this be similarity of gear mechanisms?

 

I don't think that number represents anything. From what I know, the hall sensor type mech is not that common and I think there's only one type of mechanism that uses this.
Most use an optical sensor and gears with reflective/black stripes on them. So I would look for this particular detail and then at the general layout of the gears in the manuls: if they are the same dimension, in the same location.
You can pretty much identify the mechanism just by looking at pictures in the sevice manual.

EDIT: This mechanism looks almost identical to the one used in WM-DX100. I just checked some pictures and apart from some minor differences (and the different motor assy), they are almost identical.
But the DX100 uses a reflective/black stripe on that gear, not a magnet, so what I said previously might not hold true (there might be the same mech in 2 different versions one with hall one optical).

 

how did you edit that post?

Ah ok... yes i think you're right, i looked at an EX-502 (one of least expensive i could find), which has a -60 in the mechanism, and it appears completely different gear layout in the service manual...

 

In similar mechanisms, they are also marked "K", and exactly same part number:
ex-66,ex-77, ex-88,

looked at ex-811, -555, 502/508 , EX-1 , EX-672 , EX-651 are all completely different

 

You can edit posts by using the EDIT button at the bottom of the post.

As for the mechanism, I have to admit I don't think I have seen this type apart from DX100, which is obviously not the solution in this case.
There are many types of mechanisms used in these EX series, so you must look really thoroughly in the service manuals to identify a suitable one.

But at the end, it might be that only those already mentioned (EX-66, EX-77, EX-88 and DX100) have the same mech. Will update if I find more.

 

Sony Drive gear (K), 3-730-467-01, or 373046701
also associated on sony parts site with this part: SON336575501
even on Amazon as ASIN B001DGCF76

Also used in : WM-FX70,, WM EX60, WM EX70

 

Sorry for my absence, I have not been able to access the S2Go server for some time...
The gear identified as "Gear (K)" Sony part 3-365-755-01
It's also listed on the Sony parts website, but of course obsolete. and I even found it on Amazon, but not stocked

Going through Service manuals, I have found several other units containing same part number gear:
EX66, EX77, EX88, EX60, EX70, EX707
FX70, FX77, FX707, FX777

Ordered and received a donor unit, a EX707, and will see if this can repair.

 

Comparing EX808 with donor EX707 mechanism (included free artwork!)




There is a difference on one gear with green keeper (clutch?)
small gear for direction shift, mounted under lower white gear, moves left/right freely depending on FWD/REV direction (just like EX808)
the EX707 mechanism shifted FWD/REV pretty easily, i had to manually push solenoid to start shift sequence... I will inspect cam and white arm.

 

The 2 mechanisms are the same, apart from that magnet for the hall sensor to pick up table reel rotation signal which is bigger and more elevated on the 707,
but I think the magnet can be taken out (look it's hold with 3 clips), so in my opinion everything looks identical and the 2 are interchanghable (unless one would need exactly that magnet, but it's unlikely).

Even the motor looks to be the same, although seems to have a different flex cable going to the board, but that can be swapped anyway. I'm stating for other people reading, in this case it's not needed and donor motor is trash.

 

Note medium sized gear immediately to right of the white arm, something slightly different in gears... I will check diameters...

 

Detail comparison photos, just to add to learning from post:
Comparison of "Gear K"


Donor Gear had damage on back, appeared to be from battery acid leak, though i didn't think acid would affect plastic:


White gears are exactly identical in mechanism:


Slight difference in the floating reverse arm thats mounted under the above white gear... note it pivots around that central plastic shoulder on gear


testing the rotation of this gear I felt resistance, and remembering Valentin said lubricate all gears, i dis-assembled, and found a tension spring to push on the gear... my guess is to keep the the reverse gear engaged...


I re-assembled the unit, with the donor gear:
when i tried to check forward and reverse manually, i noticed the gears tried to skip like they had earlier.
so i centered the arm and reinstalled all the small retainers , this time it seemed to shift ok (i learned you push down on the solenoid when it's time to shift)
i put it back together enough to adjust the speed potentiometer...

it seems to have l lot of W/F , i believe i need to look at capstan pinch rollers next...

 

EX808 vs EX502 vs EX172 : speed and W/F comparison using 3000 hz signal tape (Marion @FixYourAudio version):

EX808 seems to have a good bit of W/F, you can see by the light blue max/min band the speed jumped around a good bit... it had some before the breakdown, so I'm planning to change the Capstan Pinch rollers. During this sequence of posts, I've lubricated virtually every shaft, gear, pulley in the assembly, other than the motor itself.


This is my EX502 I recently cleaned up and put on a new belt (on Tapeheads forum, under "Sony WM-EX508, any thoughts/opinions about it?"}
The light blue max/min band appears narrower than the EX808 at this time


Last but not least, my $20 EX172, made in China,cheap plastic case, best performance of them all...

 

What software are you using in the previous post ? You are using a spectrum analysis, which doesn't reveal any figure about the wow&flutter.

I recommend downloading WFGUI (first link on this page): http://www.ant-audio.co.uk/index.php?cat=post&qry=library and use it insted to give us a wow&flutter figure. Otherwise these measurements won't tell much.
Choose 3000Hz (it's 3150Hz by default) and leave the measurement to DIN as it is by deafult. Then observe the indicated RMS (%) value.

 

This software is named "Audio Spectrum Analyzer dB RTA", Marina Polyanskaya developer;
The light blue lines are actually dynamic, moving with the measured output,
I look at the peak value while i adjust the RV601 potentiometer on main PC board (try to get as close to 3000 as possible, I use cal tape from Marian)
To get a feel for wow&flutter (W/F) i am looking at the magnitude of variation in the band around they instantaneous yellow line , just to give me a visual reference. again this software doesn't give me a value, just a "bandwidth"

I will get the recommended WFGUI software. thank you.

I am also planning to change the rubber pinch rollers, I have spares

I have read through the very good "Walkman Repair Tutorials", which contains much valuable instruction!(Thank you!)
One question, is there a tutorial on how to safely and properly lubricate the FX type of motor? I have taken your advice on cleaning and lubricating other parts (learning how to quickly remove the split plastic retainer rings!) but have not tried anything on the motor yet

 

I have never opened an FX/EX type motor and I am not sure if they are made to be opened. As a basic concept, they look similar to the ones used in other WM series (WM-150 and its relatives and WM-700 series).
I will attach some pictures and explain how those are opened (WM-702 motor in pictures). Note that the WM-702 has an outer metal cage, which is not present on the EX/FX series, but the way they are constructed looks very similar.

The first part that needs to come out is that metal plate on the top (reluctor ring). However, to me it seems that is part of the brass pulley, in which case they should be both pressed out as an assembly.
If this is the case, there are only 2 options available:
1. Use a specially made tool to extract it, which I am convinced is not available and never was as they only needed to assemble the motors at the factory, not disassemble.
2. Heat the brass pulley until it expands enough so you can press it with 2 flatblade screwdrivers out. However there is a risk of creating other damage to plastic parts (the back plate on which shaft sits is made of plastic for example).
You can exercise on the bad motor and tell us what you find. I would like to know myself if these motors can be lubricated, as they do come dry from factory and I have seen situations where they develop play in the bushing.

As for the spectrum analysis, I am familiar with it and know those lines are dynamic. But they do not represent the variation of the 3kHz tone, but a variation of the noise floor.
In reality there is a small correlation between the variation of the noise and wow&flutter, as the tape noise will vary with tape speed, but this is not the correct way to have a feel for wow&flutter.

You can see that the 502 has a higher noise floor (-100dB compared to -110dB), but that might just be that you measured that at a higher volume level.
To see wow&flutter you must look at what is called phase noise, meaning how rounded is the center tone at 3kHz. More rounded means more variation, hence more wow&flutter.
However, you need to look at a much more narrow frequency span to see that correctly (not at the full 20Hz - 20kHz spectrum). I don't know if that software allows the adjustment of the frequency span.
Then you must have a decent enough resolution bandwidth to really see what's going on and this is unfortunately something you probably won't have on a purely software based one.

What you have in the case of wow&flutter is even worse than what is called phase noise, because your main tone will not have a fixed frequency, but the frequency itself will vary,
meaning you will see more like a trapezoid shape (again it's not visible because you did not zoom in sufficiently, span is too large).

Added another image, giving a rough visual explanation of what you should look for. But again, spectrum analysis is not the way to do this measurement.

I recommend reading this wikipedia article for more information, although it is a bit too technical: https://en.wikipedia.org/wiki/Phase_noise