WM-D6C serial numbers and more

Yes tape quality absolutely determines head life as does frequency of use. If you were buying one that was ex BBC in the UK for example, and a number of these came up for sale a few years ago, you could expect it had been well used for field recording for broadcasts. Not sure I would buy one of these. Another guide is the Dolby sticker on the rear panel. Generally white with black font was placed on the 5 digit SN WM-D6C but black with white text was used on later 6 digit SN units. I am sure there will be exceptions and most of my research is based on models sold in the UK and EU.

 

What is too much Total is 370 euros, including shipping, which I think is still a good deal if the repair and service are within reason. I’ve uploaded a video of the erratic behavior.
[GALLERY=media, 1725]WM-D6C powered on, play, rew, ffwd by Emiel posted Jul 18, 2021 at 10:49 AM[/GALLERY]

 

370 euros for one in mint condition with original box is a good price, but it depends on what the fault it. If it's something easily fixable, or rubber parts deteriorated, it's still worth the money in my opinion.

Seems like your walkman is in pause, as the pinch roller is not in contact with the capstan. From the sound, the motor does seem to work fine and at a constant speed. However, a new rubber kit is likely needed, but that's cheap compared to the price of the walkman itself.

 

Emiel you got a good deal. Looks like it has the MDR-51 headphones and a case and strap too. Some people ask $100+ for each of these items when you want to buy separately.
The slow or dragging problem when a tape is loaded means it needs a new rubber kit - belts etc. Usual refurbishing if it was not done by previous owner.

 

Thanks @Silverera , @TooCooL4 and @Valentin for your response. I’ve switched off speed control which seems to make it a bit better. If indeed a general overhaul and new rubber kit is what is needed, I would be over the moon.

 

I seems that the pinch roller never contacts the capstan. Over the weekend I’ve tried with pause on and of and so forth, but it doesn’t change.
After reading most of the related threads I switched power supplies to prevent any damage before I did any test.
The capstan is rotating though and the unit draws between 90mAh and 100 while playing, without headphones connected.
I’ll contact the seller this week and if all goes well, I will send it to @Sergi for an overhaul.
[GALLERY=media, 1728]WM-D6C running on 5.6VAM[/GALLERY]

 

Sounds a bit unusual. If the plate lock is holding the head in the locked play position but the roller is not contacting the tape perhaps it just needs a pinch roller replacement. I have never had to change one but I have had an issue with a broken latch on the plate lock which stops the play mechanism from locking into place. If you remove the pressure on the play button the play button retracts. Not sure if the travel of the plate lock can be adjusted or how it would have slipped back in alignment so that it no longer travels the full distance it needs to so that the pinch roller exerts the correct pressure on the tape against the capstan shaft.
Hopefully an experienced tech can sort it out for you.

 

Capstan and pinch roller won’t touch in any of the modes. I tried to make a closeup shot, not great but it’ll do.
I’ll leave it at that and won’t attempt any fix myself, although @Valentin created a nice guide (here).
If indeed a new pinch roller and some other small stuff needs to be added to the bill of material of the overhaul, that won’t brake the bank.

 

I made a picture of my own unit for reference. It may be possible that the head plate indeed does not come out all the way, if you look at the casette retaining pins relative to the bridge, in your picture there is a small gap.

The tutorial in your link does not apply to the D6C. On the D6C there are 2 options to replace the roller:
1. Just remove the top panel and cut part of the plastic above the roller in order to remove it from above (that part will be below the estetic cover, so it's not very visible);
2. Remove the entire mech/PCB from the case and replace it that way; this is the recommended way, but it's more complex;

I may have some pictures with the replacement of the pinch roller on the D6C, if I find them I will create a thread covering this for people who are interested to do the replacement themselves.



P.S.: I suggest you upload pictures that are only relevant to one thread with the "Upload a File" button found in the bottom right. This way the forum's gallery can stay clean and contain only what's relevant to everyone visiting the forum.

 

Update: this D6C has been fully restored by @Valentin and is now in mint factory condition. I’ve been using it for the last 2 days with Eneloops (Pro) for playback only, will create some new mix tapes using RTM cassettes soon.

 

Here's what I have from my research (UPDATED 9-18-2024). Data from postings on Stereo2Go and Tapeheads, plus pics from units on sale at eBay. Dates and serial #s somewhat incomplete.
History of the Sony Walkman WM-D6C. Compiled from postings on Stereo2Go and tapeheads forums, as well as eBay listings of units for sale.
February 1984: Original Sony Walkman WM-D6C released. Amorphous "pointy" parabolic PA259-3602A head marked "Japan". These had screws on the side. Some say the earliest ones with parabollic head are the most desirable. Brown/green phenolic PC boards 1-611-494-11 with through-hole components. X-3305-830-1 Motor. Yellow indicators for Tape Type and Dolby NR Yellow Roman numerals for Tape Type; Only Sony logo on the leather case. Tape drive mechanism MT-D6C-20.
January 1985: Generation 2: Supplement 1 notes Dolby chip change from CX20068 to CX 20218, as well as surrounding component value changes. PCB now -12. Serial # range undetermined.
Mid 1986: Generation 3: Change from "pointy" parabolic to rounded head 35711 @ ~serial # 72000.
Spring 1988: Change to Dolby sticker color from white (silver) to black ~ serial # 117,000.
March 1994: Generation 4: Supplement 2 at ~ serial # 267,201 notes change to double-sided green glass epoxy PCB 1-651-545-12 with SMD components. Muting modules and EQ modules and DC-DC converter are part of the PCB, a lot less wires. Change to 1-541-851-11 motor.
April 1996: Service Bulletin 395 issued. The motor was changed from X-3305-830-1 to X-3370-805-1. There are some component changes and the addition of a resistor and capacitor.
April 1999: Supplement 3 shows two resistor values were changed in the French model, to lower the headphones maximum output.
June 2001: Generation 5: Supplement 4 shows main PCB changed to 1-651-545-14; motor drive servo circuit redesigned with servo IC CX069A. The servo controller is now a smaller 8 pin IC and is protected which is switched by several other transistors and a MOSFET, to prevent damage. Comparator IC added. Change to Dolby IC #2002176. Rev. 1.1 service manual was issued.
Generation 6: Change to permalloy head 35712 in serial #s ~50xxxx and above. Marking "amorphous head" on the case is no longer present (date undetermined); however, only later units had the “amorphous head” script removed from the badge on the front of the machine so it cannot be used as a reliable guide to which type is fitted. 2002: WM-D6C production discontinued.

 

This week I got a D6C that appears to be from the first generation: pointed head, silver sticker with black letters and Dolby 20068 chip. Unfortunately, there is no sticker in the battery compartment so I can check the serial number. The device is in perfect condition, it had never been opened, I replaced the rubbers and tested the Dolby levels, everything is perfect. I have here with me a D6C from the latest generation with a 35711 anamorphic head and SMD board, it was fully calibrated and works perfectly. But comparing it to my new acquisition, the older device seemed slightly brighter to me. What do you think of this, does it make sense or is it just emotion?
Another thing, is there any other indication of the serial number, except for the sticker in the battery compartment?

 

The serial number should match the number on the box if you got it with box

 

I received it without a box

 

I have six of them and serviced , the two earlier ones have the pointed head and they indeed sound brighter, I believe it's all in the head only in this case literally.

 

Well if you get one with a box as you can see the serial number in the battery compartment matches the middle number underneath the middle barcode
Now I could be out here all day emptying out this box again to show all the measuring serial numbers and boxes and all that but I just haven't got time for all that. But here's just an overview of what I just opened up

And then of course an overview to that
I have nine plastic storage bins of walkman's. Good day.

 

Literally
I recently sold a D6 that I recovered, obviously with a pointy head, it's a shame I didn't take the opportunity to compare, but the feeling is that it wasn't brighter than my D6C with SMD board. Maybe the Dolby chip also has some effect?
I've already revitalized 3 other D6Cs, all with 35711 heads and old boards, I changed modules and calibration, I had never noticed the brightness I felt on this device. Curious, because my maintenance process was the same on all of them.

 

Question on serial numbers why does mine have the letter E in front of the number?
My other D6C doesn’t. Does the E stand for something? this does have the 35711 head.

 

It looks like a very late model, looking at the print quality of the serial sticker. I don’t seem to have a Sony Walkman with serial number including an E.

 

My other one serial number 514757 and that’s really late and has the permalloy head where as I said this has the 35711 head but I have struggled for find one that has a letter in front and I always thought that this was a mid 90’s number (E291932)?

Cheers Kiwinut