WM-D6C serial numbers and more

I’m in the market for a WM-D6C so I can make Dolby C recordings to listen to on the DC2.
I was offered 2 from different sellers without serial numbers. Judging by the pictures the tags were not forcefully removed and I know batteries can leak. These are also the ones offered at a fair price, without box and accessories which I have no interest in anyway.
Would you buy one of these devices?

 

serial number tag doesn't fall by itself on D6C walkman series.
Serial number is somehow important for certain walkman units including D6C( since serial# above 267201 have better speed control chip).

to answer your question about whether or not you should buy this walkman:
If you are comfortable in repairing these units, and seller offering you a good deal then go ahead and buy it.
I wouldn't buy it since D6C is a professional walkman and I want it to be in perfect condition.

 

Thanks for mentioning this exact number. Without the tag though, I have no other means to confirm age since I won't be able to travel the distance to scrutinize the unit in person.
I'll refrain for sure from buying 1, the other 1 looks like it is in a better condition. No rush to buy though

 

Indeed, and most sellers actually put the serial # in the item description.
One of the D6Cs showed minor signs of corrosion, that could have been the cause.
Perhaps the previous owner trying to clean it too aggressively.
I'll look around for another unit - don't have yet but have no urgent need to pay extremely high eBay prices.

 

I don’t use my D6C’s as much as I use to, so I am going to let one go for a swap or sell it. It’s the one with the pointy head which everyone is after, I got it out the other day. The muting module appear to be gone, just waiting For Deb64 to service it before I put it up for a swap or sell it.

If you are interested let me know, but I am still about 2 months away from Deb64 fixing it. I would not let it go till it’s fixed and working properly.

 

Hey Emiel,
Another thing you should know about serial numbers concerning D6C and also DC2 is the fact, quality of amorphous head changed after a certain serial numbers. The best head built inside a D6C was the first version (Serial from 1 up to maybe 160.000-180.000). During the long production time of the D6C, the head changed 3 or 4 times...lots of voices say that the first one was the best one (the "hyperbolic" amorphous head with the screws on the side). Another thing, that influences the price for this special unit - maybe same for the speed control thing, boodokhan mentioned before.
All those different heads got different letters on top - so you can ask the seller if this is important for you. For me, the cosmetical condition is more important than head version. I guess I wouldn't hear the difference of quality....

 

Thanks for sharing @JK1210 , I have been trying to find all these D6C details.
Most likely I would not hear the difference either by the way.
I love the wealth of knowledge that we can accumulate by means of this forums nowadays.
What I can also recall is that the later series has a different PCB, which is less prone to some component failure and has less hand soldered, wired connections.
Are the capacitors of earlier versions more likely to fail or need replacement?
Note: as I don't plan to open the device upon purchase myself, that would only be relevant for the repair (wo) man though, when required.

Shall we create start to summarize some of the pros and cons? If somebody already has such an overview, please feel free to share!

(WM-D6: 1982-1984)
WM-D6C: 1984-2001

Serial # 0 - 180000 | Years ###

• Best amorphous, parabolic head, least prone to wear
• Complicated PCB, # of hand-wired connections

Serial # 180000 - 267200 | Years ###

• Amorphous head change, perm alloy type of a cylindrical section

Serial # 267201 - .. | Years ###

• Revised PCB with more surface mounted components
• Better speed control chip

 

Just learned that the other D6C has serial 21yyyy.
So different head and speed control board revision. According to the seller - not a specialist - all functionality is tested and okay.
Exterior in good shape, not mint obviously. Includes the box but no power supply. Around 350 euros seems fair to me, any thoughts?

 

Emiel for that price take it.

 

The later series (as indicated by SONY's service supplement 2 attached) did have an entirely different PCB: double sided, mostly SMD components, muting modules and EQ modules, DC-DC converter are part of the PCB, a lot less wires.
It is indeed less prone to component failure, especially the potted modules (CP301 and CP302). However, these modules are available as a replacement module, built with discrete components (which won't ever fail again).
Regarding capacitors, it's not a common problem in this unit.

I also want to make some clarifications on the versions of this device, especially aboout the amorphous/permalloy heads, as there is a lot of confusion created around this topic.
It seems that most people seem to believe that only the very early versions (pointy head) have amorphous heads, despite SONY kept the markings.
The truth is quite the opposite from my reasearch on this topic: only the very last models (which only include part of the serial #267201 and above) had permalloy heads.

This was discussed previously on tapeheads and Alex from A.N.T. drew this conclusion: he's an expert on the field so I really doubt he's wrong in this statement and also doubt SONY could lie so obviously with the markings and get away with it.
Here is the link to the original thread (the relevant posts also attached as screenshots): https://www.tapeheads.net/showthread.php?t=25815

1. First generation (up to ~ #180 000)

- amorphous pointy head, similar to the one used in the TC-D5M and identical to the one used in the WM-D6; this type of head has "SONY" stamped on it and it's parabollic in shape;
- through-hole PCB

2. Second generation (~ #180 000 - #267 200)

- amorphous rounded head, marked "35711"; although different than previous version, the head is still amorphous;
- through-hole PCB
- CX20218 Dolby IC in later units;

3. Third generation (~#267 201 and above)

- the early units still have the "35711" amorphous head and the marking "amorphous head" on the case;
- late units have changed the head to a permalloy one marked "35712"; on units fitted with the 35712 head, the marking "amorphous head" on the case is no longer present;
- re-designed PCB;
- late units using different servo IC (CX069A);

The first SONY service supplement (January 1985) indicates a new Dolby IC at some point (CX20218 instead of CX20068). This change likely happened somewehere at point 2: early units are fitted with the former IC, latter witht the new IC.

 

Took it. Including payment and shipping a bit over, no customs etc. since in the same country/EU.
Can’t wait to get it

 

Thank you for the additional explanation, documents and links @Valentin . I'll go through these during the weekend.

 

I have two D6 and two D6c, out of those 4 , 3 have the oem box's to them, and one is complete but the others are. hmmm.

 

Thanks for the information. Although I watched only a couple of your videos, you seem to have quite a lot of walkmans and boomboxes
I did get my D6C today, in box with some accessories. It seems though there is an issue, since the motor is running but seems to be lacking torque. I agreed with the seller that it can be returned, but as I wanted to have it serviced by @Sergi anyway, I’m might keep it.

 

Actually my research shows that only WM-D6C with 5 digit serial numbers had the "pointy" amorphous head. There is no definitive cut off number I have been able to confirm as some in the 80,000's still had that head but certainly SN 180,000 is not the final build with this head nor is it the start of the "35711" rounded amorphous head. I have a unit SN in the 135000's and it has the "35711" head and the brown PCB with many components and through the hole technology which predates the widespread use of Surface Mount Design found in units after SN 300,000's

Anecdotal evidence is that the early D6C's with the sought after "pointy head" are desired because this head is believed to have better wear properties than the later amorphous heads and certainly much better than the later permalloy heads referred to in this thread.

I have a WM-D6 and a 5 digit SN WM-D6C as well as the WM-D6C with the brown PCB and "35711" head. They are all great recorders particularly with type IV cassettes and I cannot really hear any differences between them in terms of audio quality.

Finally if you are thinking of buying a WM-D6C I would look for the units that have the "35711" head and the brown PCB which can be seen if the battery caddy is removed and a torch or smartphone flashlight is used to look through the casing vents in front of the battery bay. These are cheaper than the 5 digit SN units and will not disappoint.

 

@Silverera
I do agree with you on the fact that there is no definitive cut off number: one of the info indicating this are the first pages of the 2nd service supplements I attached, where it states different cut off serial number for different regions (US, Canadian, AEP, UK, E).
There are likely other factors, so my opinion is that judging solely by the serial number is not a good idea as it doesn't paint out the big picture.

At the end of the day, it also depends on how much one intends to use a walkmans like this: if it's used ocasionally (like once or twice a week), even the later 35712 permalloy head is likely to last a very long time.
On the other hand, if one uses it on a daily basis, at that point head durability will clearly play a much more significant role, so going for a 35711 or even a pointy head will be a good idea.
Of course, head wear will also depend a great deal on the quality of the cassettes used, as poor quality ones can ruin a head very fast.

Another very important factor is the condition of the head, as buying a unit with pointy head is not a guarantee that the head is not worn. And note that sometimes head wear is not that visible in pictures, so you may need to ask for close-ups from different angles to see more clearly.
I have seen both pointy and 35711 heads that needed lapping, so it all depends on how many hours the units have been used and if good quality tapes have been played/recorded.

A unit that has only been used with high quality tape will have uniform wear, even when it has a lot of hours (and may be used further without lapping).
On the other hand, one used with poor quality tape will have pittings and may have very uneven L/R frequnecy response (which will only be resolved by lapping, if the head is not too worn).

 

I do believe the one I bought is of the generation you described @Silverera . I will verify the PCB color without opening it, as the device was sold as fully functional but seems to lack the torque to set the tape reels in motion. Without tape, rotation is intermittent. I have not decided yet if I should send it back or go for repair.

Thanks for your point of view @Valentin . I will definitely not be using it everyday, so I am not worried about the wear of the head at this stage. However, since the device I bought is not working properly I have no way of verifying the current state in terms of sound quality of the head.

Below a picture of theD6C with serial 21yyyy. The pads of the headphone are gone and there is a minor scuff of the lid, but that is not bothering me. I’ll try to post a video of the behavior when pressing play.

WM-D6C box and accessories by Emiel posted Jul 18, 2021 at 9:54 AM

 

Emiel it looks good, if you have not paid too much for it? I would say keep it and get it fixed. Only you can determine what is too much, with regard to price you paid.
Also I guess you can request some money back since it’s not fully functional as described.