I believe the rounded, non-pointy 35711 head remained on units through the 3xxxxx serial numbers; HRP901 head part #1-543-357-11 was listed in Supplement 2 (March 1994, # 267,201). The permalloy head 35712 appeared somewhat later but I don't know when; certainly by the #5xxxxx range it was there. I don't know what the E means (Europe?) but I have also seen a serial # sticker with a 'Y' prefix.
One thing I can say is D6Cs with 35712 heads seem pretty rare, significantly rarer than the pointy one. Which makes me believe the change happened late in the production and not many such units were made. Have no idea what the E means, but I've seen some 700 series with Y in the serial an an EX80 with X in the serial. It can mean many things, like a certain factory.
Hi Dotneck, Just to add to the information you are collating, I have a D6C with Japan pointy head on serial number 71065. Hope this helps. Lee
@Lee Finney: THANKS! That does help! It confirms that the pointy heads DID remain until the 71xxx range. I have now established the change from pointy-to-rounded 35711 head at between #71237 and #72265. Do you know the original purchase date of your WM-D6C?
Hi Dotneck, Sorry I didn't buy it from new so I couldn't accurately tell you. It does have the obvious silver Dolby sticker though but I'm assuming all these pointy head D6C's were made before 1988 anyway. If I get anymore useful info, I will pass on to you. This is a great piece of work you are doing. Really informative. Thanks Lee
Evening Dotneck, Indeed it does which sort of makes sense as it's one of the last made with the pointy head. I say this as I have another on serial number 57338 that also has the Dolby 20218 ICs etc. Hope this helps. Thanks Lee
Thank you all for sharing the information - below my summary of all changes during the lifetime of the D6C. Overall, there are 3 heads, 2 Dolby ICs, 2 Servo ICs, 2 Dolby sticker colors, 2 PCB types, 2 upper housing parts (with and without amorphous), and 3 motor (assy) types. Initial release, & revisions 1-5 have amorphous heads of some type and use Servo IC CX20084. Changes between revisions are highlighted bold. 1984 - Initial release: 3602A head, CX20068 Dolby IC, X-3305-830-1 motor assy (MNF-1601A), NJM4558M line/rec IC, brown phenolic PCB. 1985 - Revision 1: 3602A head, CX20218T6 Dolby IC, X-3305-830-1 motor assy (MNF-1601A), NJM4558M line/rec IC. Ends at serial range 71237 - 72265 (TBD). Supplement 01, Jan. '85. 1986 - Change of 3602A to 35711 head between revision 1 (1985) and 2 (1994), closer to 1985 than 1994, estimated 1986. No bulletin to support, evidence provided by S2Go forum members. 1988 - Color of the Dolby sticker changed from silver to black, around serial #116000. 1991 - Revision 1 fix: incorrect capacitor reference (138->318). Bulletin 366, Jun. 20 '91. 1994 - Revision 2: 35711 head, CX20218T6 Dolby IC, 1-541-851-11 motor (MNF-1601A, once referenced to as I2CL-3026), UPC4558G2 line/rec IC, green epoxy PCB with SMD components.. Supplement 02, Mar. '94. Starts at US serial number 267200. 1996 - Revision 3: 35711 head, CX20218T6 Dolby IC, X-3370-805-1 motor assy, UPC4558G2 line/rec IC. Bulletin 395, April '96. 1999 - Revision 4: French model addition, same as AEP model except resistors R152 and R252. Supplement 3, April '99. 2001 - Revision 5: 35712 head (not amorphous, housing changed amorphous text removed), CX20218T6 Dolby IC, X-3370-805-1 motor assy, NJM4558M-TE2 line/rec IC, CX-069A servo IC + NJM2904V comparator IC (CX20084 includes comparator). Supplement 04 (and re-release manual 1.1), Jun. '01.
1991's change of 220uF capacitor designation 138 to 318 is not really a revision; it's just a correction of the schematic. The PCB was actually marked correctly. April 1996's service bulletin states a change of motor from X-3305-830-1 (original) to X-3370-805-1. I do not see mention of 1-541-851-11 motor anywhere in Supplement 2 or elsewhere. Although the color change of the Dolby sticker from silver to black (~ serial # 116xxx) was not accompanied by any significant change to the unit, it may still be useful in identifying the approximate manufacturing date of a deck.
My response below in bold: 1991's change of 220uF capacitor designation 138 to 318 is not really a revision; it's just a correction of the schematic. The PCB was actually marked correctly. Agree, will remove it revision #. April 1996's service bulletin states a change of motor from X-3305-830-1 (original) to X-3370-805-1. I do not see mention of 1-541-851-11 motor anywhere in Supplement 2 or elsewhere. See the attached screenshots from supplement 2, first and last page. Although the color change of the Dolby sticker from silver to black (~ serial # 116xxx) was not accompanied by any significant change to the unit, it may still be useful in identifying the approximate manufacturing date of a deck. I have not observed this many times before. Some This Is Sony stickers for instance are new, hard to differentiate from the original 80s ones. Can we consider this sticker evidence?
With reference to the Dolby sticker colour, I thought this was a good idea to document, but Emiel makes a very good point. The other point I guess to look out for would be for later revision 2,3 or 4 units that have had a change of base plate with older units with the silver sticker if you get what I mean, this could be rather misleading too?
I know we are discussing more than just the point head, but I would like to get it right across the board. Do we need to add PCB design, color, and components as well so we even better tell these units apart? I suppose we start with the brown PCB with lots of wires and (virtually) no SMD components and plenty of through holes? We end at green, single layer, with plenty of SMD components? Please comment and do not consider the capacitor revision, per the post above.
Aha! I now see the change of motor part #. My bad. From Deb64: "This is where it gets a bit confusing as I have seen several D6Cs with the older type PCB and the newer motor and modification, where the extra capacitor and resistor appear to be factory fitted. Were Sony still producing some non SMD type D6Cs into 1996 with the newer motors?" The Dolby sticker color change is quite obvious and a good indicator of deck vintage: As mentioned previously, this occurred ~ serial # 116,xxx, early 1988. The only PCB color change I can define is the 1994(#267,201) change to SMD components, where the board change was from brown phenolic to green epoxy. Just guesstimating from my serial # list, I put the head change from pointy to rounded 35711 at ~ mid 1986.
Might we be missing a bulletin or 2? 1 for the statement from Deb64, and second about the head change? Summary post updated, the info below has been included: a) the color of the Dolby sticker change around ~ serial # 116,xxx, early 1988. b) part of revision 2 in 1994: change to SMD components, where the board change was from brown phenolic to green epoxy. c) tentatively between revision 1 (1985) and 2 (1994) the head change from 3602A to 35711, closer to 1985 than 1994, estimated 1986.
Table and first post of of the DD Genealogy thread are updated. If you find time to review, that would be awesome.
This is my version of the WM-D6C history: February 1984: Original Sony Walkman WM-D6C released. Amorphous "pointy" parabolic PA259-3602A head marked "Japan". Brown/green phenolic PC boards 1-611-494-11 with through-hole components. 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 green glass epoxy PCB 1-651-545-12 with SMD components. Change to 1-541-851-11 motor April 1996: Service Bulletin 395 issued. April 1999: Supplement 3 shows two resistor values were changed in the French model. June 2001: Generation 5: Supplement 4 shows main PCB changed to 1-651-545-14; motor drive servo circuit redesigned with servo IC CX069A. Service manual issued as Rev. 1.1. Generation 6: Change to permalloy head 35712 in serial #s ~50xxxx and above. Date undetermined. Marking "amorphous head" on the case is no longer present. 2002: WM-D6C production discontinued.
I don't see a lot of differences, right? I am not after an own history, I want it to be objective for the table. Happy to make more changes to the table, let me know which things need to be added! The head change to 35712 is indeed not captured in any document we can access. I will add the head change post revision and re-release of service manual. It was only in production for less than a year and a half (your end of production year - date of service manual 1.1). Because of this short period, the 35712 is not commonly found in a unit that was in production for nearly 20 years. The obvious sign would be the lack of 'amorphous head' text on the housing. In generation 5 I find it important to list mention the additional comparator IC. The CX20084 had comparator circuitry in it, as it did not exist before as there was no need. Please note: 1) Supplement 3 shows the addition of the French model, as it did not exist before. Many portable audio units of that era had a French variant; I recall it was to regulate the max. output, mandatory at the time in France. 2) Bulletin 395: the reason to release it is the motor assembly change.
My latest information: 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 parabolic 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 1-651-545-11 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 to make a French model; this lowers 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. Dolby IC # 2002176. Comparator IC added. Rev. 1.1 Service Manual 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.
