For Sony Walkman WM-D6C, I am specifically trying to find the point of serial #s at which the PCB went from -11 (Dolby chip CX20068) to -12 (Dolby chip CX20218), the point where they went from "pointy" Japan head to "rounded" 35711 head (around serial #53613 to #72265), the point where the PCB color changed, AND the point at which the Dolby sticker went from white (silver) to black (around serial #108670 to #117947). If any of you have units that would help us define these changes, PLEASE post your info.
514757 for the head 35712 Black silver writing & green board E291932 for the head 35711 Silver black writing & green board Question why is there a E at the beginning of the serial number? Cheers Kiwinut
Thanks for the info. Looks like the permalloy 35712 head came later than I thought. No clue about the 'E'. 'Europe'?
One thing I am stumped about is the "version" change reported around serial # 180000. This was stated in the "DD drive genealogy" posting. I can see no change in components, values, or construction that would substantiate this claim. There was some conjecture that it coincided with a PCB color change, but this is untrue. I have seen many units both above and below the 180000 mark that have the exact same brown component side/green solder side PCB. Also mentioned was that the units above 180000 had "mostly SMD components"; again, an untrue conjecture. The main PC board remained as almost all through-hole components until serial # 267,201--this is documented in Supplement-2 (March 1994). The original PCB as well as those following all had SOME SMD components---the Dolby chips and audio ICs, as well as some components on the auxiliary boards; but in no case until Supplement 2 were there "mostly" SMD components.
Let me know what to change in the table. I was sent a lot of information for the overview and prior to your post, there was no indication that info was incorrect.
Here is my version of the history of the Sony Walkman WM-D6C. Compiled from postings on Stereo2Go and tapeheads forums, as well as eBay listings of units for sale. Dates and serial #s of changed units are somewhat incomplete. February 1984: Sony Walkman WM-D6C released. Amorphous "pointy" PA259-3602A head marked "Japan". Brown/green phenolic PC boards 1-611-494-11 with through-hole components. January 1985: Supplement 1 notes Dolby chip change from CX20068 to CX 20218, as well as surrounding component value changes. PCB now -12. Serial #s affected are unknown. Change from pointy to rounded amorphous head 35711 between serial # 71236 and # 72263. Date unknown Spring 1988: Change to Dolby sticker color from white (silver) to black between serial # 114374 and # 117947. March 1994: Supplement 2 notes change at serial # 267,201 to green glass epoxy PCB 1-651-545-12 with SMD components. April 1996: Service Bulletin 395 issued. The motor was changed from X-3305-830-1 to X-3370-805-1. April 1999: Supplement 3 shows two resistor values were changed in the French model. June 2001: Supplement 4 shows main PCB changed to 1-651-545-14; motor drive servo circuit redesigned with servo IC CX069A. Service manual was issued as Rev. 1.1. Change to permalloy head 35712 in serial #s ~50xxxx and above. Marking "amorphous head" on the case is no longer present. 2002: WM-D6C production discontinued.
