Hello friends , This thread is the fruition of a conversation we had with our fellow member @Emiel about the differences between Sony WM-DDI and Sony WM-DD10 and what exactly they are to implement them in his excellent Sony DD series spreadsheet file. As Emiel pointed there is not much on the internet , more specifically for the WM DD10 . Indeed from what evidently is out there WM DD10 service manual looks more like an one page announcement . So I proposed to open a WM-DDI and a WM-DD10 from my collection and have a first hand look and then give him a feedback with the findings. I could summarize in a sentence " Alterations in Servo section " but is more complicated than that , I have found two PCB versions for DDI and one revision for DD10 not counting a DD10 from an auction that appears with the first PCB of DDI , I know.... it's a total mess ! So a dedicated thread seemed a better idea so other collectors and users might find helpful the information and @Emiel can more conveniently choose what can be used on his file . But let's start from the beginning , below the one page S.M of DD10 : We can see with the most official way that DD10 "is almost the same as the model WM-DDI". Worth to note that the different part numbers for the PCB for the two models are unrelated with the PCB ID codes that are printed on the actual PCB s . The first column referring to pages of WM-DDI service manual. Although in column "Description" we read "MOUNTED PCB , AUDIO" I couldn't notice any significant changes in audio section. This seems to be an exclusive West Germany model , it's not clear though if that concerns DD10 model as a whole or the specifications (eg.color versions or accessories). WHAT'S INSIDE My DDI and DD10 where unmolested and opened for the purpose of this thread , DDI is in almost pristine condition but not working with leaking caps and DD10 is well used but still working great. Roughly I date DDI from 1988 and DD10 from 1989. WM-DDI PCB ID : 1-624-285-12 circa 1988 , these caps with the yellow band seem to be prone to leakage , in my walkman above need replacement. WM-DD10 PCB ID : 1-624-285-13 circa 1989 , strangely PCB retains the previous script "WM-DD1" . PCB paths have been altered slightly in many places especially around the servo IC , test points have been almost entirely omitted , as there are no schematics for this revision we can't be certain for the reasoning behind the changes. At some point maybe there was a supplement(s) to service manual , we just don't know. Furthermore I found a picture of a DD10 from an auction recaped and as a proof the seller shows the old (yellow band) caps removed. What is peculiar in this picture you'll see below is that it has a PCB with ID 1-624-285-11 earlier from the ones above possibly from 1987 judging by the dates on the ICs , mind DD10 appeared in 1989. Also this PCB ( 1-624-285-11 ) has the lowest sequential number and what appears to be the initial arrangement of parts around the servo IC as can be found in the WM-DDI S.M. PCB schematics (page 8). In conclusion what we know so far : - Sony WM-DDI had one PCB revision ( initial : 1-624-285-11 , revision : 1-624-285-12 ) with alterations in the servo section . - Sony WM-DD10 had a revised from the previous version PCB ( now 1-624-285-13 ) once more with alterations in the servo section (motor drive). EXTERIOR DIFFERENCES : SONY WM-DDI on the left SONY WM-DD10 on the right. Altered button frame on WM-DD10 WM-DDI horizontal aluminum brushing lines on the button frame . WM-DD10 brushing lines following the angle of Play-Stop buttons . WM-DDI : "DOLBY NR" , WM-DD10 : "DOLBY B" , both with yellow printings and the Dolby double D symbol , from technical point of view is exactly the same Dolby system. In all documentations and on the walkman it's DD I and not DD 1 from the Latin number one : unus , although if you noticed in all PCB versions we read WM-DD1 ! Most likely the cases on my walkmans are original , DD10s case has still the second indentation for the protective peg while DD10 has only one peg . ( if you know about a different dedicated DD10 case , or can confirm , please let me know ) The tape direction arrow is smaller on DDI . "CASSETTE PLAYER WM - DDI" inscription on DDI cassette door. "WALKMAN DD" inscription on DD10 door. DDI cassette door has a brushed aluminum logo , on DD10 is just printed : DD1o : side middle screw shorter SONY WM-DDI , SONY WM-DD10 , SONY WM-DD11 and SONY WM-DD22 was a series that used a simplified less complicated common platform for Sony's Disc Drive system .
Thank you for doing this detailed analysis @Machaneus ! I will update my overview + timeline appropriately this weekend. The conclusion from my point of view: the DD10 is the next iteration of the DD1, that allowed Sony to produce it even cheaper (and perhaps faster). A few examples from your post: Optimized PCB: reducing the number of test pads, relocation of some components; Optimizing housing processing steps: removing the need to emboss the logo, simply printing a few more characters, etc.
