Hello everyone, this is my technical post here on Stereo2Go, so first of all: thank you for maintaining such a valuable knowledge base around vintage Walkmans. I have been reading many threads here while trying to understand how Sony DD Walkman work. Regarding an issue with a Sony WM-DD9 I would now like to describe my case in detail and start a technical discussion, as I am trying to determine whether this unit is realistically repairable or whether it may be affected by the well-known DD9 cam gear problem. Observed behaviour: Immediately after inserting the battery (no key pressed), the unit starts making a loud, repetitive clicking noise. Both reels alternately make small left-right movements, as if the logic is switching between FF and REW. Both LEDs (FF and REW) are continuously lit. The unit does not respond to any keys. The behaviour only stops when the battery is removed. Checks already performed: The unit has been opened carefully. Both belts are present, intact and appear almost new. Given that the behaviour starts immediately at power-up, before any play command, I believe worn capstan rubbers can most likely be excluded in this case. End-position switches S702 and S703 were checked electrically: both are open (no continuity), which seems correct as long as the mechanism never reaches its reference end position. the switches themselves are mechanically functional. Not checked so far: Correct position of the two P-Leaver with reference to S702 and S703 switches as I don’t know how to check. Advice is very mich appreciated. Interpretation so far: From what I understand, the logic seems to be alive and actively trying to reach a valid mode reference, but never succeeds. The alternating reel movements and constant FF/REW LEDs suggest that the mechanism does not reach its end position, so the controller remains in a kind of endless initialization loop. I am aware that many WM-DD9 units with similar symptoms are repairable and that in most cases belts, rubbers or re-indexing solve the problem. However, based on the checks above and the specific behaviour, I am concerned that this could be one of the cases where the transparent green cam gear is cracked or slipping under load. As far as I understand from previous discussions here, this cam gear is specific to the DD9, not interchangeable with the common DD center gears, and unfortunately not available as a new replacement part. What I am looking for: Confirmation or contradiction from experienced DD9 repairers: does this behaviour match your experience with a failing cam gear? Are there any diagnostic tricks (short of fully dismantling the mechanism) to further differentiate between a re-indexing issue and a cam-gear-related failure? In case the cam gear turns out to be the culprit: does anyone know of potential donor units or have experience sourcing a usable replacement? I do not feel confident enough to dismantle the mechanism further myself, especially around the cam gear area, and I would like to make an informed decision before proceeding. Thank you very much in advance for your time and for sharing your experience. Best regards, Timo
@Admin please cancel this thread as I just discovered it was created in the wrong sub forum. Thank you in advance and sorry for the inconvenience cause.
