This thread covers the restoration of SONY WM-DD9. Main points of servicing this walkman are: - a general clean and re-lubrication of all rotating parts; - replacing the aged rubber parts (belts, capstan rings, pinch rollers); - check and re-adjust the motors position and flywheels thrust play; - check and adjust the pinch rollers bracket pins if necesary; - adjust the tape guides; - cleaning the switches and volume potentiomter; - adjusting the servo and Dolby levels; Dolby levels: 32mV RMS with 200nWb/m ANSI tape at test points indicated in the manual Service steps go as follows: 1. Remove the back cover, it's held in by 3 screws; 2. Remove the 2 screws holding the PCB and remove the tape holding the flex cables; 3. Desolder the battery + red wire and remove the 3 screws holding the back bracket; 4. Tilt the main PCB; 5. Desolder the flex cables going to the small servo board. This together with main board and door will be completely removed from the unit. While this step is not strictly necessary it makes work on mechanism way more convenient. 6. Remove the frame, volume potentiometer wheel, hinge and carriage; 7. Remove the plate in cassette compartment; 8. Remove the 2 drive pulleys; 9. Remove the top camgear and the gears on the right for easy access (those will need to be removed for re-lubrication anyway); 10. Remove the metal slider; 11. Remove the solenoids assembly; 12. Remove the bottom camgear; 13. Clean and re-grease the camgears, slider and shaft and re-install them; Use Molykote EM-30L for the camgear and slider and watch oil for the shaft. 14. Remove and re-oil all the gears except the reels. This step is not stricly necessary, but at this point it's highly recommended to be done given how much has been disassembled. 15. Re-oil the pulley bushings and re-install the 2 pulleys; 16. Oil the motors top bushings and polish the spindle if it doesn't look shiny; For polish run the motor on 0.8V power supply while using an 800 grit, then 2000 grit sandpaper against the spindle. 17. Check the capstan rings and replace if necessary. If possible keep the original ones and just clean and treat with rubber restore solution. 18. Oil the capstan bearings and reinstall the flywheels. Grease the top part that goes against the retainer. Check the thrust play and adjust if necessary; 19. Re-install the motors and check for motor position visually. Adjust if necessary (motor needs to be perpendicular to the flywheel). 20. Re-install the cassette compartment plate;
21. Adjust the tape guides as show in the pics. The aluminium bracket the head sits on it not straight from factory, hence why the guides sit an an angle relative to the head. You can see this by looking at the assembly from one side. This is easy to correct by installing paper shims under the guides. It's a necessary step to have proper tape path alignment in both directions. 22. If necessary, relap the head. This step is not covered here, if you want to do it will suppose you already know how. 23. Replace the pinch rollers if necessary. Do NOT use rubber only replacements as the assemblies will become eccentric. 24. Check the angle of the rollers relative to the head and capstans. Note that to do this check correctly you need to press the lever on back of the head slightly as head has a downward tilt when not engaged which will disappear when engaged. 25. If necessary bend the roller bracket pins to correct any roller misalignment. 26. Re-install the carriage, hinge, door and PCBs. Before re-installing the small PCB, clean the volume potentiometer, as it won't be accesible after that. NOTE: After re-assembly, everything on the tape path (head, rollers, capstans, guides) must be cleaned with IPA before using any tape.
Wow, outstandig tutorial. Replacing the belts has just fixed my unit but why not go way deeper... Hope to find replacement parts easely now. Thank you so much @Valentin
Hello Valentin, outstanding work let me guess your day job you write techincal manuals ? Anyway this great for future reference . Sincerely Richard
Hi, thanks for the guide! May I ask for step 14, which gears should I put oil exactly and at which points? Just the teeth? (Isn’t it commonly not recommended to lube nylon gears as they are self-lubricating?) Also do I need to put oil or grease to the pinch roller shaft?
In regard to step 14, you can see in picture 17 there are 4 gears on each side + the tabel reel (which has integrated clutches). Note it's the shaft that needs to be lubricated, not the teeth. Rather not stricly necessary than not recommended. Not recommended implies it can create harm, which is not the case if the right lubricants are used. Generally speaking, parts that rotate at high speed should be lubricated with oil, while slow speed/high friction parts (like camgears) should be greased. For oil use watch oil (doesn't need to be a specific one, any watch oil is fine), as for grease Molykote EM30L or similar.
