Hi everybody. I currently trying to get a 1990 Sony walkman, WM-507, to playback tapes. When I connect either a 1.5V battery or a DC bench supply (at 1.45V) and press play with a tape inserted, I get no spinning from motor. Furthermore, a mm reads 1.5V on the motor 4 pins (I think they are) relative to ground. The bench supply says 0A is drawn when play button pressed. Sub-note: In hindsight based on service manual I shouldnt have exceeded 1.3Vdc So far I have: - Cleaned capstan, pinch rollers, playback head - Replaced belt (including removing degraded old belt) What I suspect it could be: - Faulty motor - Less likely Bad electrolytic capacitors. Although I assume these capacitors are most likely bad as they would be 35 years old, I doubt they would have any effect on the DC motor operation. I saw this as these electrolytics are usually used for low and high pass filters, smoothing DC ripples, DC blocking etc. Any suggestions on what I could try next? I did notice alot of corrosion on the 2 poles that partly protrude through the PCB. I dont see corrosion anywhere else on board
Having 1.5V is no problem, as a fully charged alkaline would have that. So no worries there. As a sidenote, you will need new clutch gear + reel gears (those can also be glued) for a full restoration. Electrolytics (both cylindrical and flat ones sitting on one side) are also bad on these units, it's a known problem on all walkmans with this mechanism. There are 2 electrolytics in the motor servo circuit, which are likely what is preventing the motor from running. Motor is unlikely to be faulty, unless it's seized. Can it be turned by hand ?
Do you get power (1.2 - 1.5V) on pin 1 from IC601? Do you get power (1.2 - 1.5V) on pin 27 from IC301? I suspect that the switches S901/S902/S903 aren't making good contact. When pressing, the play the head assembly should push the switches closed. And as @Valentin susgested it is mandatory to change the caps, they are gone by now and leaving them in isn't a good idea. And those motors are pretty sturdy, the same motor in my WM2091 was completly seized, opened it up and the protective paint that's on top of the magnetic disc had corroded...removed all that, relubed and reassembled and its working fine again. ps service manual for the WM507 can be found on electrotanya
Yep turns by hand I tested continuity of both switch mechenisms and both good I eventually found the power fault. The trace from the power switch S901 to the B+ rail had no continuity. I soldered in a new trace and solved this issue. Now the play, rr, ff all work and drive the motor. The reason the trace got damaged is 100% because of a leaky capacitor (even though I cant see a leak Im sure theres a leak from the cap which the trace runs under) The problem though is that all I hear when playing tapes is a buzzing sound. Im prettery sure it will have something todo with bad capcaitors. I'll have to finish this project when I order the right capacitors. Its a bit of a process and Im concerned about usualling through hole caps to the pads insted of SM as the through hole caps might interfer with the mechenisms or will prevent it from fitting even if i bent then flat with the board. I dont know. Thanks for the help though guys!
great work, so it was power not reaching the board....about the buzzing sounds, that indicates bad caps in the audio line not filtering out motor noise..
Thanks mate. True EMI from motor wouldn't be filtered if caps are gone. I'll update post when I have new progress
@TP86 Did you solve the buzzing sound by changing the caps? And do you by any change own the wireless remote that comes with it? Last week bought myself a WM507 (and a 505 and a 506 with remote) and was wondering if these remotes are interchangeable with eachother...all of the above walkmans are still in transit so will be in my hands in a few weeks time....
Hi mate. I've not had a chance to fix mine yet. I do not know yet how to get access to the secondary PCB. That sounds cool that you acuired all those walkmans. I have a feeling the 506 remove will be interchangable with the others but Im not sure. Mine unfortunenly didnt come with a remote. Are you planning to also replace the SM caps?
