Hello all. Recently found a good deal on a WM-D6C, complete with replacement bands. After swapped both of those out, I was happy to find that all the buttons worked as they should, speeds reasonable. However, the audio out of both ports was not what I'd hoped: with a tape in I heard about a milisecond of music before it became a rhythmic thumping sound, not unlike a rather fast heartbeat. Without a tape in the walkman it still makes the thumping noise. Perhaps I'm chasing a rabbit hole, but I am curious in it that I do get music for that brief second when I click play. Any places to look, or suggestions as to what the issue could be? Most of the other repair threads I've read have similar, but not exactly the same issues.
Gotcha-I'll try to take a look at that this weekend and see if I can figure out which one could be causing the issue. There's a nightmarish amount of electronics in this model haha.
I'm still searching for my aux cable, but a couple updates: As to the thumping sound, it seems that I only hear it is ATT is set to 0dB, and there's no sound when set to 20dB. Not entirely sure what that indicates. I got it working! However, I didn't have all the structural screws in, and it putting it back together, it stopped working again. This leads me to believe likely a mechanical issue rather than an electrical failure, which is a little encouraging. Still, back to square one. Or less than square one, because now I can't rewind or fast forward without play already being on. Instead, I just hear a small motor that gives out after a few seconds. Here's the internals, in case anyone can make sense of them. Here's a video of the current rw ff situation;
The ATT switch is only related to MIC input. The thumping sound happends during record, playback or both ? Not working after re-assembly suggests a possible crack in the PCB in the area near the screw near battery terminals. Regarding the video, it seems the flywheel is rubbing against something. In FF/REW it can be heard the motor is not touching the rubber disc.
Thumping only happens during playback, no weird sounds during record. I've scoured the PCB but can't find anything so far-really hope I didn't crack it. It seems in FF/REW (without pressing play) nothing turns. I'm a little perplexed on the mechanism, as when in PLAY everything turns smoothly. If it's off, FF and REW turn all the right wheels/cogs manually, but when powered the motor can't seem to start anything and gives up. However, PLAY works fine. EDIT- thumping is only heard from Heaphone Out, not Line Out. Line Out just plays a very brief second of the song, and then nothing. If I FF during PLAY, I can catch a little snippet after each FF. PEAK shows a jump of red each time I get a piece of the song, and then back down to nothing.
Regarding the FF/REW, does the motor move at all when FF/REW buttons are pressed ? Is the motor position correctly adjusted (perpendicular to flywheel) ? What about flywheel thrust play ? Despite doesn't seem to be your problem, would also do this: https://stereo2go.com/forums/threads/sony-wm-d6c-no-rewind-ff.4687/ In regard to PCB crack, look in the area near battery terminals. Usually if it's cracked it's a small hairline crack and can be very hard to see. As far as the thumping goes, have you tried removing the muting module ? Does this change the behavior in any way ?
The motor moves in FF/REW, but what is the mechanism by which it turns the wheels? In play, it is obviously shifted up to make contact with the flywheel, but it doesn't seem to make contact with anything when in FF/REW without pressing PLAY first. The idler wheels and gears all turn correctly when manually moved, but I don't see how the motor can affect them. I'll try to remove the muting module and see if that does anything. Here's the audio, when directly recorded via aux, if it makes it any clearer (warning, gets a bit loud). It's just the first 10 seconds, not sure why the video is so long.
Rotation is transferred to the table reels through the big idler by touching the FG magnet part of the flywheel. But for that to happen, the flywheel needs to rotate first, which doesn't happen if motor spindle doesn't touch the rubber disc.
EDIT: Fixed it, it was due to the levers which had gotten in the wrong order. Blue should be above red, so after putting back in place FF/REW work again. . https://i.imgur.com/MtGobvl.jpeg Now, I still only hear a snippet of music and then a high pitched whine/thumping, so we'll keep checking on that. Reminder, when recorded, sounds like this:
Some diagnostic hints, perhaps: The peak meter seems to briefly show all lights when a tape is started, and then goes down to -10 with -5 blinking. If I set the volume to max, there is no blinking at -5, only a constant light at -10. If I move the rec level dial from 0-10, it also changes the peak meter. Setting the sound to Dolby B-type makes it go down to the -10 blinking, compared to Dolby C and Off type. This all corresponds with the noise I hear: less electric whine with dolby C, when the recording dial is at 0, etc.
The VU-meter peaking may be caused by imperfect contacts in the REC/PB switch. That should be cleaned. Also, has this unit been powered with reversed polarity ? Are there signs the CX20084 has been replaced ? If so I would check C138 for short circuit.
I just checked C138 and it seems fine. Previous owner only used batteries, and he was the owner for a long while, so my guess is no reverse polarity. It is definetly REC related. I found out if I plug in a mic, I can hear the full playback, however there is a loud electrical whine over it. With loud enough speakers, however, the music is clearly audible. Without a mic plugged in, the thumping comes back and it's impossible to hear the music. I'll start with the REC/PB switch, but my guess is something around there is the cause. EDIT: This only works out headphones, I should add. No sound from Line Out. It does change in pitch as I module the speed. Furthermore, no high pitched whine if the back screws on the pcb aren't screwed in. Then it plays fine, a little muted, but with no whine. Okay, what I've learned: - Thumping noise quits when something is plugged into the MIC-ATT line. Oddly enough, this MIC line works... through the output of the device? For example, if I have headphones plugged into MIC, the ear cups act as a speaker, rather than the mic on the aux cord. Still, it's necessary to have a completed circut plugged in here to function (half an aux cable doesn't work). - The high pitched whine occurs when the PCB near the DC in area is screwed in, or pushed down. Seems the less secured it is to it's normal place, the better: if I don't screw in the placement screw in this area, no issue with the electric whine. - The sound is always kind of quiet, and is very loud when starting to play or ejecting a tape. Music is louder if something is plugged into MIC in. Guessing this is the muting module, so I'll try taking this out next.
Editing update: On a whim, I tried plugging in an aux splitter... and now it works perfectly. No muting issues, peak displays correctly, comes out of both lines... I'm not entirely sure what this indicates, as without something plugged into the mic line, it doesn't work at all. If I plug a mic that is different from the headphone in, the music is muted and the mic works. If it's from the same source... perfect audio, and no recording sound. Admitedly, I'm a bit baffled.
It seems this D6C may have more than one problem: - the high pitched whining noise; given it's realted to removing the 2 ground screws, it's likely somwehere you have a floating ground. - thumping noise when nothing is plugged into the MIC in; you have to investigate if this is mechanical (PCB bending when jack inserted) or electrical (the switch inside MIC jack gets closed); However fact this problem exists on PLAY does point towards REC/PB switch. - no output on line out; this is interesting since the input of the headphone amp is fed from the line out;
