Hello, The other day, my second ever Walkman drop happened. My first one was a broken 22, which was no real problem as i trashed it anyway. The problem is that I dropped my D6C on a hard floor while putting the leather case on (ironic). I sense no mechanical problems, as the motor and transport all work well just like they always did, But the muting circuit acts up : when I press the Play button, the music starts as usual then it drops out to some static noise. It might be a capacitor's dried solder joint that got broke loose? Or maybe something about the different switches for sensing around? I do not know. The issue renders this D6C unusable, as I cannot record or playback anything on it. Thank you for reading, and thank you for your help!!!
Interesting problem (and a bit funny, sorry!: now I know why my D6 case stays safe in the box while D6 is always by my side) Lets hope that @Deb64 sees your Q: he knows D6Cs inside-out!!! My understanding is that Muting kicks in for a split-sec then gets out, not the other way around. But desoldering it would check if thats the problem. Check for broken traces/joints: a drop should not dry out electrolytics. How is Line-Out, the same noise? Does volume has any effect on noise?
Normally if a mute module fails it does so gradually. At first you get occasional loss of signal and / or distortion. Eventually the problem gets worse and you get no sound out at all. In this case, I would think the problem is due to the walkman having been dropped on a hard floor. It's difficult to diagnose this type of problem without seeing the unit but I would start by looking for cracked PCB traces and dry solder joints. It's quite common for the tracks and solder joints onto the headphone sockets to come loose over the years due to headphone jacks being pulled in and out. The dropping may have damaged an already weak headphone socket mounting further. As @Jorge says, how is the signal from the line out jack? Do you know which part of the walkman impacted the floor first (and will have taken most of the energy from the impact)? If you examine the casing, this will be where the most damage is. Were there any headphones plugged in when it was dropped? I recently repaired a D6C which had a badly damaged headphone socket which, I think, was damaged by dropping and landing on the headphone plug. It's also worth checking the PCB around the four mounting screws since the energy from the impact will have been transmitted to the PCB at these points.
It dropped face-first on the corner where it says "WALKMAN". As i said, it was nearly face first so shock mostly was spread out on the whole faceplate. As for the headphone jack, it was not dried (i reflowed the solder a few months ago). The line out give the same result. Basically the muting acts like it should, only at the start : I press play, the music comes on after just a bit, then it fades to whining in less than a second, even the level meter "hears" the whining.
I forgot to add, a wire broke loose after the drop, the black wire that connects to the auto-stop board. (see picture) I have re-soldered the wire and it did not fix the issue. The drop also broke part of the DC-DC board, but no traces were on the broken piece, so no issue on it.
I think it would be worth checking the DC-DC board thoroughly. The audio circuitry is powered from the 11V rail so if you lose that you will lose the sound. Do you still have 11V present after you have lost the sound? The board took quite an impact if part of it was broken and it's possible that you may have cracked a PCB track which is now intermittent. You may not be able to see the crack, even with a magnifying glass so you need to check each connection with a continuity meter while flexing the board. Is the metal can containing the DC converter still electrically grounded? I'm wondering if the whining sound may be coming from this if the shielded case is not grounded properly. I would also check the PCB around IC601 carefully as this will have taken quite a lot of the shock too. Check all the ground and 11V (orange) connecting wires.
Thank you for your help. I will follow up when I get my meter back, as I do not have it with me where I am right now (in a few days).
Okay, I hecked here and there with the continuity tester. By electrically grounded, do you mean that the GND pin / the metal case of it is for exemple connected to the ground, right? Are the main board mounts grounded? There was no continuity between the DC-DC case and any main board/chassis ; So I'm wondering if these should be ground themselves.
What i mean is, should there be continuity between the DC-DC converter metal can and main board screwing point? (Because i believe those are ground as well.) Sorry for not being very clear, I still struggle from time to time with the language barrier.
Yes, the metal can on the DC-DC converter should be grounded. It is soldered to the DC-DC converter sub-board by two tags. One of these tags is grounded. The black wire from the DC-DC converter is the ground connection, which connects to the grounding star point on the main circuit board. This is the point near the -ve battery terminal, where there are a lot of black wires connected. The black wires connect to grounded points throughout the WM-D6C. There are four screws which hold the main circuit board to the metal chassis. The only screw which is connected directly to 0V ground is the one nearest to the record level rotary knob. This is also connected to the spring tab, which connects the ground to the metal back panel. I have also attached a board layout drawing. It may help to print this out and mark up all the parts which are grounded, and then check these parts with your continuity meter.
Orange wire from DC-DC board was disconnected from the main board. I soldered it back in place, and now instead of fading to silence, it fades to very low volume, but i can hear music now. It sounds like an issue about a capacitor. What could cause this? I am gonna demonstrate the sound output by recording it.
Okay, here is what it does. You can also hear the very loud click coming from the player when I press Stop, it's a loud pop coming from the line In, not a mechanical noise from the pushbuttons.
It sounds as if the mute module is working, but doing the reverse of what it should do. Normally it should mute the audio output by about 44dB for about half a second when you put the walkman into play, and again when you stop. This is to suppress the loud click which occurs when the audio circuitry is powered up or powered down. In your case the audio is unmuted for about half a second (hence you are hearing the click) and then it is muting. You can still here the music faintly in the video. You mentioned earlier that you had to resolder a connection to one of the muting switches. I would suggest that you check the wiring on all the muting switches. Not only check that the correct colour is soldered onto the various switches and pads but trace the wires through and make sure that they go where they should. You need to check the connections onto the switches and the auto power off board. Also check the soldered wires onto the mute module pins against the circuit layout drawing.
I managed to track down the problem. There is no continuity between the ground and the corner of the board with the record volume knob on. I connected the ground terminal of said volume knob to a ground point that was connected to the "common star" (the point where a lot of black wires connect, right next to IC601.). And sure enough, the sound is normal and clear as it should be. For now, I am trying to find the part where the ground trace is lost, since soldering a jump wire is a bit of a dirty hack in my opinion. See the picture below.
Do you happen to have a version of the service manual with the schematic that has the ground highlighted? I don't have any. Thanks.
Unfortunately not. Your best bet is to print out the layout which I uploaded earlier in this thread and the mark the OV pads with a highlighter, and then go through and check where the OV connections are getting to on your walkman. You need to take your time and check it carefully.
I fixed my issue by.... buying another D6C, i found one "broken" for 90€ that i negotiated at 60€. (change money for a D6C!) It just needs a replacement record volume pot and the motor screws were missing.
