Hi guys I've been using my WM-D6C without issues since around March/April this year. I last used it a week ago and it was absolutely fine. Today I tried to turn it on, and while there is a battery indication light and hiss through the headphones in play mode, there is zero motor activity. Can't play/fwd/rewind, basically no sound from the motor at all (and no it's not paused either). In the time since it worked last week it has simply been sitting idle. Can anyone please help identifying what the issue might be? I have basic electronics capablity (have done some work on this device before so not completely unfamiliar with it) but might need explanations in slightly simple terms. Like I'm not sure how to test if there is current going to the motor or not, which points do I need to probe, etc.? Or any wires that may have snapped off the board? I couldnt see any at first glance. Thanks
I probed these two points with voltmeter and got 0 V, same with probing red + earth tab on the opposite side of the board. Not sure if that's the right locations but if so it suggests no power going to motor.
I have also probed these two points from the DC-DC converter expecting around 11 V, but it appears to just be the same as the battery pack voltage (around 5.3 V) ... is that what it's supposed to be? Edit: nevermind, I probed red and black, however orange and back does give a consistent 11V. So the issue isn't the DC-DC converter.
Can someone also please confirm the correct way to read pin voltages for IC601? Is it a case of putting the device in play mode then putting the red probe on the pin and the black probe on the grounding on the edge of the board next to the chip?
No not as yet I don't want to fully take it apart without doing some diagnostics first. I'm also not sure how much voltage to feed it.
I don't know either but I would start with 1.5 volts and then try 3 volts then 4.5 and a maximum of 6 volts and if it doesn't rotate with any of that then the motor is simply dead. And then you know what had it worn out.
Ok so I desoldered the motor wires and fed it 1.5 V and I can hear it move, so the motor itself is definitely alive.
Well I'm not an expert on repairing these that's for sure. But I do know basic electronics and I do solder on things but not on these little tiny things because I shake. Also, I have one of this model that's in perfect working condition complete with the box and all that. And then I have a second one that doesn't work correctly. And then I have two d6 models and then I have a bunch more Sony models of various models. Just I have a lot of them presently. At least a hundred of them or so I haven't counted them. I only use do which is a Sony freak that's freq and a WM gx670. The rest of the ones I have either need belts don't work or I just don't have time for him. I Prefer to work on boombox's.
@djsubtronic There are a couple of things to check: - do you have 6V at the emitter of drive transistor (Q601) ? - do you have 5.4V at the base of drive transistor ? - do you have 6V at pin 8 of IC601 ? - do you have 1.65V at pin 5 of IC601 ? Also check visually the area around the screw hole near the CX20084, seen D6C PCBs cracking in that area.
Thank you, as I posted above I am not 100% sure the correct way to be measuring these. - Is it correct that I put red probe on the designated pin of the IC or Q601 and the black probe on the grounding point on the right side of IC601? If not please let me know how I should be testing it correctly. - Batteries inserted or not? - Should the walkman be powered on/in play mode while I measure it? Just want to make sure I am measuring correctly and safely. Visually, the PCB seems fine - no cracks or damage.
You talk about probes? That's fabulous, but what are you probing with? In other words, what is connected to the probes are using a vom an oscilloscope or what? Me? I only use a vom which is a volt ohm meter, and I would test the unit with it powered by batteries. That way I know that I'm using the correct voltage in the unit as I test it. There you go! Here's my radio shack special. It's a auto range digital multimeter. It's a model number 22-803
@Valentin Here's the readings I got using the star point/negative battery terminal as black probe with the battery inserted and walkman in play mode: Q601 emitter: 5.24 V Q601 base: 4.68 V IC601 pin 8: 5.24 V IC601 pin 5: 0.025 V
What have you used to power the D6C? Did you use batteries or any type of DC adaptor? The motor controller chip (IC601) is very easily damaged by the use of an incorrect DC adaptor and I have seen some D6Cs with a damaged CX20084 where the motor doesn't run at all. The most common sign of a damaged CX20084 is that the motor runs too fast but that isn't always the case. There are a couple of things to check. Firstly, check the voltage on pin 7 of the CX20084. This is the "Motor on or off" signal which is used to stop the motor at the end of FF and REW. When the level is high (around 4V) the motor should run. If it is low (0V) then the motor will stop. As @Valentin suggests, there may be a problem with Q601. It is also worth checking C610, C611, C612 and C613. I had one of these go short circuit once (I think it was C612) which stopped the motor from running. I have just seen your latest post. Pin 5 of IC601 should be about 1.65V. This is a reference voltage generated within the CX20084. It is possible that C606 has gone short and is pulling pin 5 down to ground. I have seen this on a later SMD type D6C.
@Deb64 thanks for your reply. When I first got the walkman in March, I had used an original Sony 6V adapter that came with the walkman, it was fine. However I very quickly stopped using it after learning of the dangers, and have only been using rechargeable AAs. Since then I have not had any issues at all until now, and have only used batteries. Pin 7 is currently reading 5.19 V in play mode and 0.008 V in stop mode. With regards to C606, please correct me if I am wrong, I measured resistance of the circled points (based on mounting diagram in the service manual) with the probe polarity as indicated by the circle colour: The measurement was taken with batteries removed. This gave me 9.15 kOhm... if that's the correct points then I guess the capacitor is OK?
Have also measured the others: C610: doesn't seem to register as anything. I.e. no measurement but also no continuity (I used the 2 points on the extreme corner of the board for C610 based on mounting diagram). C611: 5.7 MOhm+ C612: 290 kOhm+ C613: 75 kOhm+ Edit: sometimes C610 randomly measures 6.277 MOhm, then it goes back to behaving like an open circuit.
You are not measuring across C606. You need to refer to your PCB layout. You are actually measuring across R608, which is a 10k resistor. C610 to C613 are probably OK. You would need to check with a capacitance meter and ESR meter to be certain but these very rarely fail.
Sorry, found the right pins. This also measures around 9.8 kOhm and apparently, 480 uF (though I do not know how accurate this multimeter's capacitance mode is and I measured it in place without power). I sprayed some contact cleaner around the area, and also around the capacitors and gave it a good clean. After that the walkman behaved like this for a few mins: Motor faintly running in stop mode, then some movement when hitting play and then it stopped again. After a few mins it went back to being as before aka fully dead motor.
I tried to measure all the capacitors from C601-C613 but some didn't get a reading. I was able to get the ones below: C606: 485.1 uF - rated 10 uF C607: 49.8 uF - rated 47 uF C610: 8.6 nF - rated 8.2 nF C611: 10.51 nF - rated 10 nF C612: 13.85 nF - rated 10 nF Seems mostly OK to me with the exception of C606 which seems wildly off. Possible culprit for the above situation?
