I encourage you to repair it. However, if you decide not to do so, I am interested in buying it. With the volume turned at maximum, can you hear any audio at all on the right channel ?
Yes, I'll try to unsolder the phototransistor first. Strange, I have sound on the right channel this morning and not on the left. I probably inverted the Apple Earpods yesterday althrough it's hard to believe as it is not ergonomic and I always verity that the volume control is on le right side. Nevertheless, with volume at max, I cannot ear any music, only noise. But remember, the motor stops after less than 2 seconds.
OK, phototransistor unsoldered. It was difficult because there is some glue under the component, but here it is: Now, how can I test it with the multimeter ?
Seems that strange thing was the pad underneath it. From what I can see, that's there to set the proper height of the sensor and hence the disntace between the sensor and rotating wheel. That is important, so leave it there. If you want to test it desoldered, you need an infrared source, like a remote control for a TV or something similar. Point the remote control at the sensor and measure the resistance between collector and emitter. It should measure open when no IR hits the transistor. It should measure a low value when hit with IR light. I guess you will need to solder some wires and connect them to the sensor, otherwise you will need 3 hands to do this test. But it was easier to test the voltages when it was soldered. Hope you remember which pin is which. Good luck !
Impossible for me to test this way as I don't have 3 hands ;-) I resoldered the phototransistor properly. Nothing changed, motor still stops after 2 seconds :-( I assume the problem was not bad or broken soldering
You mentioned something about shorting the collector and emitter togeher and then the motor would run. Did I understand that correctly ?
Yes, shortage C, E runs the motor continuously, but it is in fact difficult to maintain the shortage more than a few seconds with the multimeter. I'll try to measure the DC voltage at the collector. Which position of the multimeter measure selector shoul I use ?
Hi I still do not understand if the infrared diode or the receiver transistor is not working ... you can see the emitting diode with the phone camera if it works .. the phone camera also detects infrared and if the diode is ok it will see a purple glow ...
@Mighty Mightor Try what @Silver965 has suggested first. I assumed that the LED is working given the forward voltage drop it has when on, but it's better to test it that way.
@Silver965 , @Valentin , great idea ! I took a burst of pictures while the device was running (motor spinning) and cannot see the purple glow on any of the 10 photos taken. I've also tested the LED again with the multimeter: mesure taken while the device is off: 1250; pressing play: 1350; releasing play: 1250
Ok now try with a tv remote control ... point it at the phone cam to check if you actually see, when you press a button, the infrared LED flashes ... Then in PLAY mode you point the remote control on the phototransistor and if when you press a button on the remote control the motor continues to turn it means that the problem is the phototransistor led that does not light up ... it is a simple method and does not require much electronic experience
@Silver965 , you're a genius ! My iPhone 7 does not show any purple glow on photos, BUT if I point the remote control to the phototransistor, I can run the motor indefinitely. In fact, as long as I press a button on the remote control. Releasing the remote control button stops the motor. So, this means that the receiver is ok but the LED does not flash. Now I have to find a spare part for this component. Do you agree with my interpretation ? Where can I find such a phototransistor ? @Valentin said it might be difficult to find. Thanks again to both of you for guiding me on this troubleshooting.
Ok .. Looking at the diagram posted previously .. ..we do not see it but the led is always on when it is in PLAY ... it behaves like any led ... the light is reflected by the gear wheel and enters the photo alternately transistor .... in Theory you could put any SMD led ... or you have to find another donor walkman
Right, this seems to be the easyest way to go. Now I have to figure how I'll do that: SMD means you solder on the surface of the board. But the space is already taken by the phototransistor which should remain in place. Or maybe can I put the SMD LED on top of the existing LED, finding a way to solder to the board using wires ?
to test you could put it next to the original led ... and connect it with small wires .... of course you have to keep the original led disconnected
Wait a minute: the component is double: it is composed of an emitter (IR LED) and a receiver in only one component with 4 pins. The receiver must remain in place and soldered, it works. The IR LED must be replaced. I have (at least) two options: 1. keeping the 4 pins of the original phototransistor soldered and solder a new IR LED on the same holes than the old one 2. unsoldering and cutting the 2 pins of the original IR LED (keeping the other 2 of the receiver soldered) and solder the new IR LED in place with small wires as the space is already used by the old component. One more thing: the LED must be a IR LED, right ? Not any LED can work ?
It must be an IR LED. I would choose this one: https://www.tme.eu/en/details/kp-2012sf4c/ir-leds/kingbright-electronic/ I think you must either cut (risky as you can also break the transistor) the LED part of the sensor or at least file it down. Don't think there is enough clearance between sensor and rotating wheel to put a new one on top of the old.
OK, I have one in hand (local specialized shop, very handy): How can I find the good direction ? The old Led has black and red color, this one has short and long pin.
This one seems to be a 3mm or 5mm LED, which clearly won't fit, it's just too big. The long pin is the ANODE (A), the short pin is the CATHODE (K). You will need to buy a proper SMD LED to fix this unit. If you don't want to spend a lot of money fixing the unit, think about the fact that this is not the only problem. In order to fix this one, I can assume you will need to spend at least 20 euros (maybe more) to do it properly. You will likely need capacitors (the 220uF are not available from EU distributors and shipping from UK and US adds considerably).
This was so small in the shop... and so big once in the device ! Of course it doesn't fit :-( The price for fixing the unit is not a problem as soon as it remains reasonable. The main problem is ME. I searched for capacitors for another unit and found 220uF at tme.eu. But I also need 100uF 4mm and they don't have stock until june for that.
