Hello, I recently bought and restored a Sony Walkman DD2, I replaced the center gear, resoldered the audio output as well as the ground and hot wires to the battery well, fixed one of the rollers and the most recent time I opened it to lubricate some of the parts, something occurred and now no power goes through and the Walkman does not turn on. I plugged it into an external power source and the light would not turn on, nor the motor, and the capstan wheel would not turn. There does not seem to be a mechanical issue but rather an electrical one, but I don’t know what it is or what to do, I’m getting frustrated and need help. I think it may be a capacitor issue but I have nothing to prove that. Pictures can be provided if need be. Please help. - John
At the very beginning I would make sure you had the right polarity. Secondly, I would follow the electricity through the device and see where it's going and stopping. Thirdly, I'd simply put voltage across the motor and make sure it rotates. I've never repaired this particular model Walkman before so I don't know, but that's what I would do.
A capacitor failure is very unlikely, only situation that can cause such symptom is when a capacitor that's across the voltage rail (C309 for example) is short circuited. What I would do is measure the voltage on different points: main DC jack, emitter of Q306, etc. If you get 0V at emitter of Q306 (unit in PLAY), go further back towards the leaf switch and see where the circuit is open. Indeed pay careful attention about the polarity: this walkman like most of devices from that era (it's a Japanese thing) are center negative. To test the motor, use 1.5V or a AA battery. But it's unnecessary because if the power LED doesn't turn on, the problem is further back.
Thank you so much this is so helpful. Do you have any suggestions on how to fix the polarity/make sure it’s right?
It's best to measure with a multimeter before plugging in any AC adaptor. Even safer is to simply use AA rechargables (you will need the low capacity slim ones) instead. They last more than enough for normal usage. Make sure the center is negative, meaning if you put black probe on center you get a positive reading on the meter. As a suggestion, no need to quote previous posts. Instead of using the "Reply" button (which quotes automatically), type in the box below the post and press "Post Reply".
Okay, this is an example of a/c or alternating current rectangular receptacle on the left in this picture. And on the right in this picture is a DC receptacle which is round. Now also please notice in this picture that in the rectangular receptacle there are two pins and they are in the center and they receive the alternating current from the plug, likewise, in the round DC receptacle is a pin which is in the center repeat center. This is the center of the DC input to where the center pin can be found. I hope this helps you. I hope I explains it in nauseating detail. Lastly, this picture is not of a Sony product but of another product that has a AC and DC input, but it is similar to all devices utilizing AC and DC input I hope this helps you find the center pin to which to measure the voltage from.
So I went and got a multimeter, the center reads mostly positive with the black probe, sometimes the negative pops up but the polarity isn’t the issue. I am getting a 0V on the emitter (this is the cyan wire right?), but the circuit doesn’t seem to be open anywhere along the leaf switch.
Also I don’t know if it’s relevant but the center pin reads 0V while the positive and negative wires themselves read as actual values.
Don't quite understand what you mean by "center reads mostly positive", it can read either positive or negative. Also please let us know what do you mean by "center", "positive" and "negative", as we only got 2 connections here not 3. I suggest let's look at it more simple: measuring the voltage on the points indicated on the attached picture (negative probe on point circled blue, positive on what's circled red), do you get a voltage reading ? Measurements should be done on DC volts, PLAY button should be engaged.
Measuring is being done in DC volts, and when the black probe is put on the center pin of the DC port, there is a positive reading on the multimeter. When the black probe is put on the black wire, and the red probe is put on either of the two points indicated in the diagram, there is a reading. The multimeter is set to 20 DCV, and when the probes are connected the reading will shoot up from a range of .14 to .06, and usually settles around .04 or .03.
Ok, 0.04V - 0.14V is really nothing compared to the 2.5V-3V required. What about these 2 points indicated in picture attached ? If you get voltage here, but not at violet wire, the leaf switch is to be suspected.
I would like to report I fixed the Walkman and I would like to say thank you to everyone that’s helped me on this thread. I’m greatly appreciative and grateful everyone was patient with me. The issue was not on the circuit board but a smaller, sneakier issue: a faulty wire that connected to the battery hub. I don’t know why it failed when it did but it’s caked in a black residue.
Dear, i have issues with my "new" DDII too. I measured some points as asked before. Could you help me what i could check now ? Many thanks for your help and time. Best Regards Tim
