Hi I have come up against a strange problem on this machine. I am a bit of a tinkerer and enjoy getting to learn new things. After getting my own WM60 running with new belts and a clean, I cast around looking for something else to attempt to repair. I ended up with a decent looking DD11 that was billed as a non runner. I prayed it would simply need a new belt and capstan ring. Indeed they were both melted and spread around everywhere. Anyway, after a good clean, some new belts and a bit of a fight with the ribbon cable I was eventually able to try some batteries in. Ho'ho, it plays! But then I noticed that the volume level was at zero and the sound was already quite loud. Turning it up beyond level 3 the sound became a howl. This eventually seemed to settle down but then as I listened to the music I became aware of the right hand earpiece of my headphones getting warm. At the same time I noticed that if I pushed the jack plug all the way in, the sound would go off, pulling it out slightly restored the sound, pulling it out some more actually stopped the machine working and the neg side of the battery contacts (the large thick coil) got hot to the extent that it began to bury itself into the plastic case. I have no idea at all whats going on and hoped someone might possibly have some suggestions as to what the cause might be. Many thanks in advance for any help.
Hi, Given what you're saying about the headphones getting warm and the battery terminal getting hot when plugging the jack all the way, there could be an intermittent short causing this. Maybe one of the output coupling capacitors is shorted and you are getting DC to the headphones (which would explaing why they're getting warm). From what I can see, the WM-DD11 uses electrolytic SMD capacitors, which I suspect could be leaky. Please make a clear picture with the PCB to see the overall condition. How does the jack itself look ? There are also some capacitors going from the output to ground, which could be related to your problem.
Hi I managed to get a few pictures. I hope they are clear enough. Oh, it’s a DD10 not 11. Doubt it makes much difference under the circumstances. Don’t know where I got that into my head
I see nothing obvious at first glance, apart from that corrosion in the motor governor area. The capacitors do not seem to be leaky. I would proceed in cleaning the board with isopropyl alcohol. If you let the unit play with no headphones, does the negative terminal get warm ? Apart from the heating problem, does it sound ok with both bass and treble correctly reproduced (despite the loud volume) ?
Yes, I'm sure it did sound pretty good once the volume seemed to settle down and I was able to turn it up beyond level 2 without the howling. I'll clean off that crud, I think it could be residue from cleaning it with an aerosol electrical contact spray. Once I've done that I will run it again without the phones as you suggest.
Now I understand what is happening. The howling is either an amplifier oscillating due to a parasitic capacitance created by that residue or is from the motor governor (where most of the residue is located). I have a suspicion that residue is conductive, so thoroughly cleaning the board might solve the problem without doing anything else. Also clean the tape speed trimpot, the volume pot and the jack itself with a cotton swab immersed in alcohol. As a reference, you should only use isopropyl alcohol or a contact cleaner specifically designed for electronics to clean PCBs, like Deoxit or Kontakt 60. But cleanining itself is only necessary when there is battery leakeage or capacitor leakeage.
Ok thanks, I’ll give it all a good clean. As I was looking again more closely I noticed a very slim slither of solder that seems to be making contact with another component. It is so small that I wonder if it is intentional or not. I’ve tried to highlight the area.
L This is what I’ve been using. It does say suitable for circuit boards. Better to get one of the other cleaners you suggested or is this actually ok.
I wouldn't use that. It may be suitable for electrical stuff, but not electronics. From what is written on the can, it's a petroleum-based product and it's certainly not suitable for cleaning PCBs. Unfortunately, the service manual that I have for DD11 has a different PCB, so I cannot check the layout. But judging by how it looks, someone clearly put a soldering iron in there. If the 2 pads are supposed to be connected, there should be a trace. If there's not a trace, it means they're not supposed to be connected. Clean that solder and test the unit again.
I just assumed that the damaged/melted part of the jack plug was through the overheating problem. Seems more likely now that someone (not me guv, honest) has previously been in there with a soldering iron like you say. I'll attend to that and report back. Many thanks.
I removed that trace of solder and cleaned up the board as best I could until I can get some proper cleaner. Much improved now, there is no overheating and the jack plug is fine. There is still volume at level zero, but higher volumes seem ok until it eventually becomes uncomfortably loud. I would say that as it reaches level 4-5 the left channel is more pronounced. If I switch on Dolby NR the volume goes down significantly. To be honest, for my own use I could use it as is, but if you have any other ideas as to what I could try then I would give them a go. Many thanks for your assistance.
Get some proper cleaner first and clean the entire PCB, the trimpots and the volume potentiometer. Do that first and then come back with the result. After you do a proper clean I can help you more. Good luck !
Regarding the soldering, I recommend something like Hakko FX888D or Weller WE1010 (the Weller is much more common is Europe). That's about the minimum you need to do good soldering. Those cheap 30-50$ soldering stations do no have good heat transfer from the heating element to the tip and you need to get the heating element to 350 degress to get normal leaded solder to melt. Of course, there is the option to get the board to an electronics repair shop to do that soldering for you as it would not be a big deal for them and probably won't charge very much. You are lucky the jack itself is not damaged, as replacements are pretty hard to find. From what I see in the picture that brown stuff seems to be a glue that holds the switch mechanically on the PCB. Some of these connectors have tabs that get soldered onto those pads that you already have on the PCB, others don't. SONY probably designed the PCB with the pads to have the libery to use both types, depending on what they have in stock. A word of caution here, do not use super glue on that switches, because there is a very high risk of the glue getting inside and ruin the switch (I have done that in the past and learnt my lesson). Depending on how the external actuator is mounted on the casing, those switches might not even need to be secured in the front. I'm glad you find my help so useful ! I like offer help because I want people bring these devices back to life. Especially that many times the repairs are quite straight-forward. I have seen some repair proffessionals on YouTube (won't give names) who wouldn't bother to do a repair like yours (call it beyond repair) and keep the unit for themselves some of the times. The person I'm talking about did this to some very high end collectible units in mint condition. He's clearly exploiting trust that people have in his services.
Yes it's sad that people are out there who would rather make a quick buck than help someone. Sadly I know of no electronic repair shops in my area, there is one a bit of a travel away but he asked my friend for 90 pounds just to look at something with no guarantee that he could fix it. I think I'd rather improve my own skills and upgrade my equipment into the bargain. I'll take a look at the ones you mentioned. Maybe a tiny bit of epoxy resin glue to secure the switch? It does move quite easily bending it's contacts. The last thing I want is for one of those to break after getting so close to completion. I'll update this post as I go. Thanks again my friend.
I've ordered the Hakko and a set of tips. I've wanted a good soldering iron for ages and this seems like a good excuse to get one
I've used my new Hakko to resolder the jack plug, I also resoldered the the four thin wires that attach to the board, as one snapped off with all the handling etc. I am very impressed with the soldering station by the way, after using it I realise how clumsy my cheap iron is in comparison. Definitely a good investment, thanks for the recommendation. I would love to say it is now fixed but strangely the problem with the volume control has returned. There is still volume when set at zero, even louder with the Dolby off. It was definitely ok when I last reported. Is it worth giving the board etc another clean? I don't know whether this is relevant or makes sense but the left channel goes slightly quieter when turning the volume up from 0 then increases in volume as it gets to level 4'ish.
I'll give it another clean then. I am certain I removed the trace of solder that might have been shorting across, but no harm checking again.
I finally managed to get back to the walkman. I have given the whole thing a good old clean, including the jack plug and headphone plug. It is still giving the same problem. One thing I have noticed is, if I gently ease the plug of the headphone from the socket by about 2mm, the volume does perform as it should, no sound at zero. Pushing the plug all the way home brings some volume back again while still at zero, moving up to level 2 -4 seems to affect the balance between left and right. I've closely examined the inside of the plug, cleaned the contacts, they don't appear to be mishapen. I am hunting around to see if I can find another pair of headphones to try. Do the plugs ever differ slightly? The ones I have are Sony MDR A10. Other than that is there anything else I can try?
The 3.5mm jack plug is standard. The fact that when you retract the plug 2mm the sound comes to normal makes me think the problem is only on one channel. When the plug in partly retracted you get the signal from one channel in both headphones (mono). I'm starting to suspect the volume potentiometer itself. Maybe some residue is on the carbon traces of the pot and in some positions it's coupling to the wiper. That could also explain the balance problem between left and right. If you have a small brush, immerse it in alcohol and brush the entire pot a couple of times and the rotate it back and forth from min to max.
