BogMonster Posted September 20, 2009 Share Posted September 20, 2009 Bit of a long shot this as it's not a factory head unit but there is a lot of random expertise on here so you never know I have a Kenwood KDC-W534U CD/radio with a USB input via a flying lead that goes into the back of the set, fitted in the 110. About six months, maybe a year ago, the display started playing up intermittently - the display will go off completely, but all the buttons work fine and the various functions work OK just difficult to use "blind". A couple of weeks ago the intermittent fault became permanent and apart from waking up very briefly on a long run the other day, it's kaput most of the time. I called up somebody I know who bought one at the same time to see if I could borrow his front panel to try, and his went the same way six months back, exactly the same problem It seems from this http://www.fixya.com/support/t557033-no_display_kenwood_kdc_mp532u that it is probably a common fault on Kenwood kit but the model referred to is different - mine has a detachable front panel and the CD slot is hidden behind the front panel which hinges down. I have taken the front panel to bits but can't immediately see any resistors that look burnt out. Has anybody come across this same fault, any solutions? One solution is obviously to buy a new head unit but that would be £150 and I figure I can probably fix it for nothing if I can only find what the exact problem is .... and what needs doing and where (head unit or front panel). The fact that it came back on and worked fine for an hour or so the other day suggests to me that it is a similar problem to the one described on Fixya - some sort of bad connection. Replacement also has the small problem that it was a special order and we don't normally sell the USB units at work so it will be a couple of months before I can get a replacement (or a fortune for air postage) which will be a PITFA. Quote Link to comment Share on other sites More sharing options...
cipx2 Posted September 20, 2009 Share Posted September 20, 2009 It would have been great if you could try a different front panel but it seems you were unlucky. Try what's suggested on http://www.fixya.com/support/t1572372-kenwood_kdc_x590_faceplate_display - scroll down, under the "Best solution". Quote Link to comment Share on other sites More sharing options...
BogMonster Posted September 20, 2009 Author Share Posted September 20, 2009 Ah that one looks a lot more like mine in the picture. I'll pull it out on the weekend and see what the guts of the radio look like. I didn't see that thread when I was looking around. Then again I was just looking on our suppliers webpage and there is a nice new one with Bluetooth handsfree built in to it which looks awful tempting Ta Quote Link to comment Share on other sites More sharing options...
Aragorn Posted September 21, 2009 Share Posted September 21, 2009 If that doesnt work, the other option would be to strip the PCB right down, and get someone to chuck it into a solder reflow oven. Basically melts all the solder and lets it re-set, which usually cures dry joints like that. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 21, 2009 Share Posted September 21, 2009 Fixed this very thing on V8Bertha's unit (which I think was a Kenwood). It's not terribly tricky, you may need a magnifying glass though. The resistors are surface-mount so just a ~6mm square soldered to the main board (not the front panel). On his, the solder was cracked and it was almost impossible to see. A quick touch with the iron to re-melt it and good as new. Hardest part was dismantling the thing to get to them. I did take a photo but I've lost it Quote Link to comment Share on other sites More sharing options...
cipx2 Posted September 21, 2009 Share Posted September 21, 2009 Here's the schematics, exploded view, components layout etc for the KDC-W534: http://www.mediafire.com/file/jknfnayznoz/KDC-W534.pdf Quote Link to comment Share on other sites More sharing options...
BogMonster Posted September 21, 2009 Author Share Posted September 21, 2009 solder reflow oven Not really many of those round these parts CIPX, thanks, I'll rip it to bits and see what I can see. It's snowing again so I guess planting the garden after work tonight is out... If I see anything photograph-able I'll post it up for the benefit of others. The fact that it comes back on after a long period means I am pretty sure it's something like a dry joint. Fingers crossed! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 21, 2009 Share Posted September 21, 2009 Ooo just found a piccy of V8Bertha's front panel and it was exactly the same unit as yours - no piccies of the resistors unfortunately but if you post a pic of the main PCB I can get the crayons out and show you exactly where to prod it Quote Link to comment Share on other sites More sharing options...
BogMonster Posted September 21, 2009 Author Share Posted September 21, 2009 Photo attached with the lid off ... the front of the unit is at the bottom of the photo if that isn't clear. Somewhere on one of the websites about the other sort of radio, I read about 2R7 resistors and there are a bunch of five of them stuffed in the bottom right hand corner of the board near where the CD deck retaining screw goes in - is that what I am looking for? I can't see an obvious dry joint but I don't have a strong light and a magnifying glass at the moment. There are another three of the same 2R7s a bit further up on the right hand side. I have to go and find a better soldering iron somewhere anyway as soldering those with the one I have to hand at the moment would be a bit like attempting brain surgery with a shovel. Ta Quote Link to comment Share on other sites More sharing options...
cipx2 Posted September 21, 2009 Share Posted September 21, 2009 Don't worry about actually seeing the dry joints, just solder them all (the resistors I mean). My advice is not to do both terminals of a resistor/whatever one after the other. Do one terminal, let it cool down and do another terminal from another resistor on the opposite corner, then come back to the first resistor etc. Yes, those are the resistors the "Best solution" was on about. But wait for FF to sharpen his crayons, he should be able to tell you more. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 21, 2009 Share Posted September 21, 2009 Bang on - I'll save the crayons and just describe it for now: The resistors are the five black squares in the very bottom right of the board, plus the three slightly further up on the right hand side. cipx's description is basically it - a fine-tipped iron is preferable but with care you can do it with a more chunky one. Don't push against the resistors as if both sides of the solder melt it'll slide off the board and then you have a bit of a fiddle on your hands (not the end of the world though). Just melt the solder till it flows and then remove the iron. You shouldn't need to add any extra solder or anything. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted September 21, 2009 Author Share Posted September 21, 2009 A bit of rummaging turned up my old wee 12W iron, a few fine dabs of solder (there was almost none on any of the resistors, none that I could get to melt anyway and being a tiny component I didn't want to risk cooking it) and.... Fixed :) Normal service resumed at a grand cost of £0.00 (actually I need to get a quarter of a number plate sticky to attach the USB flylead back onto the dash for the USB stick so it's probably nearly £0.05). One of the resistors (the one right in the corner of the photo) came off the board as soon as I touched one end so I'm pretty sure that was the problem but I put a tiny bit of fresh solder on each end of all 8 anyway. Thank you gentlemen, much cheaper than a new wireless Quote Link to comment Share on other sites More sharing options...
cipx2 Posted September 21, 2009 Share Posted September 21, 2009 ' Welcome This means you kissed the "built in bluetooth handsfree" goodbye then? Or you put it on the Christmas list? .... but there is a lot of random expertise on here so you never know .... Now you do know Quote Link to comment Share on other sites More sharing options...
BogMonster Posted September 21, 2009 Author Share Posted September 21, 2009 TBH I don't think a handsfree would work well in a Defender due to the noise levels, and as I'm usually only using the Defender when I'm going somewhere that is miles out of mobile coverage it is of limited use anyway If I was buying a new set I'd maybe pay the extra and get one with built in Bluetooth just to try it, but a free solution is much better value for money Now I wonder how much I can buy the other chap's broken radio for to fix as a spare Quote Link to comment Share on other sites More sharing options...
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