radaddict Posted January 28, 2013 Report Share Posted January 28, 2013 Hi all. Just joined here and this is my first post. My original foray into minidiscs was with a Sony MZ-1 way back when. Sadly, it died a few weeks back. Looks like the wall wart power supply was to blame - it's only supposed to ouput 10 or 10.5 volts, but measuring it shows it's putting out 15v. So, looks like it fried whatever inside the MZ-1 (may it rest in piece). Anyway, I found a MDS-JE510 on the cheap with a jammed disc in it that I thought I'd try to resurrect. It was easy enough to free the disc. I cleaned up the mechanism and cleaned the tiny switches within. The result is the discs insert and eject without issue, sort of.... When first powering up (from a cold and unplugged state), it takes awhile before it will read the TOC -otherwise it will fail on reading the TOC and eject the disc. Perhaps something is warming up? So then, after the "warm up," it will read the TOC and it will play discs... for awhile anyway. When playing a disc, sometimes quickly and sometimes after a time, it will abruptly eject the disc, or even just power itself off. During the time that a disc is playing, the display will toggle between the time elapsed display or song title and Stereo or Mono. So, then, my question is, based on these symptoms, does anyone have a clue where to look to try to fix this? My suspicion is that perhaps the power transformer thingy (sorry for the technical term ;-) is not providing the power needed or it fluctuates (this may explain the "warm up" needed to function at all). If this is the issue, where can I source a replacement transformer? Thanks much for any guidance you can provide! Quote Link to comment Share on other sites More sharing options...
sfbp Posted January 28, 2013 Report Share Posted January 28, 2013 Start and look for OTHER threads with posts by Jim Hoggarth. With luck he'll be along in a while and can give some direct advice. The sad thing is that the JE510 seems to be one of the only common units this happens to. Something to do with using a lot of metal in the construction, which gets (even though you can't see it) rusty. Whereas later models used plastic. Right, Jim? Quote Link to comment Share on other sites More sharing options...
radaddict Posted January 28, 2013 Author Report Share Posted January 28, 2013 Start and look for OTHER threads with posts by Jim Hoggarth. With luck he'll be along in a while and can give some direct advice. The sad thing is that the JE510 seems to be one of the only common units this happens to. Something to do with using a lot of metal in the construction, which gets (even though you can't see it) rusty. Whereas later models used plastic. Right, Jim? Thanks for the reply. Yes, I've read all the posts I could find regarding the JE510 (from Jim and others). Hopefully Jim may be able to provide other info that may help me resurrect this deck. I can definitely see where rust/corrosion could play havoc in those tiny switches. Well, worst case scenario, if all my efforts fail, I will test the aerodynamic qualities of this deck ;-) Quote Link to comment Share on other sites More sharing options...
jonathanpotato Posted January 28, 2013 Report Share Posted January 28, 2013 I will test the aerodynamic qualities of this deck ;-) Sell it for spares on eBay... You can help other someone to repair its. IMO you have a problem with main µP or front panel (like if keys are pressed...). Check flat cables, bad soldering, maybe a crazy IR receiver and ground problem first. Let the transformer alone. Quote Link to comment Share on other sites More sharing options...
jim.hoggarth Posted January 28, 2013 Report Share Posted January 28, 2013 Hi. The mono/stereo flickering is simple - it is the select switch with flaky contacts. The same happens to the input select switch and to a lesser extant the timer switch. If you sort these out first , then retest the unit as spurious signals going into the IO pins of many processors can cause all kinds of weird things. The 'warming up' may well be a fault on the 'BD' board, that is the control board on the drive unit. Or it may be a laser problem. As for the third problem, the powering down is not a fault I have seen before on a JE510. Other than drive problems these are usually reliable as regards the main board and PSU. Most likely a power supply fault, but to be honest it could be anything. I had a bookshelf system once that intermittently went dead because of a faulty IR receiver. Every so often it just shorted out the 3.3v supply. But as I say, best sort out the front panel switches first and then re-appraise. Jim Quote Link to comment Share on other sites More sharing options...
radaddict Posted January 28, 2013 Author Report Share Posted January 28, 2013 Thanks all for your feedback and suggestions. Much appreciated! I'll muck about with it and see what I can do to resolve the malfunctions. BTW... My reference to testing it's aerodynamics was a joke, if perhaps a poor one. Quote Link to comment Share on other sites More sharing options...
radaddict Posted January 30, 2013 Author Report Share Posted January 30, 2013 Does anyone know the part number of the front panel push button micro switches (power, play, scroll, etc.) and where they can be sourced? Would these be acceptable replacements: http://www.onlinecomponents.com/te-connectivity-amp-brand-1825910-6.html?p=10269502 Thanks! Quote Link to comment Share on other sites More sharing options...
radaddict Posted January 31, 2013 Author Report Share Posted January 31, 2013 Hi. The mono/stereo flickering is simple - it is the select switch with flaky contacts... Well, perhaps not quite so simple I'm sorry to say. I took a somewhat heavy handed approach to troubleshooting and removed all the front panel switches and jumpered them to their default position (I can still activate a switch by bridging the jumpers). I jumpered the stereo/mono switch to stereo and the digital/analog to digital. I also cleaned everything as best I could. Interestingly enough, while the display is a bit brighter and the deck is playing somewhat better (will still abruptly eject the disc or power off whenever it pleases, but not as frequently), the stereo/mono will still occasionally toggle in the display. Curiouser and curiouser. I'm onto checking resistors - all the resistors on the front control panel are good. I can't find any faults on the control panel (doesn't mean they may not be there, just that I can't find them ;-). On to main board I suppose. Forgot to mention that when in Stereo input mode, the scroll button will also toggle between stereo and mono, but always toggling back to stereo. Holding the button will invoke the scroll function. So, there is a short somewhere - just gotta track it down. Quote Link to comment Share on other sites More sharing options...
jim.hoggarth Posted January 31, 2013 Report Share Posted January 31, 2013 You have a superb fault on this machine - I say superb, as in anyone with a love for electronic fault diagnosis would relish the chance to diagnose this. I hope I don't lose you here: Looking at the service manual schematics (page 56), the Play Mode, Repeat, Scroll, Power and Mono/Stereo switches are all assigned to Key 1 signal back to the master control processor. The method used is a voltage divider based on a resistance ladder, which feeds into an ADC input on that processor. The Key 1 line is tied up to 3.3v by a 10k resistor (see page 44 - pin 4 of IC316. R329 ties it up to B+ line). Play Mode shorts the key1 line to 0v, Repeat presents 2.2k to it, Scroll 5.5k, Power around 10k and Mono/Stereo around 20k when in the stereo position. When in Mono, the line is left floating and thus pulled up to 3v3 by R329. So you can see that switching into stereo is done by presenting around 2.2v to pin 4 of the controller IC. If 'stereo' appears when pressing 'Scroll', you would assume ohmic contacts on the scroll button. But that would not explain the other problems. I think this results from a bad 3.3v power line, either browning out or with a lot of noise on it. If you trace the line back, it goes to pin 5 of IC309, the switching regulator IC. You want to check for bad joints on this chip first. Or put a 'scope on this output and look for an obvious breakdown of the supply line - it will be very obvious and look just like noise. Alternatively it may be one of the other components in the system which connects to the 3.3v line, and it may be very hard to find. My first suggestion would be to disconnect the 3.3v terminal on the IR receiver chip - IC702. As I said before, I have had one instance of this failing and causing a dead unit. It may be a common problem! Another thought is that it is one of the many supply line capacitors, particularly the electrolytics. Try disconnecting these one at a time to see if the unit improves. If is does, replace the capacitor. Electrolytic capacitors do not have a particularly long life, and as this unit could be 15 or more years old (and could have done many thousands of hours 'on' time), I am sure at least one of these capacitors is one the way out. Jim Quote Link to comment Share on other sites More sharing options...
radaddict Posted January 31, 2013 Author Report Share Posted January 31, 2013 Awesome! Thanks much for this Jim. I don't have scope, but I can certainly check for bad joints. I've tried tapping on the board and chips to see if I could induce a failure, but I could not get it to fail consistently. Question: When you say disconnect the caps, do you mean just remove them from the circuit, or place a jumper in their place? None of the caps show physical signs of failure (that would have been too easy ;-) Good stuff! Thanks again! Quote Link to comment Share on other sites More sharing options...
jim.hoggarth Posted January 31, 2013 Report Share Posted January 31, 2013 No, don't short them! They act like tiny batteries, smoothing the power lines they are across. If you short them, the unit definitely will go bang! Just remove those capacitors (electrolytic type - in the metal can covered with shrink plastic) which you can see are across the power lines, one by one. Then replace each one before removing the next. On an almost purely digital unit like this, very few of the capacitors are going to be used as DC blocking caps on a signal line, so you can assume they are all smoothing capacitors. Are you confident you know what you are doing? Let me know you can definitely locate these caps, and that you can follow the power line on the schematic. Also, have you tried removing the IR receiver yet? Jim Quote Link to comment Share on other sites More sharing options...
radaddict Posted January 31, 2013 Author Report Share Posted January 31, 2013 Am I confident that I know what I'm doing? I know enough to be dangerous. lol! However, I know my limits and have a healthy dose of caution and respect for things that can go "bang!". I didn't think you meant to jumper the caps - hence my question to be certain. What I will likely do, to err on the side of caution, is replace the caps rather than remove and test. As you say, this thing is old and if I want to make and keep it functional, I may as well replace them as preventative maintenance. I have removed the IR receiver. It's removal had no effect on the issues. Quote Link to comment Share on other sites More sharing options...
radaddict Posted January 31, 2013 Author Report Share Posted January 31, 2013 Well, I think I've got it fixed! In spite of my previous statement that none of the caps were showing any physical signs of failure, one of the caps had indeed failed (330 microfarad, 35v). I replaced it and voila! No more stereo/mono toggling and it's been playing just fine since. Of course it may be too soon to declare victory and only time will tell if I've got all faults fixed, but I'm ecstatic with these results! Many, many thanks for your help Jim! And many thanks to everyone else for their feedback and many thanks for the mere existence of this forum! Quote Link to comment Share on other sites More sharing options...
jonathanpotato Posted January 31, 2013 Report Share Posted January 31, 2013 The replaced cap is C333 ? Quote Link to comment Share on other sites More sharing options...
radaddict Posted February 1, 2013 Author Report Share Posted February 1, 2013 The replaced cap is C333 ? Yes. Quote Link to comment Share on other sites More sharing options...
jim.hoggarth Posted February 4, 2013 Report Share Posted February 4, 2013 Good to know you are sorted out at last. Very odd that it was C333 - I would not have expected the problem to be on the FLD negative bias line, as it is effectively isolated from the rest of the system by the power transformer. The more usual problem here is the zener stabiliser diode going short, which leads to ghosting in the display. But, there you go - I don't know everything! Jim Quote Link to comment Share on other sites More sharing options...
radaddict Posted February 4, 2013 Author Report Share Posted February 4, 2013 Good to know you are sorted out at last. Very odd that it was C333 - I would not have expected the problem to be on the FLD negative bias line, as it is effectively isolated from the rest of the system by the power transformer. The more usual problem here is the zener stabiliser diode going short, which leads to ghosting in the display. But, there you go - I don't know everything! Jim Well Jim, nobody knows everything. However, you know considerably more than I and certainly more than enough to point me in the right direction. So, at least in my book, this equates to Jim knows everything! Thanks again! Quote Link to comment Share on other sites More sharing options...
sfbp Posted February 4, 2013 Report Share Posted February 4, 2013 Where do you live? (just idle, if self-interested, curiosity) Well done. Sounds like you are destined to become a resource for us..... Quote Link to comment Share on other sites More sharing options...
radaddict Posted February 5, 2013 Author Report Share Posted February 5, 2013 Where do you live? (just idle, if self-interested, curiosity) Well done. Sounds like you are destined to become a resource for us..... I'm in the US - North Carolina to be more specific. I'm happy to help where I can, but I doubt I would have been able to fix this deck without this forum. Quote Link to comment Share on other sites More sharing options...
sfbp Posted February 5, 2013 Report Share Posted February 5, 2013 Indeed,,, but we get a lot of people inquiring about such things. You could probably do quite well, if it tickled your fancy, servicing people's gear. Jim does it all but he's in England, and for anything even slightly heavy, shipment to the UK is out of the question. Cheers Stephen Quote Link to comment Share on other sites More sharing options...
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