Pioneer D-07 DAT dead vacuum fluorescent display repair

[Music] right there welcome back today we got something a little different and you'll see in a minute why I decided to do this video this is a DAT a digital audio tape player from Pioneer it's the d07 and it's actually on and believe it or not it's actually playing the problem is you don't see any proof of that on the front panel it is completely dead and in fact I can get one little light to come on if I choose the wide mode over there now the problem with this thing is it's playing perfectly there's nothing wrong with the audio reproduction just that the entire display which is a fluorescent display is completely dead over here now I found the schematic for this by the way which is a great help always is I've done some searching on the web and I've discovered that these pioneered deaths had a reputation for a burnt-out display and what I'd like to do is to determine whether that's the case or if it's something a little less ominous but the other reason I want to show you this is because I want to show you the quality of build of this piece of equipment it's absolutely unbelievable the quality of the build on this thing is really really top-notch starting with the copper cabinet the inside of this thing is copper none of that steel for you and then the way this thing's laid out it's really really well done I see these occasionally but not often enough so when I do it's always a pleasure to work on them you see the caps and some of the actual I sees about a copper strip on them that's the reduced noise you have to remember this is a digital audio tape so there's digital and analog going on in here so they went to that length and everything is so clean it is so different from what we used to seeing today that I think it's worth paying a little bit of more attention to it now these things were cheap hell they still aren't cheap but you're certainly getting what you paid for and that's more than you can say for a lot of the modern stuff feast your eyes now the problem I face is that the display is on that front board over there and to get to it I have to dismantle this whole transport remove it and do some checking but the one thing I've realized from all the reading have done and it's been quite extensive is that sometimes it's got nothing to do the display at all and it has to do with the supply so following the first rule of troubleshooting check the voltages that's exactly what I'm going to do but first of all I want to have a look at the schematic and see what voltages I should be looking for now the one thing to look for with these displays is that it usually works with the sort of thing you'd find in a tube a valve that's basically what you have here you have a grid and a node it has a filament and they've kindly provided a schematic with the pin layouts over here which gives us an idea of what to look for the legend here says f4 filament g4 grid p4 a node that we plate I suppose and we find that the terminals it's not that complex you've got the f1 f1 is a joint and and so the two end ones F 1 and F 2 will be the filament and the filament will usually be an AC voltage I'm not sure what voltage they use over here but we should be able to determine that and then all the other the other elements are controlled by you would have a grid connections 10 G 9 G so you've got all the numbers over here 9 g 8 g 7g that'll be controlled by those points over there the grids that's the number of the pin 36 37 38 and so on there's a lot of them not connected then there's also all the the anodes which I presume will be where voltage is provided I presume this will be fairly high voltage and are fairly high voltage I think with these things as about 30 volts minus 30 volts if I'm not mistaken so other than the filaments which will be AC voltage those are not connected those are all anodes for the respective letters over here we've got all the little letters on here s RP n MK J H and so on they're all marked as anodes those there are all empty or not connected and then you got the grids now I want to find where the power comes into this particular board now I've got a full it's got my full page here which shows us that Borden it's not that easy to see but if i zoom in basically the display unit is this thing you're seeing over here and it has a connection to chassis there's a small connector here to one of the other boards which has to do with the switching unit and the lead unit we're not interested in that except that'll probably take voltage as well this one is the input select board which would just be a switch yep that's what and then we've got two connectors that connects to the main board and I think this is where it gets interesting let's have a closer look we've got AC over there ground AC 2 and AC 1 those I presume will be the filament if I follow that line there there yep that goes to F and if I follow the other one AC one that goes down here all the way down here and it goes to the other F yeah so I see what I see two are the heaters if there's no AC voltage on there that display wouldn't work either then there's 5 volts where does that go to v VD 5 volts that goes to this will be the remote infrared receiving diode and it also goes goes to the switching board and it also comes down here and it actually does go to one of these but I don't think that's a supply at all I'm thinking and what I've seen so far is that the switching gets done on the main board so I think only the signals come into here now I need to find out where that switching will be I'll go back to the top thing there let's see these are all 10 16 17 18 so from pin 5 you've got you've got a nodes or plates 5 to 20 where is that and 5 so it's T T 0 T 1 T 2 and so on up to 16 so they'll go to the main board and then the esses will be the grids I need to see where that goes on the main board let me find it on the main that's the problem with us you got to jump around quite a bit okay I found where these connectors come into the main board and if I go up here I've got V AC 2 and V AC 1 and that's directed off somewhere where it's coming in it's not here there's ground and then I see something here which is interesting this point here V P P minus 31 I think that indicates - 31 volts this would be the main contributor to the display being completely off so I need to find out where this V P P comes from because I've got a feeling we've either got one or two things we've got a supply problem or we've got the actual display has just run its course because these displays do wear out and it gets to a point where whatever you do you just go and get back get them back to life and that is a real bummer because this thing will be totally useless without it not that it doesn't work but it's kind of pointless and I don't want to give up on it just yet so I'm gonna look for this - 31 volts and I've got it I've got to tell you I saw a video by a fellow youtuber called 12 outfits where he was trying to repair one of these displays and he had the same problem this - 31 volts was not there and it was actually - 31 volts he was looking for which is quite funny and I guess these are pretty standard voltages for these displays it was a totally different display but it was also - 31 volts so I'm sort of following his way of thinking and his way of thinking was was what gave me the idea that perhaps the display is still alive and that this thing can be salvaged because it really does deserve to be now - 31 volts I don't want to go look for it on I don't have to look for it anymore on the front board I can look for it on the main board which is where we're in now but I want to see where this comes in because if I can isolate this to the power supply board that one is definitely a lot easier to get to then the main board believe me this is a mess over here I don't want to undo all that so let me go find this see where this thing comes into the main board found it here it is it's connected 10 on that main board and it's VPP and it's right next to the two ACS coming in so this is going to the powerball unit jumper 10 okay this is connected 10 over here we've got 5 volts ground well this is the power supply all the various power supply points coming in so we've got 5 volts ground 12 volts ground P 9 volts P off AC 182 and VPP so let's go and find this unit power unit jumper 10 and here's the power supply this is the the power supply board the pulse by unit as they call it and there's wet ghosts connected 10 so it's this guy over here so we had five volts ground yeah this is the one 5 volts ground 12 volts 9 worlds P off AC AC and VPP okay where does that come from so VPP which has to be according to those - 31 volts comes from this transistor so this is a well this is just a regulator yeah this transistor is acting as a regulator you've got a diet over here I can't see what voltage this is 33 I'm not mistaken that's 33 j33 a this is looks like a 33 volt Zener diode so you'd have 33 volts here there are we - point seven lower than that 32 31 okay so that means that the ground has got to be this guy because that's higher than ground so this should go to ground where does this guy go to that point goes to there and it goes to there and it goes to there goes to okay goes to the FL winding secondary of the transformer it doesn't tell us what the voltage is there so that comes out here goes there and it's the top end okay and the diet's facing in so what we've got here is this must be ground ground ground ground where yep that goes to ground and the reason that goes to ground that's one side of the AC this side here is half wave rectified because you've only got one diode and it's negative because it's facing inwards in other words you rectify the negative half cycle so this point will be more negative than that point so that's 0 that's minus whatever so that's rectified and filtered through that faster there minus 35 volts over here minus 35 okay and then you've just got the pass transistor and you've got yourself rectified and regulated - 31 volt which is VPP so I'm gonna look for this voltage and I'm hoping I'm really hoping that my bet pays off because all the other voltages 5 volts goes to the switching which seems to be working all the other voltages seem to be there because the units working units working just fine it's just the display and it seems that this is the only voltage this AC and AC and VPP are the voltages that affect the display and seemingly very little else so I'm gonna go measure this where will I measure that the busiest way to measure this would be on the actual supply board and it is the last one the last pin pin nine on that connector but I think I've got access to it so that's what I'm gonna do measure this with these voltages or at least in this one and the ACA she was the ACE she connected to there okay yeah this is what happens this AC it's follow these two lines back back back back back back back back to that AC secondary and I'm not sure what voltage that is there's a hex filter cap on there and a Y filter cap on here so this is for noise and then it comes out as AC no ground reference yet it goes up here it's floating floating floating and that AC is floating and this AC should be flirting but zappity zap it to minus 16 point 5 volts using that diet over there which is a 15 volt diode so what they're trying to do is they're giving a 0 while they're putting all this AC below 0 volts because it's basically creating an offset of minus 16 volts and that just helps with the difference in voltage between probably between the grid and the heaters or between the plate and the heaters you often done want more than a certain voltage to exist between the plate and the heaters I know that in tubes you have that sometimes you reference it to the either to the grid or actually to the plate voltage a portion of the plate voltage so you don't have such a big differential between the the heaters and the actual cathode so yeah okay that looks good so I'm gonna check this out see what we've got and get back to you okay so to start I removed the that cable from the main board that's the one that's supplying five volts 12 volts nine volts AC and the VPP there's another cable here supplying that top board the input board I believe and I've actually unplugged it from that end so I don't want any voltages going to the boards I just want to test the power supply right so I'm going to connect the multimeter to ground which is the second wire just checking the screen there second wire that's right I have the amp off because I don't want to create any shorts while connecting these pins on here and to the first one I'm switching it on we should get 5 volts 5.1 brilliant switch it off again and of course we've got the capacitor holding the voltage but now I'm going to try ground to pin 3 and that should be if I touch this I'm gonna get a spark and I don't want that that should be 12 volts 12 volts good then 4 is ground as well then 5 is 9 volts so 4 5 switch it on line halts we've got it nine volts and then pin 6 is peel off and I'm not sure what that does it's probably an activator and mute or something like that then we've got pin 7 and 8 is AC and pin 9 is what I'm looking for so I'm looking for VPP benign and I want -31 switch it on oh that does not look good if I got this on huh well let me just make sure that everything connected properly this is this is too easy pen mind basically zero volts that's my - 31 volts I'm supposed to have so I has seemed to have got lucky I'm just checking this again because this thing just sounds a little bit too easy and I always get a bit suspicious when it works out too well alright I'm going to test just make sure this thing's on test the nine volts again or the five volts again that's the top one five volts yeah now I'm going to test the AC switch that off so I don't have thirty-one volts or minus thirty one volt so I'm going to check pen seven eight and I should have AC let me tell you that - AC volts and this pen eight let's try that seven and eight you sure don't bend any of those pins and that's five volts 50 Hertz that's my AC and I now have an indication that it at there the filaments or the heaters work on 5 volts I'm not sure what it's supposed to be I don't see any indication anywhere but this bloody the service manual is 71 pages long so maybe I just haven't seen it but we don't have our - 31 volts which is great news because if we don't have our - 31 volts I think we can safely assume that we don't have that we have we found the reason why the display doesn't work so now I'm going to go a bit further I want to see if the voltage is coming from the transformer I'm looking for the winding that says F in other words that winding that provides the voltage for the minus thirty one volt regulator now I'm just looking here I think yeah it actually shows it on there it says F hence those two pins over there so once again that one there ah 34 volts ac that's the one my supply is coming in okay so I've got my minus 35 rod I've got my new coil FL comes through at 30 33 was at 33 volts AC and it meets the diode and it rectifies it to that capacitor and then it goes to at minus 35 volts it goes to the collector of that transistor which is Q 401 now which one is Q 401 that's that full guy there which one is the collector not sure we have to look at this more carefully okay so that's Q 401 and I believe that is the collector over there so I have this thing on just make sure I'm getting nothing there yep so what do I get on they're not getting anything on there what should I look not getting anything on the collector it is on that was over there it's connected to the collector that's the 2.2 K I should be getting minus 35 volts this it's not even coming in there it comes in through a resistor 401 where's resistor 401 that's that one over there I'm getting minus 16 on there what about the other side that's the problem getting to the other side well the other side is actually actually let me to measure decide the diet minus 16 that's not good I should be getting minus 35 I'm getting minus 16 over here which is where the diode that's where the diode and the resistor meet I think what I'm getting there is actually I think I'm getting the result of that one diet that 16 volt or 15 volt diode so I'm not actually getting anything on there so either the diode is open all the resistors open my guess would be the diode let me try that let me switch everything off I think our diet is buggered so let's try that okay try and get the diet adjusted get it in there really tough oh the diode seems to be fine it's try reverse die it's fine can he be the resistor then let me try that the resistor that'd be it simple as that is it connected properly the resistors open the resistor is open now what is that that's our 401 our 401 is 47 ohms and it looks like oh man it looks like a quarter watt resistor and it is open now isn't that nice I wonder that resistor would open if too much current came through why would too much current come through well if we had a short on this transistor here if that shorted that would go to that would do it yeah transistor shorted or there's one other explanation which might be the case which probably explains it a little bit better and that is if this capacitor started leaking too much and if this capacitor leaks too much it increases the current flowing through the diode and the resistor and that resistor would open from excessive heat so that would imply that this capacitor could be the cause of that fault these things usually happen in tandem you don't get a resistor fading just because it wants to it's usually something else wrong with it now I'm gonna I'm gonna connect a resistor in here in parallel with this because that's open anyway and I'm going to see what happens to the voltage let me set that up so here I've got a 47 ohm resistor and I've just connected it to these leads and I've connected those leads across that resistor there so what I'm going to do now set up the voltmeter again to see if I get that minus 30 volts or - 31 volts and that should tell us whether it's just the resistor or whether the well could be the transistor that's gone as well so we'll just have to wait and see okay I have the meter now measuring between ground and the suppose it - 31 volts and I'm going to switch it on ha ha I love it I love it it's not - 31 but it's minus 30 point five I have restriction on the dim ball tester but it's drawing 40 milliamps so that's not really having any effect if I do bypass it okay - 30 point six now that would make sense to be slightly lower if the capacitor is indeed drawing more current than it should in other words if it's leaking more than it should so I think we found the problem I think what we had here is the capacitor probably started leaking cause the Nexus current draw that excessive current draw bypass to increased beyond the or created a power loss or power drop across that resistor which was in excess of its maximum and we have the resistor failed yep all right all right I'm happy I'm really happy yeah and I want to thank 12 old vids for the e for the clue because you don't get to this this quickly by yourself unless you've done it before or as in my case it seen somebody else do it and it's this is actually the result of following a hunch which happened to work which is why he's seeing the video if this had not worked I don't know if I put the video up because I would really have looked stupid which isn't difficult sometimes anyway I'm going to do the following now I'm now going to remove the power supply board which now seems what makes it a lot easier to get it out because it's just one board I think about four screws on the bottom there and I think will actually fit through the bottom or through the side and what I'm going to do is replace that resistor probably you replace that diet as well because it might have been overstressed check the zenus it's easy enough to check them with a board out I've got my Zeena tester and then I'm also gonna have a look at all the capacitors because if that one capacitor has leaked and we'll check that when I take this out I'm not sure how well the others are doing so I'm going to take this opportunity to basically renew some of the capacitors on this board and trial ensure this thing works for a hell of a lot more years okay I'm getting on with it okay here we are the board is back in place I removed it it was quite easy to remove what wasn't easy to do was to film with two cameras like I tried to do earlier on in the video so I lost a lot of footage again but didn't nevermind that was just removing some caps and bringing some caps in and testing yes ours and all that sort of jazz nothing too exciting and I found nothing too exciting either I replaced the resistor that was open I replaced that diode even though it looked okay but I think that diet had been a little stressed it was looking a little grody then those two capacitors in that power supply itself in the display supply in the - 31 volt supply regulator supply we're actually a bit higher on ESR especially the first one which is probably would cause the resistor to open so that was replaced the others I replaced a couple of them I checked them all and most of them seemed to be fine now let's sit why not what's this that uh beauty it's looking good and of course the problem was never the playing it was just the display and it's as bright as it was when this thing came out of the factory and it's working like a charm now I'm not gonna play this through amps because that's not the objective here also I don't want to get copyright strike but if you well here it's there the phone's the timer is working you can forward this you could stop and pause it you can do whatever you like with this thing it's as good as new and it's actually a hell of a piece of equipment not that we have too many deaths these days it's sort of a format that's gone out but hey cassette decks are coming back and who knows maybe this will be a fad in the future because this thing sitting gonna be around for a long long time anyway thanks for watching I hope you enjoyed this I certainly did it really is a pleasure working on this top quality gear it's it really is satisfying to put this thing back where it belongs which is in use for many many years and if you liked it please click like share subscribe and all that jazz and if you want to support the channel you can do so by going to patreon the links at the end of the video alright thanks for watching bye for now

Channel: Electronics Old and New by M Caldeira

Views: 9,293

Rating: 4.9540229 out of 5

Keywords: tube, valve, tube amp, tube amplifier, valve amp, valve amplifier, restore, restoration, tube amplifier restoration, valve amplifier restoration, repair, grundig, braun, telefunken, gryphon, power amp, power amplifier, dual mono, dim bulb tester, pcb repair, marantz vintage amp, marantz stereo amp, pioneer, d-07, d07, pioneer d-07, pioneer d07, pioneer dat, d07 dat, d-07 dat, fluorescent display, vacuum fluorescent display, florescent display

Id: xdHkDO2XXFM

Length: 35min 8sec (2108 seconds)

Published: Wed Nov 27 2019