EEVblog #808 - Fluke 196 Scopemeter Repair

hi welcome to a teardown and potential repair I hope above this a fluke 169 scope meter are kindly sent in by Ronald Bryant to the mailbag thank you very much Ronald it's a classic to channel isolated scope meter 100 megahertz one gig sample per second we've got a problem with the screen on it so let's rip it apart and see if we can fix this puppy now it doesn't actually come with the battery and it's got one of those SuperDuper recessed DC power jacks in it so I unless you've got the correct type of power jack the one I've got just doesn't fit in there you've got to have one of those special deep ones but thankfully we can just take those two screws off there and we can get in like Flynn no worries and it's got one of these evil center- our power jacks on it so instead of the usual Center positive Zoe trapped for young players anyway I powered it up our 17.5 volts on the external our DC power jack we don't have the internal battery we don't need it and you can see here is the fault and we've got all these dark horizontal lines right across but you can see everything's all the text is just fine the vertical graticule look auto everything's working just hunky-dory so there's something just wrong with those lines there now this can be one of a couple of things now the first problem could be mechanical due to the connections however they connect this LCD in there by you know zebra strips or however it's connected in there it could be hot bar attachment or whatever we don't know until we get in there tear down and take a look and just like in science with Occam's razor I'm going to put forward Dave's razor where if you've got a fault and it's you're not sure whether it's you know equally likely to be mechanical or electrical go for mechanical and of course it could actually be electrical it could be some sort of you know horizontal driver chip or something like that we don't know how this things are driven whether it has a controller built into the LCD itself whether or not it's built into the the processor and chipset driving this thing it's got a separate it graphics chip and we're not sure until we do the teardown and there's actually a third option which is the least likely in that it could be some video mapping video memory mapping issue ie a fault fault with the video memory and this was you know not an uncommon fault for really old gear that used a processor and then separate memory and then it would probably have separate video memory chip for example it could be something off a separate video memory chip but incredibly unlikely almost to the point of not even considering it because the video memory in something like this would be you know inside the processor itself and everything's fine with the text and every you know it's just it's incredibly unlikely but I thought I'd mention it so the first thing we want to do is a bit of percussive maintenance here that's a classic engineering term because if maintance I'm trying to put some flex on this but Jesus is pretty tough this fluke scope meters they're built like a brick Danny and yeah I don't like our chances but anyway doesn't seem to be anything like that and opening this puppy ups real easy to take off the bottom boot two screws two screws down the bottom here and then the whole cover lifts off it's designed to lift off because the battery is user replaceable the BP 190 battery just sits in there it's like a triangle arrangement the cells arranged in a triangle shape and there's the header connection for the custom battery in this thing which we don't have but we've got some shield in there so let's see if we can take it apart get access to the LCD and I'll tell you what I hate screws that aren't magnetic you know I've got one of these magnetizer demagnetizer very handy if you don't have one have one and we can't pick up the bloody screws yet I can pick up this huge heavy bit no problems at all but now oh and here we go we're in like Flynn I took off some of the shields here and you can let's have a look at because this is like a teardown let's have a look at the input ampere look at this is that I know look what have they done there tried to put some detail hide it I don't know it's probably some fluke custom front end would be my guess but look at the isolation slots here very nice no problems there at all and big isolation slot here separating the multimeter section from the oscilloscope section this will be an identical Channel up on that channel to up here we've got a decent look in Japanese relay there it all looks nice and neat and tidy and we've got that looks like a converter and a massive opto isolator here by the looks of it for the data transfer so this would be the isolation for the yacht power so they've just got an isolated power converter there in some custom package I've got no idea what that is vd GT in nine hmm and here's the multimeter section once again we've got some isolation slots it's all done nice and Danny looks like we've got a mod on the input there Oh p97 couple of little s oh I seasoned well that's about all she wrote unless there's something on the bottom side and once again they're isolating the pair across there but I don't see any yeah well presumably this one is the data so I could be wrong with about that but that's more likely so I don't see anything apart from that so they must be getting the data across there as well somehow there's nothing fancy happening with the chips on the multimeter section it's all jellybean stuff simple HC 405 ones you know like it's all basic look at that though that that cap in there looks a little bit how you're doing bit budged in don't like deliver that got the wrong footprint or something and no surprises for finding a Philips part in there because this is a fluke Philips our scope meter of course so that would be some sort of Philips custom front end now as far as the rest of this puppy goes we've got ourselves a little optical isolation data port on the side there there you go that would be your transmit and receive there and this is a big DC to DC converter obviously not sure that puppy is under there I think I see a Philips number so let's take a look at that and we've got ourselves a main processor up here that looks like Motorola and once again we've got one of these like what what is that it's almost like it like a heatsink like a thermal heatsink pad or something like that but there's no heatsink on it anyway flute custom chip and a fluke custom chip made by Motorola it could be an off-the-shelf processor I mean here's our flash memory for it up here could just be you know custom branded for fluke because companies are almost any chip company will do that they'll let you put your own partner but silkscreen the top of it anything you want if you order you know 10,000 or 100,000 of them or something though put anything on there you want and they've caught it the Garfield I'll call it the Garfield anyway and there's the other fluke custom chip Bart's got IBM triple o1 on there may be made by IBM perhaps hmm and what we've got on this side we've got ourselves a membrane here going down this will not be the LC that goes nowhere so it's just a thing to like just hold it in place so that is not for the LCD don't get excited I believe that's just going down for the the flat flex going down to the membrane keypad on the front the LCD is under here we can see the backlight there and flip it around tada you might be able to just see some chippies under there so we got an old-school LCD module so almost certainly the fold is on there 99.999% sure I think and you'll notice all these test pads down here it looks like they duplicate and go into the contacts the reason that they've got these test pads in here is so that in production when they test this board they can have a better nails which comes down with pogo pins onto all these so they don't have to physically insert cables in there to actually test this thing and that's just much quicker and more efficient during the production testing phase and is that some fused protection there on the battery pack looks like it and there's our high voltage our backlight inverter circuit there which goes out to the cable over this side of the wall here so we'll just take out a few more screws here a couple of standoffs and tada we are in like Flynn in Hawaii we got the bottom of the board - there we go this there's how they're getting the data across from the multimeter there we go so those took top - must be the data bricks are not the opto-isolator 's and I was wondering why the holes didn't quite line up for these shields they take all the way through so you can actually leave those metal shields in place when you take the board out and the metalwork came off easily this thing is very well designed by the way are and yep look we have rubber seal o ring seal right around the edges beautiful for you know water ingress and also our handy for our blast protection if you overload the inputs and things like that so very nicely designed this fluke Phillips me - love it anyway no surprises for finding Hitoshi LCD driver chipsets on here tashi practically own maybe they still own the LCD driver market I don't know but yeah they're they're one of the leaders so let's go to the datasheet for these things it's a little bit of active stuff happening around in here but I don't expect a fault in one of these things because once again these are probably our you know quadrants of the LCD so I don't expect and you know we're going to horizontal lines I'm or expect something with maybe you can see all the pins going out here probably some buzz maybe some zebra strips also mark hotbar flat flex attachments going to the board so I suspect it's more likely once again to be a mechanical thing happen in probably I don't know if it's all over here but anyway we'll have a look when we uh pop that thing out that's more likely than being an active fault I think anyway could be wrong hey I'll tell you what someone's had a go at this and look at this these are the clips this is how they're supposed to look like right these are the clips that compress the LCD on to the board so this is why I'm thinking that there's zebra strips under here but look you can see it looks like somebody has twisted these back and look all the ones along the side here are not ah they're not sort of you know um bent over to put force down there's only like one top and bottom what the help is what I'm going to do is apply power again and see if I can power this power this thing up and hopefully we can yep okay I haven't hooked up the backlight but we still got the still got the lines on that well you probably can't see it but we have got the lines on the screen there so now I can hopefully go around apply some pressure to that to see if it's a pressure problem oh and the metalwork our fill-out holding the membrane keypad in there there it is so I'll put that back yet by the way that was of course it was obviously the LCD cable here and the membrane a cable okay so let's see if we can get this puppy let's apply power hopefully it'll boot up there we go got our horizontal lines so haha look see that top it look there's some data missing and yes i'm careful not to touch the high-voltage backlight at all like isolated so uh this could be hard to get up i saw a line come and go there i saw a line come and go I swear I did there's got to be something in this yeah hmm I might just go in there and reseed all of those tabs just bend them all back and see if it works unfortunately not I've bent them or physically back in place you saw a couple of lines come and go there but still not sure yeah I saw just what yeah a line or two come and go there's something mechanical there but hmm might have to take the LCD apart and as it turns out fluke actually offer the complete service manual for this thing on their website fantastic why can all manufacturers do that it includes the full schematics as well for everything except the LCD module which they say during the troubleshooting in our procedure please connect a new LCD to see if the LCD is the problem the LCD is not repairable dull thanks for that but check it out I can make those lines come and go with pressure on this board I was doing it a second ago trust me ng huh yes yeah there we go there we go I can make them come and go you can see on the right hand side there I can make them come and go with pressure on that board there we go tada has got to be some sort of contact issue so we have some LCD voltage troubleshooting test points in the procedure here but it's not going to be that they're over here somewhere probably on those are test pads we saw before but it's not going to be that I reckon it's something down in here it's something in the drive I don't think it's any of the control signals because the as you saw like the text and everything the graticule everything getting over fire which means that the you know almost certainly this serial interface is just fine and dandy so Hitoshi chipset here here's the datasheet it's actually a 80 column driver so of course you can use these for both the horizontal and the vertical they're using here obviously these ones are the horizontal you can tell by their physical location going down here on the horizontal part of the screen to drive the lines like that and then we've got the three column drivers here so curiously we've only got unless there's another one on the bottom there we've only got three here you know three eights are 240 by 240 resolution screen that's what it must be so I'm just going to try and separate the LCD part from the main PCB here and I've bent all the clips back so we should be able to lift that out not sure if I have to take the backlight out I don't think so that could be separate so but I'm concerned because I think these weren't oh there was only like two or three of these that were clipped over it looks like somebody had pulled them back so somebody had a crack it fixing this thing and they couldn't you know have the same idea I do and they couldn't fix it hmm I don't know anyway it's worth a shot so let's see if we can lift this off shall we yes I've turned the power off Oh case you're wondering here we go come on you can do it pop out pop out there we go yep zebra strips hang on uh-huh as I suspected not only is their zebra strip for the horror for the vertical here vertical drivers they're not the problem but look what we've got on the horizontal tada hot bar there we go I reckon that's our problem now it goes under different names but hot berries one of them I call it hot bar because what they do is they like get literally a hot bar across here it's like a like a huge big wedge soldering iron tip and they apply pressure down in there and it's old as those in dat look at those pain-in-the-ass little individual contacts you should be able to see them in HD here but yeah I reckon we've got bad contacts in there almost guarantee it all right watch the magic if we put pressure on the vertical over here we can start see look da da da da da we can make the various parts of the vertical line up okay so if we put pressure on the whole thing there we go we can get most of it so that's the zebra strip zebra strips just fine but what we want to test is the horizontal in here so I'll try and put most pressure on here and get my poker aha look at that I'm applying pressure down in there to those hot bar attachments you can see them move look at that there you go what a bastard god yeah now as you can see there's actually two surfaces one is between the flat flex and the PCB down like this and the other is between the flat flex and the LCD glass itself and both of those have an adhesive conductive solder paste or whatever under them so when the hot bar actually goes across there at melts the adhesive and forms the solder connection as well so I don't like my chances of redoing something like this is very fine pitch but anyway we might have a shot of that but what I'm going to do is just apply pressure along here to like I did it before I was applying pressure on the PCB and we're getting some change so it's most likely to be along there if it's on the glass well that's a different thing again it I don't know that it's likely to be both so if I go across the top of the glass like that without trying to put pressure on the oh maybe but I I think I'm actually putting pressure on you saw it changes in different locations so I think I might be putting pressure on the board there so I don't think the connections are on the glass I think they're between the Flex and the PCB so that's the one I want to try and reheat and reflow and try and repair now I've never actually repaired one of these hot bar attachments and I've heard that they're real tricky and well it's better if you have the right gear I don't have the right gear but what I do happens my hot-air gun I'm gonna set it to maybe 240 or there abouts I'm all to do it and I found a pencil with I should actually get one with a new rubber tip but I'm going to actually use like a soft I don't want to go over there with my plastic pointer and use that I think that's going to be a bit hard I want something a little bit softer than that I've taped back the LCD to give me a bit of room so I'm going to have to get in there and heat it up and maybe just roll the eraser across actually what I can do is flip the end on that to get myself the good and why didn't I think of that before there we go so hopefully I can get in there with that and use that once it's heat up just roll it maybe a bit rub it across no pun intended and see if we can reflow this thing but I don't like our chances I you know so I'm going to have a go here we go we're going to heat it up and not all at once let's move it back and forth I have no once again I have no feel for this because I've never done that one before so I don't know I don't even know if this will work I have no idea but hey it's worth a shot it's a freebie and it's worth having to go there we go you mug come on and we don't want to try it try and avoid heating up the the top glass one up there so we don't want to do that we just want the lower PCB one down here and I have no idea no feel for how long to leave that because the board's got to heat up the board has thermal mass of course and of course there's no thermal mass in the flat flex so not worried about that but maybe put that worried there we go oh yeah I'm starting to up yep yep too much heat too much heat yep I'm starting to melt some of the flat flakes oops yeah I think I applied way too much heat there in the first go hope I haven't damaged the ribbon hmm let's put it back together yeah yeah I reckon 10% chance of fixing it okay here we go as I said don't like our chances but we'll give it a bill hello hello maybe I think I my out of alignment there but wow did that fix it completely Wow look at the top part it's just a matter of her Wow don't silly me still had the LCD taped back here and you're probably screaming at me um so the the vertical wasn't lined up so oops so I've put that back and let's pair it up again there we go oh I've got one little pesky lot and no no no yeah is that the trace I got some vertical happy in there but wow that's mostly fixed is that like a cursor line or is that a line on the LCD that's not fixed ah Wow but I got it I got it Wow I'd actually be happy like that even that that line was still through it awesome we don't winner chicken dinner so might just don't work that back in the frame for a bit of alignment just in case I get it don't forget to wipe all your grubby paw prints off the front of the glass because that would suck you put it back together you're all proud of the repair and there's your bloody big paw print right in the middle of it now I actually tried to reflow that connection again and I think that line is supposed to be there so it's probably a cursor but look we've got this pesky vertical line now so that's a real that's a real bummer I'm not sure what's going on there maybe there's some contamination under the zebra strip there perhaps so I just cleaned all the contacts along there and the zebra strip as well and hopefully I can get that puppy working again let's give it another try and just power this thing up and push it on no still there what's the deal a couple of minutes ago it was all um it was just one vertical line was it very thin one just like that horizontal one there now it seems to be wider so ah look looks like we've got another pesky vertical line that's come back right through there I've actually put I've bent a couple of the tabs back on the frame here so it's all putting the original pressure back on there and these are the cursors don't worry about those I just turned on cursor mode I can operate the keyboard now there we go I think I can turn cursor mode off there we go so we can see you see a line through there and we still got this line but as I said I reread it maybe it could be on the glass contact or something like that might require some or maybe I just didn't get it second on the second reflow maybe it's just not possible to get it but looks like maybe one that I missed originally is not showing up but I don't know about the black vertical stripe that's a real pain a damn bloody Murphy we almost had it we almost had it maybe with a bit more fiddly and I can do it I think it's essentially just a vertical alignment a position alignment in this direction so you've just got to get it right in the sweet spot and we should be able to get that vertical line to vanish but we've still got that one pesky horizontal line our people are going to hate me if I don't finish this and get a hundred percent perfect my apologies if I can't ahead of time wow I fixed the horizontal ones beautiful I just did some more reflow and some more our pressure on there and it looks like they're gone hopefully although maybe this one around here is still lurking along here perhaps I'm not sure but yeah anyway I got rid of the middle one and just can't quite get the vertical alignment here it's really pesky I got it you bloody beauty look at it it was incredibly touchy too it's a well horizontal position here which gives the vertical work columns here and I got to muck around with it ten times before I got that vertical strip to go away so it's really really touchy and then you have to hold it in place and then try and put the bezel on and while the alignment has to be bang on so but look I think it's fixed I think it's fixed let's go to the meter ah look at that but I don't like I don't like our chances of this thing that's staying like that I suspect it might still develop a problem but we're not winner chicken dinner Wow I didn't put my odds very high over fixing that but hey you know how'd it go got lucky oh here we go it's back together fingers crossed let's power it up and what helps if I turn the switch on here we go you hear a relay click there which is interesting um when you actually switch the thing off and on as a relay before you hit the soft power button so that's rather interesting ah yes yes I thought that was the line there I know is it yes ah there's a line shown up again damn it yep ah ah would you believe it Murphy get you every time dammit well I'm not too fussed about that I'm not going to take it back apart and enjoy that vertical alignment thing and no no I I'm gonna be happy with that and call it quits and wouldn't you believe it Murphy again the scope doesn't work after repairing the LCD I can't get anything on the bloody thing just flatline ah although to me seems to work just fine least on ohms anyway slow as a wet week on the auto-ranging there but yeah that's being on and the voltage is pretty bang on to check it out there's yeah that's I've checked it with another meter that's being on I can't get my calibrator over here easily cuz I'm tethered to this bloody power supply anyway yeah umm the multimeter seems to work the scope nope not a sausage on that scope and I've got no idea what the problem is are both channels just absolutely nothing so maybe it had a motor pool looks like an add multiple faults the LCD anyway we fixed the bloody LCD we know I'm going to call that repaired because well if this scope did work it would have been repaired umm yet Murphy will get you with that sort of thing but we did get a bit of bad luck in the end there with that lying coming back up as you saw it was a fine when I put a bit together and they want to screw the whole thing on there the line came back so you know yeah if you were keen enough you would dick around but I I wouldn't bother about that horizontal line it's off the you know the main way for window practically right at the bottom so I wouldn't worry about something like that but yet repairing these hotbar things can be really quite tricky so yeah just be careful with the amount of heat you put on there but you can't actually repair them hot air and the end of a rubber eraser on the end of a rubber pencil seems to work a treat just you know roll it across like that as you can see I didn't did a bit of wearing out there didn't like the heat but yeah just roll it across all and push it across like that and yeah you can fix these things so pretty happy with that but shame it didn't work maybe I can have another look at the scope meter but yeah I'm going to call it quits for this video and call that one I win awesome so if you want to discuss it jump on over to the EEV blog forum links down below and leave YouTube comments or blog comments and all that sort of jazz hope you enjoyed it catch you next time you

Channel: EEVblog

Views: 167,663

Rating: 4.9278097 out of 5

Keywords: fluke, scopemeter, lcd, screen repair, hot bar, reflow, how to, flat flex, cable, connection, solder, hot air, hair dryer, conductive adhesive, repair, tutorial, soldering, Fluke Corporation (Business Operation), handheld, oscilloscope

Id: Ujy-0gRspUM

Length: 31min 12sec (1872 seconds)

Published: Wed Oct 14 2015