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- เผยแพร่เมื่อ 18 มี.ค. 2019
- Repairing the faulty LCD in the Voltech PM300 power meter.
Fluke Scopemeter LCD repair: • EEVblog #808 - Fluke 1...
Forum: www.eevblog.com/forum/blog/eev...
#Repair #LCD
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This is a MGLS-24064 from Varitronix. It will fail again. Better replace it with Winstar WG-24064. They don't use hot bar shit anymore and put the 64 lines on the edges of the zebra strips. 16 on each corner. Lasts forever.
Really nice, only $14 on ebay www.ebay.com/itm/WG24064A-TGH-LCD-display/283418735066?
Sorry I brought them all out now.
@@CrematorXXX Not if you life in the Europe... like 50€+ :(
Chip Guy Vids Except it can get dirt in a way to LCD that will require to clean the zebra strips.
@@Maul9999 In theory yes. But they are so tightly pressed between glass and PCB, that usually nothing gets into the contacts.I have never seen any issues with dirt, unless it was introduced during initial assembly.
That flex connector is most likely adhered with anisotropic conductive film (ACF) via a process known as tape automated bonding (TAB) . Same method is used in television manufacturing for attaching flex connectors to the LCD and driver boards. This type of issue, commonly referred to as tab bond failure, was very common in the early days of the LCD television. In my experience, trying to reheat them never works. Sometimes we were able to wedge something between the metal bezel and the connection at the LCD, which is usually where the failure occurred, and the pressure would help to maintain contact. One of those silicone heat transfer blocks or some folded up electrical tape were what I used. It was a temporary repair which could last anywhere from minutes to years, but could never be considered reliable. The alternative was scrapping the TV, so there was really nothing to lose. So my suggestion, if the problem comes back, would be to position something under that metal bezel to apply pressure to the offending area.
For these crappy carbon non-solderable strips I've repaired them by using the microscope and having a light behind the flex, and look for gaps where light comes through the traces indicating a crack in the conductor.
I'd then take a fresh Stanley blade and slice the top layer off and repair with silver conductive trace repair, then a bit of conformal coating for bonus points.
Wow, that's some determination!
#1630 this will be back for review. Good to see you number them beforehand now :D
I've previously repurposed the heating element from a domestic vacuum sealer - works reasonably well.
I remember soldering individual wires to a Ti-83 calculator to replace the LCD flex cable. Was such a messy fix, but it worked!
What kind of wire did you used?
Nasty! Well done DJ.
BMW instrument clusters have the same problem with the same kind of hot bar attachment flex ribbon. In the automotive industry we remove the ribbon and replace it with a new one. Fortunately it's such a common problem that the ribbons are readily available.
Use elastic bands to put pressure on the screen while testing.
Quite a common problem with the original Nintendo Gameboy systems. The 'fix' seems to be to to heat quickly and evenly across the entirety of the ribbon connector with a flat/ chisel tip soldering iron. Tried it myself before and it does work! :)
Did you use a basic soldering iron or the one which allows to change the temperature?
@@ytrew9717 I used a bargain-basement 30w jobby. Worked a treat!
I have so much to learn.. keep making great content.
I bought one of these LCD displays on Ebay back in 2017 for $9 brand new including shipping. Amazing how much price can vary.
I did wonder if it would end badly... but surprisingly.... it came good! Bonza.
Yeah, once cooled down it stuck.
“Bloody trying to bloody film things is just ridiculous”. Quote of the day and something I’ve probably said too. 😅
I fix LCDs on radios and pagers all the time, I use a Hot bar attachment on a pen soldering iron and a silicone pad between the iron and the flex to keep the flex connection from melting. I've found that depending on how cheap the LCD flex connection is you can normally get one or two reheats out of it before the glue gives up the ghost.
It seems that humidity is what causes the glue on the flex to give up most the time. Or being around industrial cleaning products. One of the hospitals I take care of use Motorola LS350 pagers and their cleaning staff will kill the LCDs all the time. I've taken to putting Clear nail polish over where the LCD flex bonds to the PCB to get some more life out it. I've been doing this for about a year now and I've seen a sharp drop off on them failing. From about once every other month too better than a year.(I still haven't seen the first one I did this on come back for a new LCD yet.)
On the flip side some of the Motorola Jedi series hand held radios used these type of LCD Bonding(Like on the MT2000 and JT1000). I have one of these radios that I use for our tower crew which has yet to have the LCD fail. The unit was built in 2003 and I picked it up used in 2010. I know we have put it through a lot of snow and rain while the tower crew is using it without the LCD flex bond giving out.
I'm not really sure what they use for the glue but it seems that there is a lot of variation in it in how well it stands up to the environment you put it in.
Also, most the time I only fix the bond to the PCB, I've only had a few fail on the bond to the glass of the LCD. When the bond to the glass fails I just order a new one, I've had very poor luck fixing that side of it, mostly I think it's because my hot bar is just the wrong shape and causes too much damage when I use it on the glass. But it's not been much of an issue because that side hardly ever fails.
The technique you used there will likely fix it for a long while. The same technique is used on the Nintendo Gameboy (although using an iron rather than hot air). You nearly always notice that the display gets much worse whilst doing the heating. Only when it cools down does it start to then behave normally and the lines pop back in one at a time. It's almost like the resistance of the connection increases with the temperature I think.
A quick fix hack you could try, would be to put some kind of metal rod as a temporary heatsink on the top of the flex cable there, add some thermal paste in between, apply some pressure to the rod towards the top of the contact points, glue it on both ends, and it might just provide the surface with enough cooling to be stable. Alternatively use a long screw, file down one of the screws side so it's flat with the surface, and you'll have a rod that acts as a small cooling fin, apply some thermal paste, pressure - and glue both ends to the pcb. Might work.
The screen of my laptop had a similar problem with a ribbon band connection into the board on the screen itself. In my case it was a physical problem, which I fixed by jamming paper rolls (one or two millimeters in diameter) behind it. That put the band under tension and solved the connection problem. Until the rolls shake loose, after which I have to do it again, glue never seemed to help :D
Most of these PCB to glass flex connectors use a thermal set conductive epoxy. In production the hot bar cures and sets the epoxy which is why the flex does not detach when the bar is removed. The bad news is that once cured, it cannot be softened or re-flowed by heating again. I have personally had to clean and solder the Capton type flex cables on many LCD displays but this can only be done on the PCB side connection. Note that you can get new epoxy but it is expensive and has a very short shelf life even if refrigerated. The flex in this video looks to be conductive paint so all bets are off.
So what do you recommend to fix it?
ACF (Anisotropic Conductive Film) Bonding process flow
I run into all sorts of LCD maddness working on 2-way radios. Motorola MTS2000 Flashport's are notorious for what we call "Pixel Failure" when a line of the dot matrix display goes dead.
I seen these flex strip's micro cracking inside and that's why may be situations when booth ends connected, but no connectivity between them.. Reheat doesn't give any result and sometimes gets worse.
In this situation, that strip is glitching, it will come back and it's not fixable if that flex strip will not be replaced (can be purchased from China by pitch, trace count and size).. or other thing that may be wrong - vertical driver chip from back side have bad solder joint connection.. Anyway, it's worth checking next time.. ;)
If it fails again try reflowing ic's, I often find bare minimum solder on SMD IC's causing bad joints.
Under microscope, gently poke each pin sideways with a tiny thin sewing needle soldered to some form of handle, preferably insulated. If any pins move I resolder the lot.
While you had the display apart it would have been an opportunity to replace the electroluminescent back light. You can buy the material and cut t to size.
Thanks for the video Dave 🙂. I guess I wasn't the only one to request it lol. Gotta hate intermittent faults like these! If it fails again I'd probably just go for a new LCD that doesn't use flat flex.
I actually thought it was a 40x4 or so character LCD. Probably because they use it in text-only mode.
Yes, if it fails again I'll just replace. There seem to be many replacement that don't have use this old flex technology.
Well it's much better than it was dave :-D
I had an old multimeter with the same horrible ribbon, i made a clamp, that stopped it's little game lol.
Dave i love this kind of display and if orange ohh
I dont know why but i like monocrome lcd displays
That's a weird "1" in the "CH1". Missing the right half serif at the bottom of the one. It looked like it was missing a vertical line but it goes through the zero bellow.
Nothing broken there, just a weird font.
So weird in fact, that I suggest aliens.
Thanks.
I knew this was coming.!
There is a soldering Iron T shape which has a silicon pad in the tip of it for LCD ribbon repair
Pretty specialised. You could just use a silpad maybe.
I prepared me with one of these, just in case this important device that i got (and is sold out) will loose that much lines that it's impossible to read the numbers. Than i'll go and try to repair. Same problems with my dect phone displays. Don't like this bloody kind of connection.
@@EEVblog That flex doesn't look too fine pitch. Maybe replace it with individual superfine wires (or ribbon cable, it one exists with matching pitch) solder one end to the PCB, and glue the individual conductors on the glass with conductive silver glue. After the conductive glue sets, apply a layer of two part resin to protect it. It would be a fun project.
mrnmrn1 - Your definition of fun is not the same as mine...
@@EEVblog I meant fun... to watch ;)
Used the same approach to fix my cheap old Casio fx-991WA: gently heat the flat flex and it's fine again
Yeah I did several radio repairs with problems like this.
Very good 👍
Somehow, that's the exact same cable that the LCD game used that I tried to repair in my latest video... So far, I haven't been lucky.
How about wedging in some non-conductive foam to keep pressure on the strips you were heating up?
When I repaired lcd screens on Motorola pages back in the 90's, I simply laid a piece of wax paper across the hot bar and then ran the soldering iron, on a low setting, across the wax paper. This method worked great because you could apply pressure and controlled heat at the same time.
Appreciate
Finaly Dave rep. something...:-)
I've heard of this happening on the TI-83 series graphing calculators. That method works ofc, but the proper fix would be solder 100 or so bodge wires to replace the heat bar connector
@@johnrickard8512 And how would you make those bogde wires to stick to the LCD glass?
The proper solution is to replace the LCD with a new one, everything else is waste of time..
@@mikaelkarlsson9945 The TI-83's screen module isn't set up the way you think it is. See the following video: th-cam.com/video/-XgR5QrGHB4/w-d-xo.html
These carbon ribbons are common on automotive instrument clusters / heat-AC controls. The problem is the carbon stripes fracture. China makes repair parts for automotive use that are a few $. For examples, look up Mercedes Pixel Repair.
What's your method for cleaning the zebra strips and its physical connection to the LCD? Like, what chemical would be safe to use on the LCD side of the connection?
how about some clips to hold the display down while u work on it, bulldog clips perhaps? also what about some tinfoil to protect the screen from the heat whilst using hot air?
Try mounting a ribbon bracket on the PCB. Might get rid of one headache.
You can use a fiberglass mesh between the flat cable and the soldering iron at the temperature of 150 degrees Celsius. So the fiber will prevent the flat cable from melting.
Sorry for my english.
...... Don't apologize, your multilingual that's impressive.
you're
I know the original Game Boy has a similar issue with it's screen the only way to fix it is to apply some heat to the ribbon and use a spudger to apply pressure.
Man that was a huge problem with a lot of Yamaha, Casio and other keyboards with lcd displays. Man i fixed a metric crap load of them. Mostly by doing what you did, if not by replacing the lcd module.
Yep, if it fails again I'll just replace it.
Dave, you already know the only 100% fix
Do you have any material to connect it with an avr microcontroller?
I have to take my Fluke 87 True RMS meter apart every few months because the numbers start fading. I called Fluke about 25 years ago (it started happening about 18 months after buying it), and they said they could fix it...for $225! I told them to go screw off as that was more than I paid for the meter. Now I just un-clip the bezel, re-clip the bezel and off I go for another few months.
@Dave Micolichek I do not know, but Fluke wanted more to "reapair" the problem than to buy a new meter. That really irritated me with them. I buy their meter, but when something went wrong they wanted more to repair it than to buy a new one? Yea...that wasn't cool...
I wonder if Sangean ( PRD -3L , CC Radio Plus ) have ever heard of a similar problem?
That reminds me of original GameBoy screen repair. I did that once on an original GameBoy using a soldering iron, and I got the screen fully working again. That was until I tried to put a backlight mod in it. I ripped the screen ribbon. It sucked ass. If anything, I should have kept it. I kept hearing and reading that once your ripped the screen ribbon that it was only good for the trash, but then I found out that you could get replacement screens. DOH!!!
Yeah, once you ripped the screen thingy, and maybe cleaned it up with alcohol or something it won't gonna work the same way again, just throw it away. Back in the day it was possible with things like calculator or some toy, when the resolution of display was quite small.
Hello, maybe you can help me, I replaced the damaged lcd display of my Boafeng UV-6R.
When I install a new lcd, it has a high contrast, only when the battery is low does it allow reading.
Thanks
What are the pliers t 2:40 that look a bit like snips called?
I think you have to heat all up and then right away press all down with some silicone pad until it cools down.
Think about it as a wire you trying to solder to a SMD pad - it may spring up/out if you don't hold it during cooling down.
PS I'm not a pro just logical thinking.
You are 100% right and anisotropic conductive film.
Dave are old LCD's that start to fadeout fixable, "not enoughcontrast/black"? What is it actually that is weared out?
Older Lcds use an electroluminescent backlight instead of Led. These start to fade rather quickly. They are usually rated to have 50% brightness left after 3k hours of use.
Good thing tho is you can buy strips of it and cut it to size yourself. Its actually really easy replacing them, you only have to open the lcd assembly, replace the strip and wire it up (you can ofter wire it up exactly the same way the old strip was wired up).
do you know where I can find a display for Chauvin F203 Clamp Meter?
I really enjoy your videos, my dad was an electronic engineer in the early days of transistors replacing tubes, never taught me shit. Yeah that makes me a good bit older than you. I went on to work with wood, but find myself intrigued by the nuts and bolts of electronics. Doesn't hurt that I'm a natural born cynic and hold debunkers in high regard. Never too old to learn.
Thanks
I've broken that kind of flex on old calculators, they're veeeery touchy. Don't think I'll be trying to fix these in the future, its very hit and miss
Did you try heating/freezing the driver chips to see if THAT reproduced/eliminated the problem? It was very odd that pressure did not change anything, just heat on the board, kind of like it might be a bad chip(s) or solder connection on those SMDs...
Nothing wrong with the chips or soldering.
No need, these thing s are notorious for this. And yes, pressure did work somewhat, I found that off-camera.
I noticed comparison pics on WooWoo video, in pictures characters were fine and was like "wtf, nice photoshop skills on angled pic " I though you added segments manually :D
MY photoshop skills suck!
This was my first electronics repair nightmare when I was nine years old, the bloody flex cable broke on my Donkey Kong game and watch. I had begged my mum to buy me one for months till she finally relented for christmas. The more I tried to fix it, the worse it became but I finally got there, only to have the flex crack a few months later and that was the end of my game.
What's the name of that other platform mentioned at the end of the video? I Couldn't quite make it out.
www.bitchute.com/ I tried to access the EEVblog channel there but it doesn't seem to load.
@@kevincozens6837 Thanks, Kevin. Will give it a go too.
@@kevincozens6837
Hmmm.
Worked here.
www.bitchute.com/channel/eevblog/
Yes yes dave
(0:20) - There's still two lines out. There's a line missing right at the top there.
.
Fixed ;) pay the man..
We have one of these stuck in voltage overload
so is the lcd fixed? or just changed a new 1? the video shows lcd suddenly becomees good again...
how about heating it up and than clamping soft rubber like those white pencil erasers to it wile it cools down
Can't hurt.
This materials and chemicals they expire in short time ,not for stock at long time.
Yeah percussive maintenance still works eh?
I'd only touch around the failing contacts if you drag along the good ones you may break them. Don't fix what ain't broken they say 😀
Game boys are notorous for this.
It could be one of the driver chips starting to fail
These connections are really bad. Have tried to fix them using a soldering iron at very low temperature but also that didn't work to well.
Yep, very dodgy, and probably pot luck if you can fix it.
mod wires for each trace would be the correct way..
It is very difficult to connect mod wires to the traces on the glass except with conductive glue - and very easy to damage the traces in the process.
There's plenty of room left on the zebra strips to connect the lines, and yet they had to use this shitty hot bar flat flex. Unbelievable.
Btw many devices have an option to display a black display so you can easily test/diagnose it. If there's a pot for setting contrast then you can try setting it to the maximum, it will have the same effect.
Need a Rossmann Flux amount here
I'm sure there's someone in a small booth in Shenzhen who could replace that cable in 5 minutes.
maybe the excessive humidity when things flooded caused this.
The Signal Path just repaired an EG&G Instruments 7265 with same display issue..
I watched that video. He just replaced the CCFL backlight with an LED strip then explained the block diagram if i remember correctly.
The issue was the backlight there. But he mentioned that those flexible strips will cause problems at some time.
Please add backlight led next time .. if happens again
It already has a backlight
@@EEVblog doh! ... ok ... please put blue leds if possible :)
07:45 Peltier element with heatsink, coolsink and temperature control? 😂
I hate working on things with a janky hinge that won't fully open.
Zebra strip "repair" never worked for me... you fiddle around with it in hopes that afterwards, there will be less missing lines / segments than before. Ugh, annoying things.
WOOO HOOO
The lab all ok now Dave can't believe you might have to move again after seeing all your previous moving videos. Do you know any more on it or you have to wait to see what happens I suppose?
They got in a carpet quote guy on Monday, haven't heard back.
@@EEVblog Oh cool so you won't have to move all that kit again?
Well, yes, the carpet has to come up, that means everything has to move and be thrown into chaos. Carpet tiles would mean it can be done in stages, but still, the whole lab has to come apart again.
@@EEVblog Ouch that sucks if I wasn't half way around the world I would give you a hand. Must have been quite a rare event though. Keep the updates coming anyway great content as always I learned lots from you Dave :)
And top of lcd
#fixed
Call an engineer!!!
Hi
What about graphene woo woo paste?
Could the recent flood have caused this?
He'll probably gonna get for free a $10.000 brand new rohde and schwarz meter, courtesy of the fine people of R&S.
Yeah, design a replacement OLED display =D
@Ken Mason I like the LED style displays too. But something you have to remember is power consumption too. a lot of 7 segment displays can eat up a power budget quickly, and require a beefier PSU. They probably used LCD to keep the power consumption low.
You sound like a mr. Meeseeks
aren't these sorts of displays like 20 bucks on ebay? Just replace it if it goes bad, intermittent connector problems can keep you busy for nothing
I call that a design fault.
run on it a piece of aluminum foil & soldering iron at 150 degrees
Is it just me, or is one pixel missing off the bottom right of the "1" for CH 1?
stazeII Nope, not just you.
@@stuartmcconnachie weird. yeah, it's missing in the start too. it's like Voltech forgot that one pixel.
Nothing broken there, just a weird font.
Having lost few hours trying to fix that kind of crappy glued flex ribbon (on a couple of old cordless phones) for science, trying to find a good technique, I gave up and now consider any issue of that kind a direct to trash diagnostic...
"forgivable" issue for cheaply made consumers, programmed obsolescence plagued, devices, but not fair for hundreds of bucks professional test equipment!
I miss vfds and plasma displays so much... I manage to fix vintage glass displays of that kind, even with pins broken straight at the tube, by carefully grinding the glass and soldering thin wires on the then exposed pin. That kind of repairs are notoriously satisfying, but having to trow perfectly working products to the scrap box because of hot glue flat flex display failure is deceiving and infuriating....
They are very crappy. I suspect the fix won't last long...