EEVblog #1202 - LCD Repair Redux

LCD Wars - Return of the TAB Connection
The previous LCD repair didn't last very long. Redux time.
Installing a new 240x64 LCD module in the PM300 Power Analyser wasn't exactly a walk in the park.

#Repair #LCD #Redux

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[chouseification]

Dave, as always - you rock! Your videos are great - I went the app developer route for the most part, and haven't tinkered as much in recent years, but I was the kid who would disassemble then reassemble all their toys. I have been adding components to PCs and then building from scratch for 30+ years; had to be "that guy" in college who fixed folks dead PCs and modded their Playstations for them. :P

You and the few of the other YouTube channels have inspired me to get back into it. My gear is now at a 2 channel scope, one variable power supply, rework station with air and solder heads, little 3D printer, and the start of a good selection of Arduino/Pi/TTL components. Got lots of old power supplies to salvage to make a few more power supplies; considering getting a nice IR toaster oven and making a reflow oven... I have all of the digital logic stuff down pat due to decades of coding in tons of languages, but reminding myself about power supplies, safety caps, etc.

Thanks again for all of the wonderful videos. I'm going to need to order some reels of components from DigiKey after doing some more practice in DipTrace/KiCad; shipping will be a lot cheaper for me though - MN here. :D

[randynovick]

You know, you followed a great, intuitive troubleshooting path. I'm not as good as you, but these little demonstrations you do give me confidence to try a little harder. Thanks for that, Dave. This was great fun to watch.

[eugeneskopal]

Dave, LCD screens have different viewable angles looking down from the top or up from the bottom. They probably found that in field use, the view from the bottom was better. So they turned the LCD over. I have encountered this in my projects.

[FranLab]

Classic EEVBlog - Make it better than before!

[garbleduser]

I always use naptha to reactivate the conductive glue. While it is still stuck down, I press down with a piece of warm flat metal. Then I apply swab of naphtha to the to the edge, allowing capillary action to carry it in. I then wait 7 seconds and hit it with the hot bar for 2 seconds, then apply a dragging force (not actual movement) in the direction of the conductors for 2 more seconds. And you're done.

What can I say? It works great on zoll defibrillators!

[listerdave]

I have successfully used Z-axis conductive tape to fix a similar display. First thoroughly clean off all the conductive glue from the PCB and the ribbon, then just stick a piece of the double sided tape over the contacts and then attach the ribbon onto it and hold it down for a minute or two.
It is scary expensive if you buy a whole reel from but there are many on eBay selling short strips of it, which is all you need really.
Look for "3M Z-Axis Conductive Tape 9703".
It can also be used to temporarily 'solder' SMD chips without actually soldering them. Doesn't work in all situations but if there isn't high current or very high frequencies involved it seems to work fine.

[martinkleine]

In the manual on Page 2:
„ADJUSTING THE LCD DISPLAY CONTRAST
Switch the analyzer ON. Before pressing any other keys, press and hold the [<] or [>] key to adjust the display contrast to suit your angle of view. The [<] key will darken the display, and the [>] will make it lighter“

[BerndFelsche]

"Two pins tied together is very common" 😎 it's always common.

[marcus_w]

You're the only engineer, making money with fixing his own stuff :)

[evilgremlin]

Actually, you can buy new anisotropic conductive tape on Ali, about 70$ for a reel. I know guys who fix LCD's with it, replacing/regluing decoders. They even do custom resistive touchscreens, cutting out of bigger ones and gluing new hand-made FLC in.
The thing is tape degrades from overheating and don't stick while underheated. Also, you need to apply decent amount of pressure. So, generally, it's even trickier than soldering sandwiched chips.

[swp]

Nothing was happening with the first trimmer because there's a 0 ohm resistor (R6) across it. If you remove R6, then the first trimmer should help.

[silverknight]

12:14 there is a VR1 timmer in the bottom left of the screen on the main board.

[chefarjunaidi]

Your electronic detective work is just brilliant! Good on ya, Dave.

[roberthorwat]

Thanks Dave, another great vid. Saved me a ton of time as I am now not even going to bother trying to re adhere the hot bar strip in the display of my multi function display in the dashboard of my 2003 vintage banger. Others on various car forums have tried and failed and now I know why. New OE replacements will almost certainly cost more than the value of the vehicle - if there are any left on the parts shelves lol.

[nnsda]

Nice one. Impressed you did some extra reshoot at the end

[MrEkg]

I think this is my favorite video dave. You show your troubleshooting. Love it.

[angelioto]

I don't wanna be that guy, but i think that the first pot you've soldered in is the contrast pot, there was just a 0ohm R6, that was bridging the gap so the contrast could be received remotely, and that R6 was just shorting out your pot.

[WobblycogsUk]

As someone who is just beginning to learn electronics what you just did looks close to someone performing a miracle!

[loydsa]

Nice job Dave, interesting to see your diagnostic process. Regards Sarah

[inigoselwood]

Loving the JLC PCB pen visible at 14:19, Dave