Watch on YouTube: https://www.youtube.com/watch?v=x6bsf3BzDA0
eBay Bargain Or E-Waste? TFT LCD Monitor Job Lot Repair
Introduction
Late 90s / early 2000s TFT LCD monitors… They weren’t great, but hey, they set the scene for everything that was to come, including the monitors that we still use today. I bought a bargain eBay job lot of them - but do any of them actually work? Can I repair any that don’t?
Join me as I unbox them, test them, and attempt to fix some backlight and other faults!
Script
Hey everyone, Rees here, and welcome back to ctrl-alt-rees - and a very happy 2022 to you!
Now, you may recall me very recently saying that I wouldn’t be doing any more unboxing videos because I’d rather spend the time working on my bigger projects - so why am I sat here in front of a massive box holding a knife?
Well, as it happens new year’s resolutions were made to be broken and I promise this one is highly relevant - so let’s get on with the unboxing.
Now, the eagle-eyed among you may have spotted that there are actually multiple identical items in this box as well as a couple of bags of cables and power supplies. So what could it possibly be?
Well, let’s take a look at this…
…that’s right! A 12.1” LCD DigiPOS-branded screen - which of course goes with the Point Of Sale PC which I’ve been turning into a DOS gaming machine - and I’ve been on eBay looking for small CRT monitors specifically for that machine and the company that actually sold that to me initially - which was the clothing retailer in Coventry which are closing down - happened to have just listed a job lot of six of these matching monitors.
Now, as you can see this one does have a little bit of damage to the screen - I’m hoping there are at least some good ones in there, and even if there’s only one good one in there then that’s that’s fine, I still got a bargain just to get the matching screen for that machine.
I’m also hoping to find something else in this box but they may have shipped that separately - I’m not quite sure. So I’m going to go through all of these, I’m going to clean them up, and obviously I’m going to keep the best one for myself and any extras I’m hoping to pass on to other DigiPOS PC owners.
So let’s get the rest of these unboxed.
Now, this one looks pretty interesting actually because this one is a bit smaller - but it looks like there’s some kind of overlay on the screen. So whether this is some kind of privacy screen or something or whether it’s a touch screen overlay I’m not sure, but obviously that’s something that should hopefully become apparent with a bit more testing.
Also this one has the card logos on the back so, yeah, evidently used as part of a checkout system at some point.
Unfortunately it’s missing its sticker with the model details. So let’s continue…
…another one with one of these screen overlays, and as you can see this one’s quite yellowed as well so we’ll have to see how well this one cleans up.
So we have six DigiPOS branded 12.1” TFT LCD monitors, and of course these will be quite early TFTs so they’re probably not brilliant for gaming and stuff but they are LCDs so, you know, none of that dual scan rubbish as far as I can see.
These monitors cost me the grand total of £38 - so yeah, £30 for the six monitors and £8 for postage - and judging by the size and the weight of that box, I think the postage probably ended up costing them quite a lot more than that.
In fact they probably haven’t made any money on this - but that’s fine - their loss is my gain!
Apart from the very first one that came out of the box, the screens all seem to be in great condition - I think they should all clean up quite nicely. Obviously a couple that are a little bit yellowed, and they also came with a load of cables.
I can only see the one power supply so I’ll have to go through the box again - obviously I kind of went through very quickly so I’m hoping I may have missed a couple of those - but it seems perhaps we’ve just got the one.
But to be fair for the price I can’t really grumble and they will just be something fairly bog standard so I don’t think that’s a huge problem - and a big bag of VGA cables too! These just have a VGA on the back of course. A small, portable, VGA LCD monitor is always a handy thing to have around for testing and quickly getting stuff set up and whatever else.
So what I’m going to do now is get all of these tested, and then I’m going to get them cleaned up, and then we’ll decide what to do with them.
Oh, past Rees, so naive and full of hope. I’m so sorry I dragged us into this. Still, the people want their repair videos so I suppose we should carry on. [slow zoom on face]
We’re actually off to a good start with monitor number 1. The plastic is a little bit yellowed and the screen perhaps looks a bit dim, but that could just be dirt. Otherwise it seems to be working fine, so I’ll set this one aside.
Up next is monitor number 2, and this is one of those ones with the black frame around the screen, which I’ll take a closer look at later when I get it apart. I can see things happening on the screen so the LCD part seems to be working, but I think it’s safe to say that the backlight’s dead in this one.
On to number 3, and after some initial glitching, this monitor actually seems to work OK. Maybe just a loose connection and hopefully I can give the insides a poke and it’ll be as good as new. Maybe.
Number 4 now, and this is the first one I got out of the box with that big scratch on the front. That horizontal band across the screen looks terminal, but again this one has a working backlight which perhaps I can salvage, and maybe swap into that second monitor I tested.
Monitor number 5 - and another dead horizontal band. Perhaps I can look at reflowing the solder, or again, if I’m lucky it could just be a bad cable or loose connection internally.
Finally on to number 6 and despite some slight shallow scratches, this one again seems to work, just without a working backlight. So at least it seems we have some options.
“So, mixed results there - definitely a couple that look like they should be salvageable and they seem to be working OK.
A couple with some obvious screen damage where I think the actual panel itself is damaged beyond repair which is a shame - but only two of those I think from what I could see - and there are also a couple that were very very dark that looked like maybe the backlight had failed.
Perhaps I can salvage the backlights from the ones with the screen damage and transplant those into the ones with the failed backlights. But yeah, definitely at least one or two working perfectly fine which are usable as-is. Obviously I’m still going to clean them up.
I also worked out why they didn’t come with power supplies and it’s quite interesting. It seems the VGA cable has - and someone’s actually labeled this “AC out” - I don’t know if you can see that - the VGA cable also has the power cable built in, and of course these DigiPOS Point Of Sale PCs originally, with the original power supply, actually had an output on the back for powering the monitor.
Mine doesn’t have that anymore because I’ve obviously fitted an aftermarket power supply and I’ve lost that functionality - although it’s potentially something that I could reinstate because these seem to run quite happily on 12V DC, with a completely bog standard sized connector as well for the barrel jack, so not a lost cause at all - definitely still perfectly usable.
So yeah, let’s see where we go from here.” [maybe cut this line?]
So I decided to start at the beginning with.. er.. well. Monitor number 6. In addition to a broken backlight, this one has small surface scratches all over the screen itself so I wasn’t too bothered if I damaged it, meaning it would be excellent practice for tearing these things down.
It seems there’s a screw missing already, which isn’t a great sign.
The layout inside is really nice actually, these things were obviously designed to be easy to work on. I was particularly excited by these rather basic looking 12V backlight drivers - imagine if sorting out those backlight issues was just a case of swapping these around.
A man can but dream.
Alas, it was not to be, as further disassembly yielded lots of small bits of broken black plastic indicating that this screen has maybe been on the receiving end of some kind of major impact at some point and - as you can see - a snapped backlight tube with some obvious scorching.
As with many older LCDs, these screens are a somewhat loose sandwich of separate layers - with a white reflector at the back, a clear diffuser to spread the light of that tiny fluorescent tube at the top, and finally the actual LCD at the front.
I should take this opportunity to point out that fluorescent backlights have mercury in them, and swallowing or breathing this can lead to mercury poisoning which is pretty nasty, so be careful when tearing down your own ill-advised ebay purchases.
Setting this one aside for spares, I decided to see if I could transplant the backlight from monitor number 4 - the one with the big dent in it - into monitor number 2, which seemed to be in otherwise good condition.
So stripping down monitor number 4, I can see that the internals are in much better condition, with no broken plastic to be seen. In fact, if it weren’t for the big dent in the screen and resulting band of dead pixels, this one might actually be the nicest example here.
In addition to the insides being held together with little plastic tabs, they’re also taped, and I need to carefully cut through that to get to the backlight - and here it is, safely extracted and all in one piece. Success!
Well, actually, this is around the time my masterplan started to unravel.
You see, I popped open the intended recipient - screen number 2, and immediately I can see that something is amiss. The LCD controller board is completely different to the 2 I’ve already seen, and further disassembly reveals that the black surround around the screen - which I assumed was part of some kind of privacy filter or what have you, actually turns out to be a bezel designed to hide the fact that the panel itself is too small for the frame.
Seems we’re dealing with 2 distinct models of screen here - but there are 3 of each, so it’s not a lost cause. Or so I thought at the time, anyway.
Still filled with determination, I realised that the first screen I’d torn down - number 6 - was the only other non-bezel variant I had in need of a backlight, so - despite those light scratches on the front - that would be the recipient of the backlight I’d salvaged from monitor number 4.
The panel from monitor number 4 also has a nice solid black plastic internal frame, as opposed to the shattered one on panel number 6. But the ribbon cables look delicate and I don’t really want to risk damaging them, and the broken plastic is only in one corner anyway, so I stuck with the broken one for now.
So here we go, my first successfully repaired screen! I powered it up for its triumphant first test and…
This doesn’t seem right.
Oh! OK, looks like I left this small plug on the back unplugged - I must’ve unplugged it trying to get the screen dismantled.
So, back to that triumphant first test and…
Hmm, I’m pretty sure that dead horizontal band wasn’t there before. And it seems that no amount of poking, prodding and twisting will get it to go away.
Still, with 3 of those smaller screens still to investigate and my resolve to get at least some small victory out of this still unwavering, I put it to one side and soldiered on.
Going back to my notes, it seems like a backlight swap from monitor 5 into monitor 2 - which as you’ll remember, I stripped down earlier in the hope that the backlight from number 4 would fit - should yield results.
So I set about dismantling monitor number 5 to salvage its backlight and… ooh, it seems this is an IBM panel - very fancy indeed. Comparing the two side by side - the other one being made by Sharp - it seems the tubes might be the same size despite the panel being assembled slightly differently, but further teardown reveals that backlight number 5 is actually a completely different shape and wouldn’t fit into panel number 2.
Rapidly running out of options, I decided that monitor number 5 with its IBM panel might actually be repairable, so set about on a last ditch attempt to fix that dead horizontal band. Somehow this monitor now also had a broken power switch, which shouldn’t really be surprising after everything else that’s gone on, but at least poking around the screen actually yielded some promising results for a change. Perhaps my luck was finally turning.
So with soldering iron in hand and all other options seemingly exhausted, I thought I’d have a go at reflowing the connector. In hindsight, perhaps doing this with the monitor powered on wasn’t the best of plans, but it was a last ditch salvage attempt after all, and er… Yeah. Nevermind.
So I decided to cut my losses, throw these 4 broken monitors onto the ever growing repair pile, and fire up trusty old monitor number 3 aga- oh, great. Not only does it have these vertical lines, it’s also so dim that I wouldn’t be surprised if the backlight on this one failed as well, sooner rather than later.
I think it goes without saying that these monitors have evidently had a hard life - so for my £38 I’m left with one screen that works pretty well but is a bit on the dim side, one that works OKish with the occasional poke but in all honesty probably won’t work for long, and a big pile of e-waste that - to be honest - I doubt I can even take them to the dump as they’ll probably accuse me of trying to offload commercial waste.
In fact the easiest way to dispose of them would probably be to… Sell them to some idiot on ebay. Hmm.
Still, the other thing that I was expecting to find in the box did arrive and it was this rather cool Cherry keyboard with a built in card reader, and that all works great and is actually quite a nice keyboard, so it’s not all bad news.
So if you have any suggestions for projects that I could do with these dead monitors, do let me know in the comments - maybe fitting a modern IPS panel would be a fun experiment, or e-ink, or coming up with some kind of backlight solution for the original panels for the couple that need it.
Big thanks as always to my patrons and channel members who make these projects possible, thanks very much for watching, and I’ll hopefully see you again soon.
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DOS To POS Gaming Powerhouse Part 1: https://youtu.be/zdUwd69Mlj0
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