Re: [M100] Dead lines in the LCD
I have fixed a couple of mine with the same symptoms. The issue with mine was corroded tracks under the LCD which detected by swelling of the solder mask where the tracks were damaged. I had to rerun some of the tracks to get them working again. From: M100 On Behalf Of Gregory McGill Sent: Wednesday, 19 September 2018 6:49 PM To: m...@bitchin100.com Subject: Re: [M100] Dead lines in the LCD This problem seems relatively common. I have two units one with partial and one with a couple full columns out.. It would be nice if we could locate a replacement display to resolve the issue with a modern solution. The game machines have them... Greg
Re: [M100] Dead lines in the LCD
This problem seems relatively common. I have two units one with partial and one with a couple full columns out.. It would be nice if we could locate a replacement display to resolve the issue with a modern solution. The game machines have them... Greg On Tue, Sep 18, 2018 at 4:57 PM Jim Anderson wrote: > > -Original Message- > > something > > making marginal contact on the LCD board. When it’s flexed > > slightly, > > the lines vanish, and the case presses on it just enough to make > > the > > problem crop up. > > [...] > > Is there a common failure mode for these panels or something else > > I > > should be looking at? > > See below for what I suspect is your actual problem, but I thought I'd > answer this first: there is a common failure mode which seems to affect > mostly M100 displays as far as I know, not the T102. It's pretty common > for vertical lines of pixels reaching halfway up from the bottom or halfway > down from the top to go blank, but they don't come back if you twist or > flex anything, and they don't seem to be related to bad contact but rather > to some bad component. I don't have more detail than that as I didn't get > into repair of my bad LCDs - I bought up a few trashy-looking M100s and > salvaged their display modules and a few other parts. > > > I don’t see how the panel itself is connected to the PCB. Perhaps > > there are pads on the top side and it’s simply the friction of the > > panel sitting on the board that does it? The more I poke around, > > the > > more I think it might be the PCB to panel connection. > > It certainly sounds like it, based on twisting causing the dead lines to > re-appear. The way that the panel connects to the PCB is through a pair of > what appear to be translucent rubber-like strips (IIRC - it has been a > while since I had an LCD apart so I might be wrong about them being > translucent). This is quite common with LCDs except the strips I am more > accustomed to seeing are made out of alternating black and white segments, > so it's easy to see that they have conductive and non-conductive sections > running through their thickness. The LCD is precisely aligned with the > PCB, which has conductive pads on it, and these strips conduct through to > the (nearly invisible) pads on the LCD panel glass. > > The LCD panel is clamped to the PCB by a metal frame which surrounds it > and which has small tabs which fit through notches in the PCB and are bent > over to secure it in place and apply continuous pressure. If you remove > the LCD assembly from the top case, you can put a little extra pressure on > different spots around the perimeter of the LCD by squeezing the top of the > metal frame down against the PCB with your thumb and forefinger. Firm > pressure, but not too much - remember it's glass. You should be able to > find the magic spot where the problem is happening. If you're lucky you > might be able to bend the tabs nearest to that spot to increase the > pressure and resolve the problem without taking it apart. > > If you're not lucky, there might be corrosion under the rubber-like strip, > and you'll need to disassemble it and clean it... it's possible, but > tedious and a bit risky. I'm not going into detail on that now because > this email is already getting a bit long. :) > > > > > > > > jim >
Re: [M100] Dead lines in the LCD
> -Original Message- > something > making marginal contact on the LCD board. When it’s flexed > slightly, > the lines vanish, and the case presses on it just enough to make > the > problem crop up. > [...] > Is there a common failure mode for these panels or something else > I > should be looking at? See below for what I suspect is your actual problem, but I thought I'd answer this first: there is a common failure mode which seems to affect mostly M100 displays as far as I know, not the T102. It's pretty common for vertical lines of pixels reaching halfway up from the bottom or halfway down from the top to go blank, but they don't come back if you twist or flex anything, and they don't seem to be related to bad contact but rather to some bad component. I don't have more detail than that as I didn't get into repair of my bad LCDs - I bought up a few trashy-looking M100s and salvaged their display modules and a few other parts. > I don’t see how the panel itself is connected to the PCB. Perhaps > there are pads on the top side and it’s simply the friction of the > panel sitting on the board that does it? The more I poke around, > the > more I think it might be the PCB to panel connection. It certainly sounds like it, based on twisting causing the dead lines to re-appear. The way that the panel connects to the PCB is through a pair of what appear to be translucent rubber-like strips (IIRC - it has been a while since I had an LCD apart so I might be wrong about them being translucent). This is quite common with LCDs except the strips I am more accustomed to seeing are made out of alternating black and white segments, so it's easy to see that they have conductive and non-conductive sections running through their thickness. The LCD is precisely aligned with the PCB, which has conductive pads on it, and these strips conduct through to the (nearly invisible) pads on the LCD panel glass. The LCD panel is clamped to the PCB by a metal frame which surrounds it and which has small tabs which fit through notches in the PCB and are bent over to secure it in place and apply continuous pressure. If you remove the LCD assembly from the top case, you can put a little extra pressure on different spots around the perimeter of the LCD by squeezing the top of the metal frame down against the PCB with your thumb and forefinger. Firm pressure, but not too much - remember it's glass. You should be able to find the magic spot where the problem is happening. If you're lucky you might be able to bend the tabs nearest to that spot to increase the pressure and resolve the problem without taking it apart. If you're not lucky, there might be corrosion under the rubber-like strip, and you'll need to disassemble it and clean it... it's possible, but tedious and a bit risky. I'm not going into detail on that now because this email is already getting a bit long. :) jim
Re: [M100] Dead lines in the LCD
Greg Swallow writes: Just to be sure. Is the black insulator in place between the keyboard/LCD and motherboard? Yes, the fishpaper is in place and intact. The fault is definitely on the LCD assembly. If I lift it out, so it’s vertical, but still connected while the machine is on, gentle flexing of the board causes the problem to appear and disappear.
Re: [M100] Dead lines in the LCD
Just to be sure. Is the black insulator in place between the keyboard/LCD and motherboard? God Bless, GregS <>< - Original Message - From: "Ian Eure" To: m...@bitchin100.com Sent: Monday, September 17, 2018 7:04:59 PM Subject: [M100] Dead lines in the LCD I just got a 102 off eBay today. It was sold as working, but arrived with four dead lines in the LCD. They’re horizontal, from the 2nd row, and repeat every 16 pixels. I opened it up and it worked fine. I figured it was the cable, so I sprayed some DeOxIt in there and put it back together, only to find the problem was back again. Taking a closer look, there’s something making marginal contact on the LCD board. When it’s flexed slightly, the lines vanish, and the case presses on it just enough to make the problem crop up. It felt like a bad solder joint to me, but after inspecting every connection with a 20x loupe, I didn’t see anything obviously wrong. I suppose that still might be the case, since it’s awful hard to see the tiny SMD joints, even at 20x. Is there a common failure mode for these panels or something else I should be looking at? Based on my reading of the schematic and tapping around, I suspected M11 might have a marginal connection, so I resoldered all its legs -- still nothing. I don’t see how the panel itself is connected to the PCB. Perhaps there are pads on the top side and it’s simply the friction of the panel sitting on the board that does it? The more I poke around, the more I think it might be the PCB to panel connection. Any suggestions on what to look at to get this machine 100%? -- Ian
[M100] Dead lines in the LCD
I just got a 102 off eBay today. It was sold as working, but arrived with four dead lines in the LCD. They’re horizontal, from the 2nd row, and repeat every 16 pixels. I opened it up and it worked fine. I figured it was the cable, so I sprayed some DeOxIt in there and put it back together, only to find the problem was back again. Taking a closer look, there’s something making marginal contact on the LCD board. When it’s flexed slightly, the lines vanish, and the case presses on it just enough to make the problem crop up. It felt like a bad solder joint to me, but after inspecting every connection with a 20x loupe, I didn’t see anything obviously wrong. I suppose that still might be the case, since it’s awful hard to see the tiny SMD joints, even at 20x. Is there a common failure mode for these panels or something else I should be looking at? Based on my reading of the schematic and tapping around, I suspected M11 might have a marginal connection, so I resoldered all its legs -- still nothing. I don’t see how the panel itself is connected to the PCB. Perhaps there are pads on the top side and it’s simply the friction of the panel sitting on the board that does it? The more I poke around, the more I think it might be the PCB to panel connection. Any suggestions on what to look at to get this machine 100%? -- Ian
