I'm fixing a peice of equipment and I suspect the lcd is the problem but i'm wondering if anyone has any other ideas. The LCD is made by Optrex, here is a link to the data sheet. Unfortunately this module has been discontinued and Optrex hasn't got back to me on a direct plug-in replacement. At any rate heres what I'm seeing. When I turn the instrument on the LCD screen is full black then starts flickering, going from what would apear to be off to having lots of vertical lines, at a rate of about a second or so. Over a few minutes this flickering speeds up a bit and you can start to see the title screen...still with random vertical lines over it. Most of the time, but not always, the screen will finally turn on and stay on, then the title screen is displayed for a few seconds like its supposed then go to the next screen and all is fine. It almost seems that the screen needs a warm-up period. Funny thing is I don't need this screen to work to use this instrument, it has an RS232 interface so I can control it with a laptop, but, it wont establish a connection until all is well with the LCD display. If there is a way to bypass the display entirely and have the instrument work that would be fine too, if indeed it is the diplay causing these problems. So my questions are: 1. Is there a simple way to test this LCD display on its own to see if it powers up fine? 2. Can anyone suggest a plug in replacement? 3. Am I looking at the wrong part all toghether? Oh and just incase you're gonna ask...the supply voltages to the display are fine.
Well, first off, you posed some questions regarding the instrument you are working on... and since you didn't provide any information on *that*, we can't tell you if there is a way to bypass the display. However, there are some methods you can use to troubleshoot. 1. Does it only deal with temperature? Can you use a can of 'cool-it' or some other freeze-spray and get the unit to fail back? If so, then it is possible you have a cold solder joint somewhere. 2. Does the display use a compression fitting of some sort to the electronics? The spec sheet doesn't go into detail about that. Some displays use a conductive rubber strip with micro-scopic lines of graphite embedded in it to conduct electricity from the board to the display glass. Sometimes, dirt, or a mis-aligned case, can cause the rubber to not fully contact the glass, and thus cause the display to foul up. You may want to look into that... 3. Is the display removable? If so, have you contacted Optrex? They should be able to supply you or steer you to a replacement LCD that either they or somebody they know of manufacturers. This is because mfgs of systems don't like to buy 10,000 displays, only to find out that on their next batch of 10,000 displays, their device needs to be re-engineered. So, most display mfgs work new models in by creating 'downward compatible' replacements for previous models. You can try taking that route with Optrex, and see where it gets you... Give us more information on the unit, and what you are doing and we might be able to assist you further.
The instument im working on is an Algodue UPM6000 Power Quality Analyser. By warm-up period I just meant that it took 5 to 10 minutes after being powered up before the everything works normaly...sorry if i was misleading. Unless LCD's do need a warm up period??? But sometimes it will go on for hours and the display still wont work normally. There is a thin flexible piece of plastic with traces on it as well as the rubber strip going to the glass of the LCD. But if there was a problem there it seems to me that there would only be a problem with what is being diplayed, like a few lines missing or something like that, rather than the whole unit constantly turning on and off until at some point it just decides to start working normally. That is just speculation but it makes sense to me. Yes the display unit is removeable and I have talked to Optrex about a compatible unit...I have yet to hear back from them. So is this sounding like a problem with the diplay module to you? or might it be something to do with the processor or other electronics?
It's impossible to tell from this side. The rubber strip could still be the problem, as there is generally only one common 'ground' on the strip, and if that is what is not connecting, then it is possible that the entire display will go funky. However, seeing as it is a standard Parallel based T6396 display, you might be able to create a parallel adaptor for your PC, run software like PowerLCD on your parallel port, and try running the display seperately to see if you get the same results. That is of course, if you can get at the display itself.
However, one thing that is striking me as 'funny' is that you said the unit won't continue to boot/power-up until the display stops acting funny... Do I have this correct? If so, it could be a problem with the controller chip, or the power going to the controller chip. More than likely, the main cpu of the analyser is trying to send commands to the display unit, and expecting some kind of response. Since the unit is acting funny, it's probably not giving that response, leading to the *possible* conclusion that the display controller (the T6396) is fubar. Again, you could verify this by pulling the LCD.
Yes you have that correct. And what you say might be wrong is exactly what i was thinking was going on but I wasnt sure about how these things work. I'm not well versed with this type of electronics...I'm an analog kinda guy....but I am trying to change that. But ya i was thinking that the CPU wont do anything until it get an "all's well" from the display board. Oh and yes I can get at the display itself, in fact its already out and sitting on the desk infront of me. I'll have to look further into the PowerLCD software you mentioned. Another question; does the display controller (its a T6963C - just incase your # is a typo) blindly send out data to the other electronics on the display unit in hopes that it will get displayed properly or does it also rely again on a return signal, common sense tells me it does have two-way communication with the other electronics but I thought I'd ask. If it is the last link in the feedback loop (I dont know the digital term for this) then i can rule out the other electronics on the display unit, and I could try just replacing the T6963C since I think I'm gonna be S.O.L. on getting a whole replacement unit. It seems 128x112 is an odd configuration, the closest thing Optrex makes now is a 160x128. Heck maybe i'll try changing that T6963C anyway - if I can find one.
Unfortunately, no, the controller sends data blindly to the 'line drivers'. If you want a full description on how LCD's work, look in the LCD faq as that goes a *long* way to explaining things. You can find it as a sticky at the top of this forum. No, but knowing that you have a T6936c (yeah, my previous post was a typo....) means you are NOT limited to OPTREX for a replacement LCD. The Toshiba chip is a common one, so you aren't limited to just Optrex displays. However, one thing that I *have* noted is that ApolloDisplays - www.apollodisplays.com still lists the Optrex 128*112 Graphic LCD with the T6936c controller in thier catalog. They may have a few left they might be willing to part with. Depending on how long ago Optrex stopped producing these, you might still be able to find some in the channel.
