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Author Topic: LCD on top of Wacom = no pen detection  (Read 6030 times)
boomandvibe
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« on: January 13, 2012, 09:10:58 PM »

I'm having a problem with tablet pen detection. The tablet won't detect the pen when LCD is on top of it. My LCD is Dell 1503fp, the original build.

The LCD is just too thick. The pen's range dies at about 2/3 of the LCD's thickness.

I tried tweaking the potentiometers on the pen but there's not much improvement except the pen is acting worse without LCD. (Random clicks)

There are 3 screws of potentiometers. Do you know which one does what?
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bernard
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« Reply #1 on: January 14, 2012, 03:41:05 AM »

you still have the metal back plate, right?  Have you removed the ultrapad case?
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boomandvibe
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« Reply #2 on: January 14, 2012, 04:45:45 AM »

Which metal back plate are you talking about?

I finally managed to get some pictures.

This is as far as I could go without breaking anything.


It looks really thick.... Pen dies at about 2/3 of the thickness of the LCD.


And what are these black things around the cords?
« Last Edit: January 14, 2012, 04:47:44 AM by boomandvibe » Logged
bernard
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« Reply #3 on: January 14, 2012, 05:15:40 AM »

Behind the Wacom tablet circuit board, there is always a sheet of metal (and a foam spacer) -- you need to keep all that (sometimes it is glued but other times it can be removed).  This is important for the reading height.

The black things are for EMI control. They are ferrite cores. I would keep them there. It is supposed to reduce the interferences caused by the signals going in these wires. In theory it is good. I say theory because in the EMI/RF world, everything is theory. You can only know it works after you tried it.

Your LCD appears to have metal behind some plastic frame. Metal == big interference.

How do you know the pen dies at 2/3 the thickness of the LCD?  How did you test that?
« Last Edit: January 14, 2012, 05:25:56 AM by bernard » Logged
boomandvibe
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« Reply #4 on: January 14, 2012, 06:05:30 AM »

Yea there's metal backing. It's glued there.

So is my monitor no good? I've seen other people use the same monitor.... I spent so much effort to get it working T.T

Anyways, about the pen range, I just lifted my pen from the tablet and the tablet stops recognizing the pen at the distance that is about 2/3 of the LCD thickness.

What should I do with the monitor? get a laptop LCD or something?
« Last Edit: January 14, 2012, 06:10:50 AM by boomandvibe » Logged
bernard
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« Reply #5 on: January 14, 2012, 06:50:57 AM »

Carefully dismantle the LCD Panel to remove the metal backing.

I have never done that myself and I am not saying it is easy either.  Quite a few people have done this in this forum. Dismantling an LCD Panel also means exposing the inner "sheets" to dust.  Some panels have quite a few sheets -- but those are not glued -- they are just stacked, so you have to be careful to remember the stacking order. Also because of the dust, try to minimize the sheet manipulation and keeping it "opened/exposed" too long for nothing. Dust will not break anything, just the LCD might be less "clean", that's all.

You said you saw other people use this monitor. Do they talk about opening the LCD Panel? 
« Last Edit: January 14, 2012, 06:53:32 AM by bernard » Logged
boomandvibe
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« Reply #6 on: January 14, 2012, 07:39:56 AM »

I have accidentally removed LCD from the backing before. So yea the stackings are there. wouldn't it ruin the backlighting? Isn't the whole point of having the back panel to trap light inside?

And no, people haven't talked about opening the LCD panel. The guy who built Synthetiq essentially has the same monitor as me. So does Lintiq. They were fine with their monitors.
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bernard
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« Reply #7 on: January 14, 2012, 08:00:36 AM »

I do not know the reason for this metal, lots of panel do not have metal at all. So yeah, maybe for light blockage, but it could also be to reduce EMI emissions too. If you use Drew's trick to measure the size (a stack of paper)-- you put more and more paper until you start having problems (check different areas of the tablet).  Then you measure the thickness of the paper stack.

How far is it? And how thick is your LCD panel again?  Is there even a remote chance for this to work? Some people had to tweak their pen that they bought separately. (You tried that already, maybe you could try again?)

Maybe if the metal has a use, you could replaced it by a sheet of something else?

Make sure everything is probably grounded.  For example, the metal backplate needs to be grounded. (Sometimes it is a metallic "tape" or some other means to "connect it to ground". When opening devices, we often do not realize how much stuff was connected to ground just through the case and the screws.
« Last Edit: January 14, 2012, 08:05:51 AM by bernard » Logged
boomandvibe
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« Reply #8 on: January 14, 2012, 08:14:03 AM »

There are some copper strips around the corners of the LCD, which I thought may serve some purpose so I didn't cut them out. They were bolted down to outer metal cover. They might be the ones for 'grounding' I guess?

The backlight casing itself is also metal, and it 'fits' with the metal casing. It is taped there and if I remove the tape, it falls off.

I'll try to disaseemble the LCD and see what happens. I'll post pics.

Here's removed back metal panel from LCD.


The backlight is encased in metal. Biggest problem.

« Last Edit: January 14, 2012, 08:42:38 AM by boomandvibe » Logged
boomandvibe
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« Reply #9 on: January 14, 2012, 09:02:13 AM »

I touched LCD inverter with bare hands when it was turned on... nothing good came out of that lol. Burnt finger... great....

I put the LCD back together without the metal backing and tested it.

It works except the part where the backlight casing is, which is also metal.

Also, the monitor has alot of noise(?). seems like some interference from nearby circuit boards? I can't move them around yet. I need to get some extension cables.

The monitor has some issue. I don't know what's causing it. FFC not fitting properly? interference?

I tested without Wacom under the LCD, the white strip is still there. When I lift the board attached to the top of the LCD, the noise goes away but the white strip is there.

« Last Edit: January 14, 2012, 09:28:26 AM by boomandvibe » Logged
boomandvibe
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« Reply #10 on: January 14, 2012, 11:11:03 AM »

I think I will purchase 15" S-IPS 1400x1050 LP150E05-A2K1 panel for display. This dell monitor has given me too much problems. The FFC connector is partially broken and it becomes lose whenever I move something.

Where can I get and display controller to go with the display?

Which model is this?
« Last Edit: January 14, 2012, 11:23:53 AM by boomandvibe » Logged
bernard
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« Reply #11 on: January 14, 2012, 04:35:52 PM »

These boards are not touching to each other right?  In one of the photo, I think I see the wacom board under the lcd board and I do not see anything in between. I hope you knew this was of high importance. Make sure the circuits are not touching to each other or to metal (while powered) or this might be fatal.

The white strip is not a good sign.  This is most likely the band connection right above -- the one aligned with the strip.  "jiggle" this connection and/or look very carefully at the edges.  Any movement can break these connections.  Minimize the movements as much as possible.

Got burned with the inverter.  Darn, you are accumulating the bad news. Hope something good comes out of all this!
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bernard
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« Reply #12 on: January 14, 2012, 04:38:28 PM »

Quote
Which model is this?

A typical LVDS board. Problably a RM***** something (there are many models out there) -- in other words, we do not see any numbers on this photo, not much chance to tell which one it is. why do you need to know?
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boomandvibe
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« Reply #13 on: January 14, 2012, 06:38:07 PM »

Yea the boards are separated by a big piece of cardboard.

Id like to purchase a new lcd that doesnt require extending FFC. I have no choice but to give up on the current one bc the FFC and extender i bought has different thickness from monitor's ffc. I had to sand one down and add some foil on the other to make them fit. The ffc connector on the monitor board is semi broken.

Seems like the LP150 lcd doesnt need an extension, right?

Ive been going through other people's posts and they got their controller from njsomething but they kept making a mistake of sending a controller programmed for different resolution. Where's another good place to get the controller and the lcd?
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bernard
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« Reply #14 on: January 15, 2012, 04:50:20 AM »

The only spots we know are the ones listed in the wiki.  The only way to be safe is to buy a programmer as well. Quite annoying. I wish these boards could be reprogrammed without the need of that programmer (which is a *pain* to use because of the OS constraints).
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