Nightmare!

[drama1]

UPDATE: Crap. Back to the bottom right corner of my touch screen not working again. I took the cover of a ball-point pen and stuck it in the bottom right-hand corner as far as i could stick it in and was able to get the box to turn to black allowing me to calibrate the screen.. Turned off the M3, turned it back on and the screen needed to be calibrated again using the top of the pen. Looks like I'm off to a service center.

[r12]

now, mine doesn't work at all
XY mode doesn't change any colour...
can't access both 2 corners to calibrate

M3 will go to service center during autumn (need it to finish season...)

[Faisal Umri]

Gravity is not the cause. It is the cable that doesn’t connect properly the LCD to the mainboard. You might have thought that it was the gravity because your unit was fine after putting it upside down. Putting the unit upside down might have made the cable (the striped metal) reconnect well the slot on the PCB. When so doing, it could be possible if you left the unit on for more than 6 hours, or I heard 24 hours. The increasing heat might have made the cable metal (at the end part) expand. This helps the metal reconnect the slot on the PCB, while being helped much also by the gravity. I think this will work temporarily because after you put the unit on flat position (or after leaving it off for a long time), the metal on the end part of the cable will contract and, gravity here helps much loosen the connection, instead. Rust, dirt or improper seating of the ribbon cable is actually the problem. Here is what happened to my PA500. My touchscreen went crazy and calibration didn’t help because it could not be executed completely. It functioned partially. I could only select the upper left part. The bottom right part was inaccessible. I solved the problem. I disassembled the unit, removed the ribbon cable (TP3567S1) and found out that there was rust/dirt at the end part of the cable. I tried to clean it by using pencil eraser (a tip in the internet about how to clean/fix ribbon cable) but the rust/dirt was still there. Then I cut /trimmed (1mm) the part where I found the dirt/rust. After reseating it securely in the slot, I found my unit worked fine. I can now calibrate the touchscreen. I have not had a problem since. It has been about six months ago.

[DAR_2002]

Gravity is not the cause. It is the cable that doesn’t connect properly the LCD to the mainboard. You might have thought that it was the gravity because your unit was fine after putting it upside down. Putting the unit upside down might have made the cable (the striped metal) reconnect well the slot on the PCB. When so doing, it could be possible if you left the unit on for more than 6 hours, or I heard 24 hours. The increasing heat might have made the cable metal (at the end part) expand. This helps the metal reconnect the slot on the PCB, while being helped much also by the gravity. I think this will work temporarily because after you put the unit on flat position (or after leaving it off for a long time), the metal on the end part of the cable will contract and, gravity here helps much loosen the connection, instead. Rust, dirt or improper seating of the ribbon cable is actually the problem. Here is what happened to my PA500. My touchscreen went crazy and calibration didn’t help because it could not be executed completely. It functioned partially. I could only select the upper left part. The bottom right part was inaccessible. I solved the problem. I disassembled the unit, removed the ribbon cable (TP3567S1) and found out that there was rust/dirt at the end part of the cable. I tried to clean it by using pencil eraser (a tip in the internet about how to clean/fix ribbon cable) but the rust/dirt was still there. Then I cut /trimmed (1mm) the part where I found the dirt/rust. After reseating it securely in the slot, I found my unit worked fine. I can now calibrate the touchscreen. I have not had a problem since. It has been about six months ago.

Thanks Mr. Faisal, That really was the problem of my M3 screen touch, it's the cable was lose. I just cleaned it with medical wipe, dry it with clean smooth cloth, and Walla... the screen touch back to response again up & down. I did calibration and everything is fine.
I was going to replace the screen touch for the second time, I have tried i every solution was suggested in forum, and yours is the only one solve my problem.

Thanks again. You save me money.

[sjmarano]

To DAR-2002 (or anyone knowledgeable about this) -
Could you kindly post a few instructions about how to open up the M3 to gain access to the touch screen cable, or point one to a URL with such instructions? I'm hesitant to do this without some foreknowledge.

[Bald Eagle]

Here's some pictures of an M3 being disassembled that may be of some help.

http://neo-genesis.net/korgm3m/2StickyPadsKorgM3M.pdf

[Synthoid]

Thanks for posting that!

[mikelees]

Thanks Mr Faisal - I think you might have discovered something...

I looked at the old touch screen I took out of my M3, and the contacts are gold plated...

I then looked at the connector type in the M3 service manual (FIC SLW4R-1C7), and found that the contacts are tin plated...

Making a connection between gold and tin contacts is never recommended in electronics design - the contact is often not reliable.

For those who want to get into the technical detail, a gold-tin contact is prone to fretting corrosion, which would cause the kind of gradual failure we see on M3 touch screens. Dissimilar metal corrosion is also possible in the presence of humidity or liquid. See the "tin commandments" here: http://www.te.com/documentation/whitepa ... comrep.pdf, or another good article here: http://www.connector.com/2011/12/gold-o ... d-and-tin/.

I looked at the flex from the old touch screen under a microscope and saw some "greying" of the contact points possibly indicating fretting corrosion (hard to tell for sure unless anyone has a scanning electron microscope handy!). I also noticed that the end of the flex is badly cut, with some flakes of copper that could drop off and cause a short...

Anyway, perhaps the M3 touch-screen problem that many users have reported is nothing to do with the touch screen itself, but is actually down to bad connector choice in the design.

Your method of cutting approx 1mm from the end of the flex to move the contact point looks like it should solve the problem. The flex needs to be cut carefully and square. It's certainly worth trying this before paying for a replacement touch panel.

The bad news is that if this is the cause, then if the flex is trimmed, or the touch panel is replaced, then the tin-gold contact still remains, so is likely to fail again after a similar length of time. A contact lubricant (e.g. Caig Pro-gold) may help, but only time would tell...

[sjmarano]

To MikeLees -

In one of your previous posts on a related thread ('M3 Screen Replacement Again'), you mentioned how you were going to post some simple instructions on how you changed out your touch screen. Any chance you could do that? I think it would benefit a lot of people here who are gun-shy about attempting this operation without some knowledge going in.

Steve in Jersey

[Dav1980]

Dear Mad Warrior

Thank you! I had the same horrid issue with my Korg M3 touchscreen. I flipped it upside down and used the hairdryer at hot setting for 30 seconds and thankfully everything appears to be working amazing again. I will test if over the following weeks. You are correct, the heat seems to do something to the gel membrane.

Kindest Regards

Dav
www.RadiAsian.London

[pax-eterna.1]

****ZOMBIE THREAD ALERT****

Sorry to resurrect this thread, however I have just acquired a used M3 with some touch screen issues and wanted to ask some advice from those who know..

At first I thought the screen just needed a re calibration, and that worked for a while...this morning I turned it on and could not access the top right hand drop down arrow. Rest of the touch screen was a little bit out, but still sorta worked ok.

So I managed to get to the calibration screen (by methods described elsewhere in this thread), and re-calibrated the screen....first time did not work, but the second time it did (as in the top right drop down arrow). Rest of the screen is fine.

My question is (as I have already purchased a replacement touch screen) would a new touchscreen help this, or, as the rest of the screen is fine, it is more a software issue and ergo can only be fixed by the above methods?

[yoshi88]

To the best of my knowledge, a new touchscreen with remedy the issue. THE color display had the touch screen placed on top. Get a tech to install for you if you have never done this before for peace of mind. If you are comfortable with the work, then you can do it yourself by carefully recording your disassembly through pictures and reassemble exactly the same. There may be UTUBES that illustrate this.

****ZOMBIE THREAD ALERT****

Sorry to resurrect this thread, however I have just acquired a used M3 with some touch screen issues and wanted to ask some advice from those who know..

At first I thought the screen just needed a re calibration, and that worked for a while...this morning I turned it on and could not access the top right hand drop down arrow. Rest of the touch screen was a little bit out, but still sorta worked ok.

So I managed to get to the calibration screen (by methods described elsewhere in this thread), and re-calibrated the screen....first time did not work, but the second time it did (as in the top right drop down arrow). Rest of the screen is fine.

My question is (as I have already purchased a replacement touch screen) would a new touchscreen help this, or, as the rest of the screen is fine, it is more a software issue and ergo can only be fixed by the above methods?