FAQ

General Failure Analysis Guide

Any General Touch touch product can be divided into two function systems. One is the touch system, the other is the display system. This guide describes the common technical failures found with the touch and display systems, which you may encounter when using our products, and provides the corresponding solutions. If the failure has not been fixed after adopting the solutions contained in this guide, please kindly contact our technical support.

Failure Description: Touch Function Problem(Fail Touch Screen/Fail Touch Controller)

1. No Touch Function On the Whole TouchScreen

Excluding the possibilities of incorrectconnections of cables or either a defective RS232 port or USB port of the PC,we need to get the status of the controller LED. You can see the controller LEDvia the holes on the back cover or the shielding cover. The normal statusshould be:

1) When powering on the controller, the LED will increase in brightness for5~10 seconds and then the LED will go into the standby status, and will twinkleevery 2 seconds;

2) When you touch the screen, the LED will brighten;

3) If you are not touching the screen, the LED will be dim;

4) After a significant period of time without touch, The LED will go back tothe standby status and will twinkle every 2 seconds.

If the LED stays dim, the reason may be failures from the controller, from thecommunication cables, or from the wire board. To perform a swapping test isvery helpful in confirming the failure. The possibility of defectivecommunication cables or a defective wire board is relatively unlikely.

If the LED keeps twinkling every 2 seconds no matter whether a touch has beenplaced on the screen or not, the cause may be failures from the touch screen,from the communication cables, or from the wire board.

If the LED twinkles very fast, it indicates either that there may be adefective touch screen or controller, or that there may be a synchronisationproblem between the touch screen and the controller.

For the “No Touch Function On the Whole Touch Screen” problem, performing aswapping test is very helpful. For example, you can use an alternate controllerto test the original touch screen. If it’s OK, the problem most likely lieswith the original controller. If it’s still NG, you can use an alternate touchscreen to test. If the new touch screen resolves the problem, you candisassemble the original one and assemble the new touch screen onto the touchmonitor. If changing both the touch screen and controller does not help tosolve the problem, you can check the cables and wire board although the chanceof these being the root of the problem is relatively minor.

2.Dead Zone In Partial Area of The TouchScreen

If the dead zone is in the middle of the touch screen, the problem is alwayscaused by dust or stains accumulating on the edges of the touch screen or onthe reflection stripes of the touch screen. For this kind of dead zone, thecontroller LED will not brighten when you touch the screen in the dead zone.The solution is to remove the front bezel and clean the touch screen and insidesurface of the front bezel with alcohol and soft cloth. In the meantime, pleasepay attention to the dust-proof strips stuck onto the inside surface of thefront bezel. Where there is a defective dust-proof strip, there would also besome gummy depositing onto the touch screen, which is the root cause of thedead zone. For such situations, the defective dust-proof strips must bereplaced.

If the dead zone is on the edges and the controller LED does not brighten whenyou touch the screen in the dead zone, the solution is the same as above.

If the dead zone is on the edges but the controller LED brightens when youtouch the screen in the dead zone, the problem most likely lies with thecalibration. If this is the case, please kindly go into the touch drivercontrol panel and re-calibrate the touch screen carefully.

3.  Low Sensitivity

Youcan adjust the sensitivity level in the touch driver control panel. Level 4is the recommended level.

4.  Drifting

If the cursor always goes to the positions which are different from the pointstouched, it is known as a drifting problem. There are two kinds of driftingphenomena, as stated below:

1If the drifting of the cursor isregular, this kind of problem can be solved by calibration.

2If the drifting of the cursor isirregular, it seems that there is some interference around the touch system.Please try to adjust the sensitivity level to a lower one to solve such aproblem.

5.  Touch Screen Care and Cleaning

The touch screen requires very little maintenance. General Touch recommendsthat you periodically clean the touch screen surface. Typically, an isopropylalcohol and water solution ratio of 50:50 is the best cleaning agent for thetouch screen. You can also use straight isopropyl alcohol or any other neutralproprietary glass cleaner. Using a non-neutral cleaner may corrode the surfacelayer with special treatment and consequently cause it to lose the ability toperform its function. If the cleaner enters into the area containing thereflection stripes, they may be corroded and ultimately the touch function willbe affected.

Please apply the cleaner with a soft, lint free cloth. Always dampen the clothand then clean the screen. Be sure to spray the cleaner onto the cloth, not thescreen. This method is helpful in controlling the cleaner consumption. If thecleaner is sprayed onto the touch screen directly, it is easy to spray too muchcleaner, and then the cleaner, combined with dust and dirt, will seep into thearea containing the reflection stripes through the gap between the front bezeland the touch screen, and therefore will affect the touch function.

 

 

 


Failure Description:

1.Color Distortion

Step 1: To judge whether the color distortion ispartial to certain areas or the whole display area. If the color distortionhappens in the whole display area, please go into the OSD menu and “Auto Color”the touch monitor, and then the problem may be solved. If the color distortionremains, either affecting the whole screen or only certain areas, please go toStep-2;

Step 2: please Use another VGA cable and see whetherthe problem still persists. If it does, please go to Step-3;

Step 3: please change the A/D Board of the touch monitorand see whether the problem still persists. If it does, please go toStep-4;

Step 4: please change the LVDS cable of the touchmonitor and see whether the problem still persists. If it does, the problemmost likely stems from a fault in the LCD Panel.

Step 5: Change the LCD Panel.

2.Black lines

Step-1: Determine the root cause of the black lines.There are two kinds of black lines, as stated below:

1) The black line is akin to a dark lane. In the dark lane, the color of thepicture is normal but only the brightness is much lower. For this kind of blacklines, the problem could stem from the failed CCFL. please go to Step-3;

2) The black line is akin to a really black lane, it cannot show pixels ofother colors, so the line is always black. This kind of problem may stem fromthe A/D Board, the LVDS cable or the LCD Panel. If this is the case, please goto Step-2;

Step-2: please change the A/D Board and the LVDS cableof the touch monitor to see whether the problem still persists. If it does, theproblem most likely stems from a fault in the LCD Panel.

Step-3: Change the LCD Panel

3.LCD with color spots

Step-1: Determine the root cause of the color spots.There are several kinds of color spots, as shown below:

1) The color spots are flickering as if affected by a degree of interference.For this kind of color spots, the problem may lie with the A/D Board, the LVDScable or the video card of the PC. For this problem, please go to Step-2;

2) The quantity of light dots/ dark dots/the sum total of light dots and darkdots should be within the bounds of the General Touch outgoing specification.If the quantity of light dots/ dark dots/ dead dots//the sum total of lightdots and dark dots is more than that specified by the General Touch outgoingspecification, you can apply to change LCD Panel within the warranty period. Ifthe color spots don’t affect normal usage, we suggest that it is not necessaryto change the LCD Panel.

(Explanation: The definition of a light dot: In ablack picture, a white dot is a light dot. The definitionof a dark dot: In awhite picture, a black dot is a dark dot.)

Step-2:please change the A/D Board and the LVDS cableto see whether the problem still persists. If it does, the problem probablystems from the video card.

Step-3: Use a different video card to test the problem

4.Fail Lamps

please change the A/D Board and the LVDS cable of the touch monitor to seewhether the problem still persists. If it does, the problem probably stems fromthe LCD Panel.

Step-1: Please change the A/D Board and the LVDS cableof the touch monitor to see whether the problem still persists. If it does, theproblem probably stems from the LCD Panel.

Step-2:Change the LCD Panel

5.Black Screen

Firstly, we need to check the status of the LED on the OSD board. There arethree different kinds of status, as stated below:

1) If the LED is green, it indicates that there is a VGA or DVI signal, andthat the A/D board is OK. The problem would therefore lie with one of theInverter Board, the LVDS cable or the LCD Panel. In this situation, pleasefollow the below instructions:

Step-1: Please change the Inverter Board of the touchmonitor to see whether the problem still persists. If it does, please go toStep-2;

Step-2:please change the LVDS cable to see whether theproblem still persists. If it does, the problem probably stems from the LCDPanel.

Step-3: Change the LCD Panel.

2) An orange or red LED indicates that there is no video input signal. Theproblem may lie with either the VGA or the DVI connection. Please try to turnthe touch monitor off and on via the OSD key to see whether the problem stillpersists.. Using an alternate VGA or DVI cable will be helpful too.

3) If the LED is dim, it indicates either that the power supply of the A/D boardis off, or that the A/D Board has failed. Please try to turn the touch monitoron and off via the OSD key to see whether the problem still persists. If itdoes, please change to another A/D board.

Another solution is to check whether there is either a General Touch logo or"No Signal" is shown when restarting the touch monitor. If theGeneral Touch logo is not shown, the A/D board may be defective. If “No Signal”is shown, there is likely to be a failure with either the VGA or the DVIconnections.

Failure Description: Fail PCB

After performing a swapping test, if youcan confirm that the problem is from a PCB, changing to new PCB is the optimalsolution. Please tell us the model name of the PCB which is marked on the PCBand then we will prepare the new PCB for you.

China

Technical Supporter:chendaibin

Phone Number:+86-28-85124114-8103

Email Address:chendaibin@generaltouch.com

Technical Supporter:koulong

Phone Number:+86-28-85124114-8100

Email Address:koulong@generaltouch.com

International

Technical Supporter:raoxiangying

Phone Number:+86-28-85124114-8103

Email Address:raoxiangying@generaltouch.com

Technical Supporter:koulong

Phone Number:+86-28-85124114-8100

Email Address:koulong@generaltouch.com

No.6 Keyuan South Road, High-Tech Zone,Chengdu, China 028-85124114
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