Nextion Intelligent 7" touchscreen suddenly stopped working – 2 out of 14 displays after 8–10 months

Other Hardware Displays
1

Hello everyone,

I would like to start a new topic because we are experiencing a rather strange touchscreen problem with several Nextion Intelligent 7" displays NX8048P070-011R, and so far I have not been able to determine the exact cause.

We currently have 14 Nextion Intelligent 7" displays installed in a production environment. They have been running continuously for approximately 8–10 months.

So far, 2 out of the 14 displays have developed exactly the same problem:

The touchscreen suddenly stops responding completely.

image
image1168×859 184 KB

The interesting part is that:

  • The LCD/display itself works normally.
  • The Nextion boots normally.
  • The HMI project runs normally.
  • Serial communication still works.
  • The PCB looks normal.
  • There is no visible physical damage to the touchscreen.
  • The touch flex cable looks normal.
  • The connector has been checked and reseated.
  • But the physical touchscreen does not respond at all.

I have tried to troubleshoot the problem step by step.

1. Nextion Editor / communication test

The display still communicates correctly with the Nextion Editor.

For example, I can send a Reboot command from the Nextion Editor. The display turns off and then boots normally again.

I also tested sending data from the PC to the actual physical Nextion.

I created a simple Waveform component and used the Waveform Generator in the Nextion Editor. The waveform data is successfully displayed on the real Nextion.

So the MCU, LCD and serial communication appear to be working normally.

2. Touch/Switch test

I then created a very simple Switch/Touch Button for testing.

In the Nextion Editor simulator, the switch works normally using the mouse.

However, on the real Nextion display, touching the switch does absolutely nothing.

The switch does not change state.

I also tested a simple touch button with the same result.

3. Touch calibration

I also tried the built-in touch calibration.

The calibration screen appears with the calibration points and the instruction to touch the point, but the display does not detect any physical touch.

Therefore, the calibration cannot be completed.

4. 4-wire resistive touchscreen / resistance measurements

I also checked the 4-wire resistive touchscreen and flex cable with a multimeter.

On one of the affected displays, I measured approximately:



Pin 1 – Pin 2 = 745 Ω
Pin 1 – Pin 3 = around 10 Ω
Pin 1 – Pin 4 = 888 Ω
Pin 2 – Pin 3 = OL
Pin 2 – Pin 4 = 236 Ω
Pin 3 – Pin 4 = OL

Interestingly, the resistance between Pin 1 and Pin 4 changes when I press the touchscreen.

So I am not sure whether the touchscreen itself is defective, or whether the problem could be somewhere in the touch controller/electronics on the Nextion PCB.

5. Power supply / production environment

Initially I suspected the power supply because the touchscreen problem appeared in the production environment.

I tested the display with another 5 V power supply which had previously worked correctly.

However, the behavior is still not completely consistent, so I don't want to conclude yet that the power supply is the root cause.

The displays have been operating in a real production environment for approximately 8–10 months, so I am also wondering whether electrical noise, grounding, mechanical pressure, or long-term degradation of the resistive touch panel could be involved.

My questions to the community

Has anyone experienced a similar problem with a Nextion Intelligent 7" / NX8048P070?

I am particularly interested in the following:

  1. Can a 4-wire resistive touchscreen suddenly fail completely after several months of operation, while the LCD, MCU and serial communication continue to work normally?
  2. Are there any known problems with the touch controller circuit on the Nextion PCB?
  3. Is there a reliable way to distinguish between a defective 4-wire touch panel and a defective touch controller circuit using a multimeter or oscilloscope?
  4. Has anyone successfully replaced only the 4-wire touchscreen/digitizer on a Nextion 7" display?
  5. Has anyone experienced similar touchscreen failures after several months of operation in an industrial production environment?

I would really like to determine whether replacing only the touchscreen/digitizer is possible before replacing the entire Nextion display.

Any experience, measurements, or suggestions would be greatly appreciated.

Thank you!

Best regards,

Arip

Indonesia

Update: I finally found the cause and a working solution.

After further testing, I found that the problem was the 4-wire resistive touchscreen/digitizer, not the LCD or the main Nextion HMI.

I replaced the original 7" touchscreen digitizer with a compatible replacement panel. The touchscreen immediately started working again.

At first, the touch coordinates were incorrect, so I performed a touch calibration using:

touch_j

After calibration, the coordinates became correct and the complete HMI, including buttons, switches, keypad and numeric keypad, worked normally again.

I also tested the HMI communication before replacing the panel. For example, sending:

sw0.val=1

from Nextion Editor successfully changed the switch on the physical display. This confirmed that the Nextion MCU, HMI project and serial communication were still working.

In my case, replacing the 4-wire resistive touch digitizer solved the problem.

I have also made a 3-part video documenting the complete process:

Part 1: Diagnosis of the non-responsive touchscreen
Part 2: Testing Nextion communication using sw0.val=1
Part 3: Replacing the 7" touchscreen digitizer and calibrating it with touch_j

If you're interested, you can watch this video that I made :

Hopefully this helps anyone else experiencing the same problem.

2

Just a wild gues but maybe checking resistance between the the touch pins on the ribbon eg. X- X+ Y- Y+ and gnd or vcc whilst touching it could determin what faied (do this whilst its off) and compare the readings to a working display.

EDIT: Try measuring resistance between X- and X+ and Y- And Y+ as well

3

Since I do not have one of these displays, I will take a SWAG (Scientific Wild Assuming Guess).

I believe it has a resistive touchscreen, which is a laminated structure. It normally has two transparent conductive layers, commonly ITO (indium tin oxide), separated by tiny spacers. Pressing the screen brings the conductive layers into contact. The conductive material is therefore part of the touch-panel assembly, not simply a surface coating that should normally wash off during cleaning.

However, an industrial environment makes chemical damage quite plausible. Solvents or aggressive cleaners can attack the outer plastic layer, adhesives, seals, or conductive structure. Repeated pressure, abrasion, heat, or chemical penetration around the edges can also cause failure.

The fact that these originally worked and calibrated, but 2 of 14 have subsequently stopped detecting any touch at all, makes me particularly interested in what was used to clean them and whether the failed units were exposed to the same cleaner or cleaning procedure.

The fact that the resistance between pins 1 and 4 changes when you press the touchscreen indicates that the resistive touch panel is responding mechanically.

The OL readings are interesting. This may not be a calibration problem at all, but an open connection in one axis of the resistive touch panel, its flex cable, or the connection to the touch controller.

Can you make the same resistance measurements on one of the 12 displays that is still working? Comparing a good unit with a failed unit should tell us a lot.

4

Thanks! I did actually measure the resistance between X-, X+, Y- and Y+ with the display powered off. The readings were measurable and changed when pressing the panel, so the measurements didn't clearly reveal the failure.

I eventually replaced the 4-wire resistive digitizer, and the touch immediately worked again. The coordinates were initially offset, but touch_j calibration fixed them completely.

So it turned out the digitizer itself was defective, even though it still showed resistance on the multimeter. Thanks for the suggestion!

5

Thank you for the detailed explanation and suggestions. Your reasoning about the 4-wire resistive touch panel was very helpful.

I eventually found the cause by replacing the touch panel itself.

I replaced the original 4-wire resistive touchscreen/digitizer with a compatible 7" replacement panel. The touch function immediately started working again, while the original LCD, PCB and HMI project remained unchanged.

Interestingly, the original failed panel still showed measurable resistance with a multimeter, and some readings changed when I pressed the panel. So the resistance measurements alone did not clearly identify the failure.

After installing the replacement panel, the touch coordinates were initially incorrect. I then performed the Nextion touch calibration using:

touch_j

After the 4-point calibration, the coordinates became correct and the complete HMI, including buttons, switches and keypads, worked normally.

So at this point, based on the replacement test, I believe the 4-wire resistive digitizer/panel itself was the failed component.

I cannot confirm that chemical cleaning or environmental exposure caused the failure, although this is still a possible factor considering these displays are used in a production environment.

I have now documented the complete troubleshooting and replacement process in a 3-part video:

Part 1: Diagnosis of the non-responsive touchscreen
Part 2: Testing the HMI/serial communication using sw0.val=1
Part 3: Replacing the 4-wire resistive digitizer and performing touch_j calibration.

Thanks again for your suggestions. They helped me understand the possible failure modes of the resistive touch panel.