Samsung A53 5G No touch

[unimatrix93]

Hello everyone, I seek some advice for finding out the culprit with this phone.

The phone arrived for screen replacement, the OG screen died completely after a short fall.

The customer ordered the cheapest aftermarket display for it and I installed it.

Now the display do work, but the touch function wont.

Now I opened up the phone and I measured the voltage drop on the mb connector and I found everything in place.

Next i checked the flex cable and the connectors itself, all looks good.

After some searching, I found the service manual for the phone and after checking the touch - troubleshooting part I found this.



I don't have those caps on the board where it's mentions I should measure them. The board model number is the same with the service manual's.


Also, this is the photo I took of the original display:

What are those? They are under the glass, looks like burn marks.
The customer says the phone fall from a TV bench.

Thanks in advance!

[reformatt]

Re: Samsung A53 5G No touch

A series is hard OLED. Aftermarket are LCD, and usually garbage. Try an original OLED display.

[unimatrix93]

Re: Samsung A53 5G No touch

A series is hard OLED. Aftermarket are LCD, and usually garbage. Try an original OLED display.

I don't have an original screen for this model at hand and the customer doesn't want to pay the price for it.

Should I try to send back the LCD screen for RMA and hope the replacement screen will be good?

[reformatt]

Re: Samsung A53 5G No touch

Screen is likely faulty. Your customers attitude is fairly typical and why I don’t touch phones anymore. Too many shit kickers.

[unimatrix93]

Re: Samsung A53 5G No touch

Screen is likely faulty. Your customers attitude is fairly typical and why I don't touch phones anymore. Too many shit kickers.

I agree with you completely. I also hate when they are surprised that their cheapest aftermarket part dies by itself then they blame me for it.


Well I contact the supplier about the RMA and send back the display for replacement.

Thank you very much!

[unimatrix93]

Re: Samsung A53 5G No touch

The new replacement display arrived, same problem. I pulling my hair.

[unimatrix93]

Re: Samsung A53 5G No touch

After measuring every single pin and component around the connector, I found this resistor with a very low resistance across its ends: 30ohm

Is this normal? No other resistor has this value around the connector.

[elecsoluces]

Re: Samsung A53 5G No touch

I have a functional board and i mesure 30ohms on this resistor.
You can measure in diode mode each pin on FPC and post back results.

[unimatrix93]

Re: Samsung A53 5G No touch

I have a functional board and i mesure 30ohms on this resistor.
You can measure in diode mode each pin on FPC and post back results.

Sweet, thank you!
I will do that tomorrow!

[unimatrix93]

Re: Samsung A53 5G No touch

I have a functional board and i mesure 30ohms on this resistor.
You can measure in diode mode each pin on FPC and post back results.

Here are my results:

Bottom row
Notch left: 2.765
1: 2.421
2: 2.418
3: GND
4. OL
5. 0.994
6. GND
7. 1.575
8. 1.554
9. 1.927
10. 1,929
11. 1,918
12. 1,117
13. 1,555
14. 1,927
15. 1,938
16. 1,920
17. 1,320
18. 1,320
19. 2066
20. ol
21. ol
22. ol
23. ol
24. ol
25. gnd
26. 1.561
27. 1.333
28. 1.333
29. 1.333
30. gnd
31. 2.030
32. 2.030
33. 2.030
34. 2.030
35. 2.030
36. 2.030
37. 2.030
38. 2.030
39. 2.030

TOP row
1. ol
2. ol
3. 2.060
4. 961
5. 1.346
6. 1.331
7. 1.361
8. 1.331
9. 1.335
10. 1.094
11. 1.338
12. 1.339
13. 1.210
14. 1.519
15. 1.519
16. 1.927
17. 1.927
18. 1.928
19. 1.928
20. 1.929
21. 1.936
22. 1.940
23. 1.536
24. 1.337
25. 1.337
26. 1.338
27. 1.344
28. 1.341
29. 1.340
30. 1.335
31. 1.946
32. 1.956
33. 1.495
34. 1.548
35. ol
36. ol
37. ol
38. 0.519
39. 0.519

[elecsoluces]

Re: Samsung A53 5G No touch

Diode measurement : red probe on ground and black probe on fpc pin

Bottom row : left to right
notch left : 0.561
1: 0.665
2: 0.662
3: gnd
4: 0.700
5: 0.700
6: gnd
7: 0.516
8: 0.500
9: 0.514
10: 0.16
11: 0.732
12: 0.460
13: 0.391
14: 0.521
15: 0.458
16: 0.421
17: 0.381
18: 0.381
19: 0.768
20: 0.344
21: 0.344
22: 0.344
23: 0.344
24: gnd
25: 0.509
26: 0.391
27: 0.391
28: 0.392
29: gnd
30: 0.336
31: 0.336
32: 0.334
33: 0.334
34: 0.334
35: 0.334
36: 0.334
37: 0.334
38: 0.334
39 : 0.334

your results :OL on pin 4 is not normal 

Top row [B]left to right[/B]
1: 0.667
2: 0.665
3: 0.768
4: 0.143
5: 0.387
6: 0.389
7: 0.411 
8: 0.388
9: 0.391
10: 0.390
11: 0.390
12: 0.390
13: 0.514
14: 0.500
15: 0.500
16: 0.421
17: 0.419
18: 0.419
19: 0.419
20: 0.421
21: 0.427
22: 0.888
23: 0.508
24: 0.390
25: 0.390
26: 0.390
27: 0.390
28: 0.390
29: 0.390
30: 0.388
31: 0.513
32: 0.500
33: 0.527
34: 0.508
35: 0.633
36: 0.517
37: 0.517
38: ol
39: ol

3 OL pins on top row and 1 ol pin on bottom check fpc soldering.

[unimatrix93]

Re: Samsung A53 5G No touch

Thank you,
Will do next week, also I measured these values with black probe on ground. Should I redo it in reverse?

[Stevedb]

Re: Samsung A53 5G No touch

Normal diode mode you use plus on ground and min on data line.

[unimatrix93]

Re: Samsung A53 5G No touch

Hey here are my results with red on ground:

1: 0.717
2: 0.714
3: gnd
4: 0.767
5: 0.767
6: gnd
7: 0.569
8: 0.551
9: 0.782
10: 0.780
11: 0.783
12: 0.779
13: 0.511
14: 0.432
15: 0.789
16: 0.777
17: 0.442
18: 0.376
19: 0.817
20: 0.386
21: 0.387
22: 0.383
23: 0.382
24: gnd
25: 0.559
26: 0.456
27: 0.447
28: 0.456
29: gnd
30: 0.382
31: 0.382
32: 0.379
33: 0.381
34: 0.380
35: 0.381
36: 0.380
37: 0.380
38: 0.381
39 : 0.380


Top row [B]left to right[/B]
1: 0.718
2: 0.715
3: 0.810
4: 0.185
5: 0.452
6: 0.455
7: 0.500 
8: 0.456
9: 0.456
10: 0.453
11: 0.456
12: 0.456
13: 0.590
14: 0.556
15: 0.559
16: 0.600
17: 0.580
18: 0.580
19: 0.494
20: 0.500
21: 0.512
22: 0.1398
23: 0.558
24: 0.455
25: 0.453
26: 0.452
27: 0.456
28: 0.454
29: 0.452
30: 0.451
31: 0.568
32: 0.558
33: 0.573
34: 0.560
35: 0.687
36: 0.575
37: 0.575
38: ol
39: Slowly rising to ol

Now the only noteworthy difference I noticed is pin 22 on the top row which is 1.398.

[elecsoluces]

Re: Samsung A53 5G No touch

Top row pin 22 value is not correct, this pin is directly connected to a resitor.
resistor value : 93.3kohms.
Check this

[unimatrix93]

Re: Samsung A53 5G No touch

Top row pin 22 value is not correct, this pin is directly connected to a resitor.
resistor value : 93.3kohms.
Check this

I measure 102kohm on the resistor connected to it.

[elecsoluces]

Re: Samsung A53 5G No touch

According to the service manual this resistor is R9000.
I can't find the part list to verify impedance and tolerance.

[unimatrix93]

Re: Samsung A53 5G No touch

According to the service manual this resistor is R9000.
I can't find the part list to verify impedance and tolerance.

Since then I rebooted the phone a few times and the touch started to work fine. I reassembled the phone, then it lost touch functionality again. And it came back after a few reboot (lower volume key + pwr button).

The heck is going on with this phone?

[mon2]

Re: Samsung A53 5G No touch

cheapest aftermarket display

For us, cheap display = cheap digitizer. When we raised this feedback with our supplier (Mobile Sentrix), they simply said they would replace it. On each such case, the touch was restored and much much better than the flaky ones we had installed for the ipad (mainly what we see here).

Have you tested with a known good screen & digitizer? (sorry - have not read this entire thread).

[unimatrix93]

Re: Samsung A53 5G No touch

For us, cheap display = cheap digitizer. When we raised this feedback with our supplier (Mobile Sentrix), they simply said they would replace it. On each such case, the touch was restored and much much better than the flaky ones we had installed for the ipad (mainly what we see here).

Have you tested with a known good screen & digitizer? (sorry - have not read this entire thread).

Sadly the only other A53 screen is the original one, which is dead. My friend bought it to me for a screen replacement. He wanted the cheapest display (I recommended the one stop more expensive OLED one, the original is very expensive) but he insisted on this crap.

After I installed the new screen, the screen turned on but it did not detect touch. Then I started to check on the connectors for damage and I measured the diode values to rule out mainboard damage before I RMA the replacement screen. After did not found any obvious problem with the board I proceeded with the RMA process. The supplier sent a new screen from the same type. Same story.

After that I tought it cannot be that bad I get two faulty screen. I checked on the forum with my measurements. Thats where we found the difference on the pin 22 on the top row.

While I was searching for solutions and waiting for reply here, I rebooted the phone many times. And it started the working. But after a complete shutdown (I reassemlbed the back cover, etc) I started doing the same thing. More reboots, working again. I fear turning it off it might turn bad again.

You think this display is THAT bad?