Hello all,
I had a blank screen problem with this display that I repaired, and I thought that I would post it here in hopes that it would help someone else down the line.
Dell U2412Mb Ultrasharp
Power board: 4H.1GH02.A02
Main board:4H.1GH01.A10
Panel:LTM240CL01 by Samsung
Integrated T-CON: M240K04V0.1_HF
Problem: On powering on, LED was blue for a couple of minutes, but screen was blank/black. No OSD on screen. LED would then turn amber (sleep).
I verified that the power board was working and that the backlight was on. You have to confirm before LED goes to amber. I then made sure that the main board was sending the 5V to the integrated T-CON. The data sheet for the Samsung panel is available online if you need the pin out of the LVDS connector.
On the T-CON, I checked the fuse, which was good. I then checked all caps and diodes for shorts to ground. Found nothing there. It turned out to be the
power management chip SM4142. I could not find a datasheet for the chip to
check further before replacing, but I have listed below, voltages before and after chip change. The chip is available on Ebay for ~$9 shipped. It is a QFN-48 pin, so you're probably going to need hot air to replace it.
T-CON voltages before/after SM4142 change
VON: 4.5V / 25.7V
VSS1: 150mV / -5.6V
VSS2: 600mV / -10.1V
TVDD18: 200mV / 1.8V
TVDD12: 20mV / 1.2V
DVDD: 200mV / 1.8V
AVDD: 4.8V / 10.0V
VCC: 5.2V / 5.1V
PVDD: 5.2V / 5.1V
EVDD: 200mV / 1.8V
I had a blank screen problem with this display that I repaired, and I thought that I would post it here in hopes that it would help someone else down the line.
Dell U2412Mb Ultrasharp
Power board: 4H.1GH02.A02
Main board:4H.1GH01.A10
Panel:LTM240CL01 by Samsung
Integrated T-CON: M240K04V0.1_HF
Problem: On powering on, LED was blue for a couple of minutes, but screen was blank/black. No OSD on screen. LED would then turn amber (sleep).
I verified that the power board was working and that the backlight was on. You have to confirm before LED goes to amber. I then made sure that the main board was sending the 5V to the integrated T-CON. The data sheet for the Samsung panel is available online if you need the pin out of the LVDS connector.
On the T-CON, I checked the fuse, which was good. I then checked all caps and diodes for shorts to ground. Found nothing there. It turned out to be the
power management chip SM4142. I could not find a datasheet for the chip to
check further before replacing, but I have listed below, voltages before and after chip change. The chip is available on Ebay for ~$9 shipped. It is a QFN-48 pin, so you're probably going to need hot air to replace it.
T-CON voltages before/after SM4142 change
VON: 4.5V / 25.7V
VSS1: 150mV / -5.6V
VSS2: 600mV / -10.1V
TVDD18: 200mV / 1.8V
TVDD12: 20mV / 1.2V
DVDD: 200mV / 1.8V
AVDD: 4.8V / 10.0V
VCC: 5.2V / 5.1V
PVDD: 5.2V / 5.1V
EVDD: 200mV / 1.8V
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