Samsung LH49QMRE no image, just restarts

[suiramix]

Hi again,
I need some help to troubleshoot this 49 inch Samsung 4K... so, the tv is power up when mains cable is plugged-in without using the remote or the power switch. The LED backlight is on but no image (blank screen). The red power indicator is flickering when the remote is used and power off the unit but after few seconds restart by itself. Inspected the power supply board (BN44-00953B) no components damaged and at CNM 801 connector measured the voltages without the mainboard connected:
pin 1) NC, 2) ANA_DIM=2.81V, 3),5),7) and 9) A13V=12.77V, pin4) OD_ON/OFF=0V, 6) BLU_PMW= 3.05V, 8) POWER ON_OFF=3.90V . STB 11.88V= 12.77V
Anything suspicions so far...?
Connected mainboard cable and display cables, performed factory reset (on remote: Mute, 1, 8, 2 and Power ) the tv restarted with sound "please select your language” message…but no image on the screen !!! Power off using the remote but again same restart !!! Tried to power up with the display cables disconnected from mainboard ...same result. At this point I decided to purchase (e-bay) a new board, same P/N, (supposedly new-unused spare part)... just installed and unfortunately exactly same outcome : backlight on, no image and without any factory reset the new mainboard power up with same sound..." to select the language" !!! Questions : how can I check if the power supply or the display are defective ...is kind of hard to measure voltages on that CNM 801 connector when the MB cable is attached...can the mainboard behave "normally" (power off and remains off) without the (EDID) display connected??...Thanks again!

[suiramix]

Re: Samsung LH49QMRE no image, just restarts

Just a quick update: the mainboard is connected with the LCD panel using those two wide ribbon cables (no T-Con board) . As per electronichelponline blogspot , the OD_ON/OFF (Over Voltage Detect) (pin 4 ) 3.3Vdc : Operating Normal. If 0V or changing, an SMPS or Panel error exists ! ...mine is sometime 0V or changing ... planning to remove the lower shield of the panel and measure some voltages...

[suiramix]

Re: Samsung LH49QMRE no image, just restarts

Moving forward, using longer and thinner probes, I managed to measure the voltages at CNM 801 connector with the mainboard attached to the power board …pin 4) OD_ON/OFF is stable at 3.10V , so my guess that is ok!
Next step, due to the fact the tv is turning on as soon the AC cord is plug in, I removed the POWER ON_ OFF wire terminal from mainboard cable so there is no signal to the power supply … but no change , the voltage at pin 8) remain 3.90V no matter what ! As usual, press power button on the remote for 3 sec and the tv turns off and restarts by itself (??)…Anyone can explain how the mainboard communicate with power supply board and why is no “stand by” status...?
What are the odds the new mainboard to be defective and have exactly same symptoms as original one? Or the power supply board could be defective??? Any ideas ...

[suiramix]

Re: Samsung LH49QMRE no image, just restarts

In the meantime, still trying to find an answer for this situation, I removed the CPU (large) heatsink and measuring the voltages at the coils ...it seems everything has between 0.8 to 1.0V except six coils connected to IC400_UT labeled VPM2GMA. Google it and did not find any information on the chip !!! Based on the silkscreen prints, this ic generates all the supply rails the LCD panel, including "AVDD_17V" and "Panel_3.3V"...so with or without the LCD ribbon cables attached the first one is 0.0V and second one is indeed 3.3V...pin 1 looks like Vinput is also 0.0V (very strange). During search came across a similar situation (at remont-aud net )...can somebody is registered at this forum and is able to help me ? thanks!

[cacko85]

Re: Samsung LH49QMRE no image, just restarts

Hello.

Did you solve the problem, same thing on SAMSUNG UE49NU7179U, exactly same issues ?? Same sh*it VPM2GMA, same symptoms.
I think is a panel problem, but can't confirm.
Same unsloved problem on remont-aud forum.
Thanks.