HP ZR2740w almost dead

[miroja]

Re: HP ZR2740w almost dead

Hello. I have got also HP ZR2740W with no background light.

When i switch on mains, status LED goes to blue, after a few seconds to amber. It seems all OK, because i have no connection to PC. But i have no background light. I have got on P803 +5V on all 5V pins, 0V an +12V pins, 0V on pins 2,3 and 2,1V on pin 1.
According to hints above i pushed up pins 2 and 3 P803 (with 820 ohm resistors) to +5V and background light appears.
I found, that signal for pins 2 comes from IC U12 - Myson MTV416GMV, pin 26 and signal for pin 2 from pin 9 IC on T-CON and logic board (IC has supply 3,3V, quartz oscillator is running).
Can someone help me? Thanks a lot in advance.

Miro.

PS: Sorry for my English..

[darkdead]

Re: HP ZR2740w almost dead

Good news mines is back to life 120€+20€ the t-con board no bad deal for 27 inch screen.

[darkdead]

Re: HP ZR2740w almost dead

Yes mines just arrived but my black light was fine all led strip voltages was 30v if 60v the led are whit the issues i say up ,your was bad conector.
Mines the faulty is hard ones, was the stupid t-con board got a DC to Dc converter whit 12 v input but no output voltages for power the panel, the culpit was ici max17014a the problem was it cost 8e and no sense 20e shipping on the only web i find in europe.
Diging on ebay i find a guy selling the t con boards
http://www.ebay.es/itm/271758781230?...84.m1439.l2649
My faut is panel turn on vga detect the screen black light turn on but no image only the panel light.
The lvds power are 12v and 3,3v if anyones need the info.
PD: Teeva power board is called t-con and yes tap it may be was the issue of mines killing the max17014a.

[Hot_Dog]

Re: HP ZR2740w almost dead

As i said Teeva, i test it in dissasembled state shown on picture bellow, so there was no possibillity of short circuit in my case. But finaly figured it out and repair LCD succesfully. Problem was badly soldered conector in LED string, which caused its fall. It actually pretty well correspond with voltages i measured on v01 - v06. So if it be helpfull for someone, problem can also be there. Actually, connector had to be pretty badly soldered considering monitor has never been opened before.

[darkdead]

Re: HP ZR2740w almost dead

v04 after flash 55-50V and goes down
v05 after flash 55-50V and goes down
v06 after flash 55-50V and goes down
Sonds like open circuit may be a cold joints on the leds o may be a dead open led on theses leds strips

[Teeva]

Re: HP ZR2740w almost dead

Hot Dog,
Please try put insulation under power supply board-make sure it covers the entire board. When you put the board and main bracket down, try tapping on it to see where it touches on back LCD metal.
I attach the picture highlight below.


disassembly instruction

[Hot_Dog]

Re: HP ZR2740w almost dead

Hi. Are there any results out of this? I have ZR2740w with same behavior, it flash for a short time after power on and then goes black. Weird think is that i try to run in dissasembled to see, if there isn´t problem with short circuit between PSU and metal cover describbed by Teeva and it actually worked, but only once. after that, i unplugged cables, pluged again, and doesn´t work any more, only flash after power on again. I also try to measure voltages v01 - v06 after power on with these results:

v01 after flash 30V and goes down
v02 after flash 30V and goes down
v03 after flash 30V and goes down
v04 after flash 55-50V and goes down
v05 after flash 55-50V and goes down
v06 after flash 55-50V and goes down

I also try to measure voltages with unplugg cable:

v01 after flash 55-50V and goes down
v02 after flash 55-50V and goes down
v03 after flash 55-50V and goes down
v04 after flash 55-50V and goes down
v05 after flash 55-50V and goes down
v06 after flash 55-50V and goes down

Seems there is common problem for this monitor probably caused by single cause. Does anybody allready figured it out?

[Teeva]

Re: HP ZR2740w almost dead

If your monitor is still under warranty, then you should contact the HP tech support, I guess.

When I bought my 2740w of ebay, the seller said it would not turn on. So, when I received it I took it apart and tried to do the troubleshoot on the power supply board and I couldn't find anything wrong with it. Then I put it back together and looked under the board I saw the power board would touch the LCD metal when I shook or lightly tapped the metal bracket that hold power supply board. So I insulated the board and my monitor's been working fine since.

The link below is the instruction how to take the display apart.

[Teeva]

Re: HP ZR2740w almost dead

I just experienced this problem for the first time with my open box 2740w which I just bought. I'm still in the warranty period after only 1 week. My display has a 2013 mfg date i this is helpful.

Based on your post i shook the display side to side on the stand and sure enough it came right on. What is your level of confidence that this is the issue?

If your monitor is still under warranty, then you should contact the HP tech support, I guess.

When I bought my 2740w of ebay, the seller said it would not turn on. So, when I received it I took it apart and tried to do the troubleshoot on the power supply board and I couldn't find anything wrong with it. Then I put it back together and looked under the board I saw the power board would touch the LCD metal when I shook or lightly tapped the metal bracket that hold power supply board. So I insulated the board and my monitor's been working fine since.

[gto47]

Re: HP ZR2740w almost dead

I think the power board touched the LCD causing the shorts on power supply. To fix this, you can try insulating the power board from touching LCD by using thin plastic sheet between the power board and lcd.

There is not much clearance between power board and LCD. With little movement or shake, the power board will touch the LCD.

I just experienced this problem for the first time with my open box 2740w which I just bought. I'm still in the warranty period after only 1 week. My display has a 2013 mfg date i this is helpful.

Based on your post i shook the display side to side on the stand and sure enough it came right on. What is your level of confidence that this is the issue?

[Teeva]

Re: HP ZR2740w almost dead

Hallo, i have a big problem with my monitor.
I'll try to explain the problem with my poor english ...


Now, is out of warranty and is unusable

after a while the monitor goes off, and when i click the power button to power on again, i see the image for a second, as a flash, then it goes black again, i click the power button, another flash, then black, and so on...

i've seen is a common problem with this monitor, is the worst made monitor i've ever seen, and it was a 800€ monitor, thank you hp.

i've had this problem this summer, but after some week the problem disappeared, but now the problem is again here and i have not warranty anymore (i had to use warranty months ago...my bad)


do you think is possible to repair it?

I think the power board touched the LCD causing the shorts on power supply. To fix this, you can try insulating the power board from touching LCD by using thin plastic sheet between the power board and lcd.

There is not much clearance between power board and LCD. With little movement or shake, the power board will touch the LCD.

[budm]

Re: HP ZR2740w almost dead

Please start a new thread with good clear pictures of both top and bottom sides of your board, it sounds like the standby power supply is not working.

[fl0w3n]

Re: HP ZR2740w almost dead

Wow, very useful info here and so rare that my google searches led (no pun intended) me here and the thread is only a few days old.

I have a similar issue with my ZR2740W, but it no longer powers up or has the power light come on at all. Just flickered once last night and that was it.
I'll grab my Fluke from my work truck and follow along your trouble shooting with Wash. I am hoping mine is a power supply issue that I can fix easier than the the LED issue Wash seems to have.

Is it okay for me to post here to keep info consolidated on ZR2740Ws, or would starting my own thread as I go along be better?

[CapLeaker]

Re: HP ZR2740w almost dead

Idea is the same, just make it fit for an LED. I guess I have my head wrapped around my own problem with an RCA TV that has a ccfl backlight or backlight driver board problem that shuts down after 3 seconds. Grr.

[budm]

Re: HP ZR2740w almost dead

At this point I also say it is the CCFL. In regular CFL light bulbs you can check the heating coil, but these CCFL's seem not to have that.
So you have 2 more test options: Make a CCFL tester out of an old monitor CCFL driver board and a small power supply or a battery and check each tube,
Or:
Swap the bad CCFL power wires around with a good one and see if the 60V move with the bad CCFL.

I am afraid... you are running out of testing options after that.

This LED backlit NOT CCFL, one of the LED string has open circuit that is why it shows 60V on VO4.

[CapLeaker]

Re: HP ZR2740w almost dead

At this point I also say it is the CCFL. In regular CFL light bulbs you can check the heating coil, but these CCFL's seem not to have that.
So you have 2 more test options: Make a CCFL tester out of an old monitor CCFL driver board and a small power supply or a battery and check each tube,
Or:
Swap the bad CCFL power wires around with a good one and see if the 60V move with the bad CCFL.

I am afraid... you are running out of testing options after that.

[budm]

Re: HP ZR2740w almost dead

You can also do this:
https://www.badcaps.net/forum/showpo...&postcount=107
or this:
https://www.badcaps.net/forum/showpo...4&postcount=95

[budm]

Re: HP ZR2740w almost dead

You can verify that but removing the other VO wire and see the Voltage will also go up.
LED failure are very common in LCD TV and monitor.
No body can give you 100% answer, I do not have the unit right in front of me, I base my finding from the results you provided.
You can ask for second opinion.

[wash]

Re: HP ZR2740w almost dead

Well, the LED string attached to VO4 is the suspect, the Voltage will be higher than the other outputs due to no load connected, open LED or open wire to the LED string, but more likely to be open circuit LED.
So you will have to disassemble the panel and test the LED, not going to be easy and you will have to remove the old LED and install a new one or may be able to bypass the bad LED.
It looks like each string has 9~10 LEDs.

ok...so do you think the problem is in the panel? and the other circuits boards outside are ok?
how much are you sure? 90% 50% ?

looks like an epic work....

[budm]

Re: HP ZR2740w almost dead

Well, the LED string attached to VO4 is the suspect, the Voltage will be higher than the other outputs due to no load connected, open LED or open wire to the LED string, but more likely to be open circuit LED.
So you will have to disassemble the panel and test the LED, not going to be easy and you will have to remove the old LED and install a new one or may be able to bypass the bad LED.
It looks like each string has 9~10 LEDs.