HP ZR2740w almost dead

[wash]

Re: HP ZR2740w almost dead

5VSTBY pin,.

where is it?

PS

UNBELIEVABLE! the monitor i'm using now, has died 3 seconds ago....

[budm]

Re: HP ZR2740w almost dead

where is it?

PS

UNBELIEVABLE! the monitor i'm using now, has died 3 seconds ago....

P803: PS ON
https://www.badcaps.net/forum/attach...8&d=1418243826

[wash]

Re: HP ZR2740w almost dead

P803: PS ON
https://www.badcaps.net/forum/attach...8&d=1418243826

yes the PS ON is on the pin 3, but the 5VSTBY pin....i can't find it

is the 5v-sense?

[budm]

Re: HP ZR2740w almost dead

Sorry, +5V

[wash]

Re: HP ZR2740w almost dead

Sorry, +5V

ok so i remove the cable on the pin3, then i put a 1k between the pin 3 and one of the pin 5v (pin 12-14) then i check the voltage on the 2 big caps.

correct?

done.
it stays at @400VDC

[budm]

Re: HP ZR2740w almost dead

OK, that is good, the PFC Voltage booster is good, so now we can test the backlights by using another resistor to simulate bl_on (on/off) by connecting the resistor between the ON/OFF pin and the +5V, remove the ON/OFF wire also.
So far it sound like the main board is not putting out enough ps_on Voltage.

[wash]

Re: HP ZR2740w almost dead

OK, that is good, the PFC Voltage booster is good, so now we can test the backlights by using another resistor to simulate bl_on (on/off) by connecting the resistor between the ON/OFF pin and the +5V, remove the ON/OFF wire also.
So far it sound like the main board is not putting out enough ps_on Voltage.

i reinsert the PS ON wire?

after i connect the resistor between the on off and the 5v i have to measure the voltage on the big caps?

done.

what should happen? nothing strange happens.

[budm]

Re: HP ZR2740w almost dead

You need to force on both the PS_ON and the bl_on, you should then see the backlights come on and stay on.

[wash]

Re: HP ZR2740w almost dead

You need to force on both the PS_ON and the bl_on, you should then see the backlights come on and stay on.

ok, it doesn't happen, no flash, nothing.

[budm]

Re: HP ZR2740w almost dead

OK, that can be due to we need the signal on the V adj pin (backlights dimming control).
Can you check the Voltage on that VADJ pin? I do not know if that signal if analog or PWM.

[wash]

Re: HP ZR2740w almost dead

OK, that can be due to we need the signal on the V adj pin (backlights dimming control).
Can you check the Voltage on that VADJ pin? I do not know if that signal if analog or PWM.

the pin 1 have

4v on pin 1

[wash]

Re: HP ZR2740w almost dead

i have to measure it with the 2 resistor on the pin 2 and 3?

[budm]

Re: HP ZR2740w almost dead

Pin1 Vadj of 4V then that is OK, no need to force on that pin 1 then.
So then you do have two problems:
1) the main board is not sending enough PS_ON Voltage to turn on the PFC and other section of the power supply, we proved it by using force on with the resistor.
2) The backlights still do not come on with force on method, so it can be the LED driver circuits or the LED problem.

[wash]

Re: HP ZR2740w almost dead

Pin1 Vadj of 4V then that is OK, no need to force on that pin 1 then.
So then you do have two problems:
1) the main board is not sending enough PS_ON Voltage to turn on the PFC and other section of the power supply, we proved it by using force on with the resistor.
2) The backlights still do not come on with force on method, so it can be the LED driver circuits or the LED problem.

there is something we can do about it?

[budm]

Re: HP ZR2740w almost dead

Well, you can try to fix it to get the backlights to come on first, the problem can be the LED or the LED drivers circuit.
This will be lots of work since we do not have the diagram for the power supply/LED driver board.
You can check the DC Voltage on the P804 between
VO1 & GND
VO2 & GND
.............
..............
VO6 & GND
You will have to turn the monitor on and off six times to see if all the output show the same reading.

[wash]

Re: HP ZR2740w almost dead

Well, you can try to fix it to get the backlights to come on first, the problem can be the LED or the LED drivers circuit.
This will be lots of work since we do not have the diagram for the power supply/LED driver board.
You can check the DC Voltage on the P804 between
VO1 & GND
VO2 & GND
.............
..............
VO6 & GND
You will have to turn the monitor on and off six times to see if all the output show the same reading.

when i tested it before, it was 0.2 volt

i was using another ground, now using the grounds near the vo1 etc, the indicator of the multimeter goes UNDER the 0, what does it means?

[budm]

Re: HP ZR2740w almost dead

All six of them (VO1~V06, six outputs) and ground show 0V?

[wash]

Re: HP ZR2740w almost dead

All six of them (VO1~V06, six outputs) and ground show 0V?

no, show UNDER 0...

the indicator goes below 0, for all of them

[budm]

Re: HP ZR2740w almost dead

no, show UNDER 0...

the indicator goes below 0, for all of them

OK, I do not get it, how can it goes below 0V (GND)?
But the bottom line is that I expect to see Voltage jumps up since you did indicate that the backlights did flash on for seconds, so it does not make sense as to you did not see any voltage on any one of the six outputs at all.

[wash]

Re: HP ZR2740w almost dead

OK, I do not get it, how can it goes below 0V (GND)?
But the bottom line is that I expect to see Voltage jumps up since you did indicate that the backlights did flash on for seconds, so it does not make sense as to you did not see any voltage on any one of the six outputs at all.

i really don't know

how much should be the voltage?

is there something else to do?