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Old 12-10-2014, 04:31 PM   #21
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Default Re: HP ZR2740w almost dead

Quote:
Originally Posted by budm View Post
5VSTBY pin,.
where is it?

PS

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

Last edited by wash; 12-10-2014 at 04:46 PM..
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Old 12-10-2014, 05:12 PM   #22
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Default Re: HP ZR2740w almost dead

Quote:
Originally Posted by wash View Post
where is it?

PS

UNBELIEVABLE! the monitor i'm using now, has died 3 seconds ago....
P803: PS ON
http://www.badcaps.net/forum/attachm...8&d=1418243826
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Old 12-10-2014, 05:18 PM   #23
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Default Re: HP ZR2740w almost dead

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Originally Posted by budm View Post
yes the PS ON is on the pin 3, but the 5VSTBY pin....i can't find it

is the 5v-sense?

Last edited by wash; 12-10-2014 at 05:21 PM..
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Old 12-10-2014, 05:30 PM   #24
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Default Re: HP ZR2740w almost dead

Sorry, +5V
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Old 12-10-2014, 05:35 PM   #25
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Default Re: HP ZR2740w almost dead

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Originally Posted by budm View Post
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

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Old 12-10-2014, 06:35 PM   #26
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Default 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.
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Old 12-10-2014, 06:57 PM   #27
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Default Re: HP ZR2740w almost dead

Quote:
Originally Posted by budm View Post
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.

Last edited by wash; 12-10-2014 at 07:24 PM..
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Old 12-10-2014, 07:47 PM   #28
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Default 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.
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Old 12-10-2014, 08:10 PM   #29
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Default Re: HP ZR2740w almost dead

Quote:
Originally Posted by budm View Post
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.

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Old 12-10-2014, 08:31 PM   #30
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Default 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.
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Old 12-10-2014, 08:48 PM   #31
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Default Re: HP ZR2740w almost dead

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Originally Posted by budm View Post
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

Quote:
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4v on pin 1
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Old 12-11-2014, 09:25 AM   #32
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Default Re: HP ZR2740w almost dead

i have to measure it with the 2 resistor on the pin 2 and 3?
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Old 12-11-2014, 09:54 AM   #33
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Default 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.
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Old 12-11-2014, 10:37 AM   #34
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Default Re: HP ZR2740w almost dead

Quote:
Originally Posted by budm View Post
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?
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Old 12-11-2014, 11:08 AM   #35
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Default 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.

Last edited by budm; 12-11-2014 at 11:12 AM..
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Old 12-11-2014, 01:26 PM   #36
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Default Re: HP ZR2740w almost dead

Quote:
Originally Posted by budm View Post
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?
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Old 12-11-2014, 02:10 PM   #37
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Default Re: HP ZR2740w almost dead

All six of them (VO1~V06, six outputs) and ground show 0V?
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Old 12-11-2014, 02:45 PM   #38
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Default Re: HP ZR2740w almost dead

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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

Last edited by wash; 12-11-2014 at 02:53 PM..
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Old 12-11-2014, 03:01 PM   #39
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Default Re: HP ZR2740w almost dead

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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.
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Old 12-11-2014, 04:52 PM   #40
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Default Re: HP ZR2740w almost dead

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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?
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