HP ZR2740W - Flickered once and then wouldn't turn on

[Agent24]

Re: HP ZR2740W - Flickered once and then wouldn't turn on

So you are currently running with the original logic board etc and the other PSU?

I wonder if the original PSU was faulty and blew that transistor on the other logic board?

But you say the bad PSU has no voltage output at all?

[fl0w3n]

Re: HP ZR2740W - Flickered once and then wouldn't turn on

Yes, I am running with the original logic board.

The only thing that has changed is the PSU, the metal chassis that supports the PSU and Logic board, and I may have switched the PSU>Logic Board power cable and the Logic Board>LCD cables. I also added a cut-up ziplock bag between the back of the LCD and the PSU/Logic assembly, but I don't think it was doing anything as it was free to slide around. I figured it couldn't hurt though.

The original PSU was able to get voltage to the large main Caps, but I had zero output to the logic board.

Looking back at my notes, it looks like secondary PSU+Logic Board and the original LCD is the combo that fried the transistor. Very odd, that leads me to believe I accidentally did something wrong?
Then again, the fact that I easily got the current setup up and running first try and rather quickly makes me question whether I really did make a mistake or not.

Either way, I'm now likely going to try replacing that transistor and then seeing if I can get a working secondary going again from the leftover parts. I found that for $30 you can buy a new PSU for it, so I'm going to keep that in mind. I think it would be cooler to be able to fix it on my own, but $30 is hard to argue with.

[Agent24]

Re: HP ZR2740W - Flickered once and then wouldn't turn on

It shouldn't be too hard, if you have the working PSU. You can compare voltages and things.

Last time I had a totally dead monitor it was a shorted rectifier on the 5v rail. I tried to find the 5v rail rectifier on this PSU but can't see anything. It seems to go straight back to the transformer output. There is only an obvious rectifier for the 12v rail. In any case, you could compare the resistance from 5v rail to GND on the PSU, see if it looks lower or shorted on the bad PSU for a start.

Edit: Brainfail - check the diode on 12v too for shorts, since it's on the same transformer, if it's bad it would probably cause problems too. D604 might as well test as well.

Can you give part numbers for the ICs on the PSU? The little 8-pin SMD ones, I804, I805 and I802

[Teeva]

Re: HP ZR2740W - Flickered once and then wouldn't turn on

Here is the list of the parts(ics) that I got when I tried to repair mine:

-FDS8842NZ(AP9468G) .... I802 .... MOSFET N-CH 40V 14.9A 8SOIC.... DIGIKEY PN: FDS8842NZCT-ND

-UCC28610D ..... I804..... IC CTLR PWM GREEN MODE 8SOIN.... DIGIKEY PN: 296-34756-5-ND

-UCC28051DR .... I801.... IC PFC CTRLR TRANSITION 8SOIC.... DIGIKEY:296-27158-1-ND

-UCC25600DR ....I811.... IC REG CTRLR ISO PWM VM 8SOIC... DIGKEY:296-38315-2-ND

-ATP404-TL-H ...Q808... .. MOSFET N-CH 60V 95A ATPAK ....DIGIKEY:869-1087-1-ND

-STP13NM60N(13NM60N) ...... MOSFET N-CH 600V 11A TO-220.... DIGKEY:497-8787-5-DN

-UCC24610DR .... I805 .... IC SECONDARY-SIDE CTRLR 8SOIC.... DIGIKEY:296-27855-1-ND

-TL103WIDR(Z103WA) .... I810.... IC OPAMP GP 900KHZ 8SOIC...... DIGIKEY:296-18861-2-ND

-LM358DR ..... I815 .... IC OPAMP GP 700KHZ 8SOIC...... DIGIKEY:296-1014-1-ND

[Teeva]

Re: HP ZR2740W - Flickered once and then wouldn't turn on

Yes, I am running with the original logic board.

The only thing that has changed is the PSU, the metal chassis that supports the PSU and Logic board, and I may have switched the PSU>Logic Board power cable and the Logic Board>LCD cables. I also added a cut-up ziplock bag between the back of the LCD and the PSU/Logic assembly, but I don't think it was doing anything as it was free to slide around. I figured it couldn't hurt though.

The original PSU was able to get voltage to the large main Caps, but I had zero output to the logic board.

Looking back at my notes, it looks like secondary PSU+Logic Board and the original LCD is the combo that fried the transistor. Very odd, that leads me to believe I accidentally did something wrong?
Then again, the fact that I easily got the current setup up and running first try and rather quickly makes me question whether I really did make a mistake or not.

Either way, I'm now likely going to try replacing that transistor and then seeing if I can get a working secondary going again from the leftover parts. I found that for $30 you can buy a new PSU for it, so I'm going to keep that in mind. I think it would be cooler to be able to fix it on my own, but $30 is hard to argue with.

The power at the main cap, that's probably AC voltage. 120 vac comes in and drops down to 60vac at transformers.

If you can find the new PSU for $30, I think that's that the best way to go. I tried to find one on ebay but couldn't find any at the time.

[Agent24]

Re: HP ZR2740W - Flickered once and then wouldn't turn on

Ah, I see, Q808 is switched with the UCC24610 to provide rectification for the 5v rail instead of using a plain diode. No wonder I couldn't see one!

[fl0w3n]

Re: HP ZR2740W - Flickered once and then wouldn't turn on

Ah, I see, Q808 is switched with the UCC24610 to provide rectification for the 5v rail instead of using a plain diode. No wonder I couldn't see one!

I found this, if it helps


http://www.eserviceinfo.com/index.ph...atung+pwb-1421

[fl0w3n]

Re: HP ZR2740W - Flickered once and then wouldn't turn on

The power at the main cap, that's probably AC voltage. 120 vac comes in and drops down to 60vac at transformers.

If you can find the new PSU for $30, I think that's that the best way to go. I tried to find one on ebay but couldn't find any at the time.

This is what I found, but last night when I tried to check out it jist showed a blank page. I'll try again or call

[Agent24]

Re: HP ZR2740W - Flickered once and then wouldn't turn on

I found this, if it helps

http://www.eserviceinfo.com/index.ph...atung+pwb-1421

Not sure, I can't see anything on that page which matches your monitor or PSU - can you?

Probably best to start with comparing voltages on the PSUs, check all the controller ICs etc on bad PSU are they all getting voltage - are they getting the same voltage as the working PSU? That sort of thing

[Teeva]

Re: HP ZR2740W - Flickered once and then wouldn't turn on

Not sure, I can't see anything on that page which matches your monitor or PSU - can you?

Probably best to start with comparing voltages on the PSUs, check all the controller ICs etc on bad PSU are they all getting voltage - are they getting the same voltage as the working PSU? That sort of thing

Check on Q808 to see if you get any 5v.

[darkdead]

Re: HP ZR2740W - Flickered once and then wouldn't turn on

hello i just order a faulty HP ZR2740W, when it arrive i can help trobleshotining.
But soo far reading people there are to comon fail on the screeen led blacklight issues and scaler issues.
Tcon board and panel itslef i dont se issues at all.
one question is, the led strips operate voltage are 30v or 60v? xxx ma may be 250ma? this point is important becuse for test whit fake load instead the screen led strips becuse if one led open or shorted made the led protecting shut donw the monitor also can tricked on the led pwm chip but whit risk burn the led mosfets if led strips got a ground short.
whit the led voltage may be can tested whit whit led outside 30v 90ma led driver whitout risk burn the leds.
BTW any pcb numbers for find the monitor datasheets?
Soory for my english no my natural languaje but got enoght skill for fix it and love help others on the same boat.