HP LP3065 with partially failed PSU (USB works)

[MrYfe]

Hi,
salvaged one of these monitors from being trashed as I thought it would be a real shame since it is quite an expensive screen.
After some googleing I found this thread by freddyfena, and it turned out it was almost the same problem: Computer detects the screen and the USB hub is working, but the screen itself doesn't work (and the front LED is orange).

I followed the instructions in that thread as far as it went, and unfortunately got stuck as my problem deviated more and more from his.
I have som basic knowlegde with troubleshooting (though I'm completely blanc on ICs) and soldering, but I don't actually know that much about semi advanced electronics, so please bear with me if I'm asking what a seemingly obvious abbreviation stands for.


All of the images posted here are from the thread link to above for clarification (and I don't have a decent camera with me ...).


_________________________________________________________________
All testing was done with everything assembled outside the box (except the screen itself) with the screen turned on (ie. not standby).


PSU type/no.: Liteon PA-3171-2-LF Rev:B
Country/Mains: Norway/230 V

Outputs:
VBR: 3.31 V
VON: 0 V
24 V: 0 V <-> 5.1 V (2 s. interval)
18 V: 2.31 V <-> 17.85 V (2 s. interval)
5 V: 5.27 V


Test of points marked by PlainBill (see image):
PC 501:
In: 0.1 V <-> 5.2 V (2 s. interval)
5 V: 1.2 V <-> 5.2 V (2 s. interval)
Out1: 0 V
Out2: 0.1 V <-> 21.3 V (2 s. interval)

Large Cap: 373 V <-> 399 V

Test of L6598 (possibly defective, how do I check this?):
Pin #:
01: 0 V <-> 5 V (2 s. interval)
02: 0 V <-> 1.9 V (2 s. interval)
03: 0 V <-> 0.3 V <-> 2.5 V (1 s. interval between each step up/down)
04: 0 V <-> 1.7 V (1 s. interval)
05: 0 V <-> 0.9 V (1 s. interval)
06: 0 V <-> 3.9 V (2 s. interval)
07: 0 V
08: 0 V <-> 0.27 V (2 s. interval)
09: 0 V
10: 0 V
11: 0 V <-> 4.46 V (2 s. interval)
12: 0.5 V <-> 12.3 V (2 s. interval)
13: -- (NC)
14: 0.3 V <-> 112.6 V (2 s. interval)
15: 0.3 V <-> 113.2 V (2 s. interval)
16: 0.8 V <-> 113.3 V (2 s. interval)


Test of the two dual diodes:
#1: 406 Ohm #2: 400 Ohm


Diode test:
ZD100: 0.729 V / 2.057 V
ZD101: --- (Short Circuted)
ZD661: 0.722 V / --
ZD681: 0.717 V / --

D101: 0.395 V
D241: 0.471 V
D301: 0.203 V
D307: 0.474 V
D602: 0.601 V
D683: 0.601 V
D684: 0.600 V
D841: 0.600 V
D?00: 0.472 V
D??0: 0.471 V

I have not tested the transistors as of yet.

The black cube (text too small to see) marked at the top might be smoked. Does anyone know what this component does?

Any thoughts about this matter will be very much appreciated!

[retiredcaps]

Re: HP LP3065 with partially failed PSU (USB works)

Outputs:
VBR: 3.31 V
VON: 0 V
24 V: 0 V <-> 5.1 V (2 s. interval)
18 V: 2.31 V <-> 17.85 V (2 s. interval)
5 V: 5.27 V


Diode test:
ZD101: --- (Short Circuted)

Fluctuating voltages on the power supply like your 24V and 18V suggest the SMPS is trying to start, but cannot because something is shorted and dragging it down.

One thing that can cause the fluctuations is a shorted diode. If you measured ZD101 and found it shorted, remove it and test it out of circuit to verify it is shorted.

PS. Diode measurements usually have 2 readings. Report both and don't assume we know the other reading is "out of range".

[MrYfe]

Re: HP LP3065 with partially failed PSU (USB works)

Hi, thanks for a quick respons; unfortunately I can't say the same about mine ...

Because my DMM don't have a way to measure diodes (I borrowed a DMM to make the diode measurements) I have to get a new one so I can complete them. I will report back when I do.

PS. Diode measurements usually have 2 readings. Report both and don't assume we know the other reading is "out of range".

I'm sorry, I just forgot to take them ...

Do you think the diode measured at .2 Volts could be faulty as well?

Under are finally some pictures of my board. (Not that it is much different from freddyfenas ...)

[retiredcaps]

Re: HP LP3065 with partially failed PSU (USB works)

Do you think the diode measured at .2 Volts could be faulty as well?

Don't know until you report both measurements. Diodes usually fail shorted. If it reads 0.2V both ways, desolder and verify out of circuit.

[MrYfe]

Re: HP LP3065 with partially failed PSU (USB works)

I finally got around to make some new measurements:

In circuit:

Zener diodes:
ZD100: 0.717/2.496 V
ZD101: 0/0 V
ZD661: 0.709/2.608 V
ZD681: 0.706/--- V


Normal diodes:
D101: 0.380/--- V
D241: 0.461/1.546 V
D301: 0.194/--- V
D307: 0.463/--- V
D602: 0.586/--- V
D683: 0.588/--- V
D684: 0.587/--- V
D841: 0.589/--- V
D?00: 0.459/2.602 V
D??0: 0.456/--- V

Double (and possibly other) diodes:
D100: 0.379/--- V
D211: 0.340/0.202 V
D212: 0.340/0.202 V
D231: 0.086/0.292 V
D604: 0.092/0.766 V

Out of circuit:
ZD101: 0.689 / --- V

D301: 0.189 / --- V


Transistors:
(Measured 1-2,1-3,2-3,3-2,3-1,2-1 (Note that some may have been the othe way around))

Q100: 0.508 / 0.617 / --- / 1.341 / 0.935 / --- V
Q101: 1.293 / 0.560 / 0.628 / 2.825 / 2.888 / 0.626 V
Q201: 0.483 / 0.729 / --- / 1.848 / 1.592 / --- V
Q202: 0.472 / 0.750 / --- / 1.727 / 1.988 / --- V
Q301: 0.630 / 0.800 / 2.007 / 0.631 / --- / --- V
Q601: 0.509 / 0.607 / --- / 2.353 / 2.020 / --- V
Q661: 0.630 / 0.794 / 2.015 / 0.632 / 2.930 / --- V
Q662: 1.270 / 0.563 / 0.627 / --- / --- / 0.625 V
Q664: --- / --- / 0.638 / 2.356 / 0.595 / 0.639 V


Didn't seem like it was the zener diode ... unfortunately.
Does this make any sense to any of you?
Do you think it may be the "central IC"?


Thanks a lot for any help

[xehpuk]

Re: HP LP3065 with partially failed PSU (USB works)

I have a broken LP3065 too. Perhaps its possible to make one working monitor out of two broken?
Unfortunately its big and heavy. Not sure its worth shipping very far. Mine is in Stockholm.

[budm]

Re: HP LP3065 with partially failed PSU (USB works)

"but the screen itself doesn't work (and the front LED is orange)." That to me is that the main board is not detecting the video signal from the PC, you can have bad inverter section but the main board should still detect the video signal from the PC. There are ID pins on the VGA connector for the PC to detect if the monitor is connected to the PC or not, but for the monitor to detect the PC vidoe signals, the monitor uses one of the either RED/BLUE/GREEN signal of the VGA. What are you using VGA or DVI for the connection?
You also have 18/24v power supply section that does not work which can be due to bad component. The Zener that read shorted can be the one that is connected in parallel to the MOSFET's Source resistor (<1 Ohm).
Can I see good clear pictures of both sides of the board in 1/4 section so I can trace out the connections and be able to read the part designators?

[MrYfe]

Re: HP LP3065 with partially failed PSU (USB works)

I have a broken LP3065 too. Perhaps its possible to make one working monitor out of two broken?
Unfortunately its big and heavy. Not sure its worth shipping very far. Mine is in Stockholm.

We could make some sort of arrangment, but why don't you try to fix it?
Do you have a "to seconds to black" case, or something more like my problem?

Right now I've got some ideas to what may be wrong, but then again; I may be totally off

[MrYfe]

Re: HP LP3065 with partially failed PSU (USB works)

"but the screen itself doesn't work (and the front LED is orange)." That to me is that the main board is not detecting the video signal from the PC, you can have bad inverter section but the main board should still detect the video signal from the PC. There are ID pins on the VGA connector for the PC to detect if the monitor is connected to the PC or not, but for the monitor to detect the PC vidoe signals, the monitor uses one of the either RED/BLUE/GREEN signal of the VGA. What are you using VGA or DVI for the connection?

The monitor only supports DVI, and since this is a 2560*1600 pixel display, it uses full/dual link DVI. Although it should also work with single link DVI. Which is the only thing I've tested it with ...

The one thing that made me suspect that something was avry, was that it didn't show the usual messages "No cable connected", "Going into sleep mode" , etc., and I've never encountered a monitor that at least in some form or another doesn't have a message like this.

You also have 18/24v power supply section that does not work which can be due to bad component. The Zener that read shorted can be the one that is connected in parallel to the MOSFET's Source resistor (<1 Ohm).

Right on target

Can I see good clear pictures of both sides of the board in 1/4 section so I can trace out the connections and be able to read the part designators?

Working on a big picture, will post it, but will probably choose another host since it will be huge, and I like the possibility of scrolling over having a lot of small chunks ...

[Th3_uN1Qu3]

Re: HP LP3065 with partially failed PSU (USB works)

ZD101 is good, as tested out of circuit. The reading you are getting in circuit however indicates a short. Check all parts connected to ZD101 and you'll likely find something burnt.

[dadr]

Re: HP LP3065 with partially failed PSU (USB works)

I realize that it's been some time since the last post for this thread, but in case someone is still looking for data about the LP3065... I have 2 of these monitors and one just failed with the same symptoms that MrYfe writes about. When I physically power-up or hit the power button after it's in standby, the LED will light up green for about the time it normally searches for a signal. After that time it turns yellow (standby) even if there is a signal present.

OK, that's not really news. However, the monitor never displays text, and has no on screen settings or indicators. The only indicator I'm aware of is that the green power lamp will flash when you reach the extremes of the +/- adjustments. Hitting the input key will cycle through the DVI inputs - but it's not a fixed function. I *think* it searches for the next active input, and if there are no others it will return to the original. If there are none at all, it goes into standby. If it gets a signal and shows a picture the green power lamp eventually turns off.

I have found that the display is "identified" even by make and model when you plug it in regardless of power. I'm not sure how or why, but a completely unplugged monitor that I then attach a DVI cable (but not a power cable) will be identified as LP3065 and optimum resolution selected in the Mac OS Displays Preference panel. I wonder if DVI provides some power for this kind of function.

I have also found that the USB is powered in standby and when powered off from the front (amber or no LED) but not, of course, if you turn off the master switch in the back. I've used the USB to charge headsets and phones from USB when the computer is off and monitor is in standby.

You probably could have gotten a lot of this from the manual, which is available online from HP, but I thought this might be helpful, and I think there might be a requirement that I make a post on this board before I can start a new thread with my problem. 8-)

[MrYfe]

Re: HP LP3065 with partially failed PSU (USB works)

However, the monitor never displays text, and has no on screen settings or indicators. The only indicator I'm aware of is that the green power lamp will flash when you reach the extremes of the +/- adjustments. Hitting the input key will cycle through the DVI inputs - but it's not a fixed function. I *think* it searches for the next active input, and if there are no others it will return to the original. If there are none at all, it goes into standby. If it gets a signal and shows a picture the green power lamp eventually turns off.

Hi!
And welcome to the forum!

That is actually news, since I'm only familiar with text-based menus.
I just wanted to say that I currently don't have access to the boards untill christmas, so untill then I can't do much; and I sort of forgot that I said I was going to put up some detailed photos of the circuit boards ... will see to it when I find the time.

I have found that the display is "identified" even by make and model when you plug it in regardless of power. I'm not sure how or why, but a completely unplugged monitor that I then attach a DVI cable (but not a power cable) will be identified as LP3065 and optimum resolution selected in the Mac OS Displays Preference panel. I wonder if DVI provides some power for this kind of function.

Indeed it does. The wikipedia article on the subject covers most of what you'll need/want to know, if not, I guess you could search after the specification booklet ... anyways: DVI (as does HDMI, VGA, DP++, etc.) has both 5V (DP has 3.3V) and DDC(/DDC2) to bring screens in and out of sleep mode, and to let the screen identify itself.

You probably could have gotten a lot of this from the manual, which is available online from HP, but I thought this might be helpful, and I think there might be a requirement that I make a post on this board before I can start a new thread with my problem. 8-)

I don't think there is such a requirement, I seem to remember my first post was this thread. Anyway, thanks for pointing me to the manual (I may – or may not – have read it before I took everything apart ...); the things I found most useful (one paragraph) I have summarized below:

No video displayed and flashing green LED:
Video card must support dual-link DVI and the input signal must be set correctly. Set input signal to 2560 x 1600 at 60 Hz. Confirm the video card and video cable support Dual-Link DVI-D. Use only the DVI-D video cables
supplied with the monitor.


This means that if connected with a single-link DVI (which I did), the LED should flash green, and not go into standby as it did. Which really removes the only uncertainty aspect I haven't tried already: Turning it on with a dual-link DVI attached.

Anyhow; I guess this thing goes idle again untill christmas. Untill next time: Happy "arrrgh! what is wrong with my screen!!!"

[t256]

Re: HP LP3065 with partially failed PSU (USB works)

Replace SMD fuse F1 (2A) on the PCB LCM

[beejay]

Re: HP LP3065 with partially failed PSU (USB works)

Hello, i am a radio amateur and as such an electronic enthusiast by nature.
I am now coming back to this forum for about half a year and finally i found some time to start fixing my monitor. Hopefully i can figure this out.

As it happens i ended up with just the same monitor as above which shows a somewhat similar behaviour. The control board tries switching on the main power supply again and again. However when I checked the output voltages, they all show up as far as i can tell. The 18V on the control board side and the 24V on the backlight-inverter side.

Since my display is making a regular ticking sound when the supply is being switched on i also looked into that. It turns out to be the board controlling the TFT area. So i guess the sound is just a symptom and not a cause.(?)

Since the voltages seem to be good on first sight, i was wondering: How is the control board deciding about "power good" / "power bad". The only way i see at the moment is that, the control board looks at the 18V from the power supply going up when it enables the supply. If that is the case, could it be that the power supply is taking too long to get to the full 18V?

I just have a digital multimeter but i might get a scope from a colleague and take a closer look at what is going on during those 2s enable-intervals.

Also: Would anyone advise against that i try to "manually" switch on the power supply by disconnecting it from the rest, hooking it up to 230VAC and putting 5V to the STBN-24V signal for further diagnosis?


cheers and greetings from southern germany

[beejay]

Re: HP LP3065 with partially failed PSU (USB works)

ZD101 is good, as tested out of circuit. The reading you are getting in circuit however indicates a short. Check all parts connected to ZD101 and you'll likely find something burnt.

I looked around ZD101 a bit and the reason for MrYfe readings ("shorted") is a parallel resistor of 0.16 Ohms to ZD101. When taking the resistor out the gate of the mosfet (20N60C3) is open and the T-E legs show 0.46V in one direction and open in the other, which does not look bad to me.

Since this is a forum with caps in the title and the top of that large 180uF was not indented as the others i took it out and checked. It shows 158uF on my DMM which is a ~10% loss. Should i try to fix that?

[selldoor]

Re: HP LP3065 with partially failed PSU (USB works)

Can you post good clear pictures of your boards using manage attachments

Does the back light flash on at all?

[beejay]

Re: HP LP3065 with partially failed PSU (USB works)

I am back. It has been a busy week (and still is). So forgive me for taking a while.

Pictures of the main PSU will follow. Though they should be identical to these boards: https://www.badcaps.net/forum/showthread.php?t=13640

Here are some pictures of the backlight inverter.
From left to right:
1) location of backlight inverter board and its high voltage cabling
2) overview shot of the lower half of the board including the connector to the PSU at the top of the image (circuits are copy pasted so this kind of represents the whole inverter)
3) shot of the center section of the board

[beejay]

Re: HP LP3065 with partially failed PSU (USB works)

Now on to the main&standby power supply.

From left to right:
1) Overview of the whole board
2) control board side
3) inverter board side
4) closeup of the lower hot section with power-line connector
5) closeup of the upper hot section

For completeness here are links to the images of the backside (thanks freddyfena)
https://www.badcaps.net/forum/attach...1&d=1299451316
https://www.badcaps.net/forum/attach...2&d=1299451316

[beejay]

Re: HP LP3065 with partially failed PSU (USB works)

I tested for the issue described by Electronomo here: https://www.badcaps.net/forum/showth...ghlight=lp3065

He reported an open resistor in a divider branch of the L6561 (https://cdn.badcaps-static.com/pdfs/...1b92f46e24.pdf). Turns out there is even an example application of the IC in the datasheet that closely matches the PSU in our monitor. (see Figure 7 on page 6) Or at least the divider is exactly the same.

There are 3x serial 620kOhms. This matches the 1.8MOhms in the datasheet as well as 11kOhms towards ground from PIN3 of the IC. R100 (burried under white glue) R101 and R102. One of them gave strange measurements so i replaced them. Unfortunately this didn't change anything.

[beejay]

Re: HP LP3065 with partially failed PSU (USB works)

Does the back light flash on at all?

Sorry, i almost forgot. No it does not. I think the inverter is not being switched on before the control board decides that the main power looks good.