HP LP3065 black screen, LED lighted, USB works

[Royster86]

Re: HP LP3065 black screen, LED lighted, USB works

Hi all,

I'm in exactly the same boat as the OP - got a broken device from work with exact same symptoms.

I have dismantled it, and plan to test the components with a multimeter tonight (no visible signs of damage).

I was looking for availability on the Diodes mentioned here in case I need them. It seems I cannot find a UF1005, however a few places have UF1005-T's listed.Is that a viable alternative?

I am a beginner and never performed troubleshooting at the circuitry level before.

Turnaround for the delivery on these components seem to be a long time (8 weeks?) - is this normal?

On another thread (I think it was the one referring to using the screen with an XBOX), there was reference to holding the brightness- button while powering on seems to power up, but leave the monitor with full power (does not go into standby) - however I am now not able to revert it back to standby. One good thing I suppose is that I can see in this mode that the backlight is on, which from what I've read means that the inverter is OK?

Many thanks!

[Royster86]

Re: HP LP3065 black screen, LED lighted, USB works

The plot thickens...

I've checked and I'm getting 0.173v from D301 and not the 0.4v-0.7v I see being mentioned in the forums.

I removed it from the board and found it to be a 1N5819. After searching I found it at Maplin:

http://www.maplin.co.uk/p/1n5819-1a-...ectifier-an07h

I have now got the part (bought 2 just in case), and ran a test - now I get 0.223v on both of them.

I noticed it is listed as a Schottky, and after coming across this Wikipedia article, I found this:

http://en.wikipedia.org/wiki/Schottky_transistor -

When forward biased, a Schottky diode's voltage drop is much less than a standard silicon diode's, 0.25 V versus 0.6 V. In a standard saturated transistor, the base-to-collector voltage is 0.4 V. In a Schottky transistor, the Schottky diode shunts current from the base into the collector before the transistor goes into saturation.

The way I read this, is that it should be ~0.25v by design - which is about right for the new ones I bought, but the old 0.173v one is way out.

Or am I completely wrong?!

I'll be installing the part tonight, so I will see how it goes..

[Royster86]

Re: HP LP3065 black screen, LED lighted, USB works

Well, I've replaced D301 and this is now giving the correct readings.

Turned the monitor on and still the same as before (green power light, backlight on).

I tested ZD101 and R102 which were giving odd readings - lifted them and they then gave the correct reading.

I'm pretty much stuck now!

[Serzh]

Re: HP LP3065 black screen, LED lighted, USB works

You guys rock !!
Took the monitor apart, got the power-supply out and looked for D307. Lo and behold the PCB under the diode was brown and the diode measured about 200 both in-circuit and out-of-circuit.

The same problem.

Is it possible to replace UF1005 by UF1007 ?
Difference is only in more high reverse voltage: 1000/700 Volts instead 600/420

[budm]

Re: HP LP3065 black screen, LED lighted, USB works

You can use higher voltage rating but not lower, so that is fine.

[Serzh]

Re: HP LP3065 black screen, LED lighted, USB works

You can use higher voltage rating but not lower, so that is fine.

I think so, but why UF1007 cheaper than UF1005?
What does it mean "DC Blocking voltage" ?

maybe 600V it's kind of limit in working voltage?

[Serzh]

Re: HP LP3065 black screen, LED lighted, USB works

I fixed it last Friday by replacing D307: I used UF4007 instead of UF1005.
It's cost me less than 0,1$ !!!

Thank you so much from me and my wife!

[budm]

Re: HP LP3065 black screen, LED lighted, USB works

Thanks for the follow-up on the repair.

[Serzh]

Re: HP LP3065 black screen, LED lighted, USB works

I have burned my monitor again, under the same circumstances.
I have an idea, that it happens when video card gives the wrong parameters.
Yesterday, I was trying to run Xorg under FreeBSD on nvidia card, monitor was blinking orange for about a minute and then stopped blinking and started shine the orange color continuously. I think that diode died at that moment, even though at the last time I replaced it with higher maximum voltage parameter

[Serzh]

Re: HP LP3065 black screen, LED lighted, USB works

D307 now has about 230 ohms in both directions.
I'm going to replace it this time by HER306 diode, it has the same voltage, but several times more maximum current. What do you think about?

[chaseadam]

Re: HP LP3065 black screen, LED lighted, USB works

My monitor gave it up today. I believe it is the power supply mostly because of the"noise." I still have some high pitched hearing left and I can hear a high pitched noise pulsing slowly (power supply trying to startup?). I haven't tested the 24V output yet, but plan to.

Replacement power supplies are $120 which is pretty steep for an old power supply.

Royster86,
I read a similar low value on D301 (0.160V). Unfortunately everything else including D307 testing OK. Were you ever able to fix your monitor?

Well, I've replaced D301 and this is now giving the correct readings.

Turned the monitor on and still the same as before (green power light, backlight on).

I tested ZD101 and R102 which were giving odd readings - lifted them and they then gave the correct reading.

I'm pretty much stuck now!

[chaseadam]

Re: HP LP3065 black screen, LED lighted, USB works

Put the whole thing together to power it up and was able to hear that the high pitched noise was coming from one of the two larger transformers/chokes on the high side. I hooked up my seek thermal camera to pin point anything which was getting hot and it showed the large diode at D101 as warming very quickly.

Funny that D101 was the only diode I didn't check because of its orientation. I tested it and it was definitely bad. Replaced with a temporary diode which was a bit under spec and the monitor turned on! I will replace it with a spec or better one tomorrow.

I thought using the seek thermal camera to "see" potentially bad components was clever. Obviously it only works when the board is cold and you first turn it on and it isn't fool proof.

Also, make sure you check *all* the diodes. I missed the only one which was bad...

[Royster86]

Re: HP LP3065 black screen, LED lighted, USB works

I did actually get mine going..

Turned out to be what someone else posted in another thread:

https://www.badcaps.net/forum/showth...t=14594&page=3

From user t256:

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

I checked the fuse after I finally found it and sure enough, it was dead. Managed to find some replacements on ebay and fixed it!

However....

Now I'm having an issue whereby if I scan for hardware changes in device manager, the monitor drops off. If I have another monitor connected and I do another scan, the monitor comes back.

Every time I do a scan, it toggles the monitor (connected, disconnected, connected, disconnected). When disconnected, the LED goes orange.

No idea what the issue could be this time, but it's obviously not the fuse as if the fuse went again, I'd expect the monitor to return to it's "stuck in standby" mode.

[paladek]

Re: HP LP3065 black screen, LED lighted, USB works

Hi,

I'm new to this board....

Does anybody have the LP3065 power supply schematic.

Regards

[Knight Rider]

Re: HP LP3065 black screen, LED lighted, USB works

I have a LP3065 that doesn't work. I opened up the power supply and found that D307 was burnt. I'm seeing lots of different diode part numbers here, but it doesn't seem to match the numbers on the diode (50 05). Does anyone know which part number I should order?

Thanks

[MHTSOS]

Re: HP LP3065 black screen, LED lighted, USB works

Remove the diode and check if its full name is 1N5005.