HP LP1965 - Power light green, no image

[badandy]

Hello all, new to the forums here.

I have a HP LP1965 that has no image.

When you press the power button the green light turns on.
The backlights turn on as well. There is no image at all.

I have pulled the power supply and video boards and all of the
caps look good. They are a mixture of suscon's and capxons.
( i know c823 on the PS looks like its bulging on the top but
its flat)

Should I just go ahead and replace them or is there another
direction that I should take.

Thanks,

Andy

[jetadm123]

Re: HP LP1965 - Power light green, no image

Is the screen just plain white? If yes, it could be a blown fuse on the LCD control board.

[retiredcaps]

Re: HP LP1965 - Power light green, no image

I agree with jetadm123.

[badandy]

Re: HP LP1965 - Power light green, no image

Is the screen just plain white? If yes, it could be a blown fuse on the LCD control board.

By white do you mean that it would be the same as a normal functioning monitor displaying white fullscreen?

OR

Do you mean white as in the backlights bleeding thru the monitor?

[jetadm123]

Re: HP LP1965 - Power light green, no image

Normal functioning monitor displaying white fullscreen.

[badandy]

Re: HP LP1965 - Power light green, no image

Its completely dark, if you press the menu button nothing happens. If you press the input button, the backlights turn off for a second or two and then turn back on.

[jetadm123]

Re: HP LP1965 - Power light green, no image

Usually, there's a 5V and 12V output from the power supply. The 12V drives the inverter/backlight section and the 5V drives the logic card and LCD panel. Sounds like the 12V is good, since you're getting backlight.

Looks like you'll have to piece everything back together to take voltage readings. Measure for the 5V at the wiring harness of the power supply (hopefully, the voltages are silkscreened on the board. Look on top and bottom of board).

In your photo, I circled what I think are voltage regulators. What are the part numbers?

[Rtech]

Re: HP LP1965 - Power light green, no image

""Its completely dark, if you press the menu button nothing happens. If you press the input button, the backlights turn off for a second or two and then turn back on"".
I am still slightly confused !! from your statement above if the Screen is Dark, then are the Backlights really on ????.....only time the screen is dark normally is if there is NO backlights on ??/

[badandy]

Re: HP LP1965 - Power light green, no image

""Its completely dark, if you press the menu button nothing happens. If you press the input button, the backlights turn off for a second or two and then turn back on"".
I am still slightly confused !! from your statement above if the Screen is Dark, then are the Backlights really on ????.....only time the screen is dark normally is if there is NO backlights on ??/

I have powered it on outside the case and I can see that the backlights are on.

It looks like when you have your screensaver set to blank the screen but not power off the monitor.

[mockingbird]

Re: HP LP1965 - Power light green, no image

Change the capacitors. All of them. If the primary capacitor is Capxon, keep it. If it's a Suscon, toss it and replace it too.

[badandy]

Re: HP LP1965 - Power light green, no image

Mockingbird, do you want me to change caps on both video and power supply boards?

[badandy]

Re: HP LP1965 - Power light green, no image

Usually, there's a 5V and 12V output from the power supply. The 12V drives the inverter/backlight section and the 5V drives the logic card and LCD panel. Sounds like the 12V is good, since you're getting backlight.

Looks like you'll have to piece everything back together to take voltage readings. Measure for the 5V at the wiring harness of the power supply (hopefully, the voltages are silkscreened on the board. Look on top and bottom of board).

In your photo, I circled what I think are voltage regulators. What are the part numbers?

Sorry for the delay getting back to you guys, XMAS has been busy.

I tested 3-5 volt legs for voltage, yellow-orange-red are 5v legs, they tested at 5.24 volts each.

the part numbers for the regulators are as follows, according to your picture top to bottom

AIC1185 top
33 PM
274IB



1187 middle
-18PE
948D2


1185-33PY bottom
775IB

[mockingbird]

Re: HP LP1965 - Power light green, no image

Mockingbird, do you want me to change caps on both video and power supply boards?

Yes, the video board too. Especially the larger ones. Be careful not to rip out the pads. It's somewhat difficult with the logic board and the tiny caps. If your soldering skills aren't that great, then just replace the larger ones on the logic board.

[jetadm123]

Re: HP LP1965 - Power light green, no image

Sorry for the delay getting back to you guys, XMAS has been busy.

I tested 3-5 volt legs for voltage, yellow-orange-red are 5v legs, they tested at 5.24 volts each.

the part numbers for the regulators are as follows, according to your picture top to bottom

AIC1185 top
33 PM
274IB



1187
-18PE
948D2


1185-33PY bottom
775IB

Can you please take a voltage reading for each leg of the above devices?

[badandy]

Re: HP LP1965 - Power light green, no image

Can you please take a voltage reading for each leg of the above devices?

I took the following readings in circuit assuming that you are looking
directly at the IC with the legs facing down. Backlights were not connected lcd was not connected to video board.

for AIC1185 33 PM 274IB

left leg & center - 5.23vdc
right leg & center - 3.29vdc

for 1187 -18PE 948D2

left leg & center - 3.28vdc
right leg & center - 1.802vdc

for 1185-33PY 775IB

left leg & center - 5.22vdc
right leg & center - 3.29vdc

[momaka]

Re: HP LP1965 - Power light green, no image

for AIC1185 33 PM 274IB

left leg & center - 5.23vdc
right leg & center - 3.29vdc

for 1187 -18PE 948D2

left leg & center - 3.28vdc
right leg & center - 1.802vdc

for 1185-33PY 775IB

left leg & center - 5.22vdc
right leg & center - 3.29vdc

The first and third ICs (1185-33) are 3.3v linear regulators (as indicated by the "33" in the name). The second IC is a 1.8v regulator, so the reading you got for all 3 are good.

The problem could also be on the panel board (the one permanently attached to the LCD screen), most likely with one of the boosted voltage rails. If possible, post a few pictures of the panel board. The areas of particular interest are near the LVDS connector and around the inductor/coil.

[jetadm123]

Re: HP LP1965 - Power light green, no image

There appears to be 4 fuses, F301-304 on the logic board. Please check them for continuity. I've marked them on the photo.

[badandy]

Re: HP LP1965 - Power light green, no image

Here is a pic of the panel board.

[momaka]

Re: HP LP1965 - Power light green, no image

Check the 4 fuses that jetadm123 circled. If they are good, check fuse F5 on the panel board and also measure voltage between ground and the test point labeled "AVDD1". Should be around 10~13v I think. Post back what results you get.

[badandy]

Re: HP LP1965 - Power light green, no image

There appears to be 4 fuses, F301-304 on the logic board. Please check them for continuity. I've marked them on the photo.

All 4 have continuity.