Re: HP L1906 monitor problem

Thanks for your reply. At this point, it's starting to sound like repairing this thing isn't worth the effort... I might try my hand at replacing the CCFLs if they are readily available and not too expensive.

Fixing this is more for educational value, does anyone have a schematic?

Re: HP L1906 monitor problem

Hi PlainBill,

I tried your suggestion and all four connections flashed on. Other than shot-gunning the FETs and perhaps the PWM device, what else can I try?

Thanks,

Guy

Re: HP L1906 monitor problem

Hi alexanna,

Thanks for the data sheet. It is useful for looking at the signals on the device as well as some operational notes. I was able to capture some waveforms using an o'scope (attached). Below is a description of what I saw:

Probe 1: IC801-3 enable, approx 4-5 vdc, always present when powered up
Probe 2: IC801-2 OVP, 0vdc for approx 120 ms, then rises to 1 vdc
Probe 3: IC801-20 NDR_B, approx 75 khz, 4 vdc for 230 ms, then drops out
Probe 4: IC801-11 NDR_D, approx 75 khz, 5 vdc for 480 ms, then...

Re: HP L1906 monitor problem

Hi alexanna,
Sorry for the late reply, I have been working some late hours the last couple of days.
Yes, there is a 3vdc signal at CN902-2 (pin 2) when the video signal is present.

Q808, Q809, Q810, and Q811 are all the same device. There is no manufacturing logo, the numbers are:
4512C
AA6GL

IC801 (20 pin device) also has no logo, the numbers are:
OZT1060CN
5256744
0550C

Caps are Elite PW series, Chemi-con KY series, Elite ED series

Which caps...

Re: HP L1906 monitor problem

Hi alexanna, Thanks for your reply. I don't know which pin has the ENA/BL signal, can you tell me? Is this a DC level?

It does seem like Q808 and Q811 might be thermally stressed a bit. What are these devices?

I will try to post pictures with my reply.

Thanks!...

Re: HP L1906 monitor problem

Hi ipman, Thanks for your reply. I have an LCR meter and will check some of the 'lytics after I make several in circuit tests. I did not see any obvious signs of cap problems, popped components, or thermally stressed PCB zones. I'll let you know if I find any issues with the discretes after testing.

Hello, I have an HP L1906 monitor that died recently. When powered up, it flashes on for a second or two and then goes blank. The power LED stays on. It doesn't appear to be a backlight issue, as there is no display (it is completely blank). Does anyone have a schematic or service manual for this unit? I have read some postings about electrolytic cap replacement, but I want some detailed info in case there is a faulty IC or other discrete component gone bad. Any one out there seen some common failures?

Thanks!

Re: New Members - please post your introductions here

Hello,
Geester22 here... I want to say hello and describe myself a bit. I have been in the telecom industry for 20+ years now and have seen a lot of changes. I have been a part of and seen the good and bad of the industry (dot com busts, re-orgs, and up-staffing situations) along the way. I don't have a formal degree, but I have attended 3+ years of college in various programs and have been involved in various aspects of electrical engineering. I am not trying to toot my own horn, but I just want to describe my experience...