HP w1907 monitor blown(no power at all)

[Jasgriff]

Re: HP w1907 monitor blown(no power at all)

Here is what you need to be reading to carry out the tests that retiredcaps is refering too.

https://www.badcaps.net/forum/showpo...4&postcount=19

Not sure what is going on with your pictures I can only suggest using a different browser to see if that helps. Oh and make sure that you are using the manage attachments button.

[lipyphil]

Re: HP w1907 monitor blown(no power at all)

These are the board pictures

[lipyphil]

Re: HP w1907 monitor blown(no power at all)

Here is what you need to be reading to carry out the tests that retiredcaps is refering too.

https://www.badcaps.net/forum/showpo...4&postcount=19

Not sure what is going on with your pictures I can only suggest using a different browser to see if that helps. Oh and make sure that you are using the manage attachments button.

I will appreciate if you can show me the mosfets and bridge rectifiers so i can test them. Thank you

[Jasgriff]

Re: HP w1907 monitor blown(no power at all)

Here is retiredcaps bridge rectifier explination.

https://www.badcaps.net/forum/showpo...6&postcount=35

[retiredcaps]

Re: HP w1907 monitor blown(no power at all)

I will appreciate if you can show me the mosfets and bridge rectifiers so i can test them. Thank you

Notice everything inside the black dark line is HOT including all the heatsinks when lcd is plugged in and power on.

If you are going to learn electronics you should know how to read a pcb board.

http://en.wikipedia.org/wiki/Electro...e_designations

Red is your rectifier. Yellow is your power mosfet.

[lipyphil]

Re: HP w1907 monitor blown(no power at all)

I checked the bridge rectifier D801 and mosfet Q804 both in circuit.

Rectifier
1-2=4.86Mohm
1-3=4.82Mohm
1-4=177.7kohm
2-3=1.768Mohm
2-4=4.84Mohm
3-4=4.86Mohm

mosfet

S-G=9.09kohm
S-D=174.9kohm
G-D=191.5kohm

I guess the bridge rectifier and mosfet are not shorted.

[retiredcaps]

Re: HP w1907 monitor blown(no power at all)

I guess the bridge rectifier and mosfet are not shorted.

1) Correct. It appears that nothing is obviously shorted and the fuses are good.

2) Next are voltage measurements. See this 5 minute tutorial.

http://www.youtube.com/watch?v=bF3OyQ3HwfU

3) I suggest plugging your lcd into a power bar so that it can be turned on/off with a switch. This is because you had a burning smell and we want to cut power quickly if needed.

4) Put your black probe on a ground screw. I usually use the one closest to where I am measuring. Some people use the chassis. This is your cold ground.

Put your red probe on each one of the 8 colored pins (CN801). Set your Amprobe to measure DC voltage. Everything will be low voltage since you are on the cold or secodary side.

[lipyphil]

Re: HP w1907 monitor blown(no power at all)

Amazing the power light(blue and amber) came on or worked when i plugged it into the power bar. Before there was no light or the monitor would not response. I didnt do anything to it. All i did was remove F801 and soldered it back. Hmm whats going on? Do you think its advisable for me to assemble the monitor with the lcd screen and try if it will work.?

I also found some solder joints that were never soldered and I don't know if it was accidental or intentional by the manufacture. I have attached a picture of it. It will be weird if accidental though.

Anyway I did the voltage readings on CN801.
1 VCC5V=5.04V
2 VCC5V=5.04V
3 GND=0.00V
4 GND=0.00V
5 ON/OFF=55.9mV-56.0mV
6 BRIGHT=26.1mV-26.4mV
7 VOLUME=26.2mV
8 MUTE=0.646V

[retiredcaps]

Re: HP w1907 monitor blown(no power at all)

Amazing the power light(blue and amber) came on or worked when i plugged it into the power bar.

The main board controls the power LED. So if it is on, then the main board is working. It also means the 5V rail is working.

Do you think its advisable for me to assemble the monitor with the lcd screen and try if it will work.?

I always test with a computer hooked up so I can see my favourite wallpaper. Amber indicates it is the lcd can't find a signal and goes to sleep mode.

You don't have to reassemble anything for this kind of test. I only reassemble everything when I'm confident I fixed the issue.

I also found some solder joints that were never soldered and I don't know if it was accidental or intentional by the manufacture.

Intentional.

[lipyphil]

Re: HP w1907 monitor blown(no power at all)

I assembled the monitor and hooked it up to computer and it worked. But typing is not working which am thinking might be the keyboard. I might have damaged the broad flat cable with connector to the lcd when i was disassembling them. Apart from no typing, everything is perfect. Will change keyboard today to test.

[Jasgriff]

Re: HP w1907 monitor blown(no power at all)

When you say no typing what do you mean?

Can you see your windows screen? can you see the mouse moving around?

[lipyphil]

Re: HP w1907 monitor blown(no power at all)

When you say no typing what do you mean?

Can you see your windows screen? can you see the mouse moving around?

Yes i see everything. Mouse move around.I can even browse.

Typing i mean when i press the keyboard no text shows up.

[Jasgriff]

Re: HP w1907 monitor blown(no power at all)

Silly question how are you typing now? lol

[lipyphil]

Re: HP w1907 monitor blown(no power at all)

haha...lol...typing on a laptop

[Jasgriff]

Re: HP w1907 monitor blown(no power at all)

So it looks like your monitor is all good now then?

[lipyphil]

Re: HP w1907 monitor blown(no power at all)

I bought new keyboard and fortunately its perfect. Unfortunately It was an easy fix. Wanted it to be a difficult fix so i could learn a lot. I still learned something thanks to you all especially retirecaps and jasgriff. My next attempt will be an lcd tv. Will have to look on craiglist for a broken one.

[Jasgriff]

Re: HP w1907 monitor blown(no power at all)

Yeah I remember picking up a monitor excited to fix it only to discover that it was working fine!

However the last 3 I have picked up have had bad CCFL connections which are not so fun