Could use some help, trying to fix HP 1940 LCD

[playman]

Re: Could use some help, trying to fix HP 1940 LCD

You worked too hard. Pins 1 and 3 are connected internally. For anyone else doing this, simply test 2-3, 2-4, and 3-4. This test is simply to determine if there is a short.

allright i'll try to remember that.
So if I understood you right, #1 is broken, and therefore I should replace all 4 c5707?
The J598 goes back into the board?

[playman]

Re: Could use some help, trying to fix HP 1940 LCD

I wont be able to reply again until on monday, so just blast your thoughts at me

P.S. I wish that the edit button didint have time out on it.

[retiredcaps]

Re: Could use some help, trying to fix HP 1940 LCD

So if I understood you right, #1 is broken, and therefore I should replace all 4 c5707?

If Q808 is bad, then Q809 is its companion. Look at your board and you will see they work in pairs. So if Q808 is bad, Q809 should be replaced as well.

[playman]

Re: Could use some help, trying to fix HP 1940 LCD

If Q808 is bad, then Q809 is its companion. Look at your board and you will see they work in pairs. So if Q808 is bad, Q809 should be replaced as well.

yeah ofcourse how silly of me
allright they have all been replaced now.
Is there anything else I should do or test before I screew it back in and power it on?

[playman]

Re: Could use some help, trying to fix HP 1940 LCD

Update!

Well I just repacked it and plugged it in for testing, with 2 fingers crossed and other
hand ready on the socket

So now i'm just going to fully assemble it and leave it on for awhile, and see if it will continue to work.

Now I should be able to fix the rest of them.

thanks every one for inputs and help

With regards
Johannes

[rqbwins]

Re: Could use some help, trying to fix HP 1940 LCD

Hello.Can Anybody tell me what kind of transistor is in q885.Becouse mine was so burned that I could not read the inscription on it.Thank you in advance for your help.

[retiredcaps]

Re: Could use some help, trying to fix HP 1940 LCD

Can Anybody tell me what kind of transistor is in q885.

It is might be fu9024 (the same one as to the right of T802 and left of the big cap).

These Benq boards are infamous for having bad solder joints on the inverter transformers, shorted c5707 transistors, shorted fu9024 mosfets, and blown picofuse.

See

https://www.badcaps.net/forum/showthread.php?t=8598

[Jasgriff]

Re: Could use some help, trying to fix HP 1940 LCD

Already answered

[rqbwins]

Re: Could use some help, trying to fix HP 1940 LCD

Thank you for this quick reply.I would like to bother you guys with one more question.Which of the following transistor should I buy?

1:IRFU9024 IR CI -ROHS-
2:IRFU9024NPBF TRANZISTOR MOSFET,P I-PAK -55V-11A
3:IRFU9024N IR HEXFET(R) POWER MOSFET 55V/11A38W -ROHS-

[selldoor]

Re: Could use some help, trying to fix HP 1940 LCD

They will probably all work the U9024 is the important bit.
Where are you looking at them - digikey/mouser/elsewhere.
If the first two there will be data sheets which will give you an idea of the differences - it is usual package/ size/ manufacture or even just local product identification.
You need to check that you get one the same size as you have.
You need to get the correct mounting - surface or through hole

2:IRFU9024NPBF TRANZISTOR MOSFET,P I-PAK -55V-11A
For example IRFU9024N is the standard the PBF means it is lead free
I-pak is the package style

If you look here you can find the package style you need
http://www.irf.com/package/pkhexfet.html

[jetadm123]

Re: Could use some help, trying to fix HP 1940 LCD

Thank you for this quick reply.I would like to bother you guys with one more question.Which of the following transistor should I buy?

1:IRFU9024 IR CI -ROHS-
2:IRFU9024NPBF TRANZISTOR MOSFET,P I-PAK -55V-11A
3:IRFU9024N IR HEXFET(R) POWER MOSFET 55V/11A38W -ROHS-

You can purchase a repair kit from a Romanian seller on eBay:

http://www.ebay.com/itm/REPAIR-KIT-E...item19cebe40e0

[rqbwins]

Re: Could use some help, trying to fix HP 1940 LCD

Thank you for your help.I will post tomorrow how it turns out.

[rqbwins]

Re: Could use some help, trying to fix HP 1940 LCD

On the back of the panel I have 2 diodes of the same kind.Can someone tell me what kind of diodes are ?
I changed the tranzistors and ewerything else but I am having the same problem.
One of the diodes from the back seems to be blown.

[selldoor]

Re: Could use some help, trying to fix HP 1940 LCD

Can you post good clear pictures of the front and back of your boards
with a close up of the area with the diodes on.

[rqbwins]

Re: Could use some help, trying to fix HP 1940 LCD

There it is

[Nocta]

Re: Could use some help, trying to fix HP 1940 LCD

Those seem to be caps for me. The one on the bottom of the board says C819.

[selldoor]

Re: Could use some help, trying to fix HP 1940 LCD

Picture is poor in comparison with your earlier ones. Cant even read the board numbers
for the parts. Nevertheless I think thay may be SS24 SMB 40V 2A is that what they look like?.


Please take note about the resoldering of the boards - if you dont do it it could blow all you have
put in.



@Nocta the cap is just below the diode.

[rqbwins]

Re: Could use some help, trying to fix HP 1940 LCD

Here are the new photos.Hope that you can see better on this pictures

[selldoor]

Re: Could use some help, trying to fix HP 1940 LCD

That is a much better picture - still cant read what it says on them perhaps you can and post it. Did you check them - The traces nearby would give me some concern - do they
still conduct?

[jetadm123]

Re: Could use some help, trying to fix HP 1940 LCD

Here are the new photos.Hope that you can see better on this pictures

You never did say what problems you're experiencing. Can you please give us a more detailed description of the problem? Does the power led remain on? Do you get 2 seconds to black? A complete description of the symptoms helps members point out things to check.