HP W2338H Backlight

[NOOBCHEEF]

Hi,
I have an HP W2338H that when turned on will brighten up for a second, then go to black. Then with a flashlight I can see the monitor status and check cable. I have read around the forums and have had no luck so far in figuring it out. I sliced into the sheath of a pair of the CCFL wires going from the inverter to a CCFL and when it's first turned on, my multimeter reads decent ac voltage for a second and then goes to zero. All of the caps look fine, and as far as I can tell, no cold solder joints etc. I am a complete rookie in all this so bear with me! Any help or suggestions would be greatly appreciated! Thanks!

[retiredcaps]

Re: HP W2338H Backlight

I have an HP W2338H that when turned on will brighten up for a second, then go to black.

1) 2 seconds to black can be

a) bad caps
b) bad inverter transformer
c) bad ccfl and/or wiring

All are discussed in more detail in posts #13 and #14 at

https://www.badcaps.net/forum/showthread.php?t=10419

[retiredcaps]

Re: HP W2338H Backlight

I sliced into the sheath of a pair of the CCFL wires going from the inverter to a CCFL and when it's first turned on, my multimeter reads decent ac voltage for a second and then goes to zero.

Voltages in the above area can range from 700 to 1500V. Your multimeter may not survive if you try again.

When troubleshooting these types of problems, we typically never need to measure the voltages at the ccfls.

[alexanna]

Re: HP W2338H Backlight

Hi retiredcaps, Good to have you back!



NOOBCHEEF,It’s not recommended to check the hot wires with a voltmeter on the CCFLs.
The inverter is designed to shut voltage off to the CCFLs in an over or under voltage condition for safety.
If there is nothing obvious on the capacitors.
I have had so many problems with HP wide screen monitors caused by a CCFL and or it wiring coming loose,If you can try to rule the CCFLs out first by substituting either an entire panels lamps or if you have one or two good CCFLs try various combinations to see if the back lights will stay on.

[NOOBCHEEF]

Re: HP W2338H Backlight

Ok, thanks for all the responses! So just now I plugged in the CCFLs in one of my old Dell lcds into the HP inverter board, and the screen lights up white, so that must mean that the inverter is fine, and I have one or more bad CCFLs in the Hp's screen causing it to work for a second, then sense something is wrong/broken and shut down the CCFLs. Is it worth buying new ones and replacing them, and if it is, where to get them? Also, I haven't quite figured out how to take out the actual CCFLs, as there is a little black border around the bare screen I can't figure out how to get off. Thanks!

[retiredcaps]

Re: HP W2338H Backlight

So just now I plugged in the CCFLs in one of my old Dell lcds into the HP inverter board, and the screen lights up white, so that must mean that the inverter is fine, and I have one or more bad CCFLs in the Hp's screen causing it to work for a second, then sense something is wrong/broken and shut down the CCFLs.

You got it.

Is it worth buying new ones and replacing them, and if it is, where to get them?

Members here have good experience with

http://www.ccflwarehouse.com/

They have a tutorial on how to replace the ccfls. Warning it is a very delicate procedure.

http://www.ccflwarehouse.com/lasotu.html

As for cost effectiveness, I see that on my local kijiji, someone is selling a working name brand 22 inch widescreen monitor for $40 (which is a really good deal). New ccfls might cost arond the same? You can navigate their site and find out.

The above deal is not an usual one. Most people ask $40 for an old 17 4:3 lcd monitor.

[retiredcaps]

Re: HP W2338H Backlight

I have had so many problems with HP wide screen monitors caused by a CCFL and or it wiring coming loose

Yes, good point. It might be a loose connection.

Some things to look for

http://s807.photobucket.com/albums/y...klight%20lamp/

[NOOBCHEEF]

Re: HP W2338H Backlight

I have now got the CCFLs off, and I'm going to resolder the connections, as some of them look a little dubious.

[NOOBCHEEF]

Re: HP W2338H Backlight

So I need to replace one CCFL. Is it okay to just replace one and leave the rest original, or do I need to replace them all?

[alexanna]

Re: HP W2338H Backlight

This is what I would do,other members may have different thoughts.
If the other 3 CCFLs appear to light up at about the same brightness, I would replace just the bad one.

[PlainBill]

Re: HP W2338H Backlight

So I need to replace one CCFL. Is it okay to just replace one and leave the rest original, or do I need to replace them all?

Unless you have a cheap source of CCFLs, replacing them all is too expensive. If you figure $60 by the time you get all the parts, you don't have much margin between that cost and a new 23" monitor.

PlainBill

[retiredcaps]

Re: HP W2338H Backlight

So I need to replace one CCFL. Is it okay to just replace one and leave the rest original, or do I need to replace them all?

I'm frugal so I would just replace one.

Don't forget that ebay also has many ccfl auctions and may be cheaper than ccflwarehouse.

[retiredcaps]

Re: HP W2338H Backlight

If you figure $60 by the time you get all the parts, you don't have much margin between that cost and a new 23" monitor.

Also, based on posts here, about 50% of the people break the replacement ccfl because they get too frustrated, rush the job, and/or use the hammer mentality when it doesn't fit properly.

I just spotted a new 22 inch wide screen lcd posted on my local kijiji for $40. Great deal if I already did not have one (replaced 2 caps) and have another 3 needing repair of some sorts.

If you buy new or used, you can always sell your power and logic board on ebay as working to offset the costs. In addition, you would have 3 spare ccfls for future use!

[dpauto47]

Re: HP W2338H Backlight

ok i also have 1 of these in my shop . ck'ed it out and found 3 out of 4 ccfl's black at end of tube .causing unit to shut down. cost of repair is not worth fixing.

[retiredcaps]

Re: HP W2338H Backlight

cost of repair is not worth fixing.

Sell the power and logic board on ebay. Save the good ccfl tube as a tester.

[alexanna]

Re: HP W2338H Backlight

ok i also have 1 of these in my shop . ck'ed it out and found 3 out of 4 ccfl's black at end of tube .causing unit to shut down. cost of repair is not worth fixing.

If you decide you are going to part the unit out, I would be a candidate to purchase the thin dark LCD panel [that has the Tcon attached]. There would not even be a need to assemble the panel.

[PlainBill]

Re: HP W2338H Backlight

Good advice, retiredcaps, but dpauto47 went a different route.

Sorry, alexanna, I have the monitor. The gentleman lives about half an hour from me.

There were two broken CCFLs when I opened it up; these are long ones (535mm). There are also signs of arcing at the hot end of the CCFLs. Replacements are on order.

PlainBill

[alexanna]

Re: HP W2338H Backlight

Good advice, retiredcaps, but dpauto47 went a different route.

Sorry, alexanna, I have the monitor. The gentleman lives about half an hour from me.

There were two broken CCFLs when I opened it up; these are long ones (535mm). There are also signs of arcing at the hot end of the CCFLs. Replacements are on order.

PlainBill

I am glad you were able to get it, and are going to repair it.
The monitor is well worth the money for CCFLs!!

[PlainBill]

Re: HP W2338H Backlight

Just as a followup, I FINALLY completed the repair of this monitor. The package was delayed because of the holidays, then it was bent in transit. The replacements arrived a week ago and suddenly 'two seconds to black' appeared while reassembling the LCD panel which irked me mightily. Eventually with a little repositioning wires it went together.

Thanks, Dave

PlainBill

p.s. - No, I don't know who the kid is. But in about 12 years maybe he'll be ready to repair monitors.

pb

[RichmondJim]

Re: HP W2338H Backlight

I hope you don't mind if I revive this thread. Wonderful information presented here!
I disassembled my W2338H and looked at the power supply board and all the caps look perfect. While I had it out, I went ahead and reflowed the solder esp. on the caps and power resistor, just in case. After bench assembling the monitor, I powered it up and within the two second window, I saw some arcing on one end of one of the CCFL tubes through a space in the frame. After I remove the metal frame, what's the best way to get to the CCFL so that I can attempt to resolder the connection to the wiring? Anyone have a link?