Viewsonic 19" Flashing backlight and no display.

[ksm]

Hi , I have got viewsonic 19 " LCD Monitor VA1918wm-2. When it starts up the backlight flashes , some sort of hissing sound and shuts down. Verified No picture under bright light. Replaced 4 Capacitors, but did not help. If only one ccfl is connected flashing stops.

[Rtech]

Re: Viewsonic 19" Flashing backlight and no display.

'Hissing', can regularly be related to a wiring fault on Backlights,or less likely a dry joint somewhere on the Board.Would try some test backlights in place of the original first, and see if that corrects things before you start opening the Screen to check.

[selldoor]

Re: Viewsonic 19" Flashing backlight and no display.

There is some scorching showing on the board - can we have a picture of the back.
If it is not a bulb problem then I would change all the caps except the BIG one
with Good Quality low ESR caps - panasonic or nichicon if you can get them.

If you have no spares lamps to test with see this:
https://www.badcaps.net/forum/showth...ght=test+lamps

[ksm]

Re: Viewsonic 19" Flashing backlight and no display.

All caps expect for the big one had already been replaced. I have attached pictures of backside of the board.

A cool replacement for spare lamps .... will give it a try.

[brgil96]

Re: Viewsonic 19" Flashing backlight and no display.

Hi, I'm having a similar problem, actually it's exactly the same except that there IS (barely) visible picture under bright light. I've checked both power and input boards and no visible damage, for me that is. I can't post pictures today but I'll try to do so tomorrow.

@OP, did you end up fixing your problem?

[brgil96]

Re: Viewsonic 19" Flashing backlight and no display.

(sorry, can't seem to find the edit button) Forgot to mention, it's a Viewsonic VX2260WM

[brgil96]

Re: Viewsonic 19" Flashing backlight and no display.

sorry for the triplepost. the pics are here.

Also I should add, the hissing seems most intense at the top corners of the panel

[budm]

Re: Viewsonic 19" Flashing backlight and no display.

Hissing from top corner sounds to me like arcing from high voltage, this can be due to bad wire connection at the end of the lamp.
See example here:
http://s807.photobucket.com/user/bud...?sort=3&page=1

Do you smell any ozone?

[brgil96]

Re: Viewsonic 19" Flashing backlight and no display.

Not really, I don't. Here's what happens a bit more detailed:
If I leave the screen off for a few minutes/hours, when I turn it on, it works perfectly fine. After one or two minutes, the hissing/buzzing begins, along with the backlight flashing. This gets more intense over a few minutes, until it finally stops for like a second or two, and then the backlight goes off. If I power it off and back on it will start buzzing and flashing immediatly and goes off after like 2 or 3 seconds.

Would this happen from a bad connection? Shouldn't it start happening right away instead of only happening when the screen gets warm? I don't know, just asking

And if it is indeed my best bet, how can I get to the CCFLs to see it?

[budm]

Re: Viewsonic 19" Flashing backlight and no display.

When you have bad connection, when it gets warmer, the connection gets worst due to higher contact resistance.
Getting to the lamps is not easy, you will have to disassemble the panel to get to the lamps.
You use test lamps to verify if it is the board problem or the lamps problem.

[brgil96]

Re: Viewsonic 19" Flashing backlight and no display.

Do you know where can I get test lamps locally and how much would it cost me?

[stj]

Re: Viewsonic 19" Flashing backlight and no display.

look for neons used to decorate pc's - you can get a pair with invertor for a few $ from china.
or from an old tv/monitor

[brgil96]

Re: Viewsonic 19" Flashing backlight and no display.

Ill try to get them tomorrow or so then. One thing: the screen has two pairs of blue/pink cables, the ones for the backlight; if I disconnect one of them, the backlights dont flash BUT are only lit for about 2 seconds after I turn the screen on. Is this relevant?

[Lumberjack777]

Re: Viewsonic 19" Flashing backlight and no display.

Ill try to get them tomorrow or so then. One thing: the screen has two pairs of blue/pink cables, the ones for the backlight; if I disconnect one of them, the backlights dont flash BUT are only lit for about 2 seconds after I turn the screen on. Is this relevant?

Yes its relevant. Backlight feedback circuitry requires all of the lamps to be plugged in.

What I do is.......get a set of test lamps. Unplug 1 set of lamps. Plug in the test lamps. See if it stays lit. If it goes out, move to the next plug. Once you get to the bad set of lamps it will stay lit with the test lamps plugged in. That's your bad set.

[budm]

Re: Viewsonic 19" Flashing backlight and no display.

Make two of these:
https://www.badcaps.net/forum/showthread.php?t=19987

[Davi.p]

Re: Viewsonic 19" Flashing backlight and no display.

if you don't have want you disassemble the panel and see if some lamps have darkened ends, those have to be replaced, other way you can tell me the p/n of the 16 pin chip on the right from the under side picture of the power board.

[stj]

Re: Viewsonic 19" Flashing backlight and no display.

btw, if the lamps are gone, you can get LED upgrade kits from china on ebay for about $15.
they work very well - i'v fitted 3 sets so far.

[vinceroger69]

Re: Viewsonic 19" Flashing backlight and no display.

btw, if the lamps are gone, you can get LED upgrade kits from china on ebay for about $15.
they work very well - i'v fitted 3 sets so far.

have you got a ebay link to the ones you recomend cheers

[stj]

Re: Viewsonic 19" Flashing backlight and no display.

sorry, the ebay-store has vanished!
it was "creatall88" or something like that.

[stj]

Re: Viewsonic 19" Flashing backlight and no display.

aha - new store name!!!

linky!
http://stores.ebay.com/lcd-led-parts...p2047675.l2563