Thread: DWW-700H only diplaying for seconds

Please inform us about the warranty (I suppose it is out) and something about your abilities (I mean whether are you a handy man or not, have you any knowledge about electronics, have a multimeter or not) what are you prepared for and whether are you brave enough to open it for reparation.

I think the root of the problem can be two things:
1. It is not able to recognise the video signal any more. It can be a problem of a simple capacitor, but more often the main IC is faulty...
or
2. The backlight unit consumes too much amperes therefore the unit protects itself (the cause can be a short-circuit or overheating).
The most frequent cause of this is a fault of one FET or transistor near to the transformer. In this case the brightness is reduced.

When the backlight unit gives maximal (normal) light during the 3 secs, the problem can be around the tuning voltage that determinates the brightness by the controller IC. At the ignition the CCFL tube is driven by a near-maximal 50-50% PWM, but after it must be reduced, because the whole backlight system is designed for normal operation. There is a high voltage feedback loop that senses if the ignition is complete. This unit could be faulty, so the PWM remains maximal, therefore it consumes too much power and the protector circuit inhibits the unit.
It is important to know, that backlight and LCD are working SEPARATELY, so you can replace the backlight unit with an independent one (eg. from a PSONE or so).

When the backlight is off, the LCD keeps working, but you have to apply a strong illumination by a reading lamp and a video source with high contrast (eg thick black and white stripes or chess fields) for recognition. You must see the image on the dark LCD...
It is not neccessarily true in your case (eg. the whole monitor could be switched off), but it does worth a try...

I do not remember DWW's warranty, if it is 1 year it is still under warranty. and yes i am handy with electronics, and have a multimeter.

I do not believe it to be a backlight because i have seen laptops where the lcd backlight went out, and if you hold it to certain angles with proper lighting you can tell that the lcd is still trying to produce an image. this is a completely blank screen.

it seems like a very odd problem. because the screen will become visible again if you change resolutions or switch sources, but only visible for 3 or so seconds. being that it becomes visible when changing resolution settings on the computer (tried all resolutions) and becomes visible for a fiew seconds is the one that is really confusing me.

It CAN be one of the possibilities. The backlight of the laptops are usually one-way, w/o feedback loop...simply protected by a fuse. At overamperage the fuse blows and that's all...

Every time, you change the resolution the backlight is OFF for a moment, THEREFORE the whole cycle is initiated when it is ON again.
As I said the backlight can turn off the LCD also, it just depends on the engineering....but it is not neccessary...
Try to reduce the brightness (are you able to do that within those seconds?)
Does it last longer?

I have been repaired a 15' LCD monitor succesfully with this problem. All the simptoms were the same.

But when a warranty is still valid, there is no question - send it back to the seller or manufacturer.

But when the warranty is off, try to separate the backligh unit (if it is on the same PCB, cut the printed power wire by a knife).

i don't think its the back light, being that there is no ghost image if you shine a light on it. could it be power, when i tested it i was using a 12v testing power supply. now it is hooked right into my cars power. the manual says it can handle the extra voltage, and the diagram shows you hook it right into the cars power, but who knows. as for warranty i will find out as soon as Digital WorldWide responds to me. It has been about a week since emailing them. I guess i will email them one more time before contacting the BBB. only had to do that once before in my life but it got results. Its just depressing me because i always recommend DWW to anyone wanting a lcd. one of my friends even ordered from there. Also thanks for all your replys(being your the only one that has) if it is not under warranty what should i jab my multimeter at to narrow down the problem