Westinghouse A190E3-H01 no backlight / shutdown

[caphair]

This monitor powers on to green led you see a very quick backlight flicker but only if you're looking for it, there is an image (used flashlight to confirm) but soon after it goes into standby with orange led.

Powering on and off will continue with same symptoms. You can also hear a high pitched noise.

No bulging caps, I've tested the two P605 mosfet ic drivers in and out of circuit using a DMM set to diode range. They both tested fine, but could they still be bad? Only thing I can think of for this symptom and the associated high pitched noise. Any feedback would be appreciated.

[budm]

Re: Westinghouse A190E3-H01 no backlight / shutdown

Do you smell Ozone? May be the tube's wire is arcing?

[caphair]

Re: Westinghouse A190E3-H01 no backlight / shutdown

Do you smell Ozone? May be the tube is arcing?

Hmm no I don't smell anything

[caphair]

Re: Westinghouse A190E3-H01 no backlight / shutdown

I removed the smd timer capacitor and made a solder bridge in it's place which connects to terminal 1 of inverter ic which is the timer pin. This prevented the monitor from quickly going into standby, and you can see an image with a flashlight but no backlight at all.

[budm]

Re: Westinghouse A190E3-H01 no backlight / shutdown

The transformer high voltage side winding tested OK on both inverter transformer?
You may have to use two test lamps or build two of these to find out if it is the circuit problem or lamp problem.
https://www.badcaps.net/forum/showth...er+testing+cfl

[caphair]

Re: Westinghouse A190E3-H01 no backlight / shutdown

The transformer high voltage side winding tested OK on both inverter transformer?
You may have to use two test lamps or build two of these to find out if it is the circuit problem or lamp problem.
https://www.badcaps.net/forum/showth...er+testing+cfl

How exactly do I test the transformers? Does it matter which pins I measure resistance at? Am I looking for low or high ohms?

[budm]

Re: Westinghouse A190E3-H01 no backlight / shutdown

Can get the numbers as printed on the transformer?

[budm]

Re: Westinghouse A190E3-H01 no backlight / shutdown

I am surprised that your board looks so clean, I would still change a set of caps.
Same board is also used in this one.
http://s807.photobucket.com/user/bud...?sort=3&page=1

[caphair]

Re: Westinghouse A190E3-H01 no backlight / shutdown

can get the numbers as printed on the trasnformer?

2874001501
mb710a

[caphair]

Re: Westinghouse A190E3-H01 no backlight / shutdown

I did not get any ohm reading while trying to measure secondary side of transformers.

There are four pins and I tried ever possible combination and meter didn't move from overload.

[budm]

Re: Westinghouse A190E3-H01 no backlight / shutdown

2874001501
mb710a

I see letter A on the side.
Nothing comes up with 2874001501.

[retiredcaps]

Re: Westinghouse A190E3-H01 no backlight / shutdown

It should be in the 610 to 650 ohms range. These two start with same first 4 digits and should be good enough for a ball park estimate.

http://lcdparts.net/TransformerDetai...ProductID=3359

http://lcdparts.net/TransformerDetai...ProductID=3360

[budm]

Re: Westinghouse A190E3-H01 no backlight / shutdown

Hi Retiredcaps, his transformer is not the same as LCdparts:
https://www.badcaps.net/forum/attach...3&d=1418851047

[caphair]

Re: Westinghouse A190E3-H01 no backlight / shutdown

I don't see any other numbers than I've posted

[retiredcaps]

Re: Westinghouse A190E3-H01 no backlight / shutdown

Hi Retiredcaps, his transformer is not the same as LCdparts:
https://www.badcaps.net/forum/attach...3&d=1418851047

Ahh, I couldn't tell on a little 9 inch netbook screen when I posted. Now that I'm on a bigger 19 inch monitor, I can see the pinouts are different.

[budm]

Re: Westinghouse A190E3-H01 no backlight / shutdown

OK, try reading between point A and point B.

[caphair]

Re: Westinghouse A190E3-H01 no backlight / shutdown

OK, try reading between point A and point B.

I get .367 ohms for both on the 2k ohm scale

How important are all those globs of glue? Had to remove it to measure

[budm]

Re: Westinghouse A190E3-H01 no backlight / shutdown

The glue are there to reduce the arc over between the pins of the high voltage.
So they have the same resistance (367 Ohms) within 3%.
But I re-read your post 1 again on this statement "
This monitor powers on to green led you see a very quick backlight flicker but only if you're looking for it, there is an image (used flashlight to confirm) but soon after it goes into standby with orange led." if the inverter circuit is not working, the unit should not go into standby since there is no feedback signal that goes back to the logic board to tell the logic board to go into standby due to no backlights.
So it still can be due to unstable power supply when the inverter is turned on and start drawing lots of current and cause the power supply to squeal.
The power supply is always on the minute you plug into the outlet, when the power switch is activated, then the inverter will start drawing current, the T-CON also starts drawing current too.
So try disconnecting the cable that goes to the T-CON board on the LCD panel and see if you can power up the monitor.
At this point it may be wise to re-cap the board.
BTW, when you check the MOSFET, what resistance do you get between the Source pin and the Drain pin?

[caphair]

Re: Westinghouse A190E3-H01 no backlight / shutdown

The glue are there to reduce the arc over between the pins of the high voltage.
So they have the same resistance (367 Ohms) within 3%.
But I re-read your post 1 again on this statement "
This monitor powers on to green led you see a very quick backlight flicker but only if you're looking for it, there is an image (used flashlight to confirm) but soon after it goes into standby with orange led." if the inverter circuit is not working, the unit should not go into standby since there is no feedback signal that goes back to the logic board to tell the logic board to go into standby due to no backlights.
So it still can be due to unstable power supply when the inverter is turned on and start drawing lots of current and cause the power supply to squeal.
The power supply is always on the minute you plug into the outlet, when the power switch is activated, then the inverter will start drawing current, the T-CON also starts drawing current too.
So try disconnecting the cable that goes to the T-CON board on the LCD panel and see if you can power up the monitor.
At this point it may be wise to re-cap the board.
BTW, when you check the MOSFET, what resistance do you get between the Source pin and the Drain pin?

I thought there should be no reading between primary and secondary side of a transformer? The 367 ohms doesn't mean they're shorted?

I unplugged t-con and same issue with backlights.

Mosfet Ics I measure:
S1-D1(Two D1 pins) 570ohms
S2-D2(Two D2 pins) 530 ohms

S1-D1(Two D1 pins) 570 ohms
S2-D2(Two D2 pins) 529 ohms

[budm]

Re: Westinghouse A190E3-H01 no backlight / shutdown

"Mosfet Ics I measure:
S1-D1(Two D1 pins) 570ohms
S2-D2(Two D2 pins) 530 ohms

S1-D1(Two D1 pins) 570 ohms
S2-D2(Two D2 pins) 529 ohms"

Those are tested off the board and probe in both directions? There is body Diode on Source and Drain pin, so in one direction it should show as open circuit.