Lg flatron w2252tq-pf

[s_henya]

Hey guys,

got this monitor today,

it's working but the picture is all scrambled,

checked connections looks good,

im gussing the problem is in the logic board or the tcon board,

anyone know this problem?

[Scenic]

Re: Lg flatron w2252tq-pf

My first guess would be testing the linear voltage regulators on the controller board to see if the output is in spec.

If you have any other 20-22" LCD monitor with 1680x1050 resolution (like this one has), you could hook its panel up to this controller board to determine if it's a panel/t-con fault or the controller board itself without having to buy a replacement t-con first.

[s_henya]

Re: Lg flatron w2252tq-pf

hey, Scenic thanks for the advice,

i had a 19" lg screen with a power supply problem,

connected it and still scrambled picture,

any suggestions on repairing the board?

ebay link for buying a new one?

you said something about voltage regulators testing,

i need you to be a little more specific, never repaired a logic board before...

[Rtech]

Re: Lg flatron w2252tq-pf

It looks as though you may have qty 2 regulators on the Logic board.One looks as though it may be hidden under the Blue resistor on the left of the first photo,and the second in the bottom left hand corner.You need to advise the Part codes on them,and measure the voltages on them.
Looking at them with the 'Tab' at the top, I thing the three pins from the left are Ground, Voltage out and Voltage in.If you wish you can use the metal on the VGA input Socket as the earth point.The voltages out ,maybe, approx 3,3volts and 1.8 volts,but advising the Part codes or yourself using the Alldatasheet.com site,should let you determine what they should be.The centre pin on each device is usually connected to the Tab.

[s_henya]

Re: Lg flatron w2252tq-pf

hey Rtech,

found the v.r, check for shorts, looks good,

how do you suggest checking voltages, with screen connected /disconnected?

by the way could it be the flat cable that goes from the vga board to the tcon board?

thank you,

[selldoor]

Re: Lg flatron w2252tq-pf

Yes it could very well be the flat lvds cable in fact we usually suggest taking that off and cleaning it and replacing as a first test.

[s_henya]

Re: Lg flatron w2252tq-pf

tried cleaning with tuner 600 kontakt spray, but still no change,

is it possible for the cable to go bad without any visible damage?

im willing to try and order a replacment cable but i dont know who sells them

online.. :-)

[retiredcaps]

Re: Lg flatron w2252tq-pf

how do you suggest checking voltages, with screen connected /disconnected?

To test your voltage regulator.

1) Put your multimeter on 20 V DC if manual range.

2) Put your black probe on a ground screw (any one on the logic board will do fine).

3) Put your red probe on each voltage regulator pin EXCEPT the big fat tab. If the middle pin is "cut" and not touching the board, we want to measure that pin as well.

4) Report the part number for each regulator.

5) Report all your findings like the following example,

U101 - part number AL1117-33
pin 1 = 0.00 V,
pin 2 = 3.3 V,
pin 3 = 5.0 V

[s_henya]

Re: Lg flatron w2252tq-pf

hey retiredcaps, thanks for your response,

so:
U901: EH16A
PIN1: 0v
PIN2: 3.3V
PIN3: 5.01v

U902: EH13A
PIN1: 0v
PIN2: 1.79v
PIN3:4.5v (+-0.1v)

by the way i tested, with the lamps and screen disconnected, its a little hard otherwise, but you ment checking with them connected i will try again, i really enjoy learing new ways...
how should i continue from here? :-)

[retiredcaps]

Re: Lg flatron w2252tq-pf

U901: EH16A
PIN1: 0v
PIN2: 3.3V
PIN3: 5.01v

U902: EH13A
PIN1: 0v
PIN2: 1.79v
PIN3:4.5v (+-0.1v)

by the way i tested, with the lamps and screen disconnected, its a little hard otherwise, but you ment checking with them connected i will try again, i really enjoy learing new ways...

Ideally you want the above measurements with everything connected including a source providing a signal. Under load, the readings may behave differently.

[s_henya]

Re: Lg flatron w2252tq-pf

did the tests again this time everything connected

U901: EH16A 838j50
PIN1: 0v
PIN2: 3.3V
PIN3: 5.14v

U902: EH13A 833j13
PIN1: 0v
PIN2: 1.79v
PIN3:4.05v

you were right there is a difference

what is the next level?

maybe try reccaping the logic board or power supply im really without a lead...

[Rtech]

Re: Lg flatron w2252tq-pf

Suggest you start looking for a logic board,or possibly the same model with,perhaps a damaged screen.

[selldoor]

Re: Lg flatron w2252tq-pf

As there are only 5 caps on the board I would replace them with a good make.
They appear to be samyoung which are not great.

[s_henya]

Re: Lg flatron w2252tq-pf

hey selldoor,
where would you recommend start reccaping first, logic board or power supply?

[Th3_uN1Qu3]

Re: Lg flatron w2252tq-pf

I'd say logic board. This looks too weird to be a power supply issue.

[selldoor]

Re: Lg flatron w2252tq-pf

^^^^ditto^^^^

[s_henya]

Re: Lg flatron w2252tq-pf

recapped the logic board with no change,

BUT tested the power supply + logic board on a 19" lg screen, and it works perfectly, i think there is a problem with the tcon board, or screen.

could you guide me a little more? (voltage checking etc...)

i've added a pic of the tcon board.

[selldoor]

Re: Lg flatron w2252tq-pf

Hi - Picture is all scrambled still?

Your photo is not really sharp enough can you get it sharper take in two parts
-good light is the key try taking it outside.
Anyway what I can see
First test the fuse (i know not likely or else there would be nothing but always
good to check)

Next at each end of the board there looks like a component marked FL1/2
these are fusible links and act like a fuse. test those as you would a fuse.
Power off Metre on 200 Ohms probe on each end - report results should be same as touching the probes together.

If you tried the boards on the 19" could you try the panel on the 19"

I Think U5 might be a voltage regulator - can you get the part number off it.

[s_henya]

Re: Lg flatron w2252tq-pf

hey selldor thanks again,

U5: RT9164A
33GGAHJ0V

this tcon is very long thats why its from a distance

do you want me to take it in 3 pics?

by the way tested all 3 fuses already, all of them checked good.

[selldoor]

Re: Lg flatron w2252tq-pf

Yes 3 overlapping pics might help.

with it conected up and on check voltage at fuse.

Data sheet attached for regulator - Power off - first test it for shorts - (excert from badcaps 2 seconds to black guide)
Voltage regulators (U designation) can be bad. They can be shorted or output the incorrect voltage. The test described below only tests the former.

If you have a manual range multimeter, set it to 200 ohms (two hundred). You can test voltage regulators "in circuit" for shorts by (power off and unplugged)

a) black on pin 1- red on pin 2 - record ohms
b) black on pin 1- red on pin 3 - record ohms
c) black on pin 2- red on pin 3 - record ohms

If any reading is less than 30 ohms you might have shorted voltage regulator. Remove from circuit and repeat the tests to verify.

You can also do voltage tests with it all connected up black probe on ground
then record voltage on pin 1 2 and 3 (ignore Tab) with red probe.