Asus VW192S, no power from psu.

[senndogg]

hello.

i have an Asus display, model VW192D with no 5V and 12V power. psu model is Delta EADP-45AF.

the monitor has been serviced elsewhere before but i have no info what has been done it. i can see some caps changed and the ccfl transformer removed, but this is another issue.

tested so far:

in the secondary circuit:
fuses: ok
rectifiers: no one shorted.

in the primary:
main rectifier: ok
main DC current: around 330V
diodes: no one is shorted.
resistors: all seem good.
Q101: not shorted
voltages of C101:
except pin 2: 4.8V, all other pins show 0 voltage in respect to the (-) minus from the rectifier.

i have found a repair manual of a similar display which has this psu too, but no info about voltages was given.

any idea is appreciated. thank you.

[tom66]

Re: Asus VW192S, no power from psu.

With monitor unplugged, can you check resistance across the small cap on the primary side (not the 400V one.) If it reads very low, it could be a bad controller IC.

[senndogg]

Re: Asus VW192S, no power from psu.

there are 2 small caps in the primary side.
the first one:
is in the 4.8V rail close to the IC.
reads: TAICON 50V 6.8uF.
measures 6.9uF (measured with Uni-T UT61E in caps mode)
the resistance in the circuit with the cap removed is over 330k ohms.

the socond one:
is in a rail across the legs of the voltage transformer.
reads: Ltec 50V 47uF.
measures 49uF.
the resistance in the circuit with the cap removed is over 7M ohms.
note: the voltage across this cap when the monitor is plugged is 0V.

[senndogg]

Re: Asus VW192S, no power from psu.

sorry, 2 my faults.
in the first post i meant pin 2. which is the Vcc of the IC.
and the resistance with the cap C105 removed, that means the resistance between the Vcc and the (-) is 52k Ohms.

[selldoor]

Re: Asus VW192S, no power from psu.

"ccfl transformer removed, but this is another issue. "

Is it another issue? or is there a protection circuit so that if there is nothing on the inverter primary, the system will shut down the voltage to that section.

[Behemot]

Re: Asus VW192S, no power from psu.

I may get this display for (hopefully) good price, with white screen. Any hint? I suspect signal board or TCon and that's not what I could repair just like the power board…so not really sure if I should proceed this one.