BenQ FP767 monitor goes black after 2 seconds.

[theITguy]

Hi all, i have with me today a BenQ FP767 that isn't functioning correctly, it only shows 2 seconds of the image/light on the screen then goes black, but the power indicator light stays green. if you turn the monitor off and then back on it again displays only about 2 seconds of light.

(and before anyone says: try plugging it in in another computer, using a different cord, etc.. don't please because i have already done EVERYTHING to determine it is a fault with the monitor)

to me this problem seemed like a bad capacitor, but after opening it up and looking around, the capacitors appear perfectly good, no bulges or anything?

would anyone know what could cause this to happen and what i should look for/test?

[bomcla]

Re: BenQ FP767 monitor goes black after 2 seconds.

change the transistor "sc5707 and ceramic capacitors close to them. post a picture of the power board!

[PlainBill]

Re: BenQ FP767 monitor goes black after 2 seconds.

change the transistor "sc5707 and ceramic capacitors close to them. post a picture of the power board!

Not at all helpful. The transistors are labeled C5707; the actual part number is 2SC5707. If these transistors short the usual result will NOT be 'two seconds to black', but no backlights at all. And the capacitors are poly caps, not ceramic.

PlainBill

[PlainBill]

Re: BenQ FP767 monitor goes black after 2 seconds.

Hi all, i have with me today a BenQ FP767 that isn't functioning correctly, it only shows 2 seconds of the image/light on the screen then goes black, but the power indicator light stays green. if you turn the monitor off and then back on it again displays only about 2 seconds of light.

(and before anyone says: try plugging it in in another computer, using a different cord, etc.. don't please because i have already done EVERYTHING to determine it is a fault with the monitor)

to me this problem seemed like a bad capacitor, but after opening it up and looking around, the capacitors appear perfectly good, no bulges or anything?

would anyone know what could cause this to happen and what i should look for/test?

The most common causes are bad capacitors (some manufacturers have learned to produce ones that fail without obvious signs), and problems with the CCFLs or the wiring to the CCFLs.

A good starting point for assistance is to provide clear, sharp pictures of the power supply / inverter and attach them using 'Manage Attachments' (below the test entry area).

PlainBill

[theITguy]

Re: BenQ FP767 monitor goes black after 2 seconds.

i couldn't even find transistor labeled c5707?

and bill; if i can't see any visible signs of failure on the capacitors what can i do?

thanks.

attached is 1. the whole board
2. just some caps, they look fine? no bulging.
3. i'm not sure what this is? i'm a newb.
4. not sure
5. not sure (i just thought they looked important

[retiredcaps]

Re: BenQ FP767 monitor goes black after 2 seconds.

1) We prefer photos not at an angle like your first one. Just straight top down is fine.

2) The yellow circled components are the c5707 transistors. They have B C E marked on the board for base, collector, and emitter.

You want to see if they are shorted. Instructions are at section #2

https://www.badcaps.net/forum/showpo...0&postcount=13

If you are new to using a multimeter, see the section entitled multimeter just above in the same link

3) The red circled components are likely to be FU9024. You also want to test to see if they are shorted.

4) The green circled component is the picofuse. It is good, but likely to blow if you do not resolder all the inverter transformer pins.

5) The blue circled components are the inverter transformers. You MUST resolder all the pins with fresh solder otherwise you will have problems in the future.

6) All the other things that PlainBill mentioned about 2 seconds to black are also in posts #13 and #14 at the same link above.

[sabre504]

Re: BenQ FP767 monitor goes black after 2 seconds.

2sc5705 i have circled in red (may have 5706 on them)

yellow should be fu9024n (confirm maybe another type)

Both these items need testing for shorts
green should be pico fuse (pf701 ) test

Blue reflow solder to all transformer legs

[sabre504]

Re: BenQ FP767 monitor goes black after 2 seconds.

Poo sorry Retiredcaps beat me to it
Almost same color scheme too

[retiredcaps]

Re: BenQ FP767 monitor goes black after 2 seconds.

Half a world apart, but we almost use the same color scheme and have the exact same thought process!!

[sabre504]

Re: BenQ FP767 monitor goes black after 2 seconds.

SPOOKY

[theITguy]

Re: BenQ FP767 monitor goes black after 2 seconds.

thanks for the replies everyone.

retiredcaps: i tested the 6 transistors using that guide and these are my results

TRANSISTOR 1
a) put black probe on pin 1 and red probe on pin 2 - 630
b) put black probe on pin 1 and red probe on pin 3 - 629
c) put black probe on pin 2 and red probe on pin 3 - 499

TRANSISTOR 2
a) put black probe on pin 1 and red probe on pin 2 - 500
b) put black probe on pin 1 and red probe on pin 3 - 746
c) put black probe on pin 2 and red probe on pin 3 - 216

TRANSISTOR 3
a) put black probe on pin 1 and red probe on pin 2 - 500
b) put black probe on pin 1 and red probe on pin 3 - 758
c) put black probe on pin 2 and red probe on pin 3 - 227

TRANSISTOR 4
a) put black probe on pin 1 and red probe on pin 2 - 613
b) put black probe on pin 1 and red probe on pin 3 - 612
c) put black probe on pin 2 and red probe on pin 3 - 499

TRANSISTOR 5
a) put black probe on pin 1 and red probe on pin 2 - this one rises 1Kohm every 3 seconds? does not stop?
b) put black probe on pin 1 and red probe on pin 3 - 25.4k
c) put black probe on pin 2 and red probe on pin 3 - this one rises 1Kohm every 3 seconds? does not stop?

TRANSISTOR 6
a) put black probe on pin 1 and red probe on pin 2 - this one rises 1Kohm every 3 seconds? does not stop?
b) put black probe on pin 1 and red probe on pin 3 - 25.3
c) put black probe on pin 2 and red probe on pin 3 - this one rises 1Kohm every 3 seconds? does not stop?

any ideas? i hope i didn't get the pin numbers wrong when measuring them :S

[theITguy]

Re: BenQ FP767 monitor goes black after 2 seconds.

whoops, forgot to add the picture labeling what number capacitor i was referring too

[retiredcaps]

Re: BenQ FP767 monitor goes black after 2 seconds.

TRANSISTOR 1
a) put black probe on pin 1 and red probe on pin 2 - 630
b) put black probe on pin 1 and red probe on pin 3 - 629
c) put black probe on pin 2 and red probe on pin 3 - 499

TRANSISTOR 2
a) put black probe on pin 1 and red probe on pin 2 - 500
b) put black probe on pin 1 and red probe on pin 3 - 746
c) put black probe on pin 2 and red probe on pin 3 - 216

TRANSISTOR 3
a) put black probe on pin 1 and red probe on pin 2 - 500
b) put black probe on pin 1 and red probe on pin 3 - 758
c) put black probe on pin 2 and red probe on pin 3 - 227

TRANSISTOR 4
a) put black probe on pin 1 and red probe on pin 2 - 613
b) put black probe on pin 1 and red probe on pin 3 - 612
c) put black probe on pin 2 and red probe on pin 3 - 499

What is the unit of measure for the 4 transistors above? If ohms, is that 613 ohms, 613k, etc?

TRANSISTOR 6
b) put black probe on pin 1 and red probe on pin 3 - 25.3

Is that 25.3 ohms? Or 25.3k ohms?

any ideas? i hope i didn't get the pin numbers wrong when measuring them :S

The numbering doesn't matter. All possible combinations are tested with the above method.

[retiredcaps]

Re: BenQ FP767 monitor goes black after 2 seconds.

BTW, we will probably need a clear focused picture of the back side of the power board.

[theITguy]

Re: BenQ FP767 monitor goes black after 2 seconds.

in the 4 transistors they are just ohms sorry,

and on transistor 6 it was 25.3K ohms. i'm so forgetful.

[theITguy]

Re: BenQ FP767 monitor goes black after 2 seconds.

sorry about the reflection and the shitty image quality

[retiredcaps]

Re: BenQ FP767 monitor goes black after 2 seconds.

in the 4 transistors they are just ohms sorry,

and on transistor 6 it was 25.3K ohms. i'm so forgetful.

While the c5707s measure a bit lower than what I expected, none of the measurements show an obvious short. The fu9024s are good.

[theITguy]

Re: BenQ FP767 monitor goes black after 2 seconds.

so can we rule the transistors out?

[retiredcaps]

Re: BenQ FP767 monitor goes black after 2 seconds.

sorry about the reflection and the shitty image quality

On the back side, each inverter transformer has 10 pins. It isn't obvious to me from the photo which are the secondary pins.

So you will have to measure all the possible combinations. This should take about 10 minutes total.

See

https://www.badcaps.net/forum/showpo...1&postcount=14

for instructions. So you will be numbering the pins 1-10. It doesn't matter how you number the pins since all combinations will be measured.

Report all readings for all transformers.

[theITguy]

Re: BenQ FP767 monitor goes black after 2 seconds.

i'm giving up on this (shame on me) because it is only for a crappy monitor anyway and it's not mine, i have too much stuff on my shoulders atm. no time to repair a crappy monitor. /end thread... i guess?