electronics, repairs, service manuals and datasheets discussion community for the repairs professionals and technicians
FAQSearchMembersGroupsRegisterProfilePM'sLogin/Out
BenQ FP547 15" BLACK SCREEN
Goto page 1, 2, 3, 4  Next
 
Post new topic   Reply to topic    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs
View previous topic :: View next topic  
Author Message
tofutofu
Guest





PostPosted: Sun Jan 22, 2012 12:16 am    Post subject: BenQ FP547 15" BLACK SCREEN Reply with quote

hello everyone.

trying to found the problem in the Q5x3 power board of my benq FP547 monitor.

the problem started with black screen every few minutes . but soon become black permanent.
conecting to power and a signal, giving a green light (recognize the signal).
i changed 2 puffed cap's. with no chang.

checking the voltage on bord:
the V-inverter is 13.3v (is that OK?). but no power is geting in to the 2 small transformers (cant see any Voltage after the fu9024n mosfet-[ Q751 and Q743 on the diagram]) .

I changed the 2 couple of transistors [Q759,Q760 & Q730,Q740 on diagram] (should be 2SC5706. but I got only the 2SC5707 that was available at store ) and replaced the 2 fu9024n mosfet. but no chang.

I'm working with the diagram, but don't have any clue what to do next.

any help or idea?

the diagram URL:
elektrotanya.com/benq_q5x3-304_power-bd_acer-547.pdf/download.html
Back to top
jts1957



Joined: 24 Nov 2008
Posts: 2476
Location: Far, Far Away

PostPosted: Sun Jan 22, 2012 1:24 am    Post subject: Reply with quote

Replace FP751 and resolder all terminals of T751 & T752.
_________________
You're over there, I'm over here.
Back to top
View user's profile Send private message
tofutofu
Guest





PostPosted: Sun Jan 22, 2012 6:58 am    Post subject: need to וnderstend Reply with quote

jts1957 wrote:
Replace FP751 and resolder all terminals of T751 & T752.


thanks for your replay.
but the voltage after the fuse (pf571) is good (13.33v)...
should I replace it anyway?

does T751=Q751?

thanks
Back to top
tofutofu
Guest





PostPosted: Sun Jan 22, 2012 7:33 am    Post subject: more data Reply with quote

the BLT_on voltage :

1)when starting, (no connection to vga source)- the green light is turning on for few seconds and the voltage is 3.3v as well (and then go to 0.0v)

2)when connection to vga source- the green light is turning on permanent- voltage is 0.0v

is that all-right?
Back to top
jts1957



Joined: 24 Nov 2008
Posts: 2476
Location: Far, Far Away

PostPosted: Sun Jan 22, 2012 8:36 am    Post subject: Reply with quote

Yes

T= Transformer
Q= Transistor
FP= Fuse
_________________
You're over there, I'm over here.
Back to top
View user's profile Send private message
tofutofu
Guest





PostPosted: Sun Jan 22, 2012 10:54 am    Post subject: more data Reply with quote

tanks JTS1957, I will try that.


I just found out that when starting, (no connection to vga source)- the green light is turning on for few seconds and the voltage is 3.3v as well (and then go to 0.0v). then, the back-light is turning on for few seconds. with the message "NO SOURCE" on screen.



Back to top
tofutofu
Guest





PostPosted: Mon Jan 23, 2012 2:24 pm    Post subject: Reply with quote

I i told before, I can see the back light turn on for few second
does that means the inverter is good?
Back to top
jts1957



Joined: 24 Nov 2008
Posts: 2476
Location: Far, Far Away

PostPosted: Mon Jan 23, 2012 3:47 pm    Post subject: Reply with quote

Try connecting one CCFL bulb at a time and see if each lights for a couple of seconds.
_________________
You're over there, I'm over here.
Back to top
View user's profile Send private message
tpfutpfu
Guest





PostPosted: Tue Jan 24, 2012 12:39 am    Post subject: Reply with quote

jts1957 wrote:
Try connecting one CCFL bulb at a time and see if each lights for a couple of seconds.


tried that. both bulb are working separately for few seconds.


the BLT_ON voltage drop from 3.3v to 0.0v when the back light turned off (also when connected to VGA source)

I tried connecting 3.3v to the BLT_ON from other source. the back-light is turning on, then I can see the picture blinking on the screen every second (wile the back light is continually turned on).

anything to do from hear?
Back to top
jts1957



Joined: 24 Nov 2008
Posts: 2476
Location: Far, Far Away

PostPosted: Tue Jan 24, 2012 1:00 am    Post subject: Reply with quote

There should be FOUR bulbs - two top, two bottom. Since both bulbs on top (or bottom) share a holder, you must test them individually.


BLT_ON (backlights ON, active when LOW) - Backlights turn on for a couple of seconds ... what happens to the 3.3v/0volts?
_________________
You're over there, I'm over here.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs All times are GMT
Goto page 1, 2, 3, 4  Next
Page 1 of 4

 
Jump to:  
You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


eServiceInfo on FB - Service Manuals Free Download - Service Diagrams

Free TV Schematics Download - HARDW.net - Pinout Master - Jabse Service Manual Search - Jabse.InK  - onTap.bg

SnimkiOt.com - Poblizo.com : пътешествия