Just Repaired A BenQ FP731 17″ LCD Monitor
This LCD monitor was repaired before by a monitor repairer from other company. I found he had touched (solder marked) on all the inverter area such high voltage transformer, inverter ic, push pull transistors (C5707) and the buck royer p-channel FET FU9024N. The complaint for this LCD is display came out for a while and then shut down. After scanned thru some of the major components i did not find anything wrong with the inverter board.
Suddenly i recalled there was a case of pico fuse turned into higher ohm instead of open circuit. I checked the pico fuse with my meter and found that it did show about few ohms, by right it should have registered zero ohm! Replacing only the fuse solved the display shutdown problem in this BenQ fp731 LCD Monitor. I guess the monitor repairer might have missed the fuse because he may have though that the fuse have ohm reading means it is good.
This experience reminds you that when you want to measure the pico fuse, make sure you get zero ohm otherwise replace the fuse and retest again. If you want to learn more about LCD Monitor repair please go to my website at http://www.LCD-Monitor-Repair.com
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catamaran
March 14, 2008 at 9:15 pm
Thank you for sharing. I came to this site to read how things really are
jayson
September 11, 2008 at 9:53 am
good morning, the information that you published with regards to the problem about the benq pf731 was very effective and useful especially for those who are not familiar in troubleshooting such kind of problem and for those who want to study on how to repair lcd monitor.i hope the you will continue to published more information about lcd monitor troubleshooting and repair..thank you very much and more power to you....
admin
September 11, 2008 at 11:22 am
You are welcome!
Jestine
Jose
June 11, 2009 at 10:56 am
I like the program maintenace, more help me. I am Come from Sulawesi Tengah Indonesia
admin
June 11, 2009 at 11:08 am
Nice to know you Jose!
Jestine
Jims
December 28, 2009 at 7:25 pm
Will picofuse cause problems in CRT monitors??
Is this same as ordinary fuse or it s a kinda fusable resistor?
admin
December 30, 2009 at 2:33 am
Hi Jim,
It is different from other fuse but you can use fusible resistor as a replacement. Some pico fuse located along the B+ line and if it is broken then no B+ voltage will be present at the flyback thus no high voltage will be produced.
Jestine
RIMI
March 1, 2010 at 9:02 am
THANKS
Bob
April 29, 2010 at 7:12 am
Нi! I am from Russia. It is cool site:)
admin
April 29, 2010 at 11:06 am
Nice to know you Bob!
Jestine
John
April 15, 2011 at 7:30 am
A BenQ Q7C3 (FP767Ver2)could not been turned on/off by the front push power button, otherwise, it works normal.
Please comment any possible cause, thanks.
admin
April 15, 2011 at 7:11 pm
HI john,
You mean the moment the power is applied there is good display except that the on/off is not functioning? If yes then you may need to check the button or the MCU in the mainboard have problem.
Jestine
John
April 15, 2011 at 7:43 pm
Thank you very much Jestine for the quick response.
The button has been checked and it appears functioning properly, i.e., pull down to 0V from 3.3V while being pushed. However, the pushing button signal seems not passing through the interface board to the power board MCU, by monitoring the connector pin #2 (BLT_ON) voltage, i.e., stay at 3.3V even while the PS button was depressed.
Some new development has just come up, power up the monitor while pushing down the PW button has, somehow, manage to not being able turn on the monitor, both the interface board and the power board have power on all the buses (+12V, +5V and +3.3V), but the monitor is not showing anything. The backlight can be turned on by directly apply 3.3V to the connector pin #2 at between the boards. However, depressing the PW button does not start the monitor, the BLT_ON line is not energized with 3.3V, this pointing the finger at the logic control on the interface board. It seems to be either the eeprom on the interface board is corrupted, or the control chip is out of function. So the question is how to test the interface board with simple equipment, short of swapping the board (since there isn't board on hand to swap with)
admin
April 18, 2011 at 5:58 am
HI John,
Yes it is either the EEPROM or the MCU that give problem. The only way is to compare with a good and identical chip because there is no tester that can test if the chip is good or bad.
Jestine
Marshal
July 12, 2011 at 2:59 am
Hai, i have a problem in my benq lcd monitor. When ever i turn on cpu my monitor display goes off. Please help me how to troubleshoot this problem
admin
July 12, 2011 at 4:32 am
Hi Marshal,
It can be bulged cap, dry joints in the high voltage transformer or even one of the backlight have problem.
Jestine