Question about Proview PL713S 17" Flat Panel LCD Monitor
Display comes on for 5-10 seconds and then black.Power led is on all the time.Switch off monitor and switch it on Display again comes on for 5-10 seconds.Semiconductors on Inverter board are ok checked by replacement.Problem is on the power/inverter board panel is tested known ok.
Any help appreciated.
There is a Switch transistor to power on -off the hi voltaje for lights. Check 15V from power source go to this transistor colector, Using soldering Iron, make a juntion between colector and emiter, to short 15V to Hi voltaje power. I´m fixing 10 monitor the same trouble. I will remove a liter transistor.
Late I will post here the driver transistor number, and the replace number transistor I will use.
Pictures , etc. Best Regard
Posted on Oct 25, 2008
Yes, yes, same problem here too. Here is how I solve it:
BenQ FP51G uses a dual voltage supply. One is at 3.3V to supply the logic board (we call this output A from the power supply). The other one is to supply the CCFL backlit inverter (we call this output B from the power supply). It seems that the CCFL backlit turns on when output B reaches 25V and then turns off when the voltage drops down to 20V or 13V. I don't know what is the spec for this B supply (possibly 15V since FP51G's sister, FP71 uses 15V). I know that B supply is supplying approx 100mA into the inverter circuit, so there is not short-circuit here or a transistor blowing up somewhere.
My temporary solution is to disconnect the B output (there is a jumper with a ferrite bead on it), and replace it with an external 24V supply. Voila, the monitor is now on a new lease of life.
I don't know what is the root cause of this problem though. Possibly the CCFL is getting old? Not sure. Everthing else, including the so called capacitor leaks/bulges is just not here. I replaced the B supply capacitors and still have the problem. Therefore my last resort solution of an external supply.
Someone mentioned to short a transistor from the B output to the inverter circuit. Yes, maybe that too is possible. However, that transistor is not just a BJT, but a MOSFET, and I believe its function is to adjust the input voltage into the inverter circuit (that MOSFET is a buck converter with a TL1451 driving it). Maybe it has something to do with brightness control.
Good luck and have fun with it.
Posted on Aug 05, 2009
Posted on Jun 26, 2008
If there is constant and regular main B+ supply powering the inverter and the other circuits, then possibly the PSU (not as posted "Problem is on the power") should check out OK. And as you posted/described, "Semiconductors on Inverter board are ok...inverter board panel is tested known ok"
Might it be that there is nothing wrong with the monitor?
Perhaps what might be causing the display to be gone in 5-10 seconds is that the video signal it is receiving is beyond its capability and therefore having a hard time to compensate and eventually switches off.
Just to verify that it is not an internal fault within the monitor but probably the PC;'s setting that is the root of the problem, pls as a test run your PC + monitor with:
1. lower screen resolution of your desktop's properties.
2. it may also be of help if you likewise lower the screen refresh rate.
Both of the above may be adjusted through the appropriate settings in your Display Properties.
If your concern has not been corrected after completion of the above procedures, pls post back details of your video card (brand/model), display properties settings: a) screen resolution, color quality and Advanced/Monitor screen refresh rate.
Hope this be of initial help/idea. Pls post back as requested, how things turned up or should you need additional information.
Good luck and kind regards.
Thank you for using FIXYA.
Posted on Feb 16, 2008
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