I brought this monitor from an auction, upon testing the backlights were dead as i shone a lamp on the screen and the image could be seen.
Opening up the monitor i looked around at any obvious problem like buldging capacitors or burnt components but none to report.
There is a a 10 way connector on the board where the inverter and power supply are combined; this connects into the main video board inside the monitor .
The pins are as follows :
I tested the 12v line which is supplied from a 7812A transistor and from this all im getting is 4.3v and this is even with the monitor turned on and the video cable wired up to the pc, So i dont know if the transistor is at fault really.
Could do with a little bit of help on the subject.
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Re: 19" Proview 900p lcd monitor backlight
Change the capacitors (all but maybe the main should be done- if you
change just bad ones now, the others will take the heat and go soon).
They do not have to be bulged or leaking to be bad.
Then if that doesn't help, shoot for transistors.
I fix these and have had many pretty ones not work.
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It may be the internal backlight that is failing. You can take a flashlight and hold it close to the screen, move the flashlight all around the screen and check if you can see anything. The display will be dark, but you should be able to make out the image that is there with the flashlight technique. If you can see an image on-screen, then your backlight has failed and you will need to replace the monitor. Weather or not you see an image is not a critical issue, but a tool to verify if the backlight is off or some other issue is causing the problem.
Note, it may be difficult to detect an image on the un-light display, for example if you have a dark image as your desktop background. So make sure to fully scan your display (top to bottom, and left to right covering the entire screen) with the flashlight technique in order to see any image on-screen.
Check the cable connections to make sure they are not loose. Do you see the image still on the screen when the light goes off? You might have a bad backlight inverter which would cause the light to flicker.
spc12b, Have you tried the flashlight test yet? How old is this monitor? Your monitor has a 2 types of power supplys in it. A switch-mode-power-supply and an "INVERTER" supply. One or both of them could be having a problem. The inverter needs DC from the smps to change it into AC to light up the cold-cathode-fluorescent-tubes that are hung in back of the lcd panel. Let me know results of flashlight test. After screen goes black, hold light 1-2" from screen at different angles. Let me know if you still can see the win-desktop screen even though it is still dark.. Bye for now. louie12fix on fixya or lmistyrel @aol.com
Try looking at the LCD screen at a sharp angle to see if ghost-like video can be seen during the 'off' time of the flicker.
If video is still present even though not that visible, then either the backlight or its power supply are failing.
The color problem could also be caused by a backlight lamp that is not ionizing completely.
hi every one, i hope this helps and am proud to say/or not that i am now using my philips php-19x (aka proview 900w/Mag LT916s Model 900p/Xerox) and yes turn on the monitor 2 seconds screen goes black and the blue power light stay lit, but if you shine a torch onto the screen you can see the lcd display is working, and if you turn the power off and on the cycle starts again, like most of us we checked the web to no avail, untill yesterday. I have been playing with this monitor for 3 months on and off after a kind fellow gave me this monitor for free on uk freecycle and of course i checked all the caps on the psu/inverter pcb and more components all seemed fine checked the ccfl lamps by taking them out of the lcd panel (15 minutes to dismantle) both lamps where fine not orange, a nice bright light, and knowing that if the monitor started woking ok and the back lights did not fail it would run like this for ever until you turned the monitor off / video blanking so i was convinced that there was no fault with the psu/inverter board, and as i stated i found the solution at last (yeh) and here it is many that's to all on the bad caps forum and of course the main man -----barry wilkins-----
Re: Mag LT916s Model 900p 19" LCD dropping like flies
I have got to the bottom of this ,after I got one of scopes out (PM 97) the output of the TL 494 IC was disappearing .The IC seems to crash easily ,I think the oscillator on pins 5&6 actually stops. I cleaned the whole board with an aerosol of PCB cleaner and heated up the PCB up with a small craft heat gun to quite hot . I fitted a 0.01 mfd capacitor across the IC pins 12 to 7 to decouple the VSS supply ,because I felt the cause of the IC stopping could be interference based The monitor now runs for all day with no sign of the backlights cutting out. I found out this LCD display was made by proview.