Question about Princeton Digital LCD17 17" Flat Panel LCD Monitor

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Power up problem

I am an engineer and have traced the problem to a driver on the small high voltage circuit board. Where can I get the board which is a SAMPO QPWBGl9931DLD. The components are not labeled so replacing the driver would be impracticle. I hate to fill our landfils and would like to save it. Gary

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Re: Power up problem

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Posted on Sep 18, 2007

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Monitor doesn't have any power

Be sure you check the MOV protective components and High Voltage circuit as well. Component level repair on monitors is very tricky.
So many of the circuits are dependent on each other. You could chase your tail for a long time trying to figure out.

Nov 29, 2013 | Computer Monitors

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Samsung 2233RZ going black after 1-2sec

First if you can, try the monitor with other PC first to make sure it is not the PC problem.

If it behaves in the same fashion, then most probably has dying power supply due to bad DC filter caps, just see the top side of the caps to ensure it has not bulged up distorted.See the images bellow
12_24_2012_5_33_15_pm.jpg OR


Then there is the logic board. Plug the monitor in but do not activate the power switch so the backlight inverter circuits will be off. Check the 5vdc and the 12~24vdc to make sure they are OK. They should be tested with the load, you can use 6V 1A (6watts) lamp for the 5vdc, and car lamps such as 1157 (12v 8watts lo/26watts high) turn signal brake lamp using high filament connection for testing the 12~18vdc (or use two 1157 in series for 19~24vdc) for the backlight inverter circuits.
If the power supplies are working, the output voltages should be steady at the rated voltages. The power supply will go into shut down if it detects too much current draw due to false in the power supply or short circuits in the backlight inverter or in the logic board.

The backlight inverter circuits:
It takes the 12~24vdc and converts it to high frequency AC to drive the inverter transformers CCFL (Cold Cathode Fluorescent Lamp) assemblies. The transformers will drive the CCFL by applying the start up voltage (around 1500~2000v), when the CCFL start conducting, the voltage will drop down to about 500~800v.
The inverter has detection circuits to detect open circuit if the lamp is not attached or does not fire up after the start up voltage is applied, it will go into shut down. It will also shut down if the lamps draw too much current due to ages (when lamp gets old it will draw more current).
The inverter gets two signals from the logic board, one is the backlight ON/OFF signal, the other one is the Dimming signal for the lamps.
Common problems:
Bad filter caps, resonant caps (in the inverter output circuits), blown transistors/IC, shorted or open transformer winding.

If you are confident with your skill then go ahead else go to an authorized outlet for repairing
Do write back if you face any difficulty while working on the monitor

Dec 22, 2012 | Computer Monitors

2 Answers

It is m215hwo comes on for a few seconds then goes off


There could be few possibilities.Unfortunately, as i am not there, i could only provide few details that would help you to diagnose the problem and take an appropriate action to resolve it :-

1.If there was something wrong with the graphic card, you would see atleast some Junk data (garbled image or something) on your monitor.
2. When the monitors goes off, the light would had gone "off" or changed color (if there is a sleep mode light). But it stays white and this shows that the monitor's main board has issues. (issue can be anything like some IC getting heated up or a loose connection)

1. Make sure that the power and data cord of your monitor is fixed tight. (behind desktop and behind monitor). My guess is you have already done this.
2. Use this monitor with some other computer and see if it works fine. If it does, than there is something wrong with the graphic card or its compatibility with your monitor. If it doesnt, than get it replaced.

Mostly this happens because of a bad Data or Power cable of monitor. So replace both the cables of Acer monitor and see if it works.

If it still doesn't work than its 100% a hardware problem on the circuit board and unless its in warranty, the repair will not be worth it.

Let me know,if needed further assistance.

Hope i helped you.

Thanks for using ' Fixya ' and have a nice day!!

Apr 01, 2011 | Acer 22" X223w LCD Monitor

2 Answers

I have a v173 lcd monitor by Acer. Suddenly yesterday the screen went dark. The power seems to be working as the blue light for the power button is "on"/lit. When hitting the power button the...

You need to check the fuse (round black component next to the small green circuit board as shown on the left of the picture), DC filter caps for domed tops, DC voltages. Tho have to fix will not be worth it. The problem is more likely to be the small circuits board (on the left of the picture).

Basic LCD monitor and TV troubleshooting guide:
Failed TV and Monitors pictures:

Learn about bad caps:

Capacitors kit: he can make you a set of caps for you.

Or just make sure to use caps with low ESR, 105c, high ripple current, long life rating such as PANASONIC FM or FC series.

Mar 15, 2011 | Acer Computer Monitors

1 Answer

Checked all but not helpful. when i disconnect high voltage connectors from supply unit then power led goes stable but no display

This is typical as the SMPS power supply is shorted when the connector is on to the board. when you remove the connector, the short releases and the power resumes as the SMPS has a high current cut off for protection.
So the easy way out is to have a multimeter and check the power line to the circuit disconnected to check out the shorted driver. Once you have zeroed in to the component release and connect power supply to confirm. Now replace the shorted component.
make sure that any high voltage in circuits are discharged when you use the ohmmeter in the circuit.

Oct 11, 2010 | Philips Computer Monitors

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Flashing green light and no picture. Resetting the power source and the connections won't work.

Open the monitor and find the power PCB. Look for blown capacitors. Replace all low voltage capacitors even if they look OK.
The power PCB is overloaded by shortage in these old capacitors.
If the monitor is not fixed now, replace two more capacitors - the big one, on 400V and a very small one on 50V in the high voltage circuit.

Aug 15, 2010 | Acer V173B 17 inch LCD Monitor

1 Answer


Make sure you unplug the power the monitor and let it set for 5-10 Minutes to drain off any residual voltage. I just repaired a FP7317 with the same problem. I cleaned up bad soldering and there are 2 small transistors that are marked 2N7000. on the end of the circuit board where the lamps plug in. The are N Channel Field Effect Transistors that are for high speed, high voltage switching. One of these went open on the monitor,I replaced the pair of Transistors and it's now working fine. There's a monitoring circuit on the power supply for backlights, whether it be on a Monitor or LCD TV. If one output to a lamp goes out, the comparator senses it and shuts all the outputs down. This is known as "Protection Mode" Had the same thing happen on a 32" Funai LCD TV. It was given to me and I replaced a $5 transformer and now it's working well. I also changed out the Electrolytic caps in the power supply while I had the board out just in case one of those let go later on. The monitor worked with just the transistor replacement though. Good luck, I hope this helps.

Jan 04, 2009 | Compaq FP 7317 17" LCD Monitor

1 Answer

Capacitors??? WOMAN NEEDS HELP PLEASE!!!???

The term: "it has no power" is not specific enough. If the actual led indicator light on the front of the monitor lights up with a green color, then goes out or starts flashing, then maybe, perhaps the problem with the monitor is that the high voltage power supply for the screen backlights is not working. The common components that fail are the capacitors on the high voltage power supply board. If the capacitors are swollen or leaking, they are probably bad. You must replace a capacitor with the exact size of capacitance. You cannot replace with a "stronger" capacitor. You can replace with a higher temperature rated capacitor, if the capacitor will fit in the alloted space on the circuit board and in the case.

Aug 06, 2008 | Computer Monitors

1 Answer

Mag 19" LT916s

This is a common problem due to capacitors in the inverter circuit going bad. The inverter provides the voltage to light the backlight, so the lamp is usually not the problem.

If you open the case on the monitor (sometimes that's a challenge all by itself) and follow the wires from the backlight to the circuit board, you'll find the inverter circuit. There are normally a couple of transformers (they may be small square cases or round coils of wire on black or gray forms), some transistors, and the infamous capacitors. The caps are small cylinders with printed values on them, like 4.7uf, and also a voltage rating. Most of these are values you can find at Radio Shack, so if you or someone you know has soldering experience, you can try changing them. Stick with the original capacitance value (the uf number), but try to get a slightly higher voltage rating if you can. The voltage ratings come in standard values, like 16 volts, 25 volts, etc. The higher voltage parts will be a little bigger but should still fit. They go bad because the rating wasn't high enough to begin with. But it saves the manufacturer a little money on each unit. Make sure you observe the polarity of the capacitor (plus and minus, with some kind of marking on the circuit board to show you) when you put in the new ones.

Jun 08, 2008 | Mag Innovision 19" LCD Flat-Panel Monitor...

5 Answers

BENQ FP731s Monitor Problem white blank screen

You have a serious problem. ie. only the back light is working in your monitor. You might need to replace the TFT associate components.

May 06, 2007 | BenQ FP731 17" LCD Monitor

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