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.
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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.
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 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
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)
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
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.
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.
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.
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.
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.
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.
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.