These very expensive products are intended for broadcasting various images onto screens. They are often used to demonstrate products at presentations, training materials at seminars and conferences. Sometimes an unexpected situation occurs: the projector does not turn on, which jeopardizes the event. What to do in this case, and what malfunctions of projectors are especially common?
As statistics show, projector malfunctions are often associated with violations of the temperature conditions of the lamp, with the help of which the image is projected onto a large screen surface. This happens because the lamp gets quite hot, and the cooling system of the device cannot cope - the temperature sensors are triggered, the signal to turn on the lamp is blocked, and the image on the screen disappears. This kind of trouble can happen with any equipment, be it Benq or InFocus projectors.
All models have an independent diagnostic system - it constantly monitors the stability of all components and parts, instantly blocking the supply of electricity to the lamp when the temperature rises.
Let's look at the most common problems with projectors and possible ways to fix them.
Do not forget that different laptops are connected to the projector, which may have different image settings - so the final image on a large canvas may be of poor quality.
To ensure that the product operates stably, never forget about preventive maintenance of individual components and systems.
Quite often there are cases when a seemingly serviceable device, when connected to the home power supply, is not going to start working: the indicator does not light up, the product does not show signs of “life”. The reasons for this behavior are different:
When there are projector malfunctions described above, different devices may behave differently: indicator LEDs blink, fans make loud noise, then everything quiets down and the projector turns off. Before calling the diagnostic center or deciding to show the projector to a technician, try doing a simple check yourself.
Quite often, similar equipment does not work due to incorrect operation by users or power surges in the city power grid. Troubleshooting any complex problems should only be carried out with the help of qualified specialists. The intervention of unprofessional craftsmen or independent dismantling of expensive equipment causes mechanical damage to internal components and parts - the cost of subsequent repairs can increase significantly. If strange problems arise, then immediately call the service center, specialists will come, carry out diagnostics and eliminate the causes of the failure.
A selection of service instructions with diagrams for Benq monitors. In addition, a detailed selection of typical faults and methods for eliminating them
Problem: the monitor does not turn on, but the power indicator blinks. The malfunction is typical and immediately hints to us about problems in the power supply, so we proceed to disassembly. To do this, unscrew all the screws on the back panel of the monitor, including those disguised as plugs. The latter can be removed quite easily if you pry them off. We remove the stand from the mount and unscrew another screw under it.
We pry the case around the perimeter, releasing the latches. Sometimes you have to use physical force on particularly tight latches, but remember one rule - where the plastic fits best, the latch opens. Under the back cover there is a power supply and a signal processing board. Using narrow-nose pliers, unscrew the fastenings of the DVI and D-Sub (VGA) connectors. Disconnect the keypad connector and lift the metal screen.
On the left is the power supply board, on the right is the signal board. Swollen capacitors are clearly visible on the power supply board (marked in red). Disconnect the lamp connectors and unscrew the power supply board. The yellow capacitor is not swollen, but it is close to the radiator, so I also recommend replacing it for prevention.
Quite often, electrolytic capacitors swell if they are located close to radiators and heating components. The electrolyte in them evaporates under the influence of temperature. As a result, the dielectric gasket dries out and overheating of the container with swelling is guaranteed. After replacing all the containers, the monitor turned on.
Common problems with Benq monitors |
Benq E2200HDA on chassis ET0019NA.
Just won't turn on, the indication also does not work:
With such symptoms, 99% of the time you can safely look at the power supply; when checking, I found diode D803 ringing short, through which power is supplied to PO168, having unsoldered the diode, I found it to be fully operational. A continuity test of the seventh pin of the microcircuit relative to the housing showed its short circuit. Having replaced the microassembly with a similar one (FAN6751), the monitor started working immediately.
Benq FP71E monitor on Q7C4 chassis
When I turned on the monitor, the backlight appeared and immediately went out.. It is immediately clear that the problems are in the inverter, specifically after familiarizing ourselves with the monitor circuit, Benq determined the cause: transistors Q815 and Q816 were broken, and they burned out due to the electrolytic capacitor C824 0.22mF 160V (see amateur radio advice). A similar problem may occur in the second arm of the Q808 Q809 C826 inverter.
Benq FP71G on the Q7T4 chassis (the diagram can be downloaded from the link above).
Display backlight turns off, almost immediately, and sometimes after a few minutes of work. I took the advice of repairmen and cleaned the wires of the backlight lamps from metallized foil (There is a known defect that occurs due to metallized adhesive tape. When heated during operation of the monitor, the adhesive tape compresses the insulation and a breakdown occurs) and washed off the varnish from under the SMD capacitors in the inverter circuit, but the problem has not gone away. Further analysis of the circuit revealed a faulty electrolytic capacitor C826. After replacing it, the backlight stopped turning off.
There is a white screen on the monitor screen. Replace the faulty fuse on the LCD panel control board and remove capacitor C102
Spontaneous switching off of the matrix backlight. Poor contact in connector SN804 of the inverter board, blue wire. Take out the petals and put them back. When a defect occurs, the backlight lamps light up and immediately go out; if you turn off the faulty lamp, the remaining lamp glows longer.
Backlight turns on and off spontaneously.
The defective SMD capacitor C841, upon dismantling and inspection, turned out to be split on the bottom side. After replacement, the monitor backlight started working.
Color distortion. Control panel buttons do not work.
There is a reaction only to the "On-Off" button. If you press the others there is no change. The problem is with the EEPROM U4 24C04N chip.
Monitor won't turn on: Power supply is normal. I tried to replace the EEPROM U4 24C04N chip, the monitor turned on, but soon froze again. As I found out, the quartz Y1 24.000 was faulty, ().
Monitor turns off after 5-10 minutes
The 3.3V stabilizer in the power supply IC701 LD1117 is faulty
Benq FP72E on Q7C5 chassis
White screen. After 15 minutes of work
The U11 AAT1164 chip (analogous to max1517) is faulty. After replacing it with an analogue one, the chip began to get very hot, so I had to install it on a heatsink as a preventative measure; a similar problem often occurs in the Benq FP73G monitor on the Q7T5 chassis
All control buttons do not work except power. The button lock mode is enabled, to exit it you must press and hold the MENU button
Benq FP73E on Q7C5 chassis
No sound. The problem is in the TDA7496 chip, after replacing it the sound appeared
White screen In these monitors, this failure occurs mainly due to a blown fuse on the AU Optronics M190EG02 board. Usually in this case capacitors C11, C12, C13 fail
Benq FP91G on Q9T4 chassis
The problem is this: if you turn off the monitor after 1-2 hours of operation, it becomes larger won't turn on, the indicator does not light, and if you wait 30 minutes, the monitor turns on again. Replaced capacitor C712.
If your monitor just won't turn on. Supply voltage 3.3V reduced to 2.5V; 5V to 3.3V due to IC601 NCP1200AP40 chip.
The monitor turns off at varying intervals. Dark image.
The problem is in the inverter, check capacitor C822 (in my case it turned out to be split).
There is an inscription on the monitor Cable not connected
The fault turned out to be in zener diode D4 (I checked it with a multimeter in diode test mode, passed it in both directions)
After an hour of operation, the control buttons froze. The problem turned out to be in the ZD5 in the Exit button circuit.
Doesn't turn on. In the power supply, the resistor R603 burned out and the IC601 NCP1200AP40 microcircuit and the IC602 PC123 optocoupler were also faulty. ()
Benq FP93GS on Q9T5 chassis
Malfunction - White raster.
Check capacitor C193, transistor Q5 ELM13401CA
BENQ FP557s no response to control buttons
The reason turned out to be in the buttons themselves, namely in auto-tuning, in this case.
BENQ FP731 on Q7T3 chassis:
During the inspection, burnt radio components were identified Q743; Q751; Q741; Q753; Q742; Q752; PF751 was replaced with similar or similar ones, when turned on, fuse PF751 blew again and Q759 broke. Upon further search for the problem, a short circuit was discovered in the secondary windings of the T753 transformer.
Benq FP767 on Q7C3 chassis:
The PF751 fuse and the Q759 2SC5707 transistor are faulty due to the first leg of the T751 transformer not being soldered.
Monitor won't turn on. The power supply is faulty, namely the Q601 P7NK80ZFP transistor is broken, the IC601 NCP1200AP40 microcircuit is broken and the resistors R615 R22 and fuse F601 are broken.
Benq T705 on Q7T4 chassis
The backlight does not work.
Problems in the inverter board: Q808 transistors burned out; Q809 2SC5707 Q805 FQU11P06, fuse PF801, capacitor C826.
It turns off after a short time, the indicator does not light, the matrix is white before turning off.
There are problems in the monitor's power supply, because there is an unstable voltage at the output, 5V. It turned out that the IC601 NCP1200AP40 chip and the Q601 transistor were faulty.
BenQ T705 on Q7T4 chassis
The backlight flashes on and off. In one arm of the inverter I found burnt 2SD5707 (item numbers Q808 and Q809) and between them swollen capacitors C801 C707, C708. The yellow fuse PF801 3A also burned out.
Question: I have a problem with my BENQ monitor, the backlight does not work. When the power is on, the monitor shows nothing. Only black screen. Upon careful inspection with a llama, the image is barely noticeable. As I understand it, my problem is that the matrix backlight does not work. Monitor BENQ FR72G+D diagonal 17 inches. How much will such a repair cost and what will need to be replaced?
Answer: You are absolutely right, the matrix backlight in your monitor has failed. There may be several reasons for this. The lamps themselves could fail due to mechanical damage or burn out due to too much brightness. In this case, lamp replacement is required. The voltage inverter that supplies high voltage to the lamps could also fail. Diagnosis of the breakdown and repair must be carried out at a service center; such repairs are quite difficult to carry out independently.
Question: The BENQ monitor does not work, after turning on the monitor it blinks once in white, then just a white screen. What is the reason? How much will the repair cost approximately?
Question: The BENQ T905 monitor does not work at all, there is power to the monitor, but there is no image, what could it be from? I took it apart, everything seems to be in place, the working cable also sits fine, but there is no image. Thank you in advance for your attention.
Answer: There may be several reasons why the monitor does not work when you turn on the computer: a malfunction of the monitor itself, a failure of the video card, problems with the motherboard, problems with the power supply, incorrect installation of drivers and incorrect settings of the video system parameters, etc. If you are sure If power is supplied to the monitor, then it is worth checking other reasons. Next, check the condition of the cable connecting to the computer and its connectors. It's better to try connecting a different cable to check. If it turns out that the cable is faulty, it must be replaced. To check the functionality of the video card, insert it into a known working system unit and connect the monitor. A faulty card will immediately reveal itself. When performing this operation, be careful - the connectors on the motherboard for video cards may be different. A faulty video card requires replacement. A malfunction of the motherboard can be indicated by the self-diagnosis procedure that the computer performs every time it boots. At the same time, an initial test of all computer devices is carried out. Upon completion of a successful diagnostic procedure, a short beep will usually sound. If the motherboard is faulty, then you need to take the computer to a service center. The reason may also be problems with the processor. In this case, only the service will help.
Question: Good afternoon, why does the BENQ FP91GX monitor not work? When you turn on the computer, the screen glows white, but if you look from the side you can see a very vague image. What is the reason? How much will the repair cost?
Answer: In your case, there is damage to the monitor matrix due to a complete lack of power to the matrix. This may occur due to a broken matrix fuse or an open circuit in the matrix DC converter circuit. In any case, diagnostics are required at a service center with a further decision to repair the monitor.
Question: When I turned on the Benq FP71G (17") monitor, there was a slight bang and the light next to the power button went out. Now the Benq monitor does not turn on at all. How much will it cost?
Answer: The pop that you heard most likely occurred due to a power surge in the electrical network. In this case, the network filter protection could be triggered. In this case, turn it off and on again. But a power surge could cause the monitor's power supply to fail. In this case, it is necessary to carry out diagnostics and repairs at a service center. Before doing this, just in case, check the condition and connection of the power cord.
Question: Hello. My BENQ T705 monitor does not turn on. It stopped turning on altogether, it won’t turn on and that’s it. When you press the “on” button, the color of the button at that moment lights up green, and as soon as you release it, it immediately goes out. But the screen remained black, and there were no signs of life. What should I do in this case, and is it possible to cope with this defect myself? Thank you.
Answer: If the monitor does not show any signs of life at all, then it is the cause of the breakdown. First, check whether power is supplied to the monitor? Check the condition of the network cable and how well it is connected. Turn off and on the surge protector. If you verify that voltage is being supplied to the monitor, but it still does not work, then the problem is most likely in the monitor's power supply. For example, the problem may be with the power supply capacitors, which dry out and lose capacity, which leads to such problems. Dried out and swollen capacitors need to be replaced. It is better to diagnose the monitor and replace capacitors at a service center.
