This problem happened to me with my BenQ FP91G+ monitor. This is a 19" monitor with an old-fashioned 5:4 width to height ratio. These monitors are ideal for doing programming work as you have a large image and a lot of lines of code going down the page to help you debug the code. Replacing these monitors is expensive (~$170) because this 5:4 ratio is now rare. I have a basic knowledge of electronics so I repaired the monitor myself and it has been working perfectly ever since. If your own monitor develops the "2 seconds to black" problem then it is likely that the monitor works in the same way that mine does and so, hopefully, the repair I am going to describe, also applies to your own monitor. But even the electronics of the BenQ FP91G+ changed over time such they they stopped using "high current switching transistors" (that you will read about) and instead relied on very high current MOSFETs to do the work of both the MOSFETs (that you will read about) and the high current switching transistors. These very high current MOSFETs tend to come in a DPAK package (as will be explained later) with its back heat sink soldered onto a plate on the circuit board to dissipate the heat. It will be the same side of the board as the controlling chip with its typical 16 pins and will be difficult to desolder for testing purposes, as well at to connect it up to the component tester. But hopefully, with these later designs, these transistors will not burn out. The video board on the other side of the inverter board got smaller as well to the point where it was tiny. The only problem I have with the later designs is that I have found the brightness and contrast of the screen to be not as good as my original monitor (which I repaired) and not so easy to read lines of code.
So long as you have a basic knowledge of electronics and you are willing to get out a soldering iron and replace a few electronic components then you can easily fix this yourself, 99% of the time. Why this happens and how to fix it follows. Luckily, your monitor can nearly always be fixed using inexpensive components - in most cases, electrolytic capacitors and high current switching transistors (if it uses them).
I have a feeling that millions of computer monitors have been dumped in landfill sites when they could have been easily fixed for less money and less effort than it took to dump them. Maybe this page will help reduce global pollution.
I know that people bend wires like this because they do not have three hands. Ideally, there would be one hand to hold the component in place, one hand to hold the solder in place, and one hand to solder the component in place. But you can eliminate the hand needed to hold the solder in place and replace it with something better. Assuming you have narrow gauge solder wire then you can spiral it around a thin stiff metal rod (like the blade of a fine jewellers screwdriver) and then cut off this spiral and keep it for soldering purposes. It will not unwind itself. Then when you need to solder a new capacitor in place you cut two short lengths off this spiral with enough solder on each for the solder joint. These are to slip over the wires and the weight of these will bring it to the bottom where you are soldering. Then you hold the component in place with one hand, slip the two pieces of solder spiral over the two wires, then solder each wire in place while still holding the capacitor in place. It really is easy.
But we are not done yet. Assuming you have done this and not bent the capacitor wires then you have long wires you need to shorten. But leave about 3mm clear of the solder blob for these such that somebody looking from the back of the circuit board can see there is a likely capacitor soldered into place, plus this 3mm will give them enough room to attach the crocodile clips of an ESR meter (explained later) for quick and easy testing.
In a sense, you are slightly stealing the job of electronics repair
technicians by fixing your own monitor but please don't destroy their job
by inconsiderate soldering techniques. Try to be as professional as they
are trying to be and then everybody should be happy.
If you get the buzzing sound or the smell of ozone or
then read no further, as the problem does not lie with the inverter board
that the rest of this page is dedicated to telling you how to fix.
If you want to save time removing electrolytic capacitors from the circuit board, testing them with the SainSmart, and resoldering them afterwards, then you can use the MESR-100 V2 (~$70) to test electrolytic capacitors while still soldered on the board (the V2 version, which has a blue and yellow table of values at the bottom of the meter, is an improvement on the original version so you should order this one). Note that the MESR-100 V2 comes with test leads that are quite short, making it a little difficult to use. This is because the leads must be short enough not to have any measurable "inductance" in them so it is not a good idea to get replacement leads that are longer for this meter.
In an extreme case (<1% of cases - I don't have one of these) you will need an Anatek Blue Ring Tester (~$65) for testing transformers while still soldered on the board.
It is worth mentioning at this point that it is highly undesirable for somebody to "get clever" and stop this chip from doing its work of shutting down the backlights after two seconds. You could change its timing capacitor or timing resistor to give a longer time than two seconds or even make this time infinite, but it would be dangerous to do so as this could cause a fire.
You can easily fix this "2 seconds to black" problem yourself if you are willing to take apart your monitor and replace a few electronic components that are cheap and easily available. For very simple cases you need no test equipment at all and this might cover a bit more than 50% of the cases. For more complicated cases then you need some test equipment that will not cost the Earth - and you should consider money spent on good test equipment not as an expense but rather as money invested.
For 99% of the time, this problem occurs due to components on the inverter board that have gone bad. Electrolytic capacitors, in particular, go bad, and will fail after a time. High current switching transistors can go bad.
To fix this problem, you need to get the inverter board out of the monitor to work on it. So first you must remove the inverter board. To do this, switch off the monitor, pull the leads out (especially the power lead) and leave it for at least five minutes so that the monitor becomes safe to disassemble. Then take it apart, noting what screws go where. Your monitor will have a base and there is often a screw behind the base that needs to be removed. With all the screws out then you can slide the base out and it will give access to the final screw you need to remove. With all the screws removed then the back of the case can be levered then pulled off. There will likely be two slots at the bottom to allow something to be inserted so you can lever the case halves apart and then it should be possible to remove the back of the case by pulling on it. There will maybe be some more screws to remove to allow you access to the inverter board (remember that the inverter board is the one the power plugs into). Remove this board, making sure that you know how to put back anything you are unplugging from it. If there is any doubt about what plug goes where then mark these plugs with a felt tip pen in a way that you will know which goes where when you reassemble it.
So now you have the inverted board in front of you. You are going to run some checks on it. You should never put the power lead into this board until after you have reassembled the monitor. All the checks you are going to do should be done without connecting this inverter board to the power supply at any time. This board is capable of killing you if it is connected to the power supply and you touch it in the wrong place and connecting it up even for a second can charge the capacitors on it so that it could give you a nasty electric shock even with the power lead removed.
So now we start with a visual inspection of the components on the board. What you are looking for is bulging electrolytic capacitors (Google for more images). If you see any bulging electrolytic capacitors then this is very likely the sole cause of this problem with the monitor screen going black and if you replace those bulging capacitors with replacements of the same capacitance and at least the same voltage and at least the same temperature rating then this will likely fix the problem. When ordering these, note the dimensions. Dimensions can vary a lot for identically rated capacitors and you need one that will fit on your board. When soldering these in place then you have to make sure the stripe running the length of the capacitor is on the same side as the white blob shown on the circuit board where the capacitor leads go in, as electrolytic capacitors have a polarity and need to keep to the correct polarity (the stripe is for the negative wire).
Next thing to visually inspect are the ceramic disc capacitors where the backlight plugs go in. If any of these are cracked then they need to be replaced. It is rare for anything to go wrong with these but if they "look" wrong by appearing cracked then they are wrong. You will see that on one side there are some numbers and letters.. They are not marked in the same way as the electrolytic capacitors because they are usually so small that there is not much room for writing and so a special shorthand is used. There will be two lines of writing. The bottom line is a voltage rating such that "3KV" will indicate 3000 volts. The top line consist of two or three number, sometimes followed by a letter. The first two numbers are the significant digits for the value of the capacitor in picofarads. The third number (if there is one) is for the number of zeroes that go after the first two numbers such that 221 would mean 220 picofarads ("22" with "1" zero following it). If there is a letter following these two or three numbers then that is the capacitor tolerance code (if it lacks a capacitor tolerance code then you should assume +-20%). If one of these ceramic disc capacitors has cracked then you must replace it with one of the correct number of picofarads. If it has a tolerance code then you should also try to get replacements with at least as good a tolerance. As for the voltage, you can step this up if you want to. Suppose a "2KV" capacitor is cracked then you would be perfectly justified in replacing it with a "3KV" capacitor to make it less likely to blow again.
Given that you had bulging capacitors in the first place and/or maybe
a cracked ceramic disc capacitor and you replaced them, switched the monitor
back on and it solved the problem then you have performed a fix using just
one or more replacement capacitors and a soldering iron. All done without
the need for test equipment - a great achievement!
But, if you do not see bulging electrolytic capacitors or cracked disc capacitors or you replaced the bulging capacitors and cracked disc capacitors but this did not fix the problem then you will need an electronic component tester that is capable of testing capacitors and transistors. If you Google "Sainsmart transistor tester capacitor" then you will find a component tester that does all you need for about $25 (it does not come with the common 9 volt battery that you will need to power it). I will assume that you have a component tester that can do everything this SainSmart tester can when I explain how to trace faults in your inverter board. If you desolder a capacitor from the circuit board and plug it into the component tester then the tester will tell you its measured capacitance and its electrical resistance known as ESR. If the measured capacitance shows lower than 20% below the markings on the component then it needs to be replaced. As for the ESR value, then for electrolytic capacitors this should not show a value more than what you get when you divide 6 by the square root of the number of micro farads (you can calculate square roots using a calculator). To give a working example, in the case of a 1000µF capacitor then its ESR should not be more than 6/sqrt(1000) = 0.2 ohms (approximately). So if the ESR shown is higher than 0.2 ohms for a 1000µF capacitor then it needs to be replaced, even if it shows a capacitance in the good range of 80% or more of the value shown on the component. If an electrolytic capacitor shows a good ESR value then it is rare for it to show too low a capacitance value so we can usually rely on the ESR value alone.
You will need to test all the electrolytic capacitors and replace those that fail this test. Of course, desoldering these capacitors, checking each one and then resoldering them afterwards (making sure the polarity is correct when you resolder them as explained above) is time consuming. If you want to save time then you can use a special ESR meter designed to work with capacitors still soldered in place (i.e. "in circuit") such as the MESR-100 V2 (that costs about $70). Using one of these ESR meters then if a capacitor shows a good ESR value on the board then you can assume the capacitance value is also good and leave it in place.
So, with this more intensive testing of the capacitors, you may have replaced one or more of the capacitors that were not bulging but failed the test. All electrolytic capacitors that fail this test need to be replaced because they will give you trouble sometime in the future. But unless you came across an ESR value that was way higher than what it should be then replacing these capacitors will probably not fix the problem because you probably have some blown high current switching transistors on the board. These transistors will be near the high voltage transformers which are near where the plugs of the backlights go in and each pair of these transistors will likely share a block-shaped capacitor. These transistors will have three pins and will likely show on the board as a "Q" followed by a number. The transistors will have a metal heat sink on one side and this will coincide with a thickened white line on the circuit board so you know which way it needs to be soldered in. You will have to remove each transistor (there are probably two pairs of these) and test them in the component tester. If the component tester does not tell you it is a transistor then this transistor has blown and very likely the other transistor in the pair has blown as well. Conversely, if the component tester tells you it is a transistor then it is working okay and the other transistor in the pair will be okay as well.
This should detect the fault but if all the transistors test okay then you have a problem elsewhere with a component on the board. This would be rare as it is nearly always due to bad electrolytic capacitors and bad transistors. The fact that your monitor lit up at all when you switched it on means that the board is "nearly" working. And now you have a component tester that will accept two or three wire components so you can test other things as well. Check the ceramic disc capacitors near where the backlight plugs go in. You should be able to do this without desoldering them if you have two short pieces of wire you can put into the component tester and then use leads with crocodile (alligator) clips at both ends to join these up with the wires of the capacitors (if this doesn't work then you will have to desolder them). If the capacitor does not have a tolerance code then assume +-20%. Often, these ceramic disc capacitors will have values near to +20% of the marked value, unlike electrolytic capacitors which are often near the -20% value. If the component tester gives a value that is wildly wrong or the component tester can not work out that it is a capacitor then it needs to be replaced. The ESR value is of no interest with these and most likely the component tester will not show an ESR value. These disc capacitors do not have a polarity so you can solder them in either way, but you should make sure the side with the values marked on it is on the more visible side.
If the ceramic disc capacitors check out okay then you will find other transistors on the board. Check these, starting with the one or two transistors closest to the high current switching transistors. These are MOSFET transistors and cost a lot more than the high current switching transistors. If the component tester does not know what they are then the transistor has blown.
At this point, I am going to assume that a pair of high current switching transistors near the high voltage transformers have blown (later versions of eletronics do not have these and instead rely on very high current MOSFETs). If so then they need to be replaced. If two transistors need to be replaced then you will need to order at least four replacements, as I will explain later. Most transistors come in a choice of two package types, called IPAK or DPAK, with each package type having a different pin configuration (see example) so you need to be sure to order the correct package (usually IPAK) that matches your transistor pins once you have identified what the transistors are. You also need to consider what caused the transistors to blow in the first place and try to eliminate that possibility. One thing that can cause them to blow is that one of the pins of the capacitor they share is becoming detached from the solder. Also, that some of the pins of the high voltage transformers are becoming detached from the solder. So if you identify the pair of transistors that have blown then you also have to resolder these two capacitor pins and resolder all the pins of the associated high voltage transformers to try to remove the cause of the transistors being destroyed. If this is not done then the transistors might blow again in a few days. What can cause confusion is that a new transistor may have a fault in its manufacture and if so it has a high chance of blowing early. And if it blows it will take out the other transistor in the pair. This is why you need to order at least four replacements if two transistors have blown. So you might have gone to all the trouble of resoldering these pins and yet the transistors blow again. Then you have to replace them and resolder all the pins yet again and see if it happens again. If these transistors blow a second time then you should assume that there is a serious problem elsewhere. A prime candidate will be a short in the windings of one of the associated high voltage transformers. You will need a special "ring tester" to test the transformers if this happens. There is an Anatek Blue Ring Tester you can get for this that costs about $65. Like the MESR-100, it has a huge advantage in being capable of in-circuit testing such that you do not need to desolder the transformers before testing them which would be time consuming. And, of course, you will need more transistors for when you replace one of the transformers. But don't worry - these high current switching transistors are cheap. You can get a pack of twelve transistors for hardly anything and I recommend you do that from the outset.
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