A photographer in a nearby store brought this LCD computer screen to my shop. The problem was a blinking stand by light when hitting the power button. After hitting the power button for 4-5 times, the screen comes on but for a while then it shuts down.
The moment I heard that from the client, I know it was a capacitor problem. The guy told me that he sent it to another repair guy but he could not figure out the problem. So I told him, I will do my best in solving this problem in this LCD monitor.
I took the cover off, and started checking for bad capacitors in the primary and the secondary sections of the power supply and all checked out ok. I moved to the high tension area of the board and I found two capacitors. They were 1000uf/25 volts. I checked them with my ESR meter and both of them gave me a high reading indicating a problem there.
I replaced both of them and rested the LCD computer monitor and it worked fine. I connected the monitor to my laptop and let it run for more than two hours and it did not shut down.
I called the customer who was really shocked that is actually worked. I asked him a question to where he sent the LCD computer monitor to be fixed. It turned out that this guy is a computer guy and has no experience in electronics repair. I gave the LCD monitor to the owner and he paid well for the repair and told me how happy he was to deal with such a guy like me. He said that he has a lot of computer monitors and a lot of electronic equipment that need to be fixed. I was so happy that he liked my worked and that more repair work coming to my shop soon.
This also gave me an idea about the computer guy who could not fix the LCD monitor. I called this guy and then I went to meet him in his shop. We talked about working together; He installs computers and I can fix things needed for his customers. I was so happy to make this deal and that my business is moving forward.
A guy next door who is in the business of selling computers and computer screens brought me an LCD computer screen. The problem was ticking noise in the speakers and there was no picture.
I connected it to my laptop at the shop and there was ticking noise coming out of the speakers and the LCD panel was dark.
I have seen this kind of problem before and it was an easy fix. The moment I took the cover off, I could see a bad bulged capacitor in the secondary area of the power supply. It was a 1000uf/25 volt. Usually when there is a bad capacitor in that area, I check the others to make sure all of these capacitors are in good working conditions. All of them checked ok.
I replaced the bad capacitor and tuned the machine on. I still could hear the ticking noise coming out of the speakers. I was one step ahead when I replaced that bad capacitors but seems like there are more bad components in that area that needed my attention. I turned the machine on again and started doing voltage testing. There was a steady 300 volts at the main capacitor but when I tested the voltages at the secondary diodes, there were voltages there but not steady which gave me the indication that something is wrong in the power supply.
I asked myself, why the bulged capacitors why there is only one that has this problem, so I traced it back from that capacitor and near by it there was an SMD component that was kind of melted component. Near that SMD component was writings near it. This component was supposed to be a Zenner diode. Under a large magnification, I could read on that component 7.5 A. after a long search on the net, I came to a conclusion that this is a zenner diode 7.5 volts. I replaced it with another zenner diode but not SMD component. I soldered it in its place and turned the machine on. The ticking noise was gone and I could see the NO SIGNAL sign coming on the LCD panel.
I connected it to my laptop and I could see a picture coming on and the sound was great. I let it run for about an hour with the cover off to make sure that nothing is over heated especially that zenner diode that I soldered on that board. It was working fine. The voltages were steady and that zenner diode was ok.
I called the guy, actually yelled his name just outside my workshop door and he came running. He was happy that the machine is working fine. I was happy to see it come to life. It was great and the pay was even better.
This LCD computer monitor was brought to me and the complaint was, a dead LCD with a flicking on and off stand by light. It had an external power supply and the moment I turned it on, a green stand LED start flashing on and off. I tested the external power supply and I could see a reading of 18 volts. To make sure that the external power supply was working fine. I add a 24 light bulb (car light bulb) to the socket of power supply and I could see the light bulb coming on steady which is an indication of a working external power supply.
Upon opening the LCD monitor cover, I headed directly to the power board inside and scanned the area looking for something bulged or burnet but I could not see anything like that. With the ESR meter, I checked all the capacitors on that board and found four bad ones that went high in ohm causing the LCD monitor not to work. Usually, I find bad capacitors inside but sometimes when replacing these bad capacitors, I find other problems with either the back lights or the inverter board.
This LCD monitor, came with a separate inverter board and it has only two small tiny capacitors on it and both of them checked fine. I checked the back lights in the LCD monitor and all of them checked ok. So hopefully nothing else is bad in this monitor.
I replaced all the bad capacitors on the board which were found in these locations:
After replacing all of these, I powered up the LCD monitor and I saw it coming to live with nice vivid colors. I connected it to my laptop and let it run for more than one hour and it worked very nicely.
A customer brought three of these LCD computer monitors to my shop. All three LCD screens had the same problem. Shutting down, no screen display and the stand light was flashing.
Usually, when I see a stand by light flashing and no screen display, I know this was a power supply problem and it should be an easy fix. I opened the cover of one of the three LCD screens and soon enough I saw seven capacitors that were bulged. I opened the other two monitors and all of them had the same problem with the same exact bulged capacitors.
The power supply was a separate board than the inverter board. It was an old LCD computer screen. I took the power board out of the screen and replaced all the bad capacitors in the power supply. With the ESR meter, I checked the other capacitors on both boards the inverter and the power supply and all of them checked ok.
The bad capacitors were: two 1000UF/16 volts, two 1000UF/25 volts, one 470UF/25 volts and two 220UF/35 volts. The moment I replaced all of these bad capacitors on the three LCD screens, all three of them came to life. I was an easy fix and good income.
To me it was strange since I got all three LCD screen and all of them has the same exact problem and the same exact bulged capacitors. The job was done fast and easy and I was happy about it.
Often when you format your windows pc or laptop you will boot up to a desktop and find you have no sound or the video is not working at the correct resolution, etc.
First step is to check the cd’s that came with the computer for a driver’s cd.
If you are lucky your lan or Wlan driver was put on and you can access the internet. If not then go get them at the manufactures website. This will help greatly in getting the other drivers needed.
It is all ways good to have a spare computer working and on the internet so you can download drivers and put them on a USB , or Cd and be able to get them on to the pc you are working on.