An Unused Brand New Monitor Saved From Dump – LG 20MP48AB
This monitor was brought by an Autorikshaw driver (A three wheeler vehicle generally used in our country for passenger as well as cargo movement) who happened to come to my house when a regular customer engaged him for pickup of a TV after service. He had enquired at that time whether a computer monitor which had panel problem could be restored. I said I would give it a try.
According to him the monitor was new and was lying unused during the three year warranty period and beyond, as they had other household affairs and priorities. It was taken up recently to connect to a computer they purchased for starting up a business and was found in this condition:
The display looked like a white curtain with a lot of horizontal lines. He took it to the computer shop from where he purchased it, who mentioned that it was a panel problem and returned it. I told him it indeed was a panel problem and I might have to ascertain what caused it for which I might have to pry open the sides, with possibility of opening marks on this brand new unused monitor. He said ok. The monitor was so slim and bonded with the front frame so tight that I had to use a hacksaw blade to cut into at bottom right corner, in order to insert the blade of a removing tool.
Somehow pried open without severe damages and I was impressed with the compact mother board with its neat connection inside. The mother board was fixed inside a plastic frame, which enabled easy trouble shooting without the need to unscrew and open metal cases like I had to do in many LG monitors before. Let us have a look:
My first step was to check the VGH, VGL, V-com, AVDD and VCC voltages on the scalar board. I found these to be absolutely normal. I studied the scalar board and checked for any shorting capacitors and also checked the ESR of a few caps on the mother board. All these were normal. I also observed a few white tiny bubbles behind the screen, which are the result of fungi formation due to condensation that take place during long storage. Then the next step was to confirm that it was a panel problem and not a ground or shield problem from the mother board, for which I connected a U11 Universal board with Full HD LVDS cable and checked. (I have covered usage of this board before in several of my articles; hence I am not repeating it here) The display was same, as you can see it from the following picture:
As per my techie friends’ advice, I also fixed 10uF/25V electrolytic caps on all the five voltage points. But nothing worked which was a clear indication of internal shorts that could have happened due to the same problem of long storage in its box, top portion of which was open! One of my techie friends’ who always was ready to render a helping hand, marked the places in the scalar board and sent these to me and asked me to remove all the resistors that are in the data tracks. Let us have a look:
These tracks travel to the panel parallelly from both sides. The task was to identify only the data lines (Marked as CLK1, 2 to 6 etc.) and just lift one end of the resistor, on any one side of the scalar board. But when I checked the value of the resistance, it was showing around 48 Ohms and not 0 ohms, like in many other cases. That made my task very tough as lifting one end of these nano sized resistors was very, very strainful not only for the eyes but for the brain too. Then I asked my friend whether there was any other short cut method. He told me then just to cut the VGH line and see and that is what I gladly did on the side shown in the second picture above. But the display got worsened. I am also providing a picture of the earlier condition first, and what you see in the second picture is after cutting the VGH line:
Then I rejoined that portion and cut the R246 on the right side. Hurray! The display was absolutely normal this time, bringing joy to me like a child who was successful in his experiment:
I allowed the monitor to be on for several hours and found it to be working stably well. I did not make any attempt to open the panel case and remove the fungi formation on the back diffuser sheet, as it has a coating on it and any attempt for cleaning would only make it worse. I shared the images with my techie friend who also felt happy about the result.
Mission accomplished with satisfaction getting collected to the bag.
This article was prepared for you by Parasuraman Subramanian from India. He is 74 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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Tito Kanshulu
October 11, 2025 at 6:31 pm
Quite an interesting repair Sir. In your explanation you said that you removed R246 to make things happen. Did this resistor belong to the many resistors your techie friend told you to remove?
Parasuraman S
October 11, 2025 at 8:49 pm
R246 was the VGH line going to the other side. It does not belong to the array of resistors which carry data. Many thanks for your comments and query!
trebel
October 11, 2025 at 7:39 pm
Thank you for all your hard work.
Thank you kindly.
Good tutorial.
Cheers m8.
Parasuraman S
October 11, 2025 at 8:50 pm
Many thanks!
tree
October 11, 2025 at 8:45 pm
Awesome principal, who has accomplished a lot of repairs. Thank you.
Parasuraman S
October 11, 2025 at 11:38 pm
Many thanks!
Albert van Bemmelen
October 11, 2025 at 8:59 pm
The blue screen showed some darker big center spot. But I suppose it was not so bad that it made the picture quality useless. Or it just was a reflection on the photo. If that monitor was never used and still in its original box it better should have some dry plus dessicant Silica gel moisture absorber included to prevent these events. That silica gel is often also used internally in outside placed cameras to prevent moisture on lenses or electronic parts.
Parasuraman S
October 11, 2025 at 11:41 pm
I did not notice any problem with patterns. Customer is still using it and they also reported it to be working very well. The box did not have any moisture absorber. Perhaps the customer would have thrown it out. I have no idea. Many thanks for your valuable expert comments and inputs!
Mark J
October 12, 2025 at 2:36 am
Parasuraman you are an expert at these monitor repairs. Well done.
Parasuraman S
October 12, 2025 at 8:28 am
Many thanks, dear Mark! Credit should go to my techie friends who are always ready to help! Unfortunately, the person who helped me in this case, is no more! He died due to ailments he was suffering for a very long time! Very nice and helpful person! What to do!
Mark J
October 12, 2025 at 11:49 pm
Parasuraman sorry to hear that. All of us on this forum are your techie friends.
Parasuraman S
October 13, 2025 at 12:00 pm
Yes, ofcourse! Many thanks!
Yogesh Panchal
October 13, 2025 at 5:13 pm
Good Repair! Sir,
in CRT picture tube internal shorting is happen after very long life span of CRT Tube,But in LCD Panel internal shoring is unpredictable even in brand new panel.
Parasuraman S
October 13, 2025 at 5:47 pm
Yes, every compromising innovation has its own repurcussion! Many thanks for your comments!
Philip
October 14, 2025 at 2:15 am
This panel repair more or less relates to past incidents of LED/LCD TV shorted panels. But I have often wondered that no sign for the fault ever shows up. My point is Vdd, VGH, etc to the scalar board remain unchanged, or say, no overheating component on the scalar board despite the shorted panel. Looseing a close collegue is such an emotionally hurting experience. It causes heartache and drains one of bodily strength. Your friends demise equally affects me, for, while he was alive he contributed most generously through your educative articles of which I'm a beneficiary. Most of us readers have at one time or another gone through such sorrowful and mind disturbing moments. For avoidance of a shock that comes with dip sorrow, this leaves me often times never bothering to know the whereabouts of my old friends. Engineer Parasuraman, be strong, God will rejuvinate your spirit, and uplift and restore your excellent mood. God will provide another helping hand for your repair adventures. God bless.
Parasuraman S
October 14, 2025 at 9:30 am
Many, many thanks for your involved and concerned comments, dear Philip! After seeing many such departs in my life including very young persons and babies, I have become immune to such incidents and never get my grit disturbed in any way. I continue my work to the best of my ability with same vigour and enthusiasm. Life is a like a train and we are all passengers holding ticket to different destinations. We get in at one station and get out in another. That's all! As there is a techie group, one or other would provide guidance if and when found necessary. May God bless you!