Multiple Problems In LG Monitor Model W1943C Solved
This lovely Indonesian made LG Monitor was picked up by me from one of my techie friend’s home when I visited him recently for attending an interactive technical study-cum-work. I could not check it at his end as a 12V AC Adaptor with suitable socket was not immediately available amidst other busy schedules there. I carried it back home and took it up on the next gap that I could get.
When I applied 12V to it, it was found dead. I opened the monitor and subjected it to a thorough cleaning. Then looked for the problems by visual inspection. I could not find any bulgy capacitor as suspected. On applying the power, the input was steady; but the 3.3V for the processor was not available. The input of 5V for it also was missing. There was a buck IC APW7142 which handled the conversion of 12V to 5V. The input at pin 2 was present. But the output at pins 7 & 8 were missing. On a careful scrutiny I noticed that the IC had got punctured:
In all probability a 19.5V Adaptor might have been used instead of 12V, which caused the puncture. I replaced the IC, upon which 5 V and 3.3V were restored and the Monitor came on.
When I applied signal, there were horizontal lines on the top and it was jumping too.
I took clear photos of the scalar board and shared it with my techie friend who gave me the monitor and sought for any possible solution. He asked me to check which of the three COFs getting abnormally hot and marked a few tracks that can be cut to bypass the internal short of the panel. It was an LG Panel of a standard quality. The area marked by him was cut by me, upon which there was only a white display:
Then he asked me to reconnect the first two lines from the left, as some monitors carry V-Com voltage through the first COF to the panel. I rejoined the first two tracks, upon which, the display was absolutely normal:
Then I connected the Monitor to a computer which had come for service, connected a key board and a wireless mouse and switched it on. It was working perfectly well. I allowed the Monitor to be on for several hours, before taking it to Hospital, where I worked.
It was a gift given by my techie friend and I therefore collected only a minimum charge just to cover the cost. Mission accomplished with extreme satisfaction, which found its way to the collection:
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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You may check on his previous article on Dead Computer (Locally Assembled) Brought Back To Life
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Albert van Bemmelen
April 26, 2025 at 5:53 pm
It is still wonderous to me how easily you are often able to do these magical checks on which of the COFs are getting abnormally hot and simply cutting a few tracks to bypass the internal short of the panel!
Parasuraman S
April 26, 2025 at 6:30 pm
To be frank with you, dear Albert, I join you in your wonder. Some of these things are done with intuition working from within. As I always say, both the technician's and customer's luck should match, to fetch a good result! Many thanks for your expert comments!
Waleed Rishmawi
April 26, 2025 at 11:52 pm
Good repair article. I have seen this method used on TV panels by cutting the traces out of the T-Con but I never seen this method used on computer monitors. Thanks for sharing.
Parasuraman S
April 27, 2025 at 5:56 pm
Happy to know that it was useful! Many thanks for your continuous supportive comments, dear friend!
Mark J
April 27, 2025 at 1:48 am
Parasuraman you have good intuition. Plus you are a very good technician. good job on the repair.
Parasuraman S
April 27, 2025 at 5:57 pm
Many thanks for your lovingly encouraging comments, dear Mark!
Yogesh Panchal
April 27, 2025 at 3:52 pm
Good Job! Sir,
Sometimes we give up because of fear of unsuccessful or not sure about the outcome.
Parasuraman S
April 27, 2025 at 5:57 pm
Yes, very true! Thanks, Yogesh Bai!
Muykit
April 27, 2025 at 6:54 pm
Good job. The monitor looks big enough to be a TV. Most tvs of that size use 19V adapter. No wonder the supposed used adapter caused destruction.
Parasuraman S
April 27, 2025 at 9:51 pm
Yes, probably! Your observation deserves an applause! Many thanks!