Dull Display Problem Solved In AMIGO Patient Monitor Model MM1121
This monitor was brought to me with the complaint of dull display. I dismantled the device to troubleshoot and rectify the suspected backlight issue.
The display unit could be detached after removing the LVDS cable and LED power wires. I pulled out the LED unit after removing one holding screw.
It was connected to an LED driver board that used a single IC (PT4119) which steps down the voltage and current suitable for the LED strip. The board was under the metal sheet. Let us have a look:
I tested the LED strip with the tester and found it to be working with a reading of 7.8V:
There was no flickering or dullness. Naturally the suspicion was on the driver board. I checked the components on the board for any leak, open or short and did not find any. I connected the LED strip and applied 12V DC and found the light was very dim. So, either the IC or the coil was defective.
Instead of wasting time on the board, I replaced the board with a new one from my stock. Then re-inserted the LED strip and fixed with its screw and wired it to the new board keeping it at bottom corner for easy accessibility instead of pasting it on to the metal like how it was before. Then applied power and found the Panel brightly lit. I did not connect the LVDS cable at this time:
Then re-assembled the monitor and fixed the bezel as how it was before. I allowed the monitor to run for sufficient time to make sure that it was ok.
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Mission accomplished with ‘medical’ satisfaction getting added to the bag.
Don’t worry! The display shown is without connecting the accessories of the monitor to a human being.
So, don’t do any RIP! (HA HA)
This article was prepared for you by Parasuraman Subramanian from India. He is 76 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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