Strange Case Of Elec. Cap Defect In SONY LCD TV RC Unit
Unlike the usual cases, this RC unit belonged to my wife. She complained that it did not respond to commands. I brought it to my service table and checked to find that the batteries were good. So, I pried open it and subjected it to a thorough cleaning using IPA, which we all do normally to ensure proper contact of the carbon coated buttons with the corresponding coatings on the PCB. But the RC Unit was still not working.
The transmitter diode was also good as it showed life when checked through my mobile camera, using my analogue multimeter in X1 position, ensuring correct polarity. So the rest of the two components were the IC and one capacitor, 47uF/16V (mini type). When I checked it, it was definitely found out of range. I just replaced the cap and then tested the RC Unit and was amused to see that it was working! This is a very strange case, indeed! Usually, the crystal would have stopped working, replacement of which would bring back life for RC Units. But in this RC Unit, there was no external crystal.
Anyhow, for me it was sheer luck, if I can say so, as I could get applause from my wife for having fixed it. Mission accomplished very easily, with double satisfaction getting added to its 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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Albert van Bemmelen
August 31, 2024 at 7:12 pm
So I guess it was no real mystery here after all, it being the usual ecap culprit. lol!
Parasuraman S
August 31, 2024 at 8:14 pm
Yes, dear Albert! No mystery, but the failure of 16V ecaps on a 3V supply is very rare.
Waleed Rishmawi
August 31, 2024 at 9:59 pm
Ah the joy of replacing caps to make things work..lol. Good job my dear friend and thanks for sharing. Have a blessed day
Parasuraman S
September 2, 2024 at 8:16 pm
Ha! Ha! But only one! (LOL) Thanks, dear friend!
Mark J
September 1, 2024 at 12:05 am
Thank you for sharing. I look forward to more of your radio repairs.
Parasuraman S
September 2, 2024 at 8:15 pm
Many thanks for your wonderful supportive comments!
Tayo
September 1, 2024 at 12:18 am
Great save Maestro...
Proving once again why your wife is the luckiest woman in the world!
Parasuraman S
September 2, 2024 at 8:13 pm
Oh! That is an awesome compliment! Many thanks, dear Tayo!
Imoudu.O
September 1, 2024 at 5:53 am
Oh, i never knew IPA can be used to clean RC, i thought it will desolve away the carbon, i do use pensil carbon tip to enhance.Well i will
try this some day.Thanks for sharing.
Henrique J. G. Ulbrich
September 2, 2024 at 12:12 am
OK, Imoudu.O, the carbon from a pencil also usually solves this type of maintenance. But you must take care of the excess. I recently did a maintenance like this, but the excess of carbon powder created a leakage in one of the keys, making this key to drive permanently the RC. I could only discover this situation when seeing the LED activity with the smartphone camera. Another cleaning resolved the problem.
Parasuraman S
September 2, 2024 at 8:09 pm
Good input! Thanks!
Parasuraman S
September 2, 2024 at 8:14 pm
IPA is the safest to use on RC Units. It only cleans the dirt! But you should use a cotton bud and never apply force!
Henrique J. G. Ulbrich
September 2, 2024 at 12:16 am
Good job, Parasuraman. Did you after test the capacitor?
By the way, I recently did a RC service and noted the crystal's absence. Perhaps the RC does not need such a component (difficult for a digital circuit to operate without...) or the crystal is embedded in the IC. Anyone could explain?
Parasuraman S
September 2, 2024 at 8:11 pm
For some Remote ICs, there won't be an external crystal. It would be inside the IC itself.
I did test the cap and that is how I came to know about its defect!
Many thanks for your comments and involvement!
AdamS
September 2, 2024 at 6:12 pm
Use of a 16V electrolytic capacitor on a 3V supply is not a good idea. Whilst we all know of the problems of putting too MUCH voltage into an e-cap, if the voltage going into them is too low, it can be insufficient to keep the internal oxide (insulation) layer maintained, and they will gradually degrade over time.
Parasuraman S
September 2, 2024 at 8:12 pm
Thanks for your expert advice! That was the company's design! Moreover, I did not have any 10V cap with me!
Yogesh Panchal
September 5, 2024 at 3:13 pm
Good JOB! Sir,
Parasuraman S
September 5, 2024 at 11:56 pm
Many thanks, dear!