Yes, It Is The 32.768 Crystal That Fails, Confirmed In this LG AC Remote
Those of you, who were involved in our discussion about failure of this small metal body crystal in Remote Controls, might remember the cases. Nevertheless, I am providing the links so that we all can refresh our memories before we delve into the present case, which is a different brand and make.
https://jestineyong.com/why-the-32-768-metal-crystals-fail-in-lloyd-ac-remote-controls/
https://jestineyong.com/crystal-oscillator-found-defective-in-lloyd-air-conditioner-remote-control/
This time it was an LG AC Remote Control brought by a different customer and in this the observation was it will switch on and after the usual initialization process display, it just shuts off with no display or functions.
I pried open the RC Unit to see the inside:
(The above photo is after I replaced the crystal!) This remote was using two crystals one three pin (I think it was 400MHz) and another, the notorious culprit, 32.768 metal body crystal. I knew for sure what to do. I applied 3V to the battery terminals from an external power supply. But did a checkup with my Oscilloscope and found that the three pin crystal was oscillating, but the failure monger crystal did not:
As the legs of the metal crystal was under the LCD display on the other side and it was fixed with gum, I did not want to force it out lest it should either break or might not have proper contacts with the PCB when put back.
So, I cut the legs, bent it as hooks and inserted the legs of a new crystal and tightened it with a mini plier. Then soldered it well so that it got fixed firmly. Then applied Fevibond so that it did not vibrate. Then used my oscilloscope to check the wave forms:
The RC Unit was working very well and I fixed the back cover and put the batteries inside. It was functioning well, even though the battery cells were weak.
So, my dear techie friends, it indeed is the culprit, if we can believe what we have experienced. Mission accomplished with satisfaction impregnated with knowledge getting collected!
I invite general discussions on this finding for a better understanding!
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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Yogesh Panchal
January 4, 2025 at 3:56 pm
Good Fix! Sir,
Parasuraman S
January 4, 2025 at 7:35 pm
Thanks, dear Yogesh bai!
Waleed Rishmawi
January 4, 2025 at 5:40 pm
I fix AC remote all the time but I never had the chance to replace a faulty crystal on them. I did not know if they get bad either way...thanks for sharing. have a blessed day
Parasuraman S
January 4, 2025 at 7:36 pm
May be climate conditions also do contribute for such failures! But may I a wish you get a chance to replace crystals in future! (LOL) Thanks for your comments, dear friend!
Albert van Bemmelen
January 4, 2025 at 8:10 pm
Most of the time it are the failing silicon/rubbery pushbutton pads on my IR remotes. But the recent tip to add new graphite powder onto the conducting contact pads using cotton swabs was a very good remedy! Hope it will last for a very long time.
Parasuraman S
January 5, 2025 at 10:07 am
Adding graphite powder might be ok. But matching the resistance would be difficult. Many thanks for your comments, dear Albert!
Henrique J. G. Ulbrich
January 6, 2025 at 1:41 am
Good Job, Parasuraman. Concerning Albert´s comment, I´ve also repaired many RCs by adding graphite powder, generally with success. Only one went bad: perhaps the excess graphite powder created a wrong bridge that caused the RC to maintain the transmitting LED on continuously. Even opening again the gadget and doing a careful inspection, the wrong bridge could not be find. I did a complete cleaning trying to remove the excess powder, but nothing. As I had another spare RC I decided to not lose time anymore on that faulty RC.
Mark J
January 5, 2025 at 4:46 am
I have never had to replace a crystal yet while repairing a remote. Good job in the repair.
Parasuraman S
January 5, 2025 at 10:08 am
Yes, strange as it might seem, number of cases of failure of crystals is on the increase! Might be due to climatic conditions too! Thanks, dear Mark!