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Servicing Ikon Megaray Torch
This Ikon MegaRay LED Torch was brought to me with the complaint that it is dead. I learnt through ‘preliminary interrogation’ (LOL) of the owner that one day after charging, when he used the torch, the light diminished and finally went off. I dismantled the torch:
Checked the PCB and found that one 6 pin IC (U2) is burst. Connected a 3.7V supply to the battery terminals of the PCB and found that the Torch and its switch were working. Connected the Adaptor to the socket and noticed that both the Red and Green LEDs were lighting up.
I thought it could be due to high voltage or lightning. The number, if I am not wrong, could be 5765. But I could not get a datasheet of it from the web. I removed the IC and noticed that the PCB was also burnt underneath! I cleaned the surface as much as I could. Then connected the 5V adaptor and checked where the PS is for this IC. The 5 V appeared on pin 1 (?) marked by me just to identify. The next pin on top was the pull down for green LED (Charged indicator, perhaps). The next pin on top was connected to R3, which is grounded. The next pin exactly opposite, at the bottom was the pull down for Red LED (Charging indicator, perhaps). The middle pin on the bottom was the ground. The last pin on the right at the bottom was going to the on/off switch of the torch. Evidently, the charging voltage is passed through this IC and controlled.
Since a replacement IC was not available, as per consent of the owner, I bypassed the IC by providing a FR104 (that was a salvaged diode, so I just used it) Charging diode, and one 1k resistor to RED LED ground:
Connected the DC supply from the AC Adaptor. The Red LED lit up and voltage was present at the terminals for battery charging. I noticed then that the centre pin of the DC socket was loose! So, that could be reason for failure of the IC! Fixed it with solder (Last picture at the top).
Reassembled the torch:
Checked the torch and it worked fine. (I had charged the battery separately using my desktop PS). I connected the DC Charger and found the LED lit.
I have cautioned the customer not to over-charge, as now there is no controller. Also told him not to leave the torch for charging overnight. I liked the Torch, as it was very powerful and there was a focus adjustment at the front. Overall a good piece. But no idea where it is made!
Here is the fully zoomed picture of damaged IC:
This article was prepared for you by Parasuraman Subramanian from India. He is 68 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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