Servicing Collapsible Solar Lantern
We, the electronic technicians, especially the hobbyists, are a good contributor for preventing electronic waste and are doing a commendable service to the mankind! If we are not there, the number of sets that would have become electronic waste is unimaginable, disposal of which is always a headache for the individuals and/or concerned authorities! Here is another story of rescuing a lamp from this dump!
This is an advanced collapsible lantern, which can be charged on solar power as well as mains and is one of the products that I deal with. One of my customers brought this back saying that it is dead, after using it for many months. I twisted and pulled out the top cover and found that water had gone in, as a result of which board and battery had got shorted, leaked and the acid and water had peeped deep inside. Now, handling this is a risky thing, as it can burn the skin and spoil the tools used, as battery acid will eat its surface! This was a new challenge to me!
Even the gloves we wear can get damaged! I thought for a few minutes how to deal with it and struck with an idea. Sprayed IPA liberally, simultaneously wiping and cleaning the area with a cotton cloth. Repeated this a few times. Since the soldering on the PCB had become almost like cast iron, removed the wires shaking and pulling. I repeated the process until all the top parts were removed, wherever I could see acid leak. The acid had already damaged the reflector of the lamp partially. Completely dismantled the set:
This lamp is assembled this way: The top cover holds the battery and has the solar panel on top of it. The next portion holds the USB port (for charging mobile from it) and Power Inlet, and has the stainless steel holding brackets on both sides. A long screw goes from this to the bottom for holding the lamp portion tight, as this part moves up and down for drawing out to switch the lamp on and push it in to put it off. Once we remove the screw, we can remove that portion and can see an LED Holder, with holes in the centre as well as the positions where the LEDs are fixed on the round PCB.
Then a white dome fixed upside down, which provides a bright and evenly spread cool light. The transparent acrylic cover not only holds both the top and bottom portions like in a drum, but also serves as a protector. The next portion is the one which has a hollow tube in the centre, through which the wires from the bottom portion (from on/off switch and support battery terminals) run. This has two projections at both sides, covered by rubber sleeve and this is the portion that slides through groove provided on the outer black cover. At the round bottom of it, there is a spring fixed on one side to press the switch off when lamp is collapsed and release it when pulled up. The next part is the nut covered by a half bracket to allow wires to run through to the top, to tighten the screw from the top for holding the moving part tight. The next portion is fixed with four screws to the black outer cover, which houses the four additional batteries for extended use in any camp. The bottom cover can be twisted for removal. In some lamps this is screw type. Now, just see the pictures, in the same sequence for visual explanation:
The work that I did on this: After thorough cleaning, checked and found that all the 6 LEDs were short and the board itself cannot be reused. So took a similar 6 LED board, dimension of which was more.
Kept the old LED Board on top of this, marked the diameter, then cut the extra piece. This was possible as the extra piece had only a portion of the negative track. Increased the hole in the centre to match the old LED board. Drilled two holes like in the old board for inserting the board on two stubs provided for it in the housing. Ensured that all the LEDs are properly aligned to fit into the holes provided in the LED board housing holder. Inserted the wires from bottom and soldered the white wire to negative of the LED and soldered a Red wire on its positive.
Brought this red wire along with the yellow and another red wire from the bottom through the centre hole. Inserted the screw from the top and placed its nut at the bottom and after ensuring that the wires are not jammed in any of these and are routed freely on the sides, slightly tightened the screw for just holding it. Cleaned and scraped the joints in the main PCB to remove acid damages and retouched all points using flux. Then soldered all the wires to the main PCB at the marked places. Soldered the AC in wires, solar power in wires and finally inserted the battery on its place and soldered these two wires on the PCB. The PCB has markings on it for connections:
Completed the assembly of the lamp as described above and checked the lamp on/off when pulled and pushed in, charging by AC Power and charging by solar power. See pictures below:
Thus, this lovely lamp was saved from dump!
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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You may check on his previous repair article below: