This rechargeable table fan was brought to me with complaints of not auto cutting off when charging, led continues blinking ever since he bought it and battery is now weak, and so he abandoned it some months. So i open back cover and examine the circuit design. It uses LTHO7 charging ic which is commonly found on some li-ion torch lights. So I decided to replace charging ic thinking probably its shorted,after replacement of ic, battery and press buttons… problem same.
So I checked the LTHO7 ic circuit diagram online and compare it with what is on the fan original board circuit..not the same. So I thought of re- designing it to conform with online circuit. So i did some cutting of tracks and adding joint wires, picture below.
When I charged it, the auto cut off works but when switched on fan, blades did not work…. not rotate.So I return the circuit to its original form,fan stated to work again but auto cut off stopped working again.Well at this point I don’t know what to do, so I call owner to collect his fan, which he did.
After about two weeks he came back with complaints that battery is dead, blades will just tilt. I received fan from him and told him I will get back to him. For some days I was thinking how to solve this problem,so suddenly my brain got activated and creative mind came to play. What if I attach external LTHO7 ic complete circuit board to original fan circuit board and do some adjustment, I marvelled!! So I got this charging ic complete circuit from a torch light,see picture below.
So i desolder off its li-ion battery,than I solder two separate wires to +/- output pads of external ic circuit board, solder the two ends to +/- of the battery,then connect battery to battery input connector pin on fan original board. Drill two holes by the inner side of fan case, each for charging red/green led bulb and charging male usb respectively. Use epoxy to glue the external circuit board to fan inner case.
After glue is harden, plug phone charger to device for a period of time, latter red led light change to green, indicating battery is full. Then switched on the fan and it worked perfectly, with the charging system performing its purpose perfectly too, then call owner for collection, two weeks later I met him somewhere and asked him about the fan…in the affirmative,I received double confirmation of fan working fine from him. This is the finished repair work.
This article was prepared for you by Imoudu Onwumah from Nigeria. He is 62 years old and has just 3 years experience in electronics repairs. I started career in hotel industry as a chef, but then I was doing repairs only in electrical repairs as a hobbyist. In 2018, I decided to learn about electronics which through
Jestine’s electronics e-books and holding my hand, am an electronics techie today.
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Note: You can read his previous article on Defeat DP Rechargeable Table Fan Repaired
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Parasuraman S
February 15, 2025 at 10:20 am
That was a never give up innovative work done, dear Imoudu! Well done! Thanks for sharing! When we are charged within to solve a problem, nothing could stop us! Many thanks for sharing this inspirational article!
Waleed Rishmawi
February 15, 2025 at 12:56 pm
Good job on never give up repairs situations. Thanks for sharing and have a blessed day
Yogesh Panchal
February 15, 2025 at 3:30 pm
Good Job!Imoudu
Albert van Bemmelen
February 15, 2025 at 6:56 pm
After re-designing the circuit conform the online circuit and unexpectedly returning the circuit to its original state you didn't give up and suddenly found a successful way to solve the problem. Kudos Imoudu!
Imoudu
February 16, 2025 at 4:37 am
Parasuraman.S
Thanks for your welcoming comment
Imoudu
February 16, 2025 at 4:49 am
Waleed,Yogesh,Albert
Thanks all for your beautiful comments
Mark J
February 16, 2025 at 4:56 am
Good job on the repair Imoudu.