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Electronics => Repair => Topic started by: Snake____1 on February 25, 2018, 10:12:18 pm

Title: Repair of 8A pb-battery charger. Unkown part?
Post by: Snake____1 on February 25, 2018, 10:12:18 pm

Good evening people.

I'm at a loss trying to repair a charger. It's based off a switch mode power supply, and output just pulsates. I have checked all diodes, main resistors, optocoupler and more...
I get 350v DC on the main side, but on the secondary side it pulsates up to ~3v...

I have a TO-220 component on the secondary side I can't identify, hope someone can pitch in here... (See photos) "markings are: T410 BV4715 (Google search renders nothing)

(https://preview.ibb.co/nvgSDH/IMG_20180225_225414.jpg) (https://ibb.co/kEOw7c)

(https://preview.ibb.co/itBinc/IMG_20180225_225313.jpg) (https://ibb.co/dcpEtH)

(https://preview.ibb.co/cOwutH/IMG_20180225_230625.jpg) (https://ibb.co/kqTk0x)

Title: Re: Repair of 8A pb-battery charger. Unkown part?
Post by: 0xfede on February 25, 2018, 10:31:44 pm

Hi Snake,

it is an AOT410L from Alpha & Omega semiconductor (100V 150A MOSFET)
You can find the datasheet here:
http://www.aosmd.com/pdfs/datasheet/aot410l.pdf (http://www.aosmd.com/pdfs/datasheet/aot410l.pdf)

Best,
0xfede

Title: Re: Repair of 8A pb-battery charger. Unkown part?
Post by: Inverted18650 on February 25, 2018, 10:33:27 pm

http://www.aosmd.com/res/markings/AOT410L.pdf (http://www.aosmd.com/res/markings/AOT410L.pdf)

Title: Re: Repair of 8A pb-battery charger. Unkown part?
Post by: Snake____1 on February 25, 2018, 10:45:24 pm

Thank you @0xfede!

Strange circuitry, seems power goes straight from the SMPS transformer via a relay, to the battery, back through this mosfet and back to the transformer...

Almost seems like they are using the mosfet just for the diode...

Title: Re: Repair of 8A pb-battery charger. Unkown part?
Post by: 0xfede on February 25, 2018, 11:00:53 pm

You are welcome.

I can't say for sure if this is the case but MOSFETs are often used as reverse polarity protection. A good texas instruments application note is here:
http://www.ti.com/lit/an/slva139/slva139.pdf (http://www.ti.com/lit/an/slva139/slva139.pdf)

Best,
0xfede

Title: Re: Repair of 8A pb-battery charger. Unkown part?
Post by: Snake____1 on February 25, 2018, 11:56:44 pm

Found the faulty component! :) The OP-AMP on the bottom, the LM324. Changed it and now it's fully functional again  :-+