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Old 01-25-2010, 10:55 AM   #1
Eagle2a
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Default Reverse polarity damage to battery charger

Hello, first post requesting help on a problem. I think it falls in this forum since it's technically still a power supply. Anyway, I've been using a Xantrex 2A 3-stage battery charger/maintainer to top-off charge various lead-acid batteries. It's worked very well for that task. The other day I was in a hurry and inadvertently connected the charger with reverse polarity on a battery. Duh! I immediately knew something was wrong b/c the charger clips sparked, which never happens, so I quickly disconnected them but it was too late. Now the charger doesn't have any DC output (I've measured it with a DMM). The battery detection/status LED still lights when I connect it to a battery but the charging LED doesn't. The charger says it has reverse polarity protection but obviously it didn't work. What are the likely failure(s) and what should I check first? Do you think it can be repaired easily? I appreciate any advice. Thanks!

I've attached 2 photos of the circuit board FYI. The DC output is at the top and the 4 white wires are for the indicator LEDs.
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File Type: jpg Img_6868a.jpg (76.5 KB, 36 views)
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Old 01-25-2010, 04:02 PM   #2
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Default Re: Reverse polarity damage to battery charger

Okay I've done some more probing around and gotten more data. I now suspect the MBR1045 Schottky diode/rectifier in the right heatsink has failed shorted, especially since I'm measuring about 40 VAC in the DC output. I also suspect the large diode (blocking?) just above the transformer has also failed shorted, maybe leading to the Schottky diode failure. Any opinions?
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Old 01-25-2010, 04:28 PM   #3
stj
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Default Re: Reverse polarity damage to battery charger

desolder them & meter them "off board"
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