Battery charger blown resistor

Discussion in 'Technical Repair' started by osbaldwickscouts, Jul 15, 2017.

  1. osbaldwickscouts

    Thread Starter New Member

    Jul 15, 2017
    3
    0
    Good afternoon

    We have been using a sealey autochage12 12v/6v battery charger for many years we only use it a few times a year to charge a few batteries before some camping trips. Last time it was used the charger powers on but will not charge.

    I have checked the circuit board and found a blown resistor, I have attached pictures. I have contacted sealey to try and get a wiring diagram but as this is a discontinued model i'm not holding my breath. I tried maplins as they are the only shop around me which may have been able to help but they had no idea.

    Can anyone help identify what this resistor is?

    Thanks

    Ian
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    6,198
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    Have you tried to measure it with a dvm, are there any colours on the other side?
     
  3. osbaldwickscouts

    Thread Starter New Member

    Jul 15, 2017
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    0
    Another leader tested with a meter but said the results were not right, not sure what he means by that.

    There are no more colours on the other side of the Resistor the bottom is black where it has burnt. It's hard to see how many colour rings would have been on it we think maybe 4
     
  4. dl324

    Distinguished Member

    Mar 30, 2015
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    Can you trace the circuitry around the resistor and give us a partial schematic?
     
  5. #12

    Expert

    Nov 30, 2010
    17,702
    8,888
    Karnac the Magician says: It looks like main power in, part of a filter with the first electrolytic caps. 10 ohms or less.

    Of course, that is called magical thinking. It's just a guess.:D

    W're going to need to know something about a partial schematic (dl324) maybe how much power that board uses, and expect one of the big, black capacitors took a dump.;) Then again, the main pass transistor might have died and the circuit board tried to charge the battery all by itself.:(

    See? It's all guessing, so far.
     
  6. osbaldwickscouts

    Thread Starter New Member

    Jul 15, 2017
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    Sorry I have not posted again I have been away with work and just catching up.

    I have now been given a picture of an intact Resistor it looks like it's a 120ohm brown-red-brown-gold but the Resistor is a grayish colour I am assuming this means it's different to the blue of yellowish ones that you can buy? I had no idea there are so many different types of Resistor

    Also can these be installed the wrong way round? I am guessing if installed backwards it would have a different rating?
     
  7. IMP002017

    Member

    Jan 28, 2017
    171
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    A Resistor is Blind to the way one installs it. So either way current flows just the same.
     
  8. dl324

    Distinguished Member

    Mar 30, 2015
    4,593
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    The body color isn't significant. What's important is the wattage which you used to be able to tell by it's size until manufactures started complicating things by making smaller resistors with higher wattage ratings.
    Resistors don't have polarity.
     
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