Newbie request for help

Discussion in 'The Projects Forum' started by Trevor Rymell, Sep 27, 2014.

  1. Trevor Rymell

    Thread Starter New Member

    Sep 27, 2014
    9
    0
    Hi, Newbie here. I hope I'm posting this in the correct forum.

    I'm hoping to get some help or advice about how to repair the ballast circuit of my bench magnifier light (here) http://i74.photobucket.com/albums/i280/sacentre/20140926_225250.jpg

    It's a no-brand model from an unknown manufacturer in China and looks identical to this one http://i74.photobucket.com/albums/i280/sacentre/BenchMountedMagnifier.jpg. I don't expect the photo will help much.

    The store I bought it from earlier this year doesn't sell them anymore and couldn't care less about helping me to get it repaired. I might have just bought a new one if they'd been available.

    I'm afraid I'm not very good at fault finding and diagnostics but sometimes I get lucky with guesswork. On this PCB, I can see 2 burned resistors - R2 and R1 (just to the left of the upper SR 6863D). As far as I can tell, the damaged resistors appear to be colour coded red, black, black = 20 Ohms. Assuming someone is familiar with this type of circuit, does that sound right? One side of each resistor is connected to the left leg of the transistor viewed from the front.

    I would guess that as well as the burned resistors, the two SR 6863D semiconductors have blown.

    Can anyone tell me what the SR 6863Ds are or better still, suggest an equivalent? I've tried Googling for hours but haven't been able to find an information about them. I tried asking at my local electronics store but they didn't recognise the number.

    Thanks in advance.

    Trevor
     
    Last edited: Sep 27, 2014
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Last edited: Sep 27, 2014
  3. Trevor Rymell

    Thread Starter New Member

    Sep 27, 2014
    9
    0
    Thanks, Dodgydave
    It's worth doing if I can get hold of the 2 semiconductors. If that's impossible then it's a different story. Wouldn't mind just buying one but I don't see anything that would fit in the same place as the original.
     
  4. Trevor Rymell

    Thread Starter New Member

    Sep 27, 2014
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  5. absf

    Senior Member

    Dec 29, 2010
    1,492
    372
    It should work with a MJE13005. See datasheet attached.

    Allen
     
  6. Trevor Rymell

    Thread Starter New Member

    Sep 27, 2014
    9
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    Allen, many thanks. I'll see if I can source them and give it a try.

    Trevor


     
  7. DickCappels

    Moderator

    Aug 21, 2008
    2,653
    632
    One way to get the MJE13005's is to go to the store and buy a Compact Florescent Lamp and raid it for the parts. Be careful to not break the glass tube.

    A very good resource for troubleshooting electronic ballastas is
    http://www.pavouk.org/hw/lamp/en_index.html
     
    absf likes this.
  8. Trevor Rymell

    Thread Starter New Member

    Sep 27, 2014
    9
    0
    Many thanks, Dick, for the suggestion and the link. I'll see if there's a make/model that has the device.
    Thanks again.

    Trevor
     
  9. wayneh

    Expert

    Sep 9, 2010
    12,123
    3,048
    I have the 1300-5 transistors in a TEC cooler I'm repairing, and I'm replacing them with a part from Mouser, a Fairchild power switching transistor: FJP3305H1TU
     
    absf likes this.
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