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Robin Generator LG102 was working

Discussion in 'Troubleshooting and Repair' started by Kermet, Nov 19, 2018.

  1. Kermet

    Kermet

    9
    0
    Oct 18, 2009
    Hi, I did not realise it but our little orfin lamb chewed the engine magneto wires and i stared the motor,
    it damage the AVR as I got 300 + volts output
    replace the SCR and a cap and resistor But now only get 25 volts output ,
    Im having trouble fault finding and sure its the AVR as it was working fine before Lamby attacked it

    found manual for it
    https://www.jackssmallengines.com/pdf_documents/Robin equipment/MANUALS/LG7.PDF

    What would cause the low output ?

    Cheers
    Brett
     

    Attached Files:

  2. 73's de Edd

    73's de Edd

    2,577
    1,054
    Aug 21, 2015
    Sir Brett . . . . .

    DAMN ! . . .Sam . . . . . do I see lamb stew coming up as entree, on the immediate menu ?

    O.K. . . . . . I do see the proper ? SCR and a replaced 22 ohm film resistor nearby.
    So is where I see the cleaned up spot, being for a poly cap ? . . . which is probably being the C element of an R/C snubber pair, which are shunting the SCR. , OR, its C element could be, that also nearby disc ceramic capacitor.

    Now, in looking at that line up of conformally coated components across the bottom row.
    Don't you see:
    On row 1 :

    Item 1 as being a resistor, then a space then possibly a hefty diode ( ZENER ? ) then a space and then a resistor and then a glass diode ( ZENER ? ) and then a vert mount poly cap and then a TO-92 cased transistor and then a film resistor and then a small diode (750 mw Zener ? ) and then a small axial leaded electrolytic and then 3 more resistors on the extreme end
    Next row up:
    A glass diode( ZENER ? ) to the right of the SCR lead and then a resistor
    Top row:
    Change mounting plane to hoz and find another glass diode ( ZENER ? ) and then a metal film resistor and a final resistor on top.

    I would be testing to confirm if those mentioned locations are diodes and testing for being conventional diodes initially.
    Then a power supply and a 1K current limiting resistor should let you bias them to test as being zeners.

    Or, if being a 'po boy, with no adj power supply, one or two series 9 V batteries would suffice for up to 8 and then up to 17 volts, Zener threshold, test levels.

    I don't know the original SCR you found being used, I am unfamiliar with the one now being used.
    NXP BT151-500C . . . .as a 500V 12 A unit.
    The mentioned TO-92 cased transistor may actually be a 2 lead Diac trigger diode for the SCR gate.

    Does the low voltage output relate to there also sounding like there being a loading down of the engine ?

    Thassssssssit . . .

    73's de Edd
    ...................


    Doing a good job at some places is like peeing your pants in a dark suit; you get a warm feeling, but nobody notices it.
     
    Richard9025 likes this.
  3. Kermet

    Kermet

    9
    0
    Oct 18, 2009
    Haha Lamby is alive she chewed on wire while gen not going....
    Wow thanks so much for the effort in replying very kind
    I spent all day getting no where
    I have updated the picture/circuit with more info
    the 2sc733 seemed bad so replace with MPSA93 but still only 25volt output
    No the motor does not seem loaded when running
    im getting my 12 volts for exciting coil

    cheers 73's
    Brett
     

    Attached Files:

  4. 73's de Edd

    73's de Edd

    2,577
    1,054
    Aug 21, 2015
    Sir Brett . . . . .

    Is the viewing on the foils side of the Pee Cee Bee being good enough, such that we can see where the RGY and Bk-WY wire sets make their connections into their board components ?

    Do you realize that with the prior NPN 2SC733 ? ( which is a bit of a weird duck/ lo noise audio preamp purposed unit having a lead basing of ECB , but there is also being a VERY popular and much used PNP 2SA733 driver function transistor, having a lead basing of ECB.

    Now . . . . . your currently installed PNP MPSA93 is having an EBC basing.
    S o o o o o o o o , do you seem to presently have a transistor boo-boo ? in respect to types and / or installed basing layouts?
    Check it o o o o o o o ut.


    73's de Edd
    .....................


    In my current days, I definitely spend a lot of time thinking about the hereafter.
    I go somewhere to get something and then wonder what Iā€™m here after.
     
    Richard9025 likes this.
  5. Kermet

    Kermet

    9
    0
    Oct 18, 2009
    Arh A typo........was meant to say 2SA733 which is a PNP
    I have spend last couple hours drawing up the circuit to help understand this Beast
     

    Attached Files:

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