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Robin Generator LG102 was working

Kermet

Oct 18, 2009
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Oct 18, 2009
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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
 

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73's de Edd

Aug 21, 2015
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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.
 

Kermet

Oct 18, 2009
12
Joined
Oct 18, 2009
Messages
12
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
 

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73's de Edd

Aug 21, 2015
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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 I’m here after.
 

Kermet

Oct 18, 2009
12
Joined
Oct 18, 2009
Messages
12
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
 

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