Why is my 369JX Hammond trafo wiring failing?

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Che_Guitarra

Well-known member
Joined
Dec 22, 2012
Messages
218
Location
Australia
I'm trying to fire up my LA-2A for the fist time, but I obviously have an issue with my Hammond 369JX trafo wiring - power isn't getting through to the secondary and thus the circuit isn't springing to life.

I've followed my build guide to the tee, but info is a bit hazy in regards to how to manage all the taps coming from the 369JX trafo.  I have an extra pair of whites, blues and browns i'm not sure how to deal with, and a single purple on the secondary side.

IMG_8391_zps7a455a1e.jpg



Any trafo gurus able to help a fella out here?  ;)
 
Talk about a brain fade  :eek:  Forget this post - it's under control.  This is why you don't hook up trafos when hung over  :-[

Based on the transformer schematic the blue and white wires go to the pcb, brown and black are soldered together, and the rest are NC.

 
Maybe I spoke too soon.  I've just rewired the Hammond trafo for 240V, I have continuity through the primary,  but i'm still getting no voltage on the secondary side.  Secondary 6.3V measures for continuity, red high voltage 500V is reading 360Ω resistance, but no signs of life in the unit.  AC power input is fine, on/off working too.

Can I get someone to confirm the trafo wiring I used in the above post is correct?  Here's a screenshot of the 369JX's tap designations:

TRAFO_zps3b775727.jpg
 
Try to check continuity between one of the red tap and the red/yellow tap you put at earth/ground in your pic.

There is still a chance to use your Tx if you got continuity for one side of the secondary (you will just need 2 more 1N4007 for implementing full-wave rectification)

From the old LA2A schem I read, HV current need is about 30mA (130V voltage drop in a 4,7 Kohms res) and with one side of your Tx you can get 250V @ 70mA .
 

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