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Leader LCG-399A pattern generator, transformer mains input

Noble V-Ratter Registered

Looking for some transformer advise on a Leader Pal LCG-399A pattern generator. The mains input plug is obviously intended for the US market but a quick check of the transformer reveals possibly a solution on the taps.
Has anyone encountered the markings or how best should I tackle the 240 volts in, cant get my head around the resistances :zx:

Not been able to source a manual

Resistances between terminals; 1 & 4 linked neutral in 3-& 6 linked live in
1-2 50 Ohms
2-3 17 Ohms
1-3 50 Ohms

4-5 49 ohms
4-6 50 ohms
5-6 15 ohms

Topic starter Posted : 25/11/2015 3:08 pm
Trusted V-Ratter Deactivated Account

Hi Stephen, it looks like 2 of 120v windings in parallel, this would make sense for US use. Connecting those 2 windings in series would then work on 240 v, but beware of phasing. Might be better to try feeding in 120 and measuring the secondary voltage. Then disconnect the sec winding from the rest of the set to allow you to experiment with tappings. Beware also of false readings of resistance. Digital meter bad, AVO8 good !. Be careful not to connect the 2 primaries in series opposition, this can overheat and destroy the tx very quickly. I,m no great fan of a series lamp limiter but this would be an ideal use, if the lamp lights with no load on the sec, the primaries are probably in opposition.


Posted : 25/11/2015 5:20 pm
Noble V-Ratter Registered

Thanks Peter, couldn't quite get my head around it and what you say makes perfect sense of course.
Will have a go at that soon, its working fine on an external transformer presently......even if the colour on the ITT CVC is not.

Topic starter Posted : 25/11/2015 6:12 pm
Mark Hennessy
Reputable V-Ratter Registered

Live to 6, Neutral to 1, join 3 and 4. Job done :bba

Test with a lamp limiter, as Peter says. Use the smallest bulb you have - no more than 40W.

The tappings on pins 2 and 5 are probably for 110/220V use. I agree that the DMM might be confusing the issue somehow, although it's not something I experience. Perhaps if it is pulsing the test current? Normally a DMM supplies a known (and steady) DC current.

Posted : 25/11/2015 6:24 pm
Noble V-Ratter Registered

I use a fluke 117 true RMS which seems fine on AC but I know what you mean about spurious readings.
Thanks for taking the guess work out Mark. :aad

Couple of pictures

Topic starter Posted : 25/11/2015 6:31 pm