On Sat, 09 Apr 2011 22:24:10 -0400, Congoleum Breckenridge
wrote:

On 4/9/2011 1:37 AM, Smitty Two wrote:
In ,
Steve wrote:

snip

You might start at the beginning and make sure everything is hooked up
correctly. I mean, once you spring for yet another transformer. For
example, your latest fried transformer has six wires. The schematic
shows the secondary wire colors as blue and red. Given the location of
the blue and red wires on the pic of the transformer you have, that's
not quite intuitive.

And, it may not even be right. So I'd buy a new one, and check some
voltages on the bench. Put 120 into the black and white, and then
measure every other pair to make sure you understand which two wires are
really putting out 24 V.

Obviously, when you go to install it, clip and shrink tube the unused
wires, and make sure that leads are dressed so that they won't short
anywhere.

Then I'd be monitoring the damn thing, preferably with a voltmeter
perhaps on the primary and an ammeter on the secondary.

That 3rd transformer looks like a dual voltage (120/240) input.
If it is, it has two primary windings, and both need to be wire up to work.
Like this: http://www.eleinmec.com/figures/027_02.gif
True - SOME dual voltage primaries are wired that way, and need both
windings connected either in series or parallel to operate.
Others have a center tapped winding - 110 on one half, 220 across the
full winding - and still others have 2 separate windings that operate
independently.

Real easy to find out - even in this case with the 110v primary open.

Connect 110 across the 220 (or 120 across the 240 - let's not get
nit-picky over voltage ratings) or "high voltage" primary and check
the secondary voltage. If he only gets 12 volts it is a totally
separate and independent high voltage primary. If on the other hand he
gets 24 volts, you hit the jackpot and HE screwed up..

This type of "dual primary" circuit is very "polarity" sensitive and
the right colour wires need to be connected together, both in series
and in parallel, or the "magic smoke" comes out very quickly.

Again , like I posted before - READ the instructions.
FOLLOW the instructions, and VERIFY the result.

Part of verifying the result, or erifying an undocummented
transformer, is to check the voltage on ALL winding, used or not, to
fully understand their intended function.

If 110 across the black and white produces 110 across another pair,
that other pair is is a "complimentary" primary and should, in all
likelihood, be connected, phase for phase, across the black/white
primary pair.