What's wrong with my transformer?

[Family Hoof]

I've got a Triad FS24-500 mains transformer and no matter how I wire it it just seems to short the primary input. Before you jump to conclusions know that I had the schematic and wired it correctly first. No response! Only then did I try every other permutation. My 120AC from the wall is fine and balanced but when connected to the primary I get between 0 and 2V (shorting out, right? so the remaining ~2V is just the difference between + and - AC from wall) and at the secondary it never goes beyond 100mV or so.

This is brand new item! All I did before hooking it up was to solder some of the leads together (primary in parallel, secondary in series), and then I removed the connections to try other options. What could be wrong and why? Help!

 

[CJ]

Better ohm it out, wire for wire and post results vs wire colors.

 

[Family Hoof]

It's an 8 pin dual 115V primary to dual 12V secondary.

No pins are connected and my DMM reads the following:

primary 1 (pins 1-2) = 137 ohms
primary 2 (pins 3-4) = 155 ohms
secondary 1 (pins 5-6) = 2.7 ohms
secondary 2 (pins 7-8) = 2.45 ohms

Seemingly infinite DC resistance between windings. Hmm.. this doesn't look so bad.

I swear my wiring was okay before. No shorts. I redid it several times.

 

[Scenaria]

do you have a load on the transformer? (is it in circuit?)

 

[PRR]

> mains transformer and no matter how I wire it it just seems to short the primary input.....All I did before hooking it up was to solder some of the leads together (primary in parallel, secondary in series)

If you get the phasing wrong, the two windings will fight, and it will act near-short.

ASSuming the diagram is correct and the factory made it like the diagram, the primaries MUST be wired like this:

 

[Family Hoof]

PRR,

This makes sense. That is exactly how I had it connected. I just tried again, reversing phase several times to make sure. Nothing. I've tried all permutations at this point and get what appears to be a short no matter what.

Scenaria,

Connecting a load (circuit or power resistor) makes no difference. I just get a short.

Thanks all for the help so far! So it looks like I've got a lemon, right? How does this happen? Shorted coil internally I assume, no?

 

[PRR]

Connect the 120VAC primaries one at a time. The transformer WILL work fine, at about 75% of its VA rating. Certainly you can test unloaded and find out if one of the primaries has an internal short. If one primary is sick, and you don't need full rated power, you can just use it that way.

 

[Family Hoof]

[quote author="PRR"]Connect the 120VAC primaries one at a time. The transformer WILL work fine, at about 75% of its VA rating. Certainly you can test unloaded and find out if one of the primaries has an internal short. If one primary is sick, and you don't need full rated power, you can just use it that way.[/quote]
Already tried that and the result was the same. I even tried reversing the transformer. It's the same no matter what as if the whole thing is shorted. The only output I can get is a single secondary pin referenced to household earth gives ~1-3V.

Let me rephrase/summarize. The AC line gives me ~120V measuring across the hot and nuetral terminals. Once I connect these two wires to ANY combination of pins on the transformer, no matter which, the result is 0V across the two terminals.

 

[pstamler]

[quote author="Family Hoof"]Let me rephrase/summarize. The AC line gives me ~120V measuring across the hot and nuetral terminals. Once I connect these two wires to ANY combination of pins on the transformer, no matter which, the result is 0V across the two terminals.[/quote]

And it's not blowing your circuit breakers? And it's not catching fire, or setting your house wiring on fire?

Something here is not computing.

Peace,
Paul

 

[Family Hoof]

[quote author="pstamler"]And it's not blowing your circuit breakers? And it's not catching fire, or setting your house wiring on fire?[/quote]
No, and no.

Something here is not computing.

I agree... which is why I woke up this morning and tested all of the leads and aligator clips I was using. Guess what, 2 dead ones in a row! It works fine now. Am I great at troubleshooting, or what!? :roll: Sorry for wasting everyone's time, and thanks for the help! We can put this one in the clueless idiot Meta.

 

[Family Hoof]

[quote author="Family Hoof"]What could be wrong and why?[/quote]
Me, because I didn't think of the obvious.