Help deciphering used Power Tranformer

[perlnerd]

I just picked up a used Power Transformer. All I know is that it supposedly came from a tube organ running 6L6s. The person I got it from didn't know anymore about it and didn't know how to test it.

I figured I'd be able to get it home do a little cross referencing and figure out which leads were which. Boy was I wrong. I'm worried that I would damage the transformer if I just start hooking a line cord up to it to see what works.

I'm hoping someone can at least tell me which leads are for the primary and then I can check the rest of the voltages. Maybe someone has a trick for getting the specs of a mystery transformer?

Attached is a photo showing the wires coming out of the bottom of the transformer as well as closeups of each group of wires. If I can supply anymore info please let me know.

Thanks
Clint

[Flames1950]

Eeeek.
I'd start with the assumption that the side with fewer wires is the primary side that will go to your main household voltage. You're going to have to pick a pair to start with, take a DVM set to ohms, and check the DC resistance betwen the two wires. Keep one of the wires and move on to another for the other side, and again take a DC resistance check. Keep detailed notes of what each pair checks out to be (and from the looks of it you may have to find a new way to color code them for your own sanity, the color on the cloth is faded pretty bad.) When you've checked all possible combinations of wires on this side, you should end up with one pair that gives you the largest DC resistance, which will be for the largest voltage the tranny will work with (240VAC perhaps), and hopefully a number of smaller DC resistances as the operating voltage goes down. I'm hoping the 120VAC pair should be the DC resistance around one-half of the largest resistance you get (surely there's no reason to run it on anything less, right?)
At that point try hooking up 120VAC to that pair that gave you one-half the largest resistance and see if it smokes!! I know, that's not funny. But run 120VAC to that pair, then carefully measure the wires out on the other side. For a tranny that old, you may have a 5VAC recifier winding, a 6.3VAC filament winding, and a much larger B+ winding. Some of the wires on that side are probably center taps to the larger windings, but as you measure the voltages and take careful notes you should start to see two combinations that give you one-half the voltage of a larger combination, so you can start to guess which is the center tap.
Have fun -- are you sure you don't just wanna buy a new tranny?

[Flames1950]

After I replied above I kinda thought I should clarify a little.
When you've got the pair (on what we assume to be the primary side) with the largest DC resistance and the pair with about half that amount, they should have a wire that is common to both pairs (so you'd have two pairs, but only three wires.) Otherwise we may have gotten a measurement from one voltage tap to the next and that's not what we want. It's important to find the common wire, which I would assume to be the black, but I'd hate to bet on that.

[perlnerd]

So I set about measuring the resistance on each side of the transformer.

I would hate for this transformer to go to waste.

I'll show the readings I've gotten and see if anyone can make any sense of it.

On the right side I have the following leads:

Orange
Orange white
Red Yellow
White
Green

Here's the pairs that gave me readings:
Orange + Orange white 0.5 ohms.
white + green 0.6 ohms

On the left side I have:

orange
yellow
yellow
black
red black
red yellow
green white
red

Here's the pairs that gave me readings:
red + red yellow 24.5 ohms
black + red black 1.5 ohms
yellow + yellow 0.4 ohms

I did get some reading between leads on opposite sides ('l' means left and 'r' means right):

l orange + r orange 0.5 ohms
l orange + r orange white 0.5 ohms
l red yellow + r red yellow 25.5 ohms
left red + r red yellow 49.8 ohms
l green white + r white 0.6 ohms
l green white + r green 0.5 ohms

So it seems that similarily coloured wires from both sides show continuity.

Do any of these values mean anything to anyone?

Thanks. Any help is appreciated.

Perlnerd.