• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

James Transformers

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
According to a google search it's a phase splitting transformer.

Use your DMM to measure the resistance between all the pins. The primary will be two pins connected together but to none of the other pins. The secondary will be three pins. Which one is the center tap should be obvious from the resistance measurements. If there's another pin that doesn't appear to be connected to anything then it's probably an electrostatic shield and should be grounded.

Then the only remaining question is which way to hook up the primary. One pin goes to the power supply and one to the plate. It might not matter which way you do it, but one connection might provide better high frequency response. You could just try it both ways and listen....

If you have a signal generator and a scope then you can try driving the primary with a square wave and looking at the secondary. The ground leads on both your signal generator and scope will almost certainly be connected together through the power cords, so keep them straight. Connect the generator ground to one pin of the primary and the hot lead to the other through a 5k resistor. On the secondary side connect the scope probe ground clip to the CT and the probe itself to either end of the secondary. It will probably help to connect the two grounds together with a clip lead.

Set your signal generator to produce a 10kHz square wave, crank up the amplitude and see what you get on the scope. Switch the connections on the primary side to see if it looks different. Obviously, you'll want to look at both ends of the secondary, but you want to decide which primary connection results in the cleanest square wave on the secondary. Once you've figured that out, the pin you have grounded on the primary is the one you want to connect to the power supply in your amp.

As I said, if you don't have a signal generator and scope, then you can just try it both ways and listen.

-- Dave
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.