Electrical Guru’s Here here!

Um, 210 is a bit light. Not impossible if your neighborhood is wired for 208/120, but this is not common except for institutional (like schools, many hotels, and the like) and some commercial power systems. Most residential is wired for 240 split phase (120, 0, 120). If you have 120 to neutral from each hot leg, but only 210 between the hot legs, then I would take a serious look at the wiring to your house.

In any case, it sounds like you have a bad transformer. Normally about the last thing I look at. Even at 210v in, I would expect around 21 volts out of the transformer (10:1 turns ratio).
 
I’m in a townhouse complex so that may be part of it. I have 118vish at each leg, and 208ish when connected together.

Is there anyway to troubleshoot the transformer? Would hate to replace it only to find some how someone messed up the wiring and was feeding it 24v from the other side somehow.
Initially I was getting 24v to each side, with the other side of the multimeter on a ground. Could that have fried it?
 
HuD_91gt said:
I’m in a townhouse complex so that may be part of it. I have 120v at each leg, and 208ish when connected together.

Is there anyway to troubleshoot the transformer? Would hate to replace it only to find some how someone messed up the wiring and was feeding it 24v from the other side somehow.
Initially I was getting 24v to each side, with the other side of the multimeter on a ground. Could that have fried it?
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Ahh, a townhouse, with all gas appliances I would assume. That would explain 208V

No, testing the transformer with a multimeter could not possibly damage it. One thing I have found on autoranging digital multimeters is sometimes they will fool you by reading what you expect, but you fail to notice the mV over in the corner of the display rather than V so you are actually seeing millivolts rather than volts. I have been caught by this more than once. Perfectly possible to have a few millivolts just floating around in the air.

To test the transformer, disconnect the wires and measure across 20-21 and 30-31 with an ohm meter, the reading should be <100 ohms on either side.
 
Sometimes the transformer wires will come loose or break right at the terminal block- also I have seen cold solder joints from the factory that work for a while then fail after a bit of vibration, heat, and humidity. You may have something like that going on. It may be necessary to remove the transformer completely to give it a good inspection and/or repair and bench test. Be careful to shut off power before working on it.
-Mark
 
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Well I took the transformer out. The high voltage side the wires are almost non existent on one terminal, and honestly I didn’t see them on the other. So if it wasn’t broken, it is now. Lol. I shoved my multimeter in the whole to see if I could get continuity and no reading. The high voltage side showed 20ohms.
 
Sounds like you found the problem. Rather unusual for a transformer to fail.
 
Well I hope it’s the problem. I tried taking it apart but I can’t find the one wire.

searched Alibaba.com for a new one. Nothing stands it as exactly the same and that concerns me. Grizzly g0761 seems to have a direct replacement but it’s on back order.

then came across this one. I’m thinking it should work, it’s old, but Japanese made. I bet it would last 5x what a good Chinese one would.

www.lenmark.com

100 VA Transformer Type TRH-2

Specifications Model TRH-2 Made In Japan Condition Used Assembled Dimensions: 4 x 3.5 x 4 inches General Transformer Type Dry Auto VS Isolation Auto Electrical kVA 0.1 kVA Primary Voltage 220 volts Phase Single-phase
www.lenmark.com www.lenmark.com

thanks again for all your helps guys. I can follow wires, but as I said, AC is a bit of a grey area for me.
 
That transformer looks like a perfect replacement.
 
Suggest one more quick measure of the transformer AC voltage across 30-31. Keep an eye that the meter is on the "AC" range and an eye for V vs. mV on the readout as suggested above. I've more than once tried to measure AC while on the DC range by accident and it reads about 0V. For your question above, measuring the voltage in various ways will in no way harm the transformer.

The low input voltage of about 210 VAC instead of 230 VAC would lead to about 22-23 VAC on the output of the transformer like you reported prior when you were measuring from ground. If the transformer is NOT grounded that can just be a ghost reading. However, did you confirm if the transformer is tied to ground? To do that, unplug the mill from the wall and measure for continuity between 30 and ground and 31 and ground. Do all of the green terminals you metered to also tie to ground?

It very well could be a bad transformer but worth a quick re-check I think.
 
For this kind of stuff, you can treat it like DC; you still need to have a complete circuit with no opens, and a good power source
-Mark
 
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