Need help wiring my ST head

[Randybee1]

Hey guys, Here's an easy question for you all... I went to wire my ST head the other day and none of the wires are labelled as I expected them to be. This is a PowerSolutions head so there is no doghouse on it.There are 2 wires from one coil labeled "Z3" and "V1", the other coil is labeled "Z2" and nothing for the second wire.  Not sure which wires to wire nut together for 240 v. Any ideas?

Oh, and there is a pair of 18-20 gauge wires too, I'm guessing they are a 12v power source?

Thanks, Randy B



Alright, was going to insert pic of gen head but cannot. Can someone give me a quick and dirty tutorial?.. in the meantime I'll search for the answer

[Ronmar]

OK, it sounds as if you are light a few wires.  Have you removed the end cover that wraps around the brush end of the generator head?  There should be 8 wires involved.  You have 2 that come from the Z winding.  These connect to the AC side of the bridge rectifyer.  You have 2 that connect from the DC side of the rectifyer to the brushes.  There should be 4 remaining that would be labeled U1, U2, U3 and U4.  U1-U3 will be one 120V winding and U2-U4 will be the second 120V winding.  U3 and U4 would be connected together to form the neutral connection.  U1-N =120V, U2-N = 120V, U1-U2 = 240V...  If you have identified the Z and brush wires, you can determine the 120V windings with an ohm meter.  The only issue will then be determining polarity/phaseing to wire them in series for 120/240 operation...

[Randybee1]

Thanks!!, I checked and did not see anymore loose wires, just the ones mentioned. Here is a pic of what Ihave. The rectifier is a "modern", western style and is already hooked up.

[Randybee1]

Let's try that again.... Hopefully this picture is bigger!

[BruceM]

Someone has "prewired" this head.  It would be best to get the wiring diagram from the seller.

If no diagram is available,  I'd check the resistance of the two pairs, to see if they are in fact hooked up to two sets of coils each, with no connection between.  If so, then you can experimentally determine how to hook them up.  Run the head and see if you get near 120V on each pair.  If yes,  connect one of each pair together with one from the second pair and measure the "outside" two wire's voltage with it spinning at 1800 rpm.  If 240, you're done.  If near zero, switch one of the pairs' wires and recheck.  You should be good at that point.

The two small wires are likely leftovers from the old harmonic winding indicator and can be capped and ignored.

[Randybee1]

Thank You!, Makes sense now. I put a an ohmeter on the wires and they are paired correctly. It'll be about 3 weeks before I fire this up so I'll give an update then.

Randy B

[Ronmar]

I think Bruce is right, unfortunately those wires are severely mis-labeled.  I also agree the small yellow wires are probably leftovers from the generator "ON" light found in the original doghouse. 

[Randybee1]

Thanks for the help guys. I have 4 ST heads that I bought several years ago. This is the first one I opened. Humor me here... I know there's nothing called a"normal" ST head but if this was your
"normal" head, what would the labels on the wires typically say?

Randy B

[Ronmar]

Thanks for the help guys. I have 4 ST heads that I bought several years ago. This is the first one I opened. Humor me here... I know there's nothing called a"normal" ST head but if this was your
"normal" head, what would the labels on the wires typically say?

Randy B

From my first response above...

U1, U2, U3 and U4.  U1-U3 will be one 120V winding and U2-U4 will be the second 120V winding.  U3 and U4 would be connected together to form the neutral connection.  U1-N =120V, U2-N = 120V, U1-U2 = 240V...