I previously asked for help with the wiring of a very old 3 wire Texas T Alternator that had an in-line diode. I have found the solution and share it here in case its of use to others. Unfortunately I could not update my original thread as it kept saying password and user name incorrect for some reason.
We have managed to get this old Texas T alternator to run fine with the following wiring. We used just one of the connectors (see photo) with the diode and a charge lamp in series supplied via the ignition switch. The charge lamp is 12 volt 3.4 watt bulb however we replaced this with a 3.2 ohm 7 watt resistor as we did not want the visual indication.
Good show !!!
I have one of these also, bought new several years ago, took off the shelf last month and installed. Instructions called for the yellow wire with diode to be plugged into the vertical pin which I did. They also called for a toggle switch to be installed on that line which I did. It does not charge. I have checked both the stud lead (old gen to ampmeter) lead and the yellow wire and both are hot. It should work but does not. I wrote TT parts an email asking assistance but have not heard back from them. Anyone have any suggestions?
Jim, Do you have continuity between alternator and engine??? A very poor or no ground will cause problems.
I checked the alt body and it is grounded well.
How are you switching the alternator wire off and on when the engine is stopped? Manually every time or through the ignition switch?
Just curious. If not switched off, does the battery run down?
When I rewired my car, I ran the wire to the plus terminal on the coil box. That way you don't need a separate switch. The diode was soldered into the wire as close to the alternator connection as possible. The diode was insulated with shrink tubing .
Jim when I started looking in to this issue at the beginning of the year I had great difficulties finding the correct wiring, my diagram above worked and sounds like you have wired yours correctly (I am assuming you also have the wire on the stud bolt that would usually connect to the generator) so I am unsure why yours is not working. We have since had another one of these (clearly well used on this occasion) that did not work and that was a fault of the internal diode pack.
Tom, no the battery does not run down when ignition off. Its been a while since I sorted this but I think maybe the extra wire with the diode and charge lamp also acted as a sort of sense wire doing the switching. It defiantly did not drain the battery when switched off.
Jim, It appears that the regulator is not energizing the field so it will not charge. Is there more that one spade terminal on backside of alternator? What did the Alt originally come of off of ? Older Alts had external regulators mounted on firewall or even on the back of the Alt later on, with newer ones having it internal mounted. Alts I have used were 1 wires while the second wire you are using appears to take the place of regulator since it has resistance in series(light bulb).You did say you had power at Alt on both connections??
This was an alt made up from an import and converted with the rear housing you see above with the name cast in it. Instructions say to run a separate wire to the vertical spade as in the first drawing above and have a switch to cut it off. I have since received a revised instruction sheet that says it is recommended to not use the mag when running this set up. There is no other regulator. This unit was bought brand new and set on the shelf for several years and was installed for the first time recently.