Regulator internal configuration

[larrybl]

Working on a Garden Tractor charging system. I am indoors and can only try and run the engine with the doors open. Weather is preventing this right now. When I did get to start this it would only run for a few seconds before shutting down. I noted no + movement on the AMP meter when it did briefly run. I suspect the fuel solenoid not getting power from the regulator. I have several other machines that just use a single in-line diode for battery charging, prompting me to speculate on what the internal configuration of this regulator may be. It is a three terminal unit. The two outside terminals are connected to 28VAC stator, the center terminal Is B+ and the case is ground. I am thinking it may house a bridge rectifier in this configuration. Is there any way to confirm this without de-potting?
PS, I have checked the wire for connectivity back to the battery and it is good, and I have a new regulator on order.   

[amyk]

It would include at least a bridge rectifier, and likely a linear regulator too.

[mikerj]

Typically regulators for small engines with permanent magnet alternators use SCRs to shunt the stator output when voltage rises above regulated output.  If the reg is bad you will likely be able to use something from a small motorcycle engine, though beware as some of these are designed for a grounded charging stator (half wave rectification) rather than a fully isolated one.

[larrybl]

Ran into another issue preventing starting the machine. I measured the stator and it is floating (no continuity to ground) I have a 28vac 2A transformer that I should be able to use to check the regulator while I fix the other issue.

[larrybl]

I confirmed the regulator is good, Need to look into this further. https://www.youtube.com/watch?v=XZeqJg_Ydoo&feature=youtu.be

[larrybl]

Ever feel like you started on the wrong end of a problem, and the last and easiest thing to get to fixed the problem? After banging my head over the electrical issue and testing the regulator in the above post, I found the key switch on this machine has two run positions. I was testing everything in the run/lights position. When actually trying to start the machine I would go to the start, and return to the run/only position. I tested this and sure enough I had no voltage in the run/only position. I sprayed contact cleaner into the switch connector and everything works now. I should have the gas tank installed this weekend and do a live start on it then.

[larrybl]

Somebody can put solved in the title. Although I did not figure out the internal configuration of the regulator, I did solve the "not stay running issue" and learned that the regulator requires a 12 volt source to output a voltage verses the bridge rectifier doesn't.