Tac stopped working stator regulator or rectifier

[stevehendo34]

Unfortunately I hooked up battery backwards. Got used switch box and runs fine, but tac worked only a couple seconds.
Any ideas, can it be stator regulator or rectifier?

 

[gm280]

Okay...hooked up battery backwards syndrome... :facepalm: I have to ask, does the engine still charge the battery? I mean if you put a volt meter on the battery and crank the engine, does the voltage go up after the engine starts? If not, look at the rectifier and/or the regulator first. If either of them are toast, then replace and never ever connect the battery backwards again! I don't think you hurt the stator, but testing things will prove that right or wrong...

 

[Chris1956]

It is likely your rectifier is blown, if you have such an item. What motor are your working on?

 

[stevehendo34]

OK probably toasted rectifier 90 hp 76 tower.
I'll see If it is charging / do diode check on the full wave rectifier.
I'll check to see if the +B voltage goes up after starting

If I need to check regulator also where is that, but I think tac is on connected directly to stator output yellow wires?
Whats the Resistance value on a non-shorted non-open stator?
Could the tac brown wire be on the wrong spot should it be on rectifier stator wire yellow?
Whats the white wire on the tac plug to switchbox dose it go to tac, also shows going to choke wire, chokes work.

Fing thing not fused for dip shits like me.

 

[Chris1956]

That motor only has a stator and a rectifier. The charging is unregulated. It is likely the rectifier is bad. Replacements are avail aftermarket, and at electronics supply places.

The brown wire is the tach sender. On a '78, it would be connected to one of the yellow stator wires, at the rectifier.

White wire supplies power to the switchbox to enable spark. The red wire on the switchbox is always hot.

I am not sure of the ohm readings for the stator, but the stators are pretty tough and is likely fine.

The choke wire should be grey. No fuses on that motor, as you have found out.

 

[Faztbullet]

Start looking for a trigger as it will soon follow the switchbox......