voltage regulator overheated?

My new-style , electronic voltage regulator ( small square, "potted") has a crack in the potting. Looks like overheated. Stock alternator and zenor. Obtained a new one, instructions warn about heat, advises putting in airflow. Old -style, original with fins looks more able to handle heat. Anybody seen this cracking?
Doug

Why are you using the zener if you have an electronic regulator? If the regulated voltage from the electronic regulator is greater than the breakdown voltage of the zener there will be a constant current drain to ground. This could cause overheating of the voltage regulator. One or the other, electronic regulator or zener, never both. All of the so called electronic regulators also function as a rectifier, too. Alternator output to electronic regulator input leads, output lead is a regulated 12 VDC.

Douglass Harroun said:

My new-style , electronic voltage regulator ( small square, "potted")

Click to expand...

Sounds more like a rectifier.


The Zener is the regulator.

The part I refer to is a rectifier. Sorry about the confusion
Doug

Isn't that a hole through the middle where it's supposed to be bolted to a heatsink?

Yes-it does bolt to the frame there. The instructions say if not air cooled enough, mount to an aluminum block. How many guys do that? Anybody had one crack like mine, or fail?

Doug

Douglass Harroun said:

Yes-it does bolt to the frame there. The instructions say if not air cooled enough, mount to an aluminum block. How many guys do that? Anybody had one crack like mine, or fail?

Doug

Click to expand...

I cut a small rectangular piece of aluminum(same height as the rectifier but about an extra 3/4 inch or so on the sides). Cut some fins around the sides and bolted it between the rectifier and the original location. I think I also put a small washer in there between the aluminum and the back plate to create a bit more airflow around it. It was a $5 part at Radio shack and has been on the bike for about 15k miles.

Rectifier and zener diode are pretty much old school in this day and age, bite the bullet and treat yourself to a modern regulator rectifier unit. While you are at it fit two relays in the headlight feed to ensure you get full system voltage to the headlight.