2000 Maule M-7 235 HP Lycoming B4B5

My charging system has been signalling me something isn't right. I have an Electrsystems ALY-8420LS Alternator. The alternator is original. I'm going to replace it. Aircraft Spruce says the AL series doesn't have a internal voltage regulator.

So has anyone seen where an external regulator is mounted. I sure haven't seen one?

Thanks Rob

The M-5 drawings show them mounted under the panel on the aft side of the firewall on the right side. Mine is mounted on the forward side of the firewall using what I assume are the same mounting holes.

Make sure you check the in line fuse holder that is part of the field circuit; disassemble the fuse holder and verify that it is solid (mine vibrated apart and had to be replaced), check the one amp fuse with a meter.

The overvoltage relay could also be a culprit. It can easily be bypassed to determine if your problem goes away. Both overvoltage and regulator are located high on the right of the engine side of the firewall on my M5. Your six cylinder may be different.

Both M6s of mine have had the voltage regulator and over voltage relay type devices on engine side of fire wall, copilot side.

Modern alternator controllers (from Lamar for example) are far simpler and very affordable, everything in one box with 3 wires sticking out. I converted to this and put it on cabin side of firewall.

It was the alternator. Put a new one on. $1087 from Spruce. Problem solved. Thanks for your thoughts.