M40FA640AGP Marelli Automatic Voltage Regulator

About this part

Sensitive loads such as computers, inverters and motor drives depend on a steady voltage. The regulator is a small, inexpensive board that protects everything downstream of the generator.

Features

• Power supply voltage of 170 to 277 Volts at 50 or 60 Hertz
• Voltage sensing of 170 to 480 Volts
• Maximum continuative field current of 8 Amps
• Maximum forcing field current of 15 Amps for 1 minute forcing
• Field resistance of between 3.5 and 20 Ohms
• Weight of 670 grams

When to replace it

• Output voltage that is too high, too low or unstable
• No output voltage although the engine runs normally
• Lights flickering or voltage dipping as loads switch on
• A burnt or damaged board after a lightning strike or short

Before you order

Match the AVR to the alternator: sensing (single or three phase), excitation type (brushless or brush type), supply voltage and the physical mounting all have to suit. Note the wiring before disconnecting the old regulator.

Not sure it is the right one? A photo of the old part and the nameplate of the machine it came off is usually all the counter needs to confirm a match.

Questions