Help needed !!
1) Surface mount parts identification.
See photos of my circuit board. First pics have labels for our communication.
2) Schematic. This circuit is a voltage regulator from a 7000 watt 110 volt generator. The replacement boards are available for $400 US. Obviously I would rather spend $30 in parts and a few months having fun !
Do you have any good sources for schematics ?
Please respond directly to
Phil Strange
Kamloops BC
The DC+ DC- AC and BATT pads are where the wires to the generator were attached.
What are the rest of these parts?
The purpose of a voltage regulator is to maintain the output voltage of a generator at a desired value. As load on an AC generator changes, the voltage will also tend to change. The main reason for this change in voltage is the change in the voltage drop across the armature winding caused by a change in load current. In an AC generator, there is an IR drop and an IXLdrop caused by the AC current flowing through the resistance and inductance of the windings. The IR drop is dependent on the amount of the load change only. The IXLdrop is dependent on not only the load change, but also the power factor of the circuit. Therefore, the output voltage of an AC generator varies with both changes in load (i.e., current) and changes in power factor. Because of changes in voltage, due to changes in load and changes in power factor, AC generators require some auxiliary means of regulating output voltage.
Sensing Circuit senses output voltage of the AC generator. As the generator is loaded or unloaded, the output voltage changes, and the sensing circuit provides a signal of these voltage changes. This signal is proportional to output voltage and is sent to the comparison circuit.
Reference Circuit maintains a constant output for reference. This reference
is the desired voltage output of the AC generator.
Comparison Circuit electrically compares the reference voltage to the sensed
voltage and provides an error signal. This error signal represents an increase
or decrease in output voltage. The signal is sent to the amplification circuit.
Amplification Circuit (either a magnetic amplifier or transistor amplifier),
takes the signal from the comparison circuit and amplifies the milliamp input to
an amp output, which is then sent to the signal output, or field, circuit
Output Circuit controls the field excitation of the AC generator, and increases
or decreases field excitation to either raise or lower the AC output voltage.
Feedback Circuit takes some of the output of the signal output circuit and feeds
it back to the amplification circuit. It does this to prevent overshooting or
undershooting of the desired voltage by slowing down the circuit response
Output Voltage : Let us consider an increase in generator load and, thereby, a
drop in output voltage. First, the sensing circuit senses the decrease in output
voltage as compared to the reference and lowers its input to the comparison
circuit. Since the reference circuit is always a constant, the comparison
circuit will develop an error signal due to the difference between the sensed
voltage and the reference voltage. The error signal developed will be of a
positive value with the magnitude of the signal dependent on the difference
between the sensed voltage and the reference voltage. This output from the
comparison circuit will then be amplified by the amplifier circuit and sent to
the signal output circuit. The signal output circuit then increases field
excitation to the AC generator. This increase in field excitation causes
generated voltage to increase to the desired output. If the load on the
generator were decreased, the voltage output of the machine would rise. The
actions of the voltage regulator would then be the opposite of that for a
lowering output voltage. In this case, the comparison circuit will develop a
negative error signal whose magnitude is again dependent on the difference
between the sensed voltage and the reference voltage. As a result, the signal
output circuit will decrease field excitation to the AC generator, causing the
generated voltage to decrease to the desired output.
My generator senses 110 volts AC and sends fro 16 to 60 volts DC (4 amps?) to the rotating field.
Thanks for your help !!