Main Board Module - Picotest M3500A Service Manual

frequency of supply voltage AC2 from the transformer and then informs
main controller to set PLC (Power Line Cycle) parameters. Panel MCU will
response automatically according to the detecting result to make the VFD
operating properly.

3.4 Main Board Module

The main board module of M3500A consists of power supply circuit, analog
front-end circuit, ADC and MCU, and main control circuit. The block diagram
is shown in Figure 3-3.
Analog ADC
Main To
Front-End &
Control Panel
Circuit MCU
Circuit Module
Linear Linear
Regulator Regulator
B A
AC-IN
Power Supply Circuit
Main Board Module
Figure 3-3
As shown in Figure 3-3, input signals routed through analog front-end
circuit and then convert to digital signal by the ADC. Digital signals are sent
to main control circuit via opto-couplers. The calculated data will send to
panel module and display the result on VFD. The powers needed in these
circuits are supplied by the power supply circuit.
The discussion about power supply circuit is provided in section 3.4.1; the
circuitry theories of the analog front-end circuit and ADC & front-end
processor are shown in section 3.4.2 and 3.4.3 respectively, and section
3.4.4 provides the discussion about the main control circuit of M3500A.
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