12
3-6. DC Voltage Measuring Circuit
DC voltage circuit is attenuated as much as 1/1, 1/100, 1/1000 by R1, VR3, R5,
VR4, R6 and linked to R72.
3-7.AC Voltage Measuring Circuit
This is same as the attenuator DC voltage circuit of the AC voltage circuit, and
the attenuated signal is applied to C300 and then connected to R72 after being
converted to DC at U21 and U22.
3-8. DC Current Measuring Circuit
3-8-1. 2mA,20mA,200mA Measuring Circuit
The current applied to the input is connected to R72 through the 10-time
amplifying circuit that meets with attenuator resistance at R32, R34, R37.
3-8-2. 2000mA Measuring Circuit
The current applied to the input is connected to R72 through the 10-time
amplifying circuit that meets with R5 at the input board. At this time, the
reply in the input board starts working, but U1-3, U1-2 at the front board turn
to the low state, while U3-1 is put in the high state and connects the front
board P6 and the input board J1 with wire.
When U3-1 signal is connected to the base of Q1 after passing input board R2 and
sets Q1 in motion, the reply starts working and connects the current input
terminal to R5.
3-8-3.10A Measuring Circuit
The current applied to the input is connected to R72 through the 10-time
amplifying circuit that meets with R100 at the input board
3-9. AC Current Measuring Circuit
The AC current measuring circuit keeps its state until the output of 10-time
amplifying circuit and then becomes equal to the AC voltage circuit. The AC
current signal is amplified 10 times when applied to C300 after passing the 10-
time amplifying circuit and then linked to R72 as it is converted to DC from
U21, U22.
3-10. Resistor Measuring Circuit
The resistor measuring circuit can measure 2kohm by R4, VR1, 20kohm by R4, VR1,
R3, VR2, and 200kohm, 2Mohm and 20Mohm by R4, VR1, R3, VR2, VR201, R1. The
measurement is performed in the following way ; the source voltage of measuring
circuit is supplied to A marked on the circuit diagram by U5 output, and DC
voltage appearing in proportion between resistance to be measured and each
attenuator resistance is connected to R72.
3-11. Diode and Continuity Measuring Circuit
3-11-1. Diode Measuring Circuit
When diode is connected in the forward direction to the input, the forward
voltage is applied R18 by the voltage from R17 and the attenuated voltage by R22
is linked to R72 after passing R24.
