a. A ground logic 0 at LT (pin 3) of the BCD decoders U7-U10 causes all segments to be on. This is
used for self-test of the display indicators. The source of the signal is DISP TEST-.
b. A ground logic 0at BI/RBO of the decoder causes all segments to be off. This input is used to
flash all lights, indicating an over-range condition. The origin of the signal is BLANK+ from CCA A2.
c. A ground logic 0 at RBI of the MSD, U7-5, will cause the output to be off (blank) if the output
would normally be a decimal zero. This occurs when decimal point DP 3 or DP4 is on.
d. Decimal points are controlled by inputs to the digital display from CCA A2.
e. The plus/minus sign (U I ) is positive when PLUS SIGN+ signal is a logic 1.
f. Display indicators are dimmed by connecting DISP DIM to +V DISP through DISPLAY, .
BRIGHT/DIM switch. Voltage is reduced by CR8 and CR9.
g. The VDC, VAC, K-OHMS, STATUS A, and STATUS B indicators are dimmed by connecting
LAMP DIM to mode indicators. Voltage is reduced by VR1 and Q1.