KEPCO MBT Series - Manual (Page 124)

4-18
MBTSVC111609
wise rotation). Digital Control Board A3 then resets U3B to prepare for further movement of the
control.
“G” Option selector switch S1 routes IEEE1118 bus signals to/from the rear panel connector via
Digital Control Board A3 (A3J1 to A8J9) to/from Interface Board A14 (A8J8 to A14J2) when the
“G” option is enabled. This switch also provides a flag to the Digital Control Board to indicate
whether the “G” option is enabled or disabled. On models without the “G” option selector switch,
the IEEE 1118 bus is connected directly from A3J1 to A14J2.
4.3.9 SENSING RESISTOR AND CROWBAR CIRCUIT A10 (See Main Schematic Diagram, Fig-
ure 6-17)
The A10 assembly contains current sensing resistor A10R1, and the crowbar circuit, consisting
of triac A10CR1 which is controlled by Relay and Flags Board A2. Blocking diode A10CR2 pro-
tects the power supply against the possibility that a voltage of opposite polarity to the pro-
grammed polarity is applied to the output terminals. The A10 assembly is mounted on Heat Sink
Assembly A7, but is electrically isolated from the heat sink. The value of the sensing resistor dif-
fers between models, but is identical for all options of a particular model.
4.3.10 ALPHANUMERIC DISPLAY (LCD) A11 (See Schematic Diagram, Figure 6-25)
The alphanumeric display is a liquid crystal display used to display status, operational parame-
ters, calibration instructions. and programming information. Alphanumeric characters are sent
from Digital Control Board A3 via Front Panel Board A8 in the form of eight parallel data bits
along with control signals. Operating voltage and backlight LED voltage are provided by Front
Panel Board A8. The alphanumeric display is identical for all MBT models and options.
4.3.11 KEYPAD A12 (See Schematic Diagram, Figure 6-26)
The keypad consists of 24 momentary action switches which provide a combination of ten sig-
nals (KPAD1 through KPAD5 and D0 through D4) to Digital Control Board A3 via Front Panel
Board A8 to indicate which switch is pressed. Switch functions are completely determined by
the software. Keypad A12 is identical for all MBT models and options.
4.3.12 "G" OPTION COMPONENTS — MG, MGR MODELS
The “G” Option components function as built-in controller to permit the MBT power supply to a
remotely control up to 26 additional power supplies (see Figure 1-3) via the IEEE 1118 bus. The
“G” option components also allow the MBT to communicate with either a personal computer
(PC) or a PC-assisted controller via the IEEE 488 bus or RS232 bus, receiving commands and
transmitting status and error messages. The “G” option components are identical for all MG and
MGR models and consist of the following:
• Single Board Computer A13
• Interface Board A14
• +5V Power Supply A15
• 2-wire cable between A6TB1 and the line input of +5V Power Supply
• 9-conductor flat cable between A13J2 and A6J4 (RS232 port)