CHAPTER 4. FUNCTIONAL DESCRIPTION - TM-11-7010-201-40-50030

TM 11-7010-201-40-5/ET821-AA-MMI-050/E154 MTS/T O 31S5-2TSQ73-2-5

CHAPTER 4

FUNCTIONAL DESCRIPTION

4-1. Introduction. This chapter provides a functional description of the MTS test aid. The functional description is

presented in two levels: an overall functional description and a detailed functional description. The overall description is

supported by a functional block diagram, while the detailed description is supported by schematic diagram (figure FO-2)

and by wire lists provided in Chapter 5, Section VI.

4-2. Overall Functional Description. The MTS test aid functions as a display medium for the MTS (figure 4-1). The

MTS test aid monitors the outputs from J7 of the MTS displayed on the MTS test aid front panel. These signals are input

via the MTS test aid cable assembly and enter the MTS test aid at connector J01. During normal operation, the MTS test

aid is powered by + 5v from the MTS. While the MTS test aid is being functionally tested, + 5v is provided by an

auxiliary source. In either case, + 5v provides drive for the indicators and integrated circuits.

The following signals are routed through connector J01 to the lamp drivers of the circuit board assembly: state, X

address, card ID, Y address, self test, data lines, enable TC, and data CK. The outputs of these lamp drivers provide

ground paths for the indicators on the MTS test aid front panel. The functional error signals and continuity error signals

are inverted in the hex inverters of the circuit board, and applied to the lamp drivers. The outputs of the lamp drivers

provide a ground path for the appropriate indicators (data lines). The DATA/FUNCTIONAL/CONT switch selects which

lamp drivers have a pull-up voltage applied to their inputs. The LT (lamp test) switch applies ground to the circuit board

diode array, which provides a current path for the front panel indicators. The SCP (step clock pulse) switch provides

ground to the quadruple 2-input NAND gate (quad two) circuits. The quad two output signals are routed out of the MTS

test aid to the MTS. The BCP (single step clock pulse) and SS (stop on error) switches output to ground through

connector JO1 to the MTS.

4-3. Detailed Functional Description. Input power (+ 5v) and ground are provided through connector JOI during

normal operation on pins 256 and 258, and 257 and 259, respectively (figure FO-2 and wire lists in Chapter 5 Section VI).

When the MTS test aid is being functionally tested, input power from an auxiliary + 5v source is brought in through the

CAL + 5v and GND binding posts (red and black). In either case, the voltage is applied to the circuit board (AO1) power

plane, which is located on the front of the circuit board. The input ground is connected to the circuit board ground plane,

located on the rear of the circuit board. The + 5v and GND are available any may be picked up at the V or G pins at

each of the integrated circuit socket groups. The power plane and ground plane supply the drive necessary to operate

the indicators on the MTS test aid front panel. The indicators are wired so that + 5v is always on pin 2. Therefore, a

logic low is required at pin 1 to enable them. Two conditions will cause the indicators to light, activating the LT (lamp

test) switch, or applying a logic low from a lamp driver. When the LT switch is pressed, a ground path is provided

through each diode of the nine diode arrays to pin 1 of each indicator. This lights all 108 indicators on the MTS test aid

front panel. If a logic low is applied from a lamp driver, only the indicator associated with that particular driver will light.

The

4-1