Section II. DETAILED FUNCTIONAL DESCRIPTION

TM 11 -7010-201-40-1 /ET821 -AA-MMI-01 O/E1 54 MTS/T O 31 S5-2TS073-2-1

Section II. DETAILED FUNCTIONAL DESCRIPTION

2-7. Introduction. This section provides a detailed functional description of the MTS. The following functions are

described: timing and control, mask, control memory, error detect, self-test, probe, and power. Block diagrams support

the functional descriptions. Operation of each function is described for an in system card test. When an individual card

test is performed, the MTS simulates the UUT function.

2-8. Timing and Control Function. The timing and control function (see FO-2 in back of manual) operates sequentially

in 10 states, under control of a state generator. State generator sequencing is shown in figure 2-3. The following

paragraphs .describe the 10 states of the state generator.

State 1. State 1 is the idle condition for the timing and control function. Operation is started BY attaching the

test set probe assembly to the CUT. The card ID of the CUT is automatically generated BY the probe function and

applied to the card ID decoder logic. This starts the action of a 1-second delay one shot. The I-second delay ensures

proper probe assembly connection to the CUT. The random card ID signal, generated by the card ID decoder logic, is

applied to the self-test function and to the card ID random to-binary logic. This results in a binary-coded, seven-digit card

ID. After the I-second delay, the output of the one-shot advances the state generator to state 2.

State 2. The state 2 signal (probe connected) is applied to the card ID random-to-binary logic. This signal

enables the binary-coded card ID to all involved MTS circuits. During self-test, the probe-connected signal is applied to

the self-test function. The logic control tests the UUT for a power-on condition (greater than 4.0 vdc). If UUT power is on,

the state advance signal from the logic control enables state 3.

State 3. The state 3 signal (perform continuity test) is applied to the continuity strobe generator logic. The

resulting strobe signal is applied to the error detect function. After the strobe is generated, a. continuity test complete

signal is applied to the state generator. The test complete signal enables state 4.

State 4. The state 4 command (turn off UUT power) causes the logic control to turn off UUT power. When

the logic control senses that UUT power is off (less than 1.5 vdc), the state advance signal from the logic control enables

state 5.

State 5. The state 5 command (isolate CUT) causes logic control to isolate the card from the UUT. To isolate

the card, the probe function commands the CUT reed switch to open.

NOTE

Some circuit cards have a reed switch that is controlled by an electromagnet in the probe. Other

cards have a reed relay which opens in state 4 when UUT power is turned off. In either case, the

purpose of the switch or relay is to disconnect the +5v supply line to the CUT during testing.

The reed switch open signal triggers a 47-millisecond delay one-shot. The delayed one-shot output advances the state

generator to state 6 under control of the delayed advance signal.

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