Fluke 875 manual Latch Circuit, Circuit assumed initially in Pass Condition Fail Condition

Maintenance, Calibration, and Troubleshooting	5
Operation of Latch Circuit

U202, pins 1, 5, L (Enable pulse active; i.e. low)

From these conditions, the following must hold true.

Pin	Comment
4	Depends on 6
3	Depends on 2

Further analysis is contained in the truth table (Table 5-2).

Figure 5-2.Latch Circuit

Table 5-1. Truth Table for Pass and Fail Conditions in The Latch Circuit

(Circuit assumed initially in Pass Condition)

	Fail Condition		Pass Condition
Pin	Voltage	Voltage Comments	Pin	State	Comments
	State
4	L (low)	Since 6 is H (high)	4	H	Because 6 is L (also 5)
3	H (high)	Since 1 & 2 are Low	3	L	Because 2 is H
13	H	Connected to 3	8	H	Connected to 4
11	L	Since 13 is H	13	L	Connected to 3
9	L	Connected to 11	10	L	Because 8 is H

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