11713A Operating and Service Manual 8-15
Servicing the Attenuator/Switch Driver
Troubleshooting the A2 Driver Assembly
Assembly Overview
The A2 driver assembly contains eight pairs of driver transistors and
two driver relays.
One transistor of each pair, for example, Q9 and Q18, is in saturation
while the other transistor is in cutoff. The saturated transistor sinks
current from the + 24 Vdc supply through the load connected to the rear
panel of the driver and returns it to ground. The open collector outputs
are protected against spikes from inductive loads with clamp diodes to
both ground and the + 24 Vdc supply. The driver transistors each have
a metal tab that is attached to a common heat sink.
The relays K1 and K2 provide reversible polarity for ground and + 24
Vdc necessary to drive switches. The relay contacts are also protected
against spikes from inductive loads.
Содержание 11713A
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