Microwave Radio DS-2, Руководство оператора

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Trouble–shooting
System Overview
1-3
1
IF Diversity Switch Operator’s Guide 400462-1 Rev. A
1.8 Trouble–shooting
The power lamp must be on. If not check the prime power and F1. F1 in located inside the
unit on the PC board. The fuse is a 1/2 amp standard blow type 3 AGC. The normal current
for the DS–2 is less than 125 ma. Lamps other than the power indicator are under processor
control.
Operate the mode switch. If the manual lamp comes on, the processor is probably operating
correctly. If the manual lamp selects the receiver properly, the problem is either AGC
voltage not in the range of –.72 V to –3.4 V or a failure in the U2, U11, U12 IF switch
section or in the associated driver U% or ISO1, ISO2. If an output is defective, the
associated amplifier is suspect. If no action is obtained with the front panel switch, remove
the prime power and try again. Insure the AGC voltage is in the correct range.
Verify the power supply levels are as /– .25 V. The level at the input of U3 for a
particular analog value should be the same as at P1 with the difference in absolute value no
more than 25 mv. If the absolute voltage difference is greater, the associated op amp is
suspect.
The IF switch bandwidth is wide enough that any source greater than 5 MHz can be used
to check general levels. Unused ports should be terminated in 50 ohms to provide proper
return loss.
Failure of the status circuit can be isolated to either the driver U5 of the individual relay.
The processor U3 is a programmed part and is socket mounted. The oscillator can be
checked by monitoring R11 with an oscilloscope. The reset line at pin 2 must be above 3
V to let the processor run.
Figure 2-2 Front Panel Controls and Indicators
MODE
SWITCH
POWER
ACTIVE
AUTO MODE
MANAUL
INDICATOR
CHANNEL
A
INDICATOR
ACTIVE
CHANNEL
B
MODE
INDICATOR