Maintenance
1705A Spectrum Monitor
6- 13
Table 6- 2: Power Supply Fault Symptoms (Cont.)
Power Supply cycles OFF/ON
Output Check (Low Volts),
or High Voltage Oscillator Check (High Volts)
Does not power up
Control Circuit Check (Low Volts)
5 V not regulating
Error Amplifier Check (Low Volts)
Improper crt display
High Volts Supply
NOTE
. A 20
Ω
, 2 watt resistor should be used as a load for the Low Volts Supply.
Disconnect J4 and connect the 20
Ω
resistor between W1 (+5 V) and TP1
(secondary ground).
1.
Preliminary Checks
a.
A properly functioning and loaded Low Volts Supply will output the
voltages listed in Table 6--3. Use the DMM to measure the voltages
between TP1 and the voltage test points. If the supply is not regulating
properly, continue with the procedure.
Table 6- 3:
Low Volts Supply Voltages
Test Point
Voltage
W1 -- (+5 V)
+4.88 to +5.12 V
W4 -- (+15 V)
+14.0 to +16.0 V
W3 -- (--15 V)
--14.0 to --16.0 V
W2 -- (+40 V)
+39.0 to +41.0 V
NOTE
. The Low Volts Power Supply troubleshooting is performed without
applying ac power.
b.
Disconnect ac power from the instrument. Disconnect the instrument
from the Power Supply by removing the jumper from J4.
c.
Use the digital multimeter to measure the voltage between TP2 and the
tab (drain) of Q9. Be sure the voltage is near 0 V before proceeding.
Low Volts Supply
Summary of Contents for 1705A
Page 13: ...Service Safety Summary xii 1705A Spectrum Monitor ...
Page 17: ...Preface xvi 1705A Spectrum Monitor ...
Page 18: ...Introduction ...
Page 19: ......
Page 38: ...Operating Instructions ...
Page 39: ......
Page 61: ......
Page 62: ...Installation ...
Page 63: ......
Page 72: ...Theory of Operation ...
Page 73: ......
Page 93: ...Theory of Operation 4 20 1705A Spectrum Monitor ...
Page 94: ...Checks and Adjustments ...
Page 95: ......
Page 123: ...Checks and Adjustments 5 28 1705A Spectrum Monitor ...
Page 124: ...Maintenance ...
Page 154: ...Options ...
Page 155: ......
Page 158: ...Replaceable Electrical Parts ...
Page 159: ......
Page 189: ...Replaceable Electrical Parts 8 30 1705A Spectrum Monitor ...
Page 190: ...Diagrams Circuit Board Illustrations ...
Page 191: ......
Page 193: ......
Page 213: ......
Page 214: ...Replaceable Mechanical Parts ...
Page 215: ......
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