Maintenance
6- 16
1705A Spectrum Monitor
Table 6- 5: High Volts Supply Fault Symptoms
Symptom
Procedure
Unable to focus crt using the front-
panel control
Focus Amplifier Check
Unable to adjust crt intensity using the
front-panel control
Z--Axis Amplifier Check
Grid Drive Check
No crt display
High Voltage Oscillator Check
CRT Voltage Check
Load the Low Volts Supply with the instrument, or with the 20
Ω
resistor as
stated at the beginning of the Troubleshooting Procedure.
Focus Amplifier Check
Unsolder and lift one end of R24.
Power up the Power Supply.
Using the digital multimeter, measure the voltage between TP1 and the collector
of Q1. It should be approximately --140 V.
Reconnect the lifted end of R24.
Z-Axis Amplifier Check
Unsolder and lift one end of R8.
Power up the Power Supply.
Using the digital multimeter, measure the voltage between TP1 and the collector
of Q4. It should be approxi10 V.
Short together the base and emitter of Q5. The collector of Q4 should be
approxi100 V.
Reconnect the lifted end of R8.
Grid Drive Check
Turn off the Power Supply. Use the digital multimeter’s diode check to test
CR1, CR2, CR3, CR5, and CR6 for shorts.
Power up the Power Supply.
Using the digital multimeter, measure the voltage between TP1 and the cathode
of CR5. It should vary between approxi75 and +200 V as R58 (CRT
Bias) is adjusted.
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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