660 Chapter13
Display/Power Supply Section
A6 Power Supply Assembly
Line Fuse Blowing
1. If the line fuse blows with the LINE switch in the off position, suspect
either the input filter or the power switch cable assembly.
2.If the line fuse blows when the 8564EC and 8565EC spectrum
analyzers are turned on, disconnect the power cord and lift the drain
of A6Q102 from TP108. If the line fuse still blows, suspect CR102
through CR105.
3. If the fuse is not burned out, check A6TP108 for a voltage of between
+215 V and +350 V.
4. If the voltage at TP108 is correct, disconnect the power cord. Wait
60 seconds for the high voltage to discharge. Remove and check
A6Q102.
5. If Q102 is shorted, Q103, Q104, CR106, and CR108 are also probably
shorted. If Q102 is working properly, measure the resistance
between TP102 and TP101 (positive ohmmeter lead to TP102).
6. If the resistance is less than 1 kΩ, suspect either Q103 or Q104 in
the DC-DC Converter.
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