A6 Power Supply Assembly Troubleshooting
The spectrum analyzer uses a switching power supply operating at 40 kHz to supply the low
voltages for most of the analyzer hardware, and a 30 kHz switching supply (CRT supply) to
provide the high voltages for the CRT display. The CRT supply will be treated as a separate
supply since the remainder of A6 must be operating for the CRT supply to operate.
Kick starting occurs when there is a fault either on the power supply or on one of the other
assemblies. The power supply will try to start by generating a 200 ms pulse (“kick”) every
1.5 seconds. A kick-starting power supply often appears to be dead, but the fan will make one
or two revolutions and stop every 1.5 seconds.
Warning
n
The A6 power supply and
A6Al
high voltage assemblies contain lethal
voltages with lethal currents in all areas. Use extreme care when servicing
these assemblies. Always disconnect the power cord from the instrument
before servicing these assemblies. Failure to follow this precaution can
present a shock hazard which may result in personal injury.
n
The voltage potential at
A6AlW3
is
+9
kV.
If the cable must be disconnected,
always disconnect it at the CRT with
caution1
Failure to properly discharge
A6AlW3
may result in severe electrical shock to personnel and damage to
the instrument. See procedure 2,
“Al
Front Frame/Al6 CRT,” in Chapter 3,
“Assembly Replacement.”
n
Always use an isolation transformer when troubleshooting either the A6 power
supply or the
A6Al
HV module. When using an isolation transformer, connect
a jumper between AGTPlOl and A6TP301. This connects the circuit common
to earth ground. Remove this jumper when the isolation transformer is not
used.
Dead
Power
Supply
Use an isolation transformer and connect a jumper between
AGTPlOl
and
A6TP301.
Check
the
Supply
Voltages
1. Connect the negative lead of a DVM to
A6TP301.
2. Check TP308 for
+5
V.
3. Check TP307 for -5 V.
4. Check TP302 for
+15
V.
5. Check TP303 for -15 V.
6. Check TP304 for
+28
V.
7. Check TP305 for -12.6 V.
13-12 Display/Power Supply Section
