Troubleshooting
Interpreting Diagnostic Fault Codes 5
5-31
Crossing assembly (A17) is faulty. If the voltage is within tolerance, the diagnostic
circuit on the Oscillator Output assembly (A13) is faulty.
3605 -42S Supply Fault
The instrument is dormant and the -44 S supply is out of tolerance. Measure the
unregulated -44 S voltage on the Filter/PA Supply assembly (A18). COM = TP22, HI =
TP9. The voltage should be -45V to -75V. If the voltage is out of tolerance, the Filter/PA
Supply assembly (A18) is faulty. If the voltage is within tolerance, measure the regulated
-44 S on the Regulator assembly. (A17) COM = TP9, HI = TP16. The voltage should be -
42.0V to -45.6V. If the voltage is out of tolerance, the Regulator/Guard Crossing
assembly (A17) is faulty. If the voltage is within tolerance, the diagnostic circuit on the
Oscillator Output assembly (A13) is faulty.
3606 LH Com Ground Fault
The Current/Hi Res assembly (A7) connects LHCOM to the SDL line where it is
measured by the adc circuit on the DAC assembly for 0V ±50 mV relative to RCOM.
3607 -5lH Supply Fault
The instrument is dormant and the -5 LH supply is out of tolerance. Measure the
unregulated -5 LH voltage on the Filter/PA Supply assembly (A18). COM = TP3, HI =
TP6. The voltage should be -8V to -16V. If the voltage is out of tolerance, the Filter/PA
Supply assembly (A18) is faulty. If the voltage is within tolerance, measure the regulated
-5 LH on the Regulator assembly. (A17) COM = TP10, HI = TP15. The voltage should
be -4.7V to -5.3V. If the voltage is out of tolerance, the Regulator/Guard Crossing
assembly (A17) is faulty. If the voltage is within tolerance, the diagnostic circuit on the
Switch Matrix assembly (A8) is faulty.
3608 +5rLH Supply Fault
The instrument is dormant and the +5 RLH supply is out of tolerance. Measure the
+5 RLH voltage on the Regulator/Guard Crossing assembly (A17). COM = TP10, HI =
TP14. The voltage should be +4.9V to +5.5V. If the voltage is out of tolerance, the
Regulator/Guard Crossing assembly (A17) is faulty. If the voltage is within tolerance, the
diagnostic circuit on the Switch Matrix assembly (A8) is faulty.
3609 +8RLH Supply Fault
The instrument is dormant and the +8RLH supply is out of tolerance. Measure the
+8RLH voltage on the Regulator /Guard Crossing assembly (A17). COM = TP10, HI =
TP17. The voltage should be +10V to +20V. If the voltage is out of tolerance, replace
fuse F1 on the Regulator/Guard Crossing assembly. (A17) If the voltage is within
tolerance, the diagnostic circuit on the Switch Matrix assembly (A8) is faulty.
3610 +PA Supply Fault
The instrument is configured to the dc 220V range. The Power Amplifier is set for 22.1V,
219V, and -219V and the +PA supply is measured for the nominal +180V and +360V
±10% by connecting MUX1 to the SDL line which is measured by the adc circuit on the
DAC assembly. In order to identify the faulty assembly the +PA supply will have to be
measured. Power off the instrument and remove the Power Amplifier assembly from the
chassis.
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