HP 83522A Service Notes page 255

Model 83522A
NOTE
Service
The values of the factory-select resistors are stamped on a
label, attached t o the RF casting. Matching resistor sets are
supplied with replacement YOs and must be installed on the
A6 YO assembly. The new label, indicating the replacement
resistor values, should be attached t o the RF casting.
If the A6 YO Driver Assembly is replaced, the shaping resistors
from the defective board must be reinstalled i n the new
assembly.
NOTE
If the YO needs little or no compensation, some of the factory-
select resistors may be omitted.
+5V Regulator A9
@
A9Q3 is a +5Vdc regulator mounted in a single package. It receives the +5V
UNREG line (slightly more than 5V) from the mainframe, and regulates it for
use in the plug-in RF components, A7 Marker, and A8 Sampler assemblies.
A6 YO DRIVER/AS REFERENCE RESISTOR TROUBLESHOOTING
NOTE
All reference designators refer t o the A6 assembly, unless
othetwise noted.
The A6 YO Driver and A9 Reference Resistor assemblies are primarily
responsible for controlling the R F output frequency. A failure in these
assemblies usually results in large frequency errors that are independent of
sweep time. (Frequency errors that change with sweep time are usually related to
delay compensation. Refer to Service Sheet A7.) Frequency errors on the order
-
of 500 MHz or less may be due to improper calibration. The problem may be
relieved by performing the Frequency Accuracy adjustment in Section V.
General
Check that all power supply voltages are present. +20V (on the A6 assembly)
and -40V (on the A12A1 assembly) supply the YO. Ensure that cable plugs are
correctly seated over the correct jacks throughout the plug-in. With the line
power off, remove and reseat the A6 assembly to assure good motherboard
contact.
NOTE
Unless specifically stated otherwise, the troubleshooting
waveforms and voltages described below occur when the
plug-in is sweeping across its full range (INSTR PRESET
conditions).