Model
83522A
Service
Check the voltage at TP6. If it is at 7.5 Vdc, suspect the PIN Mod
0
Driver
or the Modulator. If it is below
+4 Vdc, suspect the Detectors and Detector
Leg.
No Power
NOTE
Turn off line switch before removing or installing any
assembly.
NOTE
With the
ALC
assembly removed from the plug-in,
27.8
kHz
square wave modulation is not available in the
83522A.
To check the
RF
components, remove the A4 ALC assembly from its
socket. This removes all bias from the modulator and should allow
maximum power through the RF path. If full power (over
4-15 dBm) is then
detected, the RF amplifier
(A14), cavity oscillator (A16), and DC Return
(A15), are verified. Suspect primarily the detector. Also inspect the
modulator, as well as the A4 PIN Mod
0
Driver and Detector Selection
Switch.
If power is still missing, enable the plug-in markers and check that the
MKR light flashes. If it does, then the failure must be limited to the
DCI
Directional Detector. If the markers do not work, check the A12
YIG
Oscillator, A17 Mod/Mix, ~16 Cavity Oscillator, and A14 Amplifier. Refer
to RF troubleshooting procedures for details.
If removing the A4 assembly causes full unleveled RF power to appear,
reinstall the board and check
A4TP6. If less than +4 Vdc is found, check
continuity from
A4TP6 to the PIN Mod
0
Driver circuit. If A4TP6 is at +7.5
Vdc, suspect any circuitry between the Detector Selection Switch and
A4TP6, particularly the Log Amp.
Power Sweep/Flatness
If power increases smoothly with frequency, and POWER SWEEP is NOT
selected, suspect problems with the A5 FM Driver assembly.
NOTE
Turn off line power before removing or installing any
assembly.
Remove the A5 board from the plug-in. If the situation improves, suspect a
failure on the A5 assembly.
If the
RF
power is leveled within approximately 5 dB, refer to Section V,
Adjustments, in this manual, and perform the Internal Leveled Flatness
adjustment procedure.
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