HP 83522A Service Notes page 188

A4 ALC TROUBLESHOOTING (CHANGE 8) (Cont'd)
If power is still missing, enable the plug-in markers and check that the MKR light flashes. If
it does, the failure must be limited to Directional Detector DCl. If the markers do not work,
check the A12 YIG Oscillator, A1 7 Modulator/Mixer, A16 Cavity Oscillator, and A14
Amplifier.
If removing the A4 assembly causess full unleveled RF power to appear, reinstall the board
and check A4TP5. If less than
-
2 Vdc is present, verify that the voltage across R49 is zero.
If A4TP5 is greater than +5 Vdc, suspect any circuitry between the Detector Selection
Switch and A4TP5, 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.
CHANGE 8