HP 437B - ANALOG BOARD TROUBLESHOOTING (continued)

HP 437B
Service Sheet BD1
(© MICROPROCESSOR J CONTROL
Figure 8-3. A4U16, U18 Pinout Diagram
The digital control signals for the Analog board have now been verified.
Continue with the troubleshooting procedure for Service Sheet A4a.
Service Sheet A4a troubleshooting
1. Press the Power Meter’s SET RANGE key. Select range 3.
2. Press the dBm/W key for a reading in watts.
3. Set the range calibrator as follows:
FUNCTION ceiscswiiieevecieianeeden sess CALIBRATE
RANGE. osei adie ces pad aadudenoeta wee cohesaee 1 mW
4. Verify that the level at A4TP10 (C-GND) is equal to A4TP9 (A-GND)
+5.00 mV.
5. Set the oscilloscope as follows:
Vertical Sensitivity ......... ccc eee ce cece eee eeeeenes 5V/div
SWECD i idavs oa. cewie Saeed Se ercie weeded Oo40 Wass Hee Madre 1 ms/div
COU PLN iceceaet spire Ree Oa os ea tees Ras OHNE ae Nioa le oe DC
TriQQering. 2 ..ccscsseseesvaws vee eieaedaneal eee yess Internal
6. Connect the oscilloscope to A4TP3 (220 Hz). Verify the signal shown in
Figure 8-4.
SERVICE §-33