artisan 8640B - Fixed-Frequency Modulation Oscillator Adjustment; Power Supply Adjustments

Model 8640B TM 9-4935-601-14-7&P
ADJUSTMENTS
5-25. POWER SUPPLY ADJUSTMENTS
REFERENCE:
Service Sheets 22 and 23.
DESCRIPTION:
A digital voltmeter is used to check the power supply voltages. They are then adjusted for the correct voltage. This
procedure should be performed before making any other adjustment.
EQUIPMENT:
Digital Voltmeter .........................................................................HP 3480B/3484A
PROCEDURE:
1. Set LINE switch to ON. The fan should run and five LED's located on power supply boards (A18, A20, and A22)
should be lit.
2. Connect DVM to each of the test points listed below. The voltages should be within the tolerances shown; if not,
adjust appropriate resistor for a reading within the indicated tolerances.
Test Point Adjust Voltage Level
-5.2V A18TP5 A18R2 -5.200V ± 10 mV------*
+5.2V A20TP10 A20R16 +5.200V ± 10 mV-----
+20V A22TP4 A22R7 +20.000V ±10 mV-----**
-20V A22TP9 A22R19 -20.000V ±10 mV------***
+44.6V A20TP4 A20R8 +44.600V ±100 mV----
* For ambient temperatures other than 25 c. modify the voltage level setting by -4.2 mV/ C.
** Perform FM CAL adjustment (paragraph 5-38, step 8) and time base adjustment (paragraph 5-41).
** Perform VARACTOR BIAS adjustment (paragraph 5-38, step 12).
5-26. FIXED-FREQUENCY MODULATION OSCILLATOR ADJUSTMENT
REFERENCE:
Service Sheet 9.
DESCRIPTION:
A digital voltmeter is used to monitor the audio oscillator's output while setting its level. The AUDIO OUTPUT LEVEL
dial is also adjusted.
5-8
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