Adjustment Procedures
5-10 2715 Spectrum Analyzer Service Manual
7. Adjust R680 (LOCK) so that the waveform on TP270 is locked to the
waveform on TP250. An unlocked waveformexhibits a noticeable amount of
jitter. Whenthe waveform locks, a sudden shift of the waveform occurs and
the jitter goes away.C ontinue adjusting R680 counterclockwiseuntil lock is
lost or the potentiometer is fully counterclockwise. Make a note of the range
through which the signal stays locked. CenterR 680 in thenoted range.
NOTE. The waveform at TP270 has phase jitter due to pulse width modulation.
8. Varythe line voltage from 90 VAC to 240 VAC while checking for no loss of
lock. Readjust R680 if lock is lost. Reset the line voltage to nominal line
voltage.
9. Check the power supplies as per Table5--3.
Table5 -3: Power Supply Tolerances
Power Supply VoltageRange
-- 11 V --10.2Vto--11V
+5 V Adjustedwith R937
+10 V +10.0Vto+10.8V
+20 V +21Vto+24V
+50 V +47Vto+51V
+115V +109Vto+117V
10. Turn offthe graticule lights (DSPL 6).
11. Enable the checkerboard pattern by pressingUTIL522an d set INTENSI-
TY fully clockwise.
12. Set R703 (Z AXIS) on the Power Supply board to midrange position.
13. Monitor TP120 with the Multimeter and the --2.75 KV test point with the
High VoltageProbe.
14. Adjust R669 (DTC) on the Power Supply board for --2835 V at the
-- 2.75 KV test point. A toleranceof +40 V and --30 V applies to the --2835 V
when R669 reaches either endstop.