Figure 8-13. Quick Tuning Check Test Setup - HP 5501B Operating And Service Manual

8-65. This procedure consists of monitoring test point TP16 on A3 with an oscilloscope to determine
the relative amplitudes of F1 and F2 with the heater turned off. If the sampler, photodiode, and
amplifier are functioning properly and the heater is turned off, the traces on the oscilloscope will
show switching to different levels as it monitors the sampling of F1 and F2. With continued
observation of the trace switching, these levels which correspond to F1 and F2 will change
amplitudes since the tuning is uncontrolled.
8-66. To perform the quick isolation procedure, proceed as follows:
a. Observe the READY LED on the rear panel of the HP5501B. If after approximately 6
minutes from power-up (cold start), the LED begins flashing, you can assume that the
clock, dividers, state machine, warmup and power amplifier stages are working properly.
b. Remove the HP5501B covers as described in paragraph 8-55.
c. Connect a dc-coupled oscilloscope to A3TP16 on A3 as shown in Figure 8-13. Also see
Figure 8-24 (Component Locator) for test point locations.
d. Enable the laser high voltage section by setting the TEST-NORMAL switch (A1S2) on A1
Connector board to TEST.
e. On A3, change HEATER jumper, JMP 7 from NRM to OFF.
f. Set oscilloscope controls as follows:
g. Timebase to 2 milliseconds/division or faster.
h. Trigger to normal. Adjust the triggering for minimum flickering of the trace.
i. Vertical attenuator to 0.05V /division for X10 probe use or to 0.5V /division when using a
direct probe. Set coupling to DC.
j. To simulate a failure to observe how the waveforms at TP16 behave, move JMP 3 LIQ
CRYS jumper to ACT. Note that the scope trace wanders up and down in a very smooth
continuous manner with varying speed. If this occurs in step h, the liquid crystal switch
or A3U11 is defective. Return JMP 3 LIQ CRYS jumper to original position.
8-20

Figure 8-13. Quick Tuning Check Test Setup

HP5501B
Service