HP 8562E, Service Manual

Page: 368 / 482

Refer to function block M of A2 controller schematic diagram (sheet 1 of 4) in the
HP 8560 E-Series Spectrum Analyzer Component Level Information.
The Z output function block contains the absolute value circuits which determine the intensity
of vectors drawn on the display. The vector length is approximated by the sum of the X
length and Y length. The voltage corresponding to the X length, AX, is converted to current
by R274. If the voltage is negative, it is amplified by 2 in
converted to current by
and added to the current from This effectively turns both negative and
positive voltages into positive currents, hence absolute value.
1. Short pin 13 to ground
2. Connect channel A of an oscilloscope to pin 2. Connect channel B to
3. Set an oscilloscope to the following settings:
Amplitude scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Sweep time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lms/div
Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..External
4. Externally trigger the oscilloscope off the signal at pin 8 (LBRIGHT).
5. The waveforms should look like those illustrated in Figure If the waveform at
pin 2 is bad, troubleshoot the X line generator (function block D of the A2 controller
schematic, sheet 1 of 4).
6. If the waveform at pin 14 is bad, troubleshoot the Z output circuit (function block
M of A2 controller schematic, sheet 1 of 4).
7. Remove the short from pin 13 to ground. Short pin 1 to ground.
1 0 . 0 0 . 0 0 v 1 . 0 0 0 . 0 0 0 s
S K 1 9 8
Figure Delta X Waveform
8. Move the oscilloscope channel A probe to 5201 pin 14.
Controller Section 1