9. If LKBD-RESET is incorrect and a pulse is not present at each of. the LKSCN outputs of
U602
when a key is pressed, check for LWRCLK and LSCAN-KBD.
RPG
Interface
Refer to function block J of A3 Interface Assembly Schematic Diagram in the
HP 8560 E-Series Spectrum Analyzer Component Level Information.
U608B latches the RPG direction from the two RPG outputs, RPG-COUNT and
RPG-COUNTl.
Counterclockwise RPG rotation produces low-going pulses which result in a
high output on U608B. Clockwise RPG rotation results in a low output from U608B. U612A
provides the edge to trigger one-shot U423B, which generates a 90 ms pulse. This pulse gates
U610A for counting of RPG pulses by
U606.
Gates U610D and U614D prevent retriggering of
U423B until its 90 ms pulse has timed out.
Note
Elsewhere, RPG-COUNT1 is referred to as
RPG-01
and RPG-COUNT is
referred to as RPG-02.
1. Monitor A3U4Ol pin 2 with a logic probe or oscilloscope. Pulses should be present as the
RPG is rotated.
2. Monitor A3U608 pin 12 as the RPG is rotated. Pulses should be present.
3. If pulses are missing at both points, check for power and ground signals to AlAlWl and
AlA2Wl.
If both power and ground are there, the
AlA
RPG is probably defective.
4. If pulses are missing at only one point, check for an open or short on AlAlWl and
AlA2Wl.
If these cables are working properly,
AlA
RPG is probably defective.
5. Press
LUNE)
to turn spectrum analyzer off and disconnect AlAlWl from A3J602.
Jumper A3U608 pin 12
(RPG-COUNTl)
to
U608
pin 14
(+5
Vdc). Jumper
U401
pin 2
(RPG-COUNTl)
to U511 pin 11 (HDPKD-CLK). This provides a 7.8 kHz square wave
to the RPG-COUNT input of the RPG Interface.
6. Press (LINE) to turn spectrum analyzer on.
7. Check A3U608 pin 9 for narrow, low-going pulses approximately every 90 ms.
8. Check A3U608 pin 13 (LRPG-RESET) f
or narrow, low-going pulses approximately every
90 ms.
9. Check A3U612 pin 5 for narrow, low-going pulses approximately every 90 ms.
10. Check
U608
pin 5 (HRPG-IRQ) f
or narrow, high-going pulses approximately every 90 ms.
11. If HRPG-IRQ is correct but LRPG-RESET is incorrect, check U505 pin 13
(LKBD/RPG-IRQ) f
or narrow, low-going pulses approximately every 90 ms.
12. If HRPG-IRQ
and
LKBD/RPG-IRQ
are correct but LRPG-RESET is incorrect, suspect
a failure on the A2 controller assembly.
13. Check
U610
pin 3 for a 7.8 kHz square wave. Check
U606
pin 2
(HRPG-RESET)
for
narrow, high-going pulses approximately every 90 ms. Refer to Table 8-5 and check the
frequencies at divide-by-16 counter A3U606.
14. If all the checks above are correct but the spectrum analyzer does not respond to the
RPG, suspect a problem in either the
AlA
RPG or the
AlAl
Keyboard.
8-8
ADC/lnterface
Section
