HP 8562E, Service Manual

Page: 282 / 482

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