Rpg Interface - HP 8560A Service Manual

RPG Interface

See function block J of A3 Interface Assembly Schematic Diagram (sheet 3 of 6).
Counterclockwise RPG rotation produces low-going pulses which result in a high output on
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.
1. Monitor A3U401 pin 2 with
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
4. If pulses are missing at only one point, check for an open or short on AlAlWl and
5. Set the m switch off and disconnect AlAlWl from A3J602. Jumper A3U608 pin
12 (RPG-01) to U608 pin 14 (f5 Vdc). Jumper U401 pin 2 (RPG-02) to U511 pin 11
(HDPKD-CLK). This p rovides a 7.8 kHz square wave to the RPG-02 input of the RPG
Interface.
6. Set the m switch 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 7-5 and check the
frequencies at divide-by-16 counter A3U606.
14. If all the checks above are correct but the analyzer does not respond to the RPG, suspect
a problem in either the AlA RPG or the AlAl Keyboard.
15. Set the [LINE] switch off.
16. Reconnect AlAlWl to A3J602 and remove all jumpers.
7-8 ADC/lnterface Section
logic probe or oscilloscope. Pulses should be present as the
a