HP 8560A, Service Manual

Page: 281 / 450

13. Monitor pin 9 (LV_STB) with an oscilloscope or logic probe. This is the strobe
for the A4 Log Amplifier/Cal Oscillator assembly.
14. Press and check that pulses occur when toggling between
LINEAR
and
LOG .
Interface Strobe Select
See function block K of A3 Interface Assembly Schematic Diagram (sheet 3 of 6).
Interface strobe select generates the various strobes used by circuits on the A3 Interface
Assembly. Tables 7-10 and 7-11 are the truth tables for demultiplexers
and
Table 7-10. Demultiplexer Truth Table
Selected
Pin
15, LSCAN_KBD
Pin
14, not used
Pin
13,
Pin 12, LDAC2
Pin 11,
Pin 10, not used
Pin 9, not used
Pin 7,
IA1 IA2 IA3
L L L
H L L
L H L
H H L
L L H
H L H
L H H
H H H
Table Demultiplexer Truth Table
Selected Output Line IA1 IA2
Pin 15, L L L
Pin 14, LINT_PRIOR H L L
Pin 13, LADC_DATA1 L H L
Pin 12, LDAC_DATA0 H H L
Pin 11, HCNTR_LDO L L H
Pin 10,
H L H
Pin 9, LRPG_RD L H H
Pin 7, LADC_REGO H H H
7-28 Section