Agilent Technologies 8753ES Option 011 Service Manual page 273

Check A10 by Substitution or Signal Examination
If the 4 MHz REF signal is good at the A10 digital IF assembly, check the A10 assembly by
one of the following methods:
• Substitute another A10 assembly or
• Check the signal/control lines required for its operation. The pins and signal sources of
those lines are identified in
providing the necessary signals. These signal checks allow you to determine which
assembly is faulty. Some of the waveforms are illustrated by
If the substitute assembly shows no improvement or if all of the input signals are valid,
continue with "Check the 4 kHz Signal" on page
signals or consider the A10 assembly faulty.
Table 8-1 Signals Required for A10 Assembly Operation
Mnemonic Description
DIFD0 Digital IF data 0 (LSB)
DIFD1 Digital IF data 1
DIFD2 Digital IF data 2
DIFD3 Digital IF data 3
DIFD4 Digital IF data 4
DIFD5 Digital IF data 5
DIFD6 Digital IF data 6
DIFD7 Digital IF data 7 (MSB)
L DIFEN0 Digital IF enable 0
L DIFEN1 Digital IF enable 1
L DIFEN2 Digital IF enable 2
DIFCC Digital IF conversion comp.
DIFCLK Digital IF serial clock
DIF DATA Digital IF serial data out
L ENDIF L=enable digital IF
L INTCOP L=interrupt, DSP
Chapter 8
Table 8-1. It is possible that the A9 assembly may not be
8-11. Otherwise, troubleshoot the suspect
A10
Location
P2-27
P2-57
P2-28
P2-58
P2-29
P2-59
P2-30
P2-60
P2-34
P2-5
P2-35
P2-33
P2-4
P2-3
P2-17
P2-2
*Check for TTL activity.
Receiver Troubleshooting
Check the 4 MHz REF Signal
Figure 8-4
Signal See Figure
Source
A9P2-27 *
A9P2-57 *
A9P2-28 *
A9P2-58 *
A9P2-29 *
A9P2-59 *
A9P2-30 *
A9P2-60 *
A9P2-34 *
A9P2-5 *
A9P2-35 *
A10P2-33 Figure 8-4
A10P2-4 Figure 8-4
A10P2-3 Figure 8-4
A9P2-17 Figure 8-5
A10P2-2 Figure 8-5
and Figure 8-5.
8-9