HP 83522A Service Notes page 263

Model 83522A
Service
Verify operation of U9, MarkerIRF Switch Control, by making the following key
entry:
Press 8350A INSTR PRESET CW
SHIFT
O 0
2 GHzs
0
3
M2
5 5
Hex Data mode
Address location 2C03 (U9)
Hex Data Write
Enters byte with alternate
highllow states
Check the outputs of U9 for the alternating highllow pattern. To obtain the
complement of each of the U9 outputs, press
.
. (AA).
This will expose any
locked latch registers.
To verify operation of U13, Delay Compensation Control, make the following
key entries:
MI 2
G H z s 0
1
Address location 2COl (U13)
M2 Hex Data Write
5 5
Enters byte with alternate
highllow states
Check the outputs of U13 for the alternating highllow pattern. To obtain the
complements of each of the U13 outputs, press
. .
.
Check the outputs of U13
again.
Markers
To troubleshoot A7 for marker failure symptoms, start by using an oscilloscope
to check Test Points 1, 2, and 3.
Press 8350A:
INSTR PRESET
CF
1 GHz
s
A F 1 MHz
ms
TIME
1 0 MHz
ms
Press 83522A:
AMPTD MRK
Engage the 1 MHz frequency marker and check TPl. The signal should
represent a TTL pulse approximately 2 cm wide. See Figure 8-57. Likewise, the
pulse at TPl should be 4 cm wide for 10 MHz Markers, and 6 cm wide for 50
MHz Markers. If these pulses appear to be incorrect, check that analog switch
U2A,C,D is switching properly. If it is, check the output pulse widths of the
monostable multivibrators against the data given in Table 8-12.