8751A-12
SUPERSEDES: None
Continued
DATE: 16 December 1991
8751A Network Analyzer
Serial Numbers: 0000J00000 / 3123J00500
0000A00000 / 3123A00114
Duplicate Service Notes: None
Modification to fix the intermittent lock up/PRESET operation
To Be Performed By: Agilent-Qualified Personnel
Parts Required:
Part No. Qty Description
08751-69551 1 A51 GSP Re-built Assembly
Situation:
8751As may intermittently lock up, or perform unexpected PRESET operations suddenly,
if a X’tal OSC (pn 1813-0484) is used at A51U42 on the 8751A A51 GSP board.
This will be caused by the A51U42 X’tal OSC which does not oscillate properly.
The X’tal OSC at A51U42 has been changed to an X’tal OSC (pn 1813-0865) to solve the
problem. All A51 boards currently supplied for replacement has the new X’tal OSC at
A51U42.
1 of 3
AUTHOR: MT
ENTITY: 3301
© 1992 AGILENT TECHNOLOGIES
PRINTED IN U.S.A.
SERVICE NOTE
ADMINISTRATIVE INFORMATION
MODIFICATION RECOMMENDED
SERVICE NOTE CLASSIFICATION:
ACTION
CATEGORY:
LOCATION
CATEGORY:
CUSTOMER INSTALLABLE
ON-SITE
SERVICE CENTER
RESPONSIBLE ENTITY: 3355 UNTIL: 16 December 1993
ADDITIONAL INFORMATION:
IMMEDIATELY
ON SPECIFIED FAILURE
AGREEABLE TIME
AVAILABILITY:
PRODUCT’S SUPPORT LIFE
RETURN
SCRAP
SEE TEXT
SERVICE
INVENTORY:
RETURN
SCRAP
SEE TEXT
USED
PARTS:
STANDARDS:
LABOR: 1.0 hrs
Page 2 Service Note 8751A-12
Solution/Action:
Perform the following procedure to check if the X’tal OSC (pn 1813-0484) is used at
A51U41. If the X’tal OSC (pn 1813-0484) is used, replace the A51 board with new one.
1. Remove the top cover from the 8751A.
2. Remove two screws restraining a plate over the A51 assembly, and remove the
plate.
3. Disconnect all cables from the A51 assembly.
4. Remove A51 assembly from the 8751A.
5. Check if “1813-0484” is tagged on the A51U42 X’tal OSC component as shown in
Figure 1. If it’s written, replace the A51 board.
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