Service and Repair
5
Agilent L4532A/ 34A Service Guide
75
Testing the Power Supplies
The main p ower su p p ly is always active wh en t he ac lin e power cor d is
con n ect ed to lin e p ower. The p ower swit ch p laces t he digitizer in st an d by
mod e.
To ver ify t he p ower sup p lies:
1
Remove t he d igitizer cover s (see
page 82
).
2
Make su r e t he ac p ower lin e is con n ect ed pr op er ly.
3
Measu r e th e followin g volt ages u sin g t he d igitizer chassis as t he
r efer en ce. The test p oin ts ar e shown in t he figu r e on t he n ext p age.
C A U T I O N
To prevent equipment circuit damage, always toggle the line power switch
to put the digitizer in standby, remove any input cables, and disconnect
the digitizer from the ac mains before removing or replacing any
assembly.
Supply
Remarks
+ 12 V Unswitched ( 0.1 V
)
This supply is active whenever the digitizer is connected to the
power line. If the supply is missing, unplug the connector to the
Carrier board and retest the supply at the power supply
connector. If this supply is still not correct, power supply
assembly replacement is indicated. Removing the power supply
is described beginning on
page 85
.
+ 12 V Switched
This supply becomes active when the power switch is pressed.
A failure of this supply indicates a failure of the power switch or
the Carrier/ Processor Board assemblies. If this supply is
missing, unplug the connector from the Digital board and retest
the supply at the connector to eliminate a Digital Board loading
issue.
- 12 V Switched
This supply is used by the Digital Board assembly. If this supply
is not present, a failure of the Carrier/ Processor Board assembly
is indicated. A failure of this supply can cause self-test to
indicate a failure of the Digital Board. If this supply is missing,
remove the Analog Board(s) and retest to eliminate an Analog
Board loading issue.
N O T E
The power supply contains a built in 3.15 A, 250 VAC protective fuse. This fuse is
captive, and is not replaceable. If this fuse blows, replacement of the entire
power supply is recommended.
