HP 54520 Series Service Manual page 109

CAUTION
CAUTION
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Chapter 6: Replacing Assemblies
To remove and replace an acquisition hybrid
To remove and replace an acquisition hybrid
Use the following procedure to remove and replace an acquisition hybrid. When necessary,
refer to other removal procedures.
ELECTROSTATIC DISCHARGE!
Use grounded wrist straps and mats when servicing the main assembly. Electrostatic
discharge can damage electronic components.
You do not have to remove the main assembly before replacing an acquisition hybrid.
To understand the sequence of parts, use the accompanying illustration.
To Remove
Remove the cover and power supply.
Use a T-6 Torx driver to remove two > Go screws (2)
screws that secure the heatsink HEATSINK
spring, then remove the heatsink. SPRING
Use a 3/16 hex driver to remove four
standoffs that secure the top plate.
Lift the hybrid off of the connector
assembly.
To Replace
The location of pins and other locator
features will guide the alignment of parts.
This assembly cannot be assembled.
incorrectly without forcing.
Install the hybrid with the three avasia
corner holes over the three large
locator pins. é
Install the top plate with the three
cut-out corners over the three locator
pins.
Tighten the hybrid carefully. Excess
force or improper procedure may break
the hybrid, which is very expensive to
replace.
Loosely install the four hex standoffs.
Use a 5 mm (3/16 in) torque driver set
to 0.34 Nm (3 in-Ibs) to tighten the
standoffs in the following sequence.
a Tighten any standoff to specifications.
b Tighten the standoff directly opposite
the first one to specifications. sien
TOP
PLATE
CONNECT 1 OR
PC BOARD
BOTTOM
PLATE
¢ Tighten the remaining two standoffs to specifications.
Check for the graphite pad on the underside of the heatsink, then install it with the
hole that is near one comer toward the front of the instrument.
When the heatsink is installed properly, you will be able to see the adjustment potentiometer
through the hole in the heatsink.
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