Repair Procedures; Repair Procedures; Transformer Replacement - HP 8340B Manual

Power Supplies/Fan
Repair Procedures
TRANSFORMER REPLACEMENT
Transformer Removal
Refer to
Figure
1-6.
1.
Disconnect
line power, and remove the instrument top and bottom covers.
2.
Wait
for the A19
power-on safety indicator to go
out.
3.
Remove the
A19 capacitor assembly:
a.
Remove two flange screws (item
1).
b.
Remove two side panel screws (item 2).
4.
Disconnect transformer wires from the A62 motherboard:
a.
Remove the seven screws (item 3) connecting the transformer secondary wires to
the
motherboard.
b.
Remove the wire clamp screw
(item
4) from
the side panel.
c.
Remove the two screws
(item 5) holding the blue transformer
secondary wires
to the
bottom of the motherboard.
5.
Mechanically disconnect the rear panel assembly
(item 6):
a.
Invert the instrument and remove three rear panel screws (item
7).
b.
Remove the
ASS assembly protective cover.
c.
Remove three rear panel screws
(item 8).
d.
From inside the instrument, push the rear panel
out.
e.
Pull
the rear panel out and away from the fan housing.
6.
Desolder all transformer primary wires from the line
module.
7.
Remove the
four
1/4
inch
screws (item
9a), and the four
3/8
inch
screws
(item 9b), from the
side
panel.
8.
Remove the
last two screws as follows:
a.
Remove
the cables from A25J1 and A25J2.
b.
Remove the A24, A25, A26, A27, and
A28 assemblies.
c.
Using
an
offset posidriv, remove the two transformer screws on the side of the transformer
enclosure closest to the front panel.
d.
Turn the instrument on its
side and remove the
transformer,
carefully pulling
one end out
a
short distance, and then the other.
e.
Remove the metal plate from the side of the transformer and place
it
on
the new
transformer.
1-18
Power
Supplies/Fan Repair Procedures
HP 8340B/41B