MAINTENANCE
ACCESS PROCEDURES
3.
Using your fingernail, pry the grey tabs on the
LCD bezel free from the screw posts and
remove.
4.
To reassemble, reverse the above procedures in
a logical order.
4-19. BACKUP
FUSE
REPLACEMENT
4-20.
Use
the following procedure to replace the backup
fuse
(F2):
1.
Complete the Calibration Access procedure.
2.
Using a wide flat-blade screwdriver, pry the
fuse
out from the fuse holder. (Refer to Figure
4-l for the location
of
F2.)
3.
Replace the defective fuse a 3A,
600V
fuse (mfg.
part no. BBS-3).
4-21 . AC LINE VOLT AGE SELECTION
4-22.
The
8050A
is
configured
at
the factory for a
specific ac line voltage. The configured ac line voltage
is
listed on a decal located on the bottom of the unit. Line
voltage changes require the ordering of a new transformer
for the instrument. Refer to the Main PCB Assembly
parts list in Section 5 for the part number
of
the required
transformer.
NOTE
Instruments
with
Option
8050A-01
Rechargeable
Battery
use
a
different
procedure
for
changing the ac line voltage.
Refer to Section 6
for
this procedure.
4-23.
Use
the following procedure to change the
ac
line
voltage configuration on the 8050A:
I.
Complete the Calibration Access procedure.
2.
Remove the transformer and replace it one for
the intended line voltage.
3.
Relocate
the
white wire (from the power
receptacle) to the pcb hole labeled with the
correct voltage.
4.
Remove the case and relabel the ac line voltage
designation on the decal
at
the bottom of the
instrument.
4-24.
dB
Reference Impedance Power-Up Setting
4-25.
The following procedure sets the default (at power
up)
dB
reference impedance to anyone
of
the 16available
impedances. In the standard configuration (no diodes
installed), the default reference impedance
is
6000.
l. Complete the Display PCB Access procedure.
2.
Locate the diode mounting positions on the
Display PCB Assembly (just to the right of the
calibration access holes, viewed from the front
of the instrument).
3.
Refer to Table 4-2 and install diodes
as
shown
for the desired reference impedance.
4.
Reassemble the instrument.
Table 4·2.
dB
Impedance Selection
REFERENCE
IMPEDANCE
CR8
CR9
50
-
--f+-
75
-
""*--
93
~
-
110
--*-
-
125
-M-
-
135
-H--
-
150
--l+-
__,.__
250
-w--
__,.__
300
-H--
-M-
500
-14-
__,.__
600
-
-
800
-
-
900
-
-
1000
-
-
1200 -
~
8000 -
--f+-
Diode Type:
Use
Fluke P/N 203323 (1N4448, 1N914
or
equivalent)
4-4
CR10
CR11
--!+-
-
""*--
-M-
-
-
-
--f+-
-14-
-
__,.__
-K-
-
-
-
-H-
__,.__
-
-K-
-I+-
-
-
-
__,._.
--M-
-
-M-
-I+-
-
-
-
-I+-
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