Tektronix LumaColor II J18, Instruction Manual

Page: 72 / 114

Troubleshooting
6–6 J18 Photometer Instruction Manual
4. Remove the five screws that attach the A1 board to the A2 board.
5. Gently pull the two boards apart, taking care not to bend the
connector pins on the A1 board.
6. Connect the battery to the A1 board and turn on the power
switch.
7. Connect the voltmeter to the V
BB
test point and ground.
Check V
BB
for a voltage of +7.2 V or higher. Refer to Figure 6–1
for test point locations.
J12
J92
–VR
GND
n/c
V
BB
V
CC
Figure 6–1: Test Point Locations on the A1 Board
If the voltage at V
BB
is less than +7.2 V, the problem is the battery,
not the power supply. If the voltage is +7.2 V or greater, proceed to
Step 8.
8. Hold the connection at ground and check for a voltage of +5.75 V
±
0.15 V at the V
CC
test point.
9. While still connected to ground, check the –VR test point for a
voltage of –0.22 V
±
0.04 V.
If the voltages at test points V
CC
and –VR are correct, the problem is
not the power supply. If these voltages are not correct, the A1 board
must be replaced.
Troubleshooting
6–6 J18 Photometer Instruction Manual
4. Remove the five screws that attach the A1 board to the A2 board.
5. Gently pull the two boards apart, taking care not to bend the
connector pins on the A1 board.
6. Connect the battery to the A1 board and turn on the power
switch.
7. Connect the voltmeter to the V
BB
test point and ground.
Check V
BB
for a voltage of +7.2 V or higher. Refer to Figure 6–1
for test point locations.
J12
J92
–VR
GND
n/c
V
BB
V
CC
Figure 6–1: Test Point Locations on the A1 Board
If the voltage at V
BB
is less than +7.2 V, the problem is the battery,
not the power supply. If the voltage is +7.2 V or greater, proceed to
Step 8.
8. Hold the connection at ground and check for a voltage of +5.75 V
±
0.15 V at the V
CC
test point.
9. While still connected to ground, check the –VR test point for a
voltage of –0.22 V
±
0.04 V.
If the voltages at test points V
CC
and –VR are correct, the problem is
not the power supply. If these voltages are not correct, the A1 board
must be replaced.