General Maintenance
If the voltage at the output of the supply is not zero, but still not correct, check the
input voltage. If the input voltage is in the correct range, then disconnect the cable
at J17 from the main board and recheck the output voltage. If the voltage is still
not correct then replace the power supply.
If the no-load output voltage is correct, then reattach the cable to the main board
and measure the current by clamping the ammeter around the red wire. If the
current is less than 20 Amps, and the voltage is still bad, then replace the power
supply. If the current is more than 20 Amps, then remove module boards and
recheck the current. If it is still high then replace the main board. If not then test
with one option board at a time to
fi
nd the one with excess current and replace
that board.
Secondary Power Supply
Tests
There are multiple secondary supplies that are derived from the main 5 V supply.
Be sure all eight 5 V fuses are good (as noted in
Primary Power Supply Tests
)
before checking the secondary supplies.
First, check that the green LED DS19 is on which indicates there is some 5 V from
the main supply.
Next, check if any of the three red LEDs (DS5, DS6, or DS7) are on. These
indicate failures on the general 5 V, general 3.3 V, and processor 1.5 V supplies,
respectively. If these are lit, the most likely causes are the fuses near J17, but if
those are OK replace the main board.
Next, check the secondary supplies as shown in the table. (See Table 5.) Each
supply has a test point on the Main board. (See Figure 3 on page 35.) If any
supplies are out of range, replace the main board.
Table 5: Main board secondary supplies
Nominal (+V)
Allowed range (+V)
Labeled as
1.8
1.7 to 1.9
+ 1.8 V
Fan
5 to 13.5
FAN_PWR
+5
4.75 to 5.25
+ 5 V
3.3
3.2 to 3.4
+ 3.3 V
2.5
2.4 to 2.6
+ 2.5 V
1.5
1.4 to 1.6
+ 1.5 V
1.0
0.95 to 1.05
+ 1.0 V
+5A
4.75 to 5.25
+ 5 VA
-5A
-4.75 to -5.25
– 5 VA
1.2
1.2 to 1.4
+ 1.2 V
28
WVR7200 Waveform Rasterizer Service Manual
