General Maintenance
CPU. The CPU fau
lt LED is DS680. The CPU section also h as DS591, which
is a duplicate of the FAULT LED, and DS590, which is a duplicate of the audio
fault light.
The CPU can detect that t he fault line is asserted. If the user has configured the
alarm section to monitor hardware faults, then alarms will be generated and / or
logged as set by the user. Since the CPU has access to many of the individual error
flags, some of these are displayed on the diagnostic log.
The CPU can also assert the fault line f or some failures during initialization and
power on self test (POST).
If the CPU is asserting the fault line, then replace the main board.
Primary Power Supply
Tests
This section describes methods for verifying the proper operation of the waveform
rasterizer primary power supply.
WARNING. Some parts of this test require removing the insulating safety shield.
To avoid personal injury, be careful not to contact the circuitry while the shield is
removed. Be sure t o replace the shield as soon as possible to prevent injury.
The main power supply accepts 100 to 264 VAC and outputs 5 VDC. The output
voltage at the supply must be between 4.9 and 5.3 V for correct operation. On the
main
board, the common 5 V supply must be between 4.80 and 5.25 V.
If the voltage at the output of the supply is not correct, check the input voltage. If
the i
nput voltage is in the correct range, then replace the power supply.
If the s upply output voltage is zero, then check the input circuit. The voltage
sho
uld be the same at the line cord, at the input to the power supply, and on both
ends of the fuse on the input to the supply. If the input voltage is correct while
the output is not, replace the supply. If the input voltage is not correct replace the
element in the chain that is not passing the AC input.
If the power supply output is correct, a lso check the fuses F40, F50, F51 and F160
in the 5 V system near the main board power connector J581. All should have 5
V on both sides. If not, replace the fuse. (See Figure 4-1.)
Secondary Power Supply
Tests
There are multiple secondary supplies that are derived from the main 5 V supply.
Be sure all fuses are good (as noted in Primary Power Supply Tests)before
checking the se condary supplies.
First, check the digital secondary supplies as shown in the following table. Each
supply has an LED and a test point. If any supplies are out of range, replace the
mainboard. (SeeFigure4-1.)
4–14 WVR6020, WVR7020, and WVR7120 Waveform Rasterizers Service Manual
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