Specifications

Chapter 4: Troubleshooting
Power Supply Troubleshooting
58
7 If there is still a short circuit, remove both acquisition boards and unplug them from
the backplane assembly.
8 Measure each assembly individually to see if there is a short between the +12V trace
and ground (see Figure 4- 12). You should see a resistance of about 2000 ohms between
the +12V trace and ground on a good acquisition assembly. Make sure you make the
measurement using a DVM with the red lead plugged into the HI input and the black
lead plugged into the LO or COMMON input of the DVM. If there is a short between
these two traces, the reading you get will be very low (near 0 ohms). Replace either
assembly if needed.
Figure 4-12 Measuring the acquisition assembly resistance between +12V and ground
If no shorts are found on the bulk +12V supply trace or if you have fixed all the shorts
and the oscilloscope still will not turn on, follow these steps, which include replacing
parts with known good parts until you discover the problem.
1 Replace the bulk +12V power supply with a known good supply.
2 If the oscilloscope still does not power on, replace the motherboard with a known good
one.
3 If the oscilloscope still does not power on, then the backplane assembly is causing the
problem and must be replaced.
4 Once the faulty board or switch is discovered, be sure to reinstall all other parts that
were removed, as they were not the cause of the problem.