Specifications

Chapter 4: Troubleshooting

Power Supply Troubleshooting

plugged into the LO or COMMON input of the DVM. On a good backplane assembly,

you should measure about 700 ohms. If there is a short on this board, you would

measure something very near 0 ohms.

3 If there is a short, disconnect the power cable to the front panel (see Figure 4- 9) and

redo the resistance measurement.

4 If the short is gone, replace the front panel assembly and verify that the oscilloscope

now powers on.

5 If there is still a short circuit, disconnect the two large connectors that provide power

to the motherboard (J1201 and J1202) from the backplane assembly (see the circled

cable connections in Figure 4- 11) and redo the resistance measurements across the

FET (Q1409) or the bulk supply input pins on the backplane assembly.

6 If the short is gone, replace the motherboard assembly and confirm that the unit will

power on.

Figure 4-10 Power supply disconnect

Figure 4-11 Cable connection into backplane