Troubleshooting The Power Supply; Table 6-5: Troubleshooting The Power Supply - Tektronix TDS2022C Technical Reference

Troubleshooting the Power
Supply

Table 6-5: Troubleshooting the power supply

Supply Voltage range 1
35 V 30 V to 40 V floating.
DC DC
Pin 2 connected to +3.3 V on the Main board.
+6 V 5.5 V to 6.5 V
+3.3 V 3.0 V to 3.6 V.
Requires minimum load to maintain regulation.
-4 V -5.0 V to -3.5 V
Line -2 V to 6 V open circuit.
trigger
±1 diode drop when attached to the Main board.
1
With 3 W minimum load; still functions with no load.
TDS2000C Series Oscilloscope Service Manual
To troubleshoot the power supply, follow these steps:
1. Remove the rear case. (See page 6-10, Rear Case.)
2. Use the test oscilloscope to measure the voltages from the power supply
module at J101 on the Main board module. The following table lists the
voltages you should expect to see.
Maximum
current draw
15 mA
1.0 A
1.8 A
0.8 A
1 mA
3. If all of the voltages are present, the Main board is probably defective.
Replace it.
4. If all or some of the voltages are missing, turn off the oscilloscope and
disconnect the cable at connector J101 on the Main board module.
5. Turn on the oscilloscope and check the voltages at the loose end of the cable
disconnected from J101, checking for the same voltages as in step 2.
6. If all of the voltages are missing, check the line fuse on the power supply
module. If the fuse is defective, replace the power supply module.
7. If the fuse is okay, and all or some of the voltages are missing, the power
supply module is probably defective. Replace it.
J101 power J101 return
pins pins
1 2
4 3, 5, 8, 10
6, 7 3, 5, 8, 10
9 3, 5, 8, 10
11 3, 5, 8, 10
Maintenance
Derived
supplies
+28 V LCD
+5 V
3.3 V, +2.5 V
-2.5 V
Line trigger
6–29