Tektronix TDS1001C-EDU, Service Manual

Page: 92 / 114

Maintenance
Troubleshooting the Main
Board
To troubleshoot the Main board (acquisition module), follow these steps:
1. Remove the rear case. (See page 58, 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.
Table 25: Troubleshooting the Main board
Supply Voltage range 1
Maximum
current draw J101 power
pins J101 return
pins Derived
supplies
35 V 30 V
DC
to 40 V
DC
fl oating. Pin 2 connected
to +3.3 V on the Main board.
15 mA 1 2 +28 V LCD
+6 V 5.5 V to 6.5 V 1.0 A 4 3, 5, 8, 10 +5 V
+3.3 V 3.0 V to 3.6 V. Requires minimum load to
maintain regulation. 1.8 A 6, 7 3, 5, 8, 10 3.3 V, +2.5 V
-4 V -5.0 V to -3.5 V 0.8 A 9 3, 5, 8, 10 -2.5 V
Line
trigger -2 V to 6 V open circuit.
±1 diode drop when attached to the Main
board. 1 mA 11 3, 5, 8, 10 Line trigger
1
With 3 W minimum load; still functions with no load.
3. If all of the voltages are present, the Main board is probably defective.
Replace it.
Running Diagnostics The oscilloscope runs an extensive self-diagnostic routine at every power-on.
Running the diagnostics from the Service menu will provide no additional
information and therefore is not needed. The menu selections are only used during
manufacturing of the oscilloscope.
Troubleshooting Input
Connections
Follow these steps to troubleshoot the input connections only if the oscilloscope
appears to function normally in every way, but an input signal is not getting into
the oscilloscope as expected.
80 TDS2000C and TDS1000C-EDU Series Oscilloscope Service Manual