Maintenance
Troubleshooting the
Display
To troubleshoo
t a nonfunctional display, follow these steps:
1. Remove the rear case. (See page 6-10, Rear Case.)
2. Turn on the osc
illoscope and verify that the display lights up. If it does
not, either the display or power supply is defective. If this procedure is not
conclusive, continue with Troubleshooting the Power Supply. (See page 6-29,
Troubleshooting the Power Supply.)
NOTE. Without a functional display module, the simplest way to verify that the
oscilloscope is on and functioning is to check for a signal at the output. The Probe
Comp outpu
t generates approximately a 5 V, 1 kHz square wave.
3. Use the test oscilloscope and the TPP0201 probe to probe the display cable
connect
or at J201 on the Main board. The following table describes the
signals you should expect to see.
See the exploded diagrams in Replaceable Parts for the location and
orientation of the connector on the Main board.
Table
6-6: Troubleshooting the display
Signal at J201 Description, Color
Pin1(markedwith◄)Nofixed pattern. Depends on display data.
Pin 2
No fixed pattern. Depends on display data.
Pin 3
No fixed pattern. Depends on display data.
Pin
4
No fixed pattern. Depends on display data.
Pin
5
No fixed pattern. Depends on display data.
Pi
n6
No fixed pattern. Depends on display data.
P
in 7
No fixed pattern. Depends on display data.
P
in 8
No fixed pattern. Depends on display data.
Pin9 26.5V
DC
1
Pin 10
Ground
Pin 11 +3.3 V
DC
Pin 12 HI when display active
Pin 13
Data rate clock. 1.36 MHz Square wave
Pin 14
Line rate clock 11.4 kHz, 500 ns high pulse from low baseline
Pin 15
Frame rate clock 43 Hz, 350 ns high pulse from low baseline
Pin 16 Floating
Pin 17
Ground
Pin 18
Ground
1
Value varies with temperature, contrast setting, and display type.
5. If all the signals are present, the display module is probably defective.
Replace it.
6–30 TDS2000C Series Oscilloscope Service Manual
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