Tektronix 1502C User Manual

Appendix C: Operator Troubleshooting

1502C MTDR User Manual

At power on during initialization only.

The instrument expects the pulse height to be slightly less than two major
divisions high and adds gain to make the pulse exactly two divisions high. This
message indicates that the pulse is non-existent, too small, or that the gain
circuitry is not working correctly.

If there is no pulse after pushing the MENU button, no measurements can be
made. Have the instrument repaired.

If the pulse is there and less than two divisions high, you probably can make
useful measurements. Run the Offset/Gain Service Diagnostic.

Refer the instrument for repair. If the instrument passes, use the SET VERT REF
to make the pulse exactly two divisions high. The instrument’s front-end board
needs repair, but it is often possible to make measurements.

At power on during initialization only.

The instrument expects the pulse height to be slightly less than two major
divisions high. This message indicates that the pulse is greater than two divisions
in amplitude with no additional gain added.

This message usually means that the front-end board pulse circuitry is no longer
properly terminated. If the waveform does not change when a 50 

W terminator or

cable is attached, the internal cable or front-panel connector is probably
disconnected or broken and no measurements can be made until they are
repaired.

If the waveform does respond normally when a 50 

W terminator or cable is

connected, the failure might be in the gain circuitry on the Main board or in the
hybrid circuit.

Have the instrument repaired. If a pulse is present, distance measurements can be
made. If the pulse is more than two divisions high, the millirho scale is not
calibrated and loss measurements should not be made.