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This procedure applies to all DTM-151-S units with software version 7.0 and above and where the display shows “Bad Cal”.




This procedure is not applicable if any physical/parts modification was made or the original Analogue board serial number was changed on the DTM unit. Likewise, if unit was subjected to extreme pressure, sparks, or mishandling, unit must be sent back to Group3 for total re-calibration.




  1. Make the original Calibration Certificate handy. The calibration info is listed on it.

  2. Attach a working 4-range, Group 3 probe (LPT-141, MPT -141, LPT-231, MPT-231).

  3. On the DTM serial board, set switches 2 and 3 to ON on DIP switch SW2.

  4. Attach fibre optic cable to port (if FTR is used) or the RS-232 serial cable connector from the terminal to DTM unit (if RS-232 is used). Refer to pages 3-4 to 3-8 of the user’s manual on how to set up the communication. Additional set-up information provided on pages 3-9 to 3-12.

  5. Power on the DTM. The terminal emulator should display the DTM model and software version. It also shows that the DTM unit is communicating with the emulator.

  6. Press “CTRL+X” in succession to “Reset” the unit. (Quotation marks are omitted when typing the commands.)

  7. Type “*CALIBRATE” to set DTM on calibrate mode.

  8. Press “D” on keyboard to display the current calibration info of DTM.

  9. Type “ISB” to inspect error. The emulator should show “Damaged”.

  10. Type “SSB” to clear the error.

  11. Type “ISB” again to inspect the chip. It should show “Ok” on the emulator terminal.

  12. Type “ERASE” to erase the old calibration factors of the unit.

  13. Type “D” to verify that the calibration factors are erased. See example below.

  14. Type “Q” to quit calibration. Unit is now ready to accept commands for Manual Input of Calibration factors.

  15. Follow procedure on "Manual Encoding of Cal Factors" for DTM-151-S model.

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