1) Turn Rotary Knob to "OFF" position.
2) Press and hold "SELECT" and "HOLD" buttons, and then turn "Rotary Switch" from "OFF" to "" function position within one second.
3) "000.0" is displayed
4) Input 000.0, press "SELECT" and then "REL" buttons simultaneously
5) Wait till reading is stable, press "SELECT" and then “HOLD” buttons simultaneously.
6) “300.0” is displayed
7) Input 300.0, press "SELECT" and then "REL" buttons simultaneously
Wait till reading is stable, press "SELECT" and then “HOLD” buttons simultaneously.
9) “3.000k” is displayed
10) Input 3.000k, press "SELECT" and then "REL" buttons simultaneously
11) Wait till reading is stable, press "SELECT" and then “HOLD” buttons simultaneously.
12) “30.00k” is displayed
13) Input 30.00k, press "SELECT" and then "REL" buttons simultaneously
14) Wait till reading is stable, press "SELECT" and then “HOLD” buttons simultaneously.
15) “300.0k” is displayed
16) Input 300.0k, press "SELECT" and then "REL" buttons simultaneously
17) Wait till reading is stable, press "SELECT" and then “HOLD” buttons simultaneously.
18) “3.000M” is displayed
19) Input 3.000M, press "SELECT" and then "REL" buttons simultaneously
20) Wait till reading is stable, press "SELECT" and then “HOLD” buttons simultaneously.
21) “30.00M” is displayed
22) Input 29.80M, press "SELECT" and then "REL" buttons simultaneously
23) Wait till reading is stable, press "SELECT" and then “HOLD” buttons simultaneously.
24) Turn to OFF to terminate the calibration
Attached is the procedures to calibrate BM257 resistance function. If the problem of your unit is only for 600 OHM range, you may turn meter off right after proceeding with "Procedure 8th". Please be careful. Wrong calibration operation may lead to ..... .