Hello,

I have an old Data Precision (USA) 1350 "3 1/2" Digit LED type Multimeter from the 70's era. It works great, except after performing a calibration the low K ohm scales are displaying readings are generally out by more then 5 percent.

So, the first step of calibration is adjusting the time base or oscillator to 40 KHZ( +/- 200Hz) for the AD7107. The next step is the Gain calibration by inputing a DC reference voltage of 1.900 volts, and adjusting a pot to this voltage on the display. The last step is balance, where a lead wire is tied back from the red banana jack to pin 36 (Hi Ref) AD7107, and is adjusted to 50 millivolts (+/- 50mv)

The multimeter readings are very good, except for the Low resistance scales..

Does anyone have any ideas on why?

Examples: 475 ohm 1% resistor it reads 430 ohms.
2K Ohm 1% resistor, it displays 1861 ohms

Thanks,
Neil