SOLVED : Help with Solartron Schlumberger 7151 DMM calibration. - Page 1
Forum section: electronics / general

author: PascalNE
author_rank: Regular Contributor
timestamp: November 27, 2024, 11:47:33 pm
content: Hello, Im currently experiencing issues with calibrating the solartron 7151 Im not sure if this is an issue with my method or if my multimeter is faulty. I will describe my situation below:Equipment: Solartron 7151, AR488 GPIB controller, 10kohm precision resistor (actual val 9.99982Kohm)I send the following commands using a program I have made in c# (although I have also tried just sending the commands using serial)MODE KOHMRANGE 20CALIBRATE ON(connect 0 source), LO 0, (Screen displays "LO pt" and then "-000005")SELECT OFFSET C = 10(connect resistor) HI 199998 ( Screen displays "HI pt" and then "+106510")WRITE (Displays "error 10" (CAL outside limits))CALIBRATE OFFFirst off I know the GPIB is working as I can communicate just fine with it and make measurements and use programs normally.The issue is when I use the HI command it seems to be taking the reading incorrectly as the count it displays after is "106510" which is not the measurement it should be making. When the measurement is made out of calibration mode and the same offset is applied the multimeter reads 19.9983.I have tried it without the offset but the count after HI was the same. Does anyone have any Idea what might be going on?( I have attached the command reference and calibration manual)Any help would be appreciated.Thanks, Pascal.

author: PascalNE
author_rank: Regular Contributor
timestamp: November 27, 2024, 11:50:44 pm
content: Here is the calibration section sorry

author: ch_scr
author_rank: Frequent Contributor
timestamp: November 28, 2024, 06:20:42 am
content: I'm not sure but "HI 199998" seems like 19k not 9k

author: PascalNE
author_rank: Regular Contributor
timestamp: November 28, 2024, 09:12:25 am
content: Yes that’s because of the 10k offset to make it closer the full scale of the 20k range

author: Kleinstein
author_rank: Super Contributor
timestamp: November 28, 2024, 09:48:35 am
content: I don't think tricking the meter with the offset constant would help in calibration mode. It has a chance to got wrong and would hardly help.Better use the 10 K resistor as is - if the meter complains, one would need another resistor in the 9-10 K range and use 2 in series.

author: PascalNE
author_rank: Regular Contributor
timestamp: November 28, 2024, 01:21:30 pm
content: I think it should work since it mentions it in the calbration manual as something you can do. Trying it without the offset gets the same result. The issue is that the reading it makes while calibrating is different to what it is when not calibrating. Do you think the multimeter might just be faulty?

author: Andy Watson
author_rank: Super Contributor
timestamp: November 28, 2024, 01:58:49 pm
content: Have you been able to change any of the calibrations? I notice that the sequence you describe does not mention enabling the calibration with the rear-panel jack. ?It's a long time since I dabbled with a 7150, but IIRC the calibration values have to be within a certain range for the meter to accept the new value.

author: PascalNE
author_rank: Regular Contributor
timestamp: November 28, 2024, 02:16:35 pm
content: I have now managed to calibrate the multimeter the only thing I changed was setting the RANGE to auto. I don't really have any idea why this worked as its not mentioned anywhere in the manualand I am 100% sure the range was set correctly.Thanks for you for your responses anyway