Calibration of Extech EX330 - Page 1
Forum section: electronics / testgear

author: AB2ZI
author_rank: Newbie
timestamp: October 14, 2014, 05:49:41 pm
content: Hello everyone. Among my collection of meters is an Extech EX330 which is slightly off in the AC and DC ranges. There are a number of pots inside but they are not labeled and I am unable to find either a schematic or calibration procedure on line.Does anyone here have this info?Thanks in advance and regards,Kevin AB2ZI

author: kc9qvl
author_rank: Regular Contributor
timestamp: October 15, 2014, 02:57:50 am
content: Send extech tech support an email.mailto:support@extech.com

author: AB2ZI
author_rank: Newbie
timestamp: October 19, 2014, 12:55:35 pm
content: Thanks Peter.73, Kevin AB2ZI

author: int2str
author_rank: Regular Contributor
timestamp: September 24, 2015, 09:45:17 am
content: Sorry to revive such an old thread, but it's the first Google search resultDoes anybody have the calibration procedure for the EX330?Through trial-and-error, I've figured these out:VR1 - Adjusts capacity measurementVR2 - Adjusts AC Volts measurementVR3 - Adjusts DC Volts measurementVR5/VR6 affect temperature, though I'm not entirely sure what their relation isThere is one more trim-pot under VR1 (VR4?) but I can't figure out what it does.

author: int2str
author_rank: Regular Contributor
timestamp: September 24, 2015, 07:20:51 pm
content: Extech came through on the info!For reference:4.1.0 mVDC Adjustment4.1.1. Set the EX330 to mVDC.4.1.2. Apply 100.0mVDC to the input sockets of the EX330.NOTE: The display should indicate “100.0 mV.”4.1.3. Adjust VR3 until you have a reading of 100.0mVDC.4.2.0 VAC Adjustment4.2.1. Set the EX330 to VAC.4.2.2. Apply 1.000VAC/ 60Hz into the input sockets of the EX330.NOTE: The display should indicate “1.000 VAC”.4.2.3. Adjust VR2 until the UUT displays a reading of 1.000VAC.4.3.0 Capacitance Adjustment4.3.1. Set the EX330 to CAP.4.3.2. Apply 100.0nF into the input sockets of the EX330.NOTE: The display should indicate “100.0 nF”.4.3.3. Adjust VR1 until the UUT displays a reading of 100.0nF.4.4.0 Temperature Adjustment4.4.1. Set the EX330 to Deg C.4.4.2. Apply 25°C into the input sockets of the EX330 using a type K thermocouple wire.NOTE: The display should indicate “25°C”.4.4.3. Adjust VR5 until the UUT displays a reading of 25°C.4.4.4. Apply 750°C into the input sockets of the EX330.OTE: The display should indicate “750°C”.4.4.5. Adjust VR6 until the UUT displays a reading of 750°C.4.4.6. Set the EX330 to Deg F.4.4.7. Apply 77°F into the input sockets of the EX330.NOTE: The display should indicate “77°F”.4.4.8. Adjust VR7 until the UUT displays a reading of 77°F.

author: Distelzombie
author_rank: Frequent Contributor
timestamp: April 18, 2018, 06:39:18 am
content: How do I get 1V 60Hz the easiest way? I only have DC sources afaik, and I accidentially turned VR2 instead of VR3.I have a 5V, 10V precision voltage reference. I used that to calibrate DC. Is there a way to divide the voltage accurately by 100?

author: coromonadalix
author_rank: Super Contributor
timestamp: April 18, 2018, 07:35:03 am
content: 1v 60hz is very doable with a signal generator, and you can make an voltage divider with 20 turns trimpots

author: Distelzombie
author_rank: Frequent Contributor
timestamp: April 18, 2018, 07:54:33 am
content: The only Signal generator I have is my smartphone and my laptop. And on both I don't know what amplitude or volume results to 1V. I guess they can reach 1V.What do you mean "20 turns" pot? I thought I need to know amps to know how much voltage gets dropped by a resistor. I only have one Multimeter and nothing else, until maybe next month.