Calibration of Extech EX330

[AB2ZI]

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

[kc9qvl]

Send extech tech support an email.

mailto:support@extech.com

[AB2ZI]

Thanks Peter.

73, Kevin AB2ZI

[int2str]

Sorry to revive such an old thread, but it's the first Google search result
Does anybody have the calibration procedure for the EX330?

Through trial-and-error, I've figured these out:

VR1 - Adjusts capacity measurement
VR2 - Adjusts AC Volts measurement
VR3 - Adjusts DC Volts measurement
VR5/VR6 affect temperature, though I'm not entirely sure what their relation is

There is one more trim-pot under VR1 (VR4?) but I can't figure out what it does.

[int2str]

Extech came through on the info!

For reference:

4.1.0 mVDC Adjustment
4.1.1. 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 Adjustment
4.2.1. 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 Adjustment
4.3.1. 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 Adjustment
4.4.1. 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.

[Distelzombie]

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?

[coromonadalix]

1v 60hz is very doable with a signal generator,    and you can make an voltage divider with 20 turns trimpots

[Distelzombie]

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.