DMM Innova 3320

DSC_3630

Innova has a couple of multimeters, this is their midrange model. They all have the probe holders sticking out to the sides.

DSC_3626 DSC_3627

The meter comes in a blister pack with a comparison of the different meter models on the back.

DSC_3629

The pack includes the meter, a manual (That can also be downloaded) and probes.

DSC_3633
DSC_3635

The standard probes a slightly on the small side and are rated for 600V CAT II like the meter.

DSC_3636

The plugs are fully shrouded and nearly standard probe size. They are interchangeable with standard probes.

DSC_3644 DSC_3643

The range switch can be turned by one hand with the meter lying down or standing on the tilting bale.
The marking of "10MegOhm input" is a bit ridiculous, nearly all meters have that.

DSC_3631
DSC_3632

The meter has an elastic strap on the back.

DSC_3642

It makes it slightly more difficult to use the tilting bale.

DSC_3641

But makes it possible to attach the meter to an arm, may be practical sometimes.

DSC_3649

The probe holders in function.

DSC_3650

Battery and fuse replacement requires opening the meter.



Display

DSC_3645

Nearly all the segments are shown during power on (The battery test symbol is missing).

DSC_3646

Typical display during usage, it will show the number and selected measurement

DSC_5139

The battery tester has 3 leds in addition to the voltage readout, the leds are green, yellow and red and give a rough evaluation of the battery state. There is some light spill between the 3 position, but because the leds are different colors it is not a problem.



Functions

DSC_3647

This meter has no SELECT button and each range has its own position on the rotary switch.
Rotary switch:

Input

DSC_3648


Measurements
DMMschema




Tear down

DSC_3650

To get into the meter two screws must be removed.

DSC_3651

There is a screw under a PTC, this is not a very good design.

DSC_3653

DSC_3652

DSC_5124

Four screws more and the circuit board can be removed. The pink zebra stibe that connect the display to the circuit board can be seen through the display lcd.

DSC_5125


DSC_5126


The 3 leds for battery test and a few other parts are mounted on this side.

DSC_5132

DSC_5133

DSC_5134 DSC_5135

DSC_5137

DSC_5127

The input has a PTC for protection in ohm ranges (besides the input terminal) and a glass fuse for protection of current and battery ranges.
There are 3 resistors for battery check 9V (R28: 150ohm), 1.5V (R29: 89ohm), 6V & 12V (R31: 60ohm). The the low current ranges are a 1 ohm resistor below the 10A current shunt.
I would expect that the Quad OpAmp (IC2: LM324) is the comparator that handles the leds. Input for voltage is two resistors (R23a & R23b: 2x5Mohm).
The meter has 3 trimpots to for calibration, one is probably for the battery tester.
I am not very impressed with the way the crystal is mounted, it is very close to touching R34 (The body of crystals is isolated from the actual crystal inside).

DSC_5128

DSC_5129 DSC_5131

DSC_5130

DSC_5138



Conclusion

The CAT rating is fairly low, but do not live up to modern standard with unfused ampere range and a 250V mA fuse in a 600V meter.
The meter is a fairly basic meter, but it has most ranges needed for general around the house or car work and in addition to that it has a easy to use battery tester, the leds makes it easy to decide how good a battery is (But watch out for the mA range, a battery in that range will blow the fuse). The meter is not for electronic or mains work. Precision is close to spot on.



Notes

How do I review a DMM
More DMM reviews