DMM UNI-T UT195DS

DSC_7902

This is a industrial grade DMM designed for electricians. This is the the most advanced of the meters in the 195 series.

DSC_7899

I got it without the box, but in the pouch.

DSC_7900

With all parts inside.

DSC_7901

That was the meter, the probes and a Chinese manual (I could download an English version).

DSC_7903
DSC_7904

Probes are branded UNI-T and rated for 20A, they have very low resistance this means the 20A rating is probably good enough.

DSC_7905

With a tip cover they are CAT IV 600V or CAT III 1000V, without CAT II 1000V (This is fairly standard for probes).

DSC_7906

The plugs are fully shrouded, but the shroud is a bit short

DSC_7910 DSC_7922

The meter is a bit heavy and the range switch easy to turn, this means it can easily be used with one hand, either lying flat or standing.

DSC_7907

All the red plastic is slightly rubberized in feel including the range switch.
The red plastic works as bumpers from any direction.

DSC_7908 DSC_7909

DSC_7913

The battery/fuse compartment is sealed and due to that the lid uses 5 screws, that usual stays in the lid (i.e. no lost screws).

DSC_7912

The flashlight led and a hanger.



Display

DSC_7916

All the segments are shown during power on. A few symbols are not used by this meter.

DSC_7917

Typical display during usage, it will show the number and selected measurement and sometimes the secondary display.
Secondary display functions:

Functions

DSC_7918

Buttons: Rotary switch:

Input

DSC_7919


Measurements
1uF

A look at the capacity measuring waveform with a 1uF capacitor.

DMMInputVoltageSweepHz

Frequency input is 3Mohm to 10Mohm up to 12V where it drops to 3kOhm

DMMInputVoltageSweepmVDC

mVDC is high impedance up to about 3V.

DMMschema




Tear down

DSC_7969

I had to remove 6 screws to open the meter. This meter uses metal inserts for the screws and they stay in the bottom (very nice).

DSC_7970

DSC_7971 DSC_7972

The flashlight, it uses two metal strips for contact to the circuit board.

DSC_7973

The main DMM chips are hidden under a metal can.

DSC_7974

DSC_7975


Four small screws and for larger screws at the input terminals, then I could remove the circuit board.

DSC_7976

To see the buttons I needed to remove 3 more screws.

DSC_7978

A flex circuit board is used for the buttons.

DSC_7979

DSC_7977

DSC_7980

DSC_7981

DSC_7982

DSC_7983

I am not that happy about the can, I need to remove the display and backlight, before I can remove it.

DSC_7984

Two screws to remove the display, solder two wires to remove the backlight and four more soldering to get the can away.

DSC_7986

The 20A shunt (R23A & R23B) is really large in this meter, that probably means it can handle 10A for a very long time without getting too warm. The smaller current ranges are handle by two smaller resistors (R24: 1ohm & R25: 99ohm), with a diode bridge (D9..D13) and transient diode (TVS1) for protection. The voltage input has two paths, both protected with dual PTC's (PTC1, PTC2, PTC1A1, PTC2A1) and MOV's (SG1, SG2, SG3). The voltage path is 4 resistors (R1..R4: 4x2.5Mohm) with the optional LowZ resistor (R21: 300kohm).
There is also a lot of transistor pairs for protection mv (Q3 & Q4), ohm & capacity (Q7 & Q8 and Q5 & Q6), frequency (Q1 & Q2). There is also a pair switched into the voltage input when in the uA range (Q9 & Q10), I wonder why.
All the diodes near the battery terminals (DD1..DD6 & D4..D8) I supposed are used for coding the range switch correctly for the multimeter IC.
The two chips (U7 & U8: marked PAO) are probably voltage regulators. The larger chip (U4: ES5) is a RMS converter. Below the can we have the multimeter chip (ES222), a microprocessor (U2: EFM32ZG222F32, 32kB flash, 4kB ram), a EEPROM (U5: 24256E 32Kx8) and a LCD driver (U3: HY2613B 4x36).

DSC_7987

DSC_7988 DSC_7990

DSC_7989

DSC_7985

The only part on this side is the LDR for automatic backlight and then there is the pads for the range switch and LCD display.

DSC_7991





Conclusion

This meter has a lot of protection, i.e. the CAT rating is probably correct.
This meter has a good selection of ranges and functions, including peak, LowZ and flashlight. With the fairly high AC bandwidth the LPF function can also be useful. The automatic backlight looks like a useful feature. I am missing temperature and average.

This meter looks to be a rather robust meter



Notes

UNI-T do often make rebranded meters, i.e. it may exist with other names on it.

How do I review a DMM
More DMM reviews