DMM BSide ZT301

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This is a cheap DMM with all common function.

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The meter arrived in a fairly anonymous multimeter box, but the checked illustration on the back matches the meter.

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It included the DMM, a pair of probes, a thermocoupler and a manual.

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The probes has removable tip covers, but is only rated for CAT-II, even with the covers on.

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The plug is fully shrouded, but is slightly smaller than standard probe plug size.

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A standard cheap termocoupler.

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When using the tilting bale the meter is nearly stable enough to turn the switch, but the meter is very smooth and will easily slide around.

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Display

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The above picture shows all the segments on the display.

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Typical display during usage, it will show the number and what measurement is selected.
The current software version has a bug, in manual ranging the manual annotation will disappear when using the range button.


Functions

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Buttons:
Rotary switch:

Input

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Standard probes cannot be fully seated in the terminals, but they will make contact. Banana plugs fits perfectly.



Measurements 1uF

A look at the capacity measurement waveform.

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Frequency input impedance.

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The 10A range is not stable near full current, it drift 2% in 15 seconds.
There is not much sound from the buzzer.



Tear down

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Four screws and the back could be removed. The missing part of the enclosure is not something I have done, but was present in the meter.

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As usual the circuit board is made to fit the enclosure.

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I had to remove 3 more screws and loosen two clips before I could take the circuit board out.

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To removed the display I had to remove two more screws and two clips.

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The uAmA current input uses the two resistors next to the 10A fuse (R23, R24: 99ohm, 1ohm) with the protection diode next to the 0.8A fuse (D5: 6V8). The voltage input has 3 paths, one for voltage (R29, R30: 2x5Mohm), one for ohm drive (PTC1) and one for sense ohm, Hz, temperature (R25: 900k). The PTC has a transistor pair for extra protection (Q3, Q4), for the other inputs it must be handled by the DMM chip.
Next to the DMM chip is a EEPROM (IC1: 24C02A).

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On this side is only the pads for the LCD and the switches.

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Conclusion

As usual I am very doubtful about the CAT rating, it must survive full voltage on the ampere input, but they are not rated for that, neither are the fuses.
The meter has many ranges and some functions (REL, min/max), but are missing some of the more advanced functions.
The meter can do min/max, test leads and the backlight do not turns off after 15 seconds.

It will call it fairly good DMM for hobby use, but keep it away from anything with mains voltage and lots of amps.



Notes

This meter exist with many different names on it and small variations in functions.
Check the Aneng AN8008 meter for a smaller version of this meter.

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