DMM HY-19E

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This is a fairly cheap DMM with 20000 count display.

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It arrived in a universal DMM cardboard box, the illustration do not match the meter.

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It included the DMM, a pair of probes, a thermocoupler and a couple of instructions sheets (manual).
The manual is without branding, it only says 19E

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No tip covers on these probes that is rated for 1000V Cat III and 10A
This means the rating is wrong.

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The plug is fully shrouded, but shorter than standard probes.

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The thermocoupler is the typical cheap construction.


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The polarity markings for the battery is not very easy to see, there is a small + and - symbol at the bottom of the battery box.



Display

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The above picture shows all the segments on the display.
It has two readouts and a bargraph at the bottom.

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During AC Voltage or current measurement the secondary readout will show frequency.
The bargraph looks like it has many steps, but that is a cheat, it is grouped in 5 bar groups.

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Typical display on other ranges.

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NCV shows dashes depending on the strength of the electric field.



Functions

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Buttons: Rotary switch:

Input

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Measurements 1uF

A look at the capacity measurement waveform when measuring 1uF.

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Frequency input resistance.

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The AC tolerance is a bit misleading, 0.06% is only 12 count at 20000, i.e. the count is the significant factor here.
The AC range cannot handle large DC voltages.




Tear down

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I had to remove four screws to open the DMM.

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It has ceramic fuses.

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The large one is rated for 380V and 100kA, the current rating is very impressive, but the voltage is too low for a 750VAC/1000VDC meter. On the circuit board below the fuse it says 10A/250V

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Circuit board is not shaped like the box, but is more rectangular.

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I needed to remove 8 small screws to get the circuit board out.

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And two more for the display.

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The two resistors beside the large fuse are mA and uA current shunts with diode protection (D3 & D4).
The voltage input shunt is 4 resistors (R61, R62, R63, R64: 4x2.5Mohm), isolation distance is a bit low between them. The input protection for ohms is a PTC (PTC1) and two transistors (Q5, Q6). The 9V supply is regulated with IC6.
The meter is built from a LCD driver/processor and a multimeter chip with a EEPROM for calibration and an external reference.


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No parts on this side, only areas for the different switches.
But I am missing the NCV antenna. Playing with a mains wire around the meter it looks like the sensitive area is next to the HOLD and SELECT buttons. Looking at the circuit board there is a thin track there.

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Conclusion

As usual on cheap(er) DMM's the CAT rating is wrong.
Because the mA range only goes to 200mA the burden voltage is not that bad and it has a A range with even lower burden voltage that has more than enough resolution for higher mA. With this DMM the battery must be replaced when the battery symbol shows or there is a risk of wrong readings.
The PEAK function does not work on this meter.
The meter has all the common functions for a multimeter with exception of min/max. The NCV, dual display and bargraph are nice additions. There is some precision behind the higher resolution at least in VDC, ohms do also look very good.



Notes

This meter exist with many different names on it and small variations in functions.

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