DMM DT9208A

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This is a cheap manual range multimeter. It has a lot of ranges.

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I got the meter in an envelope with some protective wrapping around it.

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It included the DMM, a pair of normal probes, a thermocoupler and a manual for this series of multimeters (i.e. DT92xxA).

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No tip cover on these small probes.

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And no real shroud on the plugs.

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The thermocoupler is the usual cheap model with loose bananaplugs.

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The range switch is a bit difficult to use single handed when meter is on the tilting bale, it slides around. You also have to be a bit careful with placing it correctly, the detents are not perfect at secure in the selected range.

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It is easiest to remove the rubber sleeve before changing battery.



Display

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The display is only the numbers, sometimes a minus sign and a battery symbol. There is no indication of selected range or units.



Functions

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Buttons: Rotary switch:
Input

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Measurements 1uF

A look at the capacity measurement waveform.

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Frequency counter is not very precise. Specifications are fairly bad and display is slightly worse.
Some capacity ranges show about 10% too low. The 200Mohm range is very sensitive to noise.
The 20A range will drift significantly at 20A



Tear down

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3 screws and the back could be removed.

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it is cheapest to produce a rectangular circuit board and it is made as small as possible.

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6 more screws to get it out.

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It was 4 screws around the switch and two at the display.

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The 3 resistors near the 20A input (1R00, 9R00, 90R0) is for the 3 low current ranges. They also have a fuse, but it is SMD, i.e. not easily replaceable. There is a OpAmp (LM358) with some resistors and diodes, this is probably the rectification for AC ranges. The green PTC is probably used for ohm (But not capacity) ranges. There is two 4504 (4.5Mohm) resistors in series, that is the input impedance in VDC and VAC.
I suspect that the HC4538 in the top corner is used for frequency measurement, i.e. it generates pulses that is integrated to a analog voltage that can be measured by the chip (This explains the bad precision). This means the HC14 Hex Schmitt-Trigger may be used for the capacity measurement. The 5 resistors near the COM input is the ranges for capacity.
The big red 450V capacitor is not used for voltage input.

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This meter has lots of adjustment, there was also one on the other side of the circuit board.

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The way the legs on the PTC is twisted do not look safe.



Conclusion

The meter is unfused, this means best to keep away from mains voltages and anything with high current.
This is a cheap meter and most ranges are fairly precise, but even though it has many ranges, it is also lacking a lot of ranges compare to a autoranging meter.
It can be used for hobby purpose and around the house, but make a single mistake with the mA range and a new meter is required.



Notes

This multimeter is sold with many different type numbers on it and other multimeters also use this type number.

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