Mini review teardown, generic DT-266F clamp meter, aka POS

[Lightages]

My friend has a propensity for destroying multimeters. He leaves them outside in the desert sun, loses screws for battery doors, steps on them, drops them, etc ...

We were in  town in Chile renowned for its tax free zone and cheap imports so he decided to pick up the cheapest meter just so he had a multimeter. I warned him it would be bad at $18 equivalent and I was right. It feels like if you hold it with too tight a grip you can crush the housing. It creaks and groans and you can feel the joint between the two halves moving just as you hold it. The clamp feels like if you let it snap close to quickly that the clamp will break.

The selector dial feels very wimpy, and the detents are more reminders of where to stop more than actual positive clicks that will keep the dial in position. If you rotate it too quickly it can get positioned in almost any spot near the detent, but not quite on it. This can result, I think, in erroneous readings. I say "I think" because I could not repeat the circumstances each time but sometimes the meter would read way off until I tweaked the dial. It could be other reasons for it to be way off randomly.

The leads are mediocre, and are labelled as 1KV/10A CAT.III, lol yeah right. The meter reads within spec, when it reads correctly, on what I could test. I did not test too much as I was just checking this for my friend to let him know if it was even close. The update speed is between 2 and 3 times per second which surprised me. The continuity test takes a full second, yes one full second, to respond.

Here are the images. No way I would trust this thing at even 600V CAT.II as it says....





I know this one will last less than anything else he has had his hands on.

[Spawn]

Is there a resistor under the heat shrink to the clamp itself? That’s one way to calibrate it in factory I guess 

[SeanB]

New battery cover design, and a few more ranges as normally these only have AC current, Ac volts and rerersistance and continuity with the 2 external ranges repeated across the dialN Not terribly bad, and good enough to measure current with, though the voltage ranges are a little worrying. Careful of that socket marked EXT, it is connected direct to the input of the 7106 COB when it is in the high resistance position with no protection.

[T4P]

It's for a insulation test module, the mode doesn't measure high resistances  I've seen the accompanying external module

[pravardhan]

Hi,

Does this meter (M266) show AC current properly? As mine doesn't show properly and its new 

There is one Trim Pot at the LM358 IC which comes from the Clamp CT. So, how to calibrate it? 

And, also there is a gap at the bottom (inside the meter) of the clamp, it is normal for the gap or is it have to get touched? 

Please help me out...

Bye,
PRAVARDHAN