100V 10A DSN-VC288 DC Voltmeter Ammeter Review – calibration problems

[aidept]

Can not do more with that potentiometer.
Did you said that there is a resistive divider there? I saw you replaced one resistor there.
I will try to replace one too. Any advice which of them?
I want a linearity on a scale no more than 2 Amps.

[Kiriakos GR]

Can not do more with that potentiometer.
Did you said that there is a resistive divider there? I saw you replaced one resistor there.
I will try to replace one too. Any advice which of them?
I want a linearity on a scale no more than 2 Amps.

An resistor divider, this is the circuit which will trim-down voltage.
In a way, this is similar to what a potentiometer will do too.

You are not the first person over planet earth, that you do discover the specific circuit limitations (VA digital meter).
This will never work properly.

The branded version of this item from DEREE in Taiwan, this has superior quality control speaking of electronic parts in use and over all functionality.
 
The five digits (non-branded similar gadget) this has lesser issues, but its slow as turtle, usable only for review of a DCV charger.

Once I got lucky, and this revision of VA meter still works as expected since 2016.
But non-branded items this is always a lottery, and I do not recommend it any more.
You better buy food with you money, instead of making rich an large portion of dishonest Chinese people.
https://www.ittsb.eu/forum/index.php?topic=1030.msg2940#msg2940
 

[aidept]

Just want to learn electronics not to make rich China people.

[Kiriakos GR]

Just want to learn electronics not to make rich China people.

Good choice !   

But be aware that, what ever I type as reply, this is a message for the many other readers too.
Several years ago, there was available small educational KIT about electronics learning,  PCB along parts and instructions.
Only electronics them delivered by developed countries they come with instructions today.
 
Here is a good example of dedicated digital panel meters and shunt.
https://www.ittsb.eu/forum/index.php?topic=735.msg3103#msg3103

[aidept]

You right.
But with this piece of sh** amp/voltmeter I've been learning a lot. Because is faulted and forced me to find the schematic, to try to understand what is wrong, why errors and so on.

[aidept]

Looking now for a 4  digit volt/ampermeter capable for displaying negative values of the current.

[Kiriakos GR]

You right.
But with this piece of sh** amp/voltmeter I've been learning a lot. Because is faulted and forced me to find the schematic, to try to understand what is wrong, why errors and so on.

The major problem of STM85103F3 Chinese chip, this is that you are not aware which part will fail first of it.
Even today the Chinese factories are incapable to do proper chip encapsulation, and air bubbles are killing the chip.
Usually it fails at amp section.

The schematic this is not factory made, its a crude description of surrounded passive components.

Car electricians they are well aware of analog ammeter with center of 0 Ampere, this having positive and negative scale.