I note in that picture that the meter, although not in use, is set to its most sensitive range: 200mV DC. 
It is a golden rule that, if there is not an off position on the selector (which the Extech does have) is that the meter should always be left set to the highest possible voltage range - in this case 1000VDC - to provide the greatest degree of protection to the meter.
As an example, imagine what would happen to that meter if you connected it to a 450V HT rail and omitted to set the correct range first! After all, accidents can and do happen!
That tear down comments on the poor quality of the soldering. This is not uncommon. Many items like this are made by numerous manufacturers and build quality varies enormously. From memory, I think Bangood are usually well respected for the quality of the items they sell. Without taking it apart you won't know how good (or bad!) the quality of your new acquisition is.
It is a golden rule that, if there is not an off position on the selector (which the Extech does have) is that the meter should always be left set to the highest possible voltage range - in this case 1000VDC - to provide the greatest degree of protection to the meter.
As an example, imagine what would happen to that meter if you connected it to a 450V HT rail and omitted to set the correct range first! After all, accidents can and do happen!
That tear down comments on the poor quality of the soldering. This is not uncommon. Many items like this are made by numerous manufacturers and build quality varies enormously. From memory, I think Bangood are usually well respected for the quality of the items they sell. Without taking it apart you won't know how good (or bad!) the quality of your new acquisition is.
