New Rigol dho804 oscillocope

I use  the power adaptor provided in the accessories box and I connect it to the AC power source (220 V, 50 Hz ).

The document you uploaded above, says  DC, 12 V, 4 A every time

Yes, so do you think it's largely a charger voltage issue?

I don't know. But if the power supply can deliver 75% of the required power, it's hard to validate if it is anything else...

It could be that Rigol re-designed the power requirements.  Certainly the newer version of the manual calls for 15V 3A.  I wouldn't plug anything in without checking with Rigol first what the specific instance based on serial number requires.

Ok, Thank you very much, I should contact Rigol service  to know if the power adapter came with scope is a correct or not.

(Yes), and give them a photo of the error, and how long it takes from powering on to the error

I mean: no, contact the vendor. Rigol will most likely ask you to do that anyway

Yes, I understand the difference here.  My point is that there seems to be a (perhaps older) version requiring a 12V 4a PD3 power supply and a newer version requiring a 15v 3A PD3 power supply.  The OP seems to have the latter supply but possibly a former instrument but it isn’t wholly clear: perhaps there is an unrelated fault (maybe using a 15v supply for a 12v instrument caused a problem), perhaps the PSU is wrong.  Is he reading the wrong version of the manual??  I wouldn’t be plugging any old supply into an instrument that is new and under warranty.

anniel747  I have original  power adapter for Toshiba laptop 15V 5 A , Can I try to connect it to scope.

Well, maybe you should take a multimeter and check the polarity of both power adapters at the output connector.
Of course, the decent instrument should have a polarity protection at the input, but at modern times, nobody can be sure, because the cutting of costs. 

Well, maybe you should take a multimeter and check the polarity of both power adapters at the output connector.
Of course, the decent instrument should have a polarity protection at the input, but at modern times, nobody can be sure, because the cutting of costs.