AMIR BORJI university research professor

my best guess is that it is some kind of EMI issue...it may be generated by the scope itself but it is somehow enhanced when it is in my house.<br> I moved it to a very quiet room with absolutely no electrical equipment running (not even light bulbs) and it still failed<br> although strangely the amount of DC offset on ch3 and 4 was a little less.<br> I also made a haphazard shield (faraday cage but not quite) around the scope and then ran SPC and still failed<br> then when I sent it back to Keysight, it passed. I asked the technician to run it several times over a period of 5 days<br> and also to move it to another office and he did and it always passed so he sent it back to me ...<br> other than this the scope works and measurements are very accurate, BW is about 600MHz and pretty flat...DC ffset accuracy is good&nbsp;<br> and performance test data (done twice) also shows that everything is in spec...<br> <br> &nbsp;

unit has always had latest firmware
I also tried 2.31 with no change

no, self test always passes.<br> there is no autozero function<br> &nbsp;

yes I also used it with an isolation transformer and chagned the voltage to other than 120V (tried down to 100V) but didnt help<br> I dont think my house is particularly humid or hot either...but the scope passed SPC whenever it was with Keysight lab<br> the date of the last passed SPC in the scope also verifies that it did pass when it was there.<br> <br> <br> &nbsp;

I have a DPO3054 which required calibration. But it was working fine and passing SPC all the time
I sent it in to Keysight Cal Lab and they performed full performance tests before and after factory adjustments were done
and scope was passing SPC and all tests were excellent and in spec
so I receive the scope and right out of the box it fails SPC (after warm up) and also has about 1mV DC balance (offset) at 1mV/div
on ch 3 and 4 and a less on channel 1 and 2 but still out of spec even though the "after" test show it was about 0.03mV

so I sent it back to Keysight lab and right away the scope passes SPC 4 times and another full performance test shows it is in spec
and the technician ran SPC for me several more times and it passed

I receive the scope and exactly the same issue as before :-( :-(

I moved it to other rooms in the house and also into the basement but it never passes SPC

any idea!!??