(Don't know if I should make a new question, but it's partly related to my previous question).
I bought an old second hand oscilloscope (see Is my oscilloscope working or not?), a Philips PM 3253.
After some initial problems (and help of Electrical Engineering) I got it to work, however, except for the first half an hour, now every 10 minutes the mains group of the house goes 'down'... I don't know the exact English term... It means I have to go to the 'fuse box' close of the house to turn on the group switch back on.
Is there some easy solution for this or things to check on the oscilloscope, or is it some setting causing it?
(My electrical knowledge is not high)
At the end of the day I could have the power on for half an hour on without having the computer (on the same group on). Today I used a separate power mains outlet for the oscilloscope; maybe I put too many devices on an extension box. I will leave both on for an hour to see if it helps.
Update: I did some more testing and the solution was putting the power of the oscilloscope directly to a wall outlet (and not running through extension outlets).
Also I have added a cable to ground from a wall outlet to the oscilloscope GND input on the back.
I still have some problems with the oscilloscope but I will spend another post to it after I did some more tries to fix it myself. Thanks for your help!