Hi!
I need a bit of help, I killed my scope but actually I'm not sure what cos the problem.
Here is the diagram how I connected the scope to a unit.
First I connected the crocodile clip from my probe to the ( - ) and after that I put the positive tip of my probe on
the output of the NE555 and BINGO!
PSU, USB ports on PC and scope are gone.
Here is a detailed description:
My electronic what I tried to measure was a sort of PSU from a FAX machine with an NE555 ic.
I disconnected the NE555 from the circuit and tried to measure with my PC based scope.
The scope was connected to my desktop PC, so I know so far about the problem with the earth of the main power supply...
In my case, I connected first the crocodile clip to the NE555 gnd.
Then I powere up the unit which is powered from the main wall connector where is a voltage of 220V.
At this moment everything was fine.
When I touched the output of the NE555 with my scope probe the hell goes on.
PSU, all usb ports and the scope was gone.
I have to say, the PSU of the FAX machine was a switching mode power supply.
Here is my block diagram:
If I messed up with the earth of the PC and the - of the rectifier diode bridge the stuff would blow up
immediately after I put the crocodile clip to the NE555 gnd. Or I'm wrong?
I know this is a stupid question and situation but I can't figure out the problem.
Any idea?
Thank's.