Hi all,
I've recently had a problem were I've had a couple of QFN-16 DC-DC converters blowing inside a microscope camera
and I'm thinking ground loop issue?
The setup is.. Almost everything I'm powering is run from one wall outlet, which has 3 multi plug blocks connected to it with about 20 outlets available.. Don't panic.. The
max consumption is about 800W if everything is switched on (which it never is.) I've tested the house wiring with a socket tester and it shows that
all the Earths are good (also in the plug block extensions.)
I have an HDMI lead from my computers capture card that goes off to the microscope camera, the camera is also powered from a separate 12v DC PSU. When the HDMI
lead and the 12V DC connector are plugged in together and the microscope camera switched on, the DC-DC converter on the microscopes internal power supply fails
permanently. After replacing 2 of them I knew something was amiss.
I've tested AC voltage from the end of the HDMI lead where it would enter the back of the camera to the computers USB and sound ports etc, and I get about 4v Max and 3.5uA.
So onto the 12v DC PSU... When testing the end of the DC connector back to the DC PSU's body.. .. On AC I'm getting 100v & 170uA ... And I can see the sparks
.. This is
blowing the DC-DC converter isn't it? I've tried some other laptop PSU's which do change the uA values a little, but not enough of a difference the warrants swapping the DC PSU.
What can I do to remedy this issue please?