Hi,
Just bought a some instruments and got this Tektronix 7313.

The scope is turning on but the screen get totally green after a few seconds.

If I install the 7b53an module in any of the 3 places, the scope is loosing the 5v rail (the plug-in is working, no issue with it)
Installing a vertical module like the 7a15 is not disturbing the 5v.

Any idea what could cause this issue?
I will sign the PSU tomorrow to check if something is bad there.
Alex