sparks & little noises

[rizoma]

I'm using two bench single rail power supplies connected as bipolar and if I plug the power connector one pin at a time to my circuit I ear a little noise when I connect the positive and ground and a little spark while connecting  the negative  pin. Other than that the circuit works fine, this is just a one shot thing.
Should I worry about that?

[alsetalokin4017]

Are we allowed to know the make/model of the power supplies, and any details (like for instance a schematic) of the circuit you are powering with them?
 

[rizoma]

Hi! I'm attaching the board, sorry got no schematics, and about the psusss:

I'm using two really old italian bench power supplies so I don't think that can help much since there's no documentation about them anyway they are:
- alpha elettronica al-266s
- g.b.c. nt0410-00"
Other than that they seems to work fine, never had any problem with these...
thanks!