switching power supply

[august]

Hi.

I bought a switching power supply  dc 27v. The house sparked smalls when it touched ground (there was 115v). My basic knowledge from $50 Robot tutorial helped to find the problem. There was thermal paste without insulation between regulator and heat sink. I fixed that, now it looks fine.

My question, is it normal for power supply  to get warmer without load then on load? (The load means stepper motors are running.)

Thanks for help 

[Soeren]

Hi,

I bought a switching power supply  dc 27v. The house sparked smalls when it touched ground (there was 115v). My basic knowledge from $50 Robot tutorial helped to find the problem. There was thermal paste without insulation between regulator and heat sink. I fixed that, now it looks fine.

"Looks fine"? 

Why do you think it should be isolated from the heat sink?
If you didn't use either a nylon screw or a special isolating nylon washer to isolate the screw (or whatever holds the device onto the heatsink) it ain't.

If you have 230V, there should be 115V on the box (due to two small noise reduction caps from phase and neutral to ground).
Such a supply must be grounded (or the mentioned caps removed) to avoid 115V on the box.

My question, is it normal for power supply  to get warmer without load then on load? (The load means stepper motors are running.)

Absolutely not!
Sounds like your "fix" didn't cure it - something's very wrong and you better get it fixed before it burns down your home.

[august]

They used here springs (omega shape) instead of screws.

Yep, I have 230V

Each regulator has ceramic or tape to isolate from heat sink. But this one was filled up only with more than enough paste,
Maybe the earlier owner broke it or forgot it (my speculation), but anyway somebody did something in it earlier and was more beginner then I. He forgot to check it with multimeter,

The heat is coming from another part of the power supply from another regulator

"""  Absolutely not!
Sounds like your "fix" didn't cure it - something's very wrong and you better get it fixed before it burns down your home. """
I guess I should buy another one which is a new one this time,

Thanks for your reply !!