Grilled power supply, again...

Hi all,

I think I've grilled my second power supply, and I really don't know why, and how not to reproduce it again, any hint?

I was just running a test on the 3 motors, moving the extruder on XYZ axis, only the 3 stepper motor drivers cards were connected to the power supply, and it stopped in the middle of the test.
Now, when I'm trying to switch it on, it start for less that a second and stop again...

Going to buy a new power supply tomorrow, any recommendation?

Why do you think it is the powersupply? Are you using a PC ATX supply? I would be surprised if you could blow one up....

Try metering it just on the bench without anything connected.

J.

Yes, it's a PC ATX supply, with a homemade switch to switch it on.

Without anything connected, the power supply fan begin to turn, than stop in less than a second.

Does it have current sense lines you need to connect up?

If the fan comes on it must be working.

J.

... for driving stepper-motors i likely use linear controlled power-supplies, not switched.

My favorized powersupply for heavy steppers is a group of 8 parallel arranged and synchronized LM317 controlled by an UA741CN.

Here every LM317 is capable of 1,5 Amps and in parallel i have a powersupply with 12 Amps continuous adjustable until 28 Volts - it works since nearly 15 years without faults and it already had some serious shortcuts with fuming and exploding components in the load

Switching current can interfere with the pulsed power-drain of the motors and some of the regulating isn't cpable of continuous withstanding the inductive backforce of the coils, so my experience with switching power-supplies isn't so good ...

Viktor

John W: I don't know how to diagnostic that, any help?

Viktor: that sounds good, can it be buy in the street? what kind of shop? That's been only 3 month I live in Madrid, and I only know where to find pc-shops

[www.reprap.org]

Have you followed this?

J.

Hi Alexandre,

i build this powersupply many years ago as a DUY-project from "Elektor" - a german electronic-magazine.

You can find similar schematics on the web - if you didn't find them and want to build this on your own, then i can sketch the schematics ...

Here the old prototype:


And here an optimized PCB with two inserted LM317:


... other side:


Viktor

Viktor,

While your 'old' technology works (and I do like it myself) its so horrendously inefficient its unbelievable, SMPS is much better, line volts insensitive to boot.

J.

Thanks John, I'll look for these sense lines tomorrow, the strange ting is it was working perfectly for a while

Thanks Viktor, but I think I'll stay on the pc-supply side

I've connected the sense wire, it doesn't help, same behavior: fan begin to turn for less than a second, then stop.

I'll go to buy another alim tomorrow, I'm just a bit scare now to have the same problem as I don't know how it comes.

Thanks a lot.

Have you checked that he PS_ON# pin is correctly pulled low?

I had similar symptoms on a PC once. The fan ran for about one second at switch on, then the PSU powered off. It was caused by the motherboard not driving the PS_ON# line correctly.

Alvin

ATX12V PSU spec
[www.formfactors.org]