Power Supply Woes

[gmay3]

So I went to turn on my power supply switch (after no installation or wiring changes since I last printed) and my printer turned on for less than half a second then shut off and will not turn back on. It is slightly cold (55-60F) in the are the printer is located.

I have an 8" i3v with a ATX power supply. I quickly looked at the wiring connections and did not see an issue. I have yet to ring out my wiring system.

Before I do so:
1. Do these supplies have an internal glass fuse that I should check first?
2. Has this happened to anyone before?

Many thanks!

[sniffle]

ummm, i don't remember fo sure but i'm pretty sure atx power supplies have resetable fuses... i believe the were designed to be non user serviceable

[lovincup]

You aren't by chance using a powerstrip that popped it's protection?

[TopJimmyCooks]

Do you have the resistor or whatever across the 5v so that it is shown a load upon startup? Do you have the 3.3v sense wire tied to 3.3v? I have found that newer ATX's will work sometimes without these being done, but much less reliably.

[gmay3]

Thanks all!

sniffle, are you saying that ATX power supplies do not have replaceable fuses?

lovincup, I am using a 1 to 3 outlet extension cord, it does not have protection. I'm still successfully powering the rasberry pi power supply with this extension cord.

TopJimmyCooks, I forget exactly what I did (I'll have to go back and look) but I followed Colin's 8" i3v build guide to allow the ATX power supply to power on.

[gmay3]

Looking back, I think I connected the green ATX "sense" wire to ground.

[N5QM]

The green wire is PS-ON and connecting it to ground tells the PS to power on and supply the other rails, so double check that to make sure it is still connected.

In addition, even with it off, you should be getting 5v from the purple wire, which is the standby power leg.

[gmay3]

OK so here's an update after a little debugging. I unplugged the connector to the RAMPS board and the power supply and everything else (fans lights) powered up fine. I turned off the supply, plugged back in the RAMPS and the LCD once again flickered on and then the power supply stopped. (as a side note the supply needed some time to recover before I was able to power up again with the RAMPS disconnected.

So now I have ruled out a damaged supply and the 12V wiring to the fans and LEDs. I must have a short or other issue with my RAMPS board.

If anything jumps out to anyone of something to check first please let me know! I already checked the screw connections on the RAMPS board and everything seems tight and fine.

[N5QM]

Hmm... Unplug everything from the RAMPS board and try to power it up, then add one component at a time?

Be sure to disconnect your Raspberry Pi as well.

[printbus]

Do you have a multimeter? With power off, probe the 12V power input at RAMPS and measure resistance. I read about 100 ohms on mine.

I don't think it takes down the 12V supply, but improperly connected endstops can short the Arduino 5V to ground, shutting down at least the Arduino. We had PM'd about jumpering across the polyfuses on RAMPS - did you do that? If so, maybe that makes a difference on whether 5V problems on RAMPS can affect 12V. Normally the polyfuse would just open in case of an overcurrent.