Inadvertantly connected 3 DMD's to 12v 5A- Fixable?

The Dot Matrix Display (DMD) is a 32x16 array of high-brightness LEDs for visually striking effects. [Product Page]
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Aussie_Wombat
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Joined: Tue May 22, 2012 12:52 pm
Location: Adelaide, South Australia

Inadvertantly connected 3 DMD's to 12v 5A- Fixable?

Post by Aussie_Wombat » Sun May 27, 2012 7:23 am

Feeling like a real idiot about now... :oops:

I inadvertantly connected 3 DMD's to a 12v 5A psu.

Amazingly the middle one still works..

Can the others be repaired , or are they toast?

Looks like I got to go back to Jaycar and get another 2 DMD's, with a 5V 5A psu.... :(

I built a psu from an old computer psu, but it shuts down when I connect one DMD (on the 5v rail)... any ideas?

Cheers Dennis..

cef
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Freetronics Staff
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Re: Inadvertantly connected 3 DMD's to 12v 5A- Fixable?

Post by cef » Sun May 27, 2012 7:48 am

Which 5V rail on the PSU are you using?

Most ATX PSU's have a +5V Standby rail (which is low current - usually called +5VSB) and a few 5V high current rails (usually just called +5VDC).

Also, most PSU's need to be told to 'turn on' (jumpering the PS_ON Ground/Common is all that's required), otherwise the Standby (+5VSB) rail will be the only one with voltage.

http://www.smpspowersupply.com/connectors-pinouts.html might be useful to you.

maverick25ss
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Joined: Wed Mar 21, 2012 4:03 am

Re: Inadvertantly connected 3 DMD's to 12v 5A- Fixable?

Post by maverick25ss » Sun May 27, 2012 1:59 pm

I modded an ATX psu awhile ago too. I needed a load across the 5v line to stay on, ( maybe a 10 ohm 10 watt resistor) and I think I needed to connect the pwr_ok wire to one of the 3.3v lines too but don't quote me. We are in the middle of moving so mine is packed away with eveything. Check out www.instructables.com and you should be able to piece together enough info to get one going.

Aussie_Wombat
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Location: Adelaide, South Australia

Re: Inadvertantly connected 3 DMD's to 12v 5A- Fixable?

Post by Aussie_Wombat » Mon May 28, 2012 12:26 pm

off topic but

I followed one of the instructables tutorials to build this one..

I am using a "Speed ATX-580W" psu

the green goes to black, as the psu has a switch on the back.
the purple and gray(ash) are not connected to anything.
The black is ground, 6 wires to the black banana post (BP)..
...orange, 4 wires going to the green banana post ( no brown wire in PSU)
...red, 4 wires going to red banana post
... red , 1 wire goes to the 10W, 10 Ohm power resistor, then joins to ground. Code on side is 10W10RJ
...yellow, 3 wires go to the yellow banana post
... blue, 1 wire goes to the white banana post.

Turn psu on, fan starts
multimeter readings from black BP to ***************STICKER ON SIDE SAYS
green BP -- + 3.376 V *************** + 3.3v 33A
red BP -- +5.05 V ***************+ 5.0V 45A
YELLOW BP -- +11.98 V *************** +12 V 19A
WHITE BP -- -23.45 V *************** -12V 0.5A

Purple wire has +5V, and gray wire has +5 V

Plug in a small string of led modules, and string lights up ( 12V )

plug in an old hard drive to one of the old plugs i left on psu, and the psu shutsdown...
connect the DMD to the +5v ( red BP ) and the psu shutsdown....

Strange that the blue wire is supposed to be -12V but reads as -24V

Any ideas....

Just bought a 5V 4A plugpack from altronics, and am using that to power DMD's...

dtbaker
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Joined: Sat Jun 02, 2012 12:52 pm

Re: Inadvertantly connected 3 DMD's to 12v 5A- Fixable?

Post by dtbaker » Mon Jun 11, 2012 7:05 am

Hey Aussie_Wambat

Do your screens look like this after connecting them to 12v?

viewtopic.php?f=26&t=684

or do they display nothing at all?

Aussie_Wombat
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Joined: Tue May 22, 2012 12:52 pm
Location: Adelaide, South Australia

Re: Inadvertantly connected 3 DMD's to 12v 5A- Fixable?

Post by Aussie_Wombat » Mon Jun 11, 2012 9:09 am

@dtbaker

Nah they both look like this
20120611_165754.jpg
dead dmd
Cheers Dennis

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