# Arrrrggghh!! Power supply fried?



## Screaming Demons (Sep 15, 2008)

I'm sure they can be fixed with enough know-how, but it would probably be easier just to set up another one.


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## Bilbo (Mar 8, 2007)

Yeah, probably... don't have the time this year and I do have a couple spares. I'll have to find the tutorial I used last time. 

Thanks though.


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## Gryphon (Sep 28, 2011)

If you have old at power supplies just hook up to black and yellow for 12 volts and black and red for 5 volts.


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## Bilbo (Mar 8, 2007)

The ones I have need a load applied to work, I believe. I had to put a resistor between the grey and black if I remember correctly.  I'll try again tomorrow. Thanks, Gryphon. 

I think black and blue is 3volt.


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## CreepyCreations (Oct 16, 2011)

Some of the supplies also require a connection between the green wire and ground (black) to even start up.


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## Raven's Hollow Cemetery (Jul 3, 2011)

Bilbo said:


> The ones I have need a load applied to work, I believe. I had to put a resistor between the grey and black if I remember correctly. I'll try again tomorrow. Thanks, Gryphon.
> 
> I think black and blue is 3volt.



Blue is -12v and black is ground on ATX spec power supplies...this gif is just the easiest for most to read. That's why you're not getting power, blue is a reference -12v signal and not to be used under load. Grey should have zero effect, being that it's the "Power Ok" which helps the motherboard determine that everything is working correctly during post. Non importa for jumpering a computer psu into operation.


Red wires from the psu are +5vdc, orange are +3.3 vdc, yellow is +12 vdc, and black is common ground.


To add to what CreepyCreations said, to power up the psu, you have to put a jumper (or use a switch to make the connection) between the green and black wires. It's not very likely that it fried. It's just connected backwards, and most psu's built in the last 5 or so years have short protection built into them. Hope that helps 











Even though the pic is for a 20 pin ATX spec, the color codes are current for all 24 pin ATX power supplies too. Also, don't use the purple +5v VSB or the White -5v, both are for the motherboards PWM power phase reference, and not intended to handle loads (same as the blue & grey).

Edit: Things do change a bit for *some* OEM power supplies (OEM's meaning Dell/HP/Acer/etc), and if you're using one of them, let me know and I'll look up the pinout for the specific brand/model.


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## Bilbo (Mar 8, 2007)

This is why I LOOOOOVE this forum and its members!! I'll give this a try when I get home. 

So, just to review: 

Put a jumper between the green and black (ground) and wire the orange to my 3v posts and that should do it?

What if it's not an ATX supply? I'm not 100% sure.

I wonder why the blue wires worked all this time without issues??



I will also check the manufacturer for a couple of the spares I have. Thanks for the hope, RHC!!


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## Raven's Hollow Cemetery (Jul 3, 2011)

Yeppers, you've got it.  And...no problem at all, always glad to help out  


If it fits in any full ATX to m-ATX computer case (and wasn't built into a mini itx case or some other weird form factor OEM build), then it's ATX specification. Who is the manufacturer of the power supply, just out of curiosity? Like I noted earlier, their are a few of the OEM manufacturers that change things around a little (to make it nearly impossible for mere mortals to work on/troubleshoot, lol! And to make extra $$$ off of their overpriced, gouging "factory service"). 


Don't worry though, I have all of the different OEM pinouts from every model at my disposal, a model # & manufacturers name will help greatly in that unlikely event.


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## Bilbo (Mar 8, 2007)

I'll check as soon as I get home. Thanks again. 

The directions I had when I made this also had me putting a load (resistor?) across two of the lines so the supply would recognize it and work... Does that sound right?


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## Raven's Hollow Cemetery (Jul 3, 2011)

I forgot to mention that you _shouldn't need a load resistor_ on a switching power supply unless your triggering say...LED's w/ a very fast (think milliseconds & nanoseconds) response time needed. That is only true for lightning fx and other such fast reacting circuits are needed, & where a nearly instantaneous response is very desirable. Then using a load resistor to keep that specific rail from switching off is definitely a must. This is especially true with the later model 80+% certified efficient psu's. But in most cases by far, definitely not needed. 


Although knowing what the application that your using it for would help w/ making a final recommendation on the load resistor.


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## fravak (Dec 11, 2006)

Yes. Some supplies need a load to run properly. No 5v load, no 12v or 3.3v output. I have a couple of supplies that need to be "reset" after shorting out or power failures. All I have to do is unplug it from the wall, make sure the switch on the supply is turned on, and then touch the green and black together to turn it on. Doing this a couple times and then plugging it into the wall takes care of it.


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## Bilbo (Mar 8, 2007)

Thanks, Fravak, I'll try that as well. 

Right now I'm running about 30 3v tea light candles and two wiper motors, if that helps.


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## Raven's Hollow Cemetery (Jul 3, 2011)

Bilbo: As long as one of the motors is running constant, you won't need a load resistor at all. That's not to say that you don't need current limiting resistors on the tea lights, because specs on the psu orange wire are +3.3 vdc. Which will make them a bit more bright, and shorten their lifespan as well. 





fravak said:


> Yes. Some supplies need a load to run properly. No 5v load, no 12v or 3.3v output. I have a couple of supplies that need to be "reset" after shorting out or power failures. All I have to do is unplug it from the wall, make sure the switch on the supply is turned on, and then touch the green and black together to turn it on. Doing this a couple times and then plugging it into the wall takes care of it.



The mistake your making is not hard wiring the green (ATX logic wire) to ground. That's why your having to reset after a power interruption whether by timer, or just an accident. Short the pins permanently with a paper clip, or if you have molex mini-fit male pins, simply make a slightly more professional jumper. There is even an easy way out if you'd prefer to just buy a solution to the problem: 

20 pin version

Or:

24 pin version


Basically, it looks like this when done w/ a proper connector, and pinned out. But it's simple enough to make one self.


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## Bilbo (Mar 8, 2007)

The unit that stopped working is a Dell NPS-200 PB - 73m. My spare is a Compaq 277910-001. 

The Dell doesn't have a green wire that I can see. Tried jumping green/black on the Compaq and the fan didn't start.

There is a green/yellow wire that goes directly from the 115/230v switch to the case, that's the only one. The wiring schematics from when I wired it had the grey (labeled "remote" on the board) to my switch, then to the ground. I had a load (10 ohm? 10% dale 10w, it says) wired from orange to black then blue with white stripes to 3v posts, red to 5v and yellow to12v. 

I think Dell may just be wired differently?

Here's the link I used to wire it a couple years ago... http://web2.murraystate.edu/andy.batts/ps/powersupply.htm


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## Raven's Hollow Cemetery (Jul 3, 2011)

Yep, they are both those weird proprietary psu's. Found the pinout on the Dell. The ATX logic wire (PS# ON) is brown in that particular unit. This is a snip from Dell's tech manual on it showing the full 20 pin pinout. Running 2 wiper motors off that psu isn't a particularly good idea, being that the current max's out @ 7.5a on a 12.8 VDC rail, and a secondary rail @ 12 VDC 4.5A on a good day, and those models are pretty old. Only a little bit of strain on a wiper motor could've easily blown either, or both rails. I don't recall if they are internally fused, but you may want to check to see. 


On a proprietary OEM psu though, you are right to be running a load resistor. That said, I'd junk it or reserve it for something that consumes much less amperage, like a vent motor or three. Then get a cheapo Diablotek 500w or something similar for about $20-$30 to run the wiper motors. Whatever you do though, don't use Diablotek in your computer, they are absolute junk with huge amounts of ripple, sag, and frequent voltage spikes which won't affect a wiper motor a bit.  












The Compaq I'm going to have to dig around for the specs on. But I'll see what I can come up with and get back to you a.s.a.p.


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## Raven's Hollow Cemetery (Jul 3, 2011)

Well I found the HP/Compaq service manual for the Evo510 that psu was typically found in, and there is nothing on the pinouts whatsoever. I'll keep digging, but it's not looking good. Also, that supply specs out at roughly the same as the Dell model, which again isn't really appropriate to run wiper motors off of imo.


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## funhousejoe (Oct 1, 2008)

kinda makes me think a good way of doing this would be to just get a female atx plug so sipplies could be swapped out . easy way to do that is buy a power supply extension cable for like $2

http://www.amazon.com/ATX-Power-Supply-Extension-Cable/dp/B000BSLPZA


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## funhousejoe (Oct 1, 2008)

kinda makes me think a good way of doing this would be to just get a female atx plug so sipplies could be swapped out . easy way to do that is buy a power supply extension cable for like $2

http://www.pimfg.com/Product-Detail/ATX-POWER-EXT

http://www.amazon.com/ATX-Power-Supply-Extension-Cable/dp/B000BSLPZA


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## Bilbo (Mar 8, 2007)

Raven's Hollow Cemetery said:


> Yep, they are both those weird proprietary psu's. Found the pinout on the Dell. The ATX logic wire (PS# ON) is brown in that particular unit. This is a snip from Dell's tech manual on it showing the full 20 pin pinout. Running 2 wiper motors off that psu isn't a particularly good idea, being that the current max's out @ 7.5a on a 12.8 VDC rail, and a secondary rail @ 12 VDC 4.5A on a good day, and those models are pretty old. Only a little bit of strain on a wiper motor could've easily blown either, or both rails. I don't recall if they are internally fused, but you may want to check to see.
> 
> 
> On a proprietary OEM psu though, you are right to be running a load resistor. That said, I'd junk it or reserve it for something that consumes much less amperage, like a vent motor or three. Then get a cheapo Diablotek 500w or something similar for about $20-$30 to run the wiper motors. Whatever you do though, don't use Diablotek in your computer, they are absolute junk with huge amounts of ripple, sag, and frequent voltage spikes which won't affect a wiper motor a bit.
> ...


I was hoping it wasn't something like that. No time/money to replace the supplies right now.

I think I can tap temporarily into a running computer to run my LEDs and just not have the rocking chair and turning butler head this year. 

Quick question about the LEDs running off 3.3 v from the power supply. I know they need resistors to make them last longer... Since I have them all coming in on a single line but in parallel would a single resistor cover the all at the source or do I need to rig every single one? I know there are calculators that would figure this out for me, but I'm tired and lazy. Plus you seem to know what your talking about where I just know enough to be dangerous.


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## Bilbo (Mar 8, 2007)

Another idea... my wife has an old laptop AC adapter. It outputs 18.5V 4.9A. Would this run a wiper if I hooked it up to the slow pin?


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## Raven's Hollow Cemetery (Jul 3, 2011)

Bilbo said:


> Another idea... my wife has an old laptop AC adapter. It outputs 18.5V 4.9A. Would this run a wiper if I hooked it up to the slow pin?


You very much could use the laptop power adapter, with the easiest way being a LM7803 voltage limiter circuit with a 1Ω 1/4w resistor in line w/ the LED's for current limiting, but you'd have to use 5 of them (LM7803's) to take full advantage of the full output of the AC adapter, and they'd have to have heatsink's to deal with that much over voltage. You can sub the more widely available LM7805's, but you'll need to up the resistor value to 120Ω 1/4w to handle the current limiting on the 5v that the LM7805 outs. 

Part's list for the voltage limiter (5 of each):

-1n4001 diodes
-LM7803 (or LM7805) voltage regulator & TO-220 package heatsinks
-330 nF capacitor * see note
-100 nF capacitor * see note 


* note: ceramic disc type is best for this application.


Schematic relevant for both LM types:










The question is whether or not it's AC out (The power adapter, in which case you'd have to use a full wave bridge rectifier to make use of it), or if it's DC out, you're good. A half wave rectifier can be used, but it's very wasteful with respect to power draw. 


To answer the question about using a single resistor on a parallel LED configuration, yes it's definitely doable. But, the number of LED's in parallel, as well as the Vdrop per LED in the circuit must be known before an accurate schematic can be calculated. In fact, for your application, a series parallel circuit is the most efficient way to run groups of LED's. 


You'll still need a parallel LED calculator to do that though. 





funhousejoe said:


> kinda makes me think a good way of doing this would be to just get a female atx plug so sipplies could be swapped out . easy way to do that is buy a power supply extension cable for like $2
> 
> http://www.pimfg.com/Product-Detail/ATX-POWER-EXT
> 
> http://www.amazon.com/ATX-Power-Supply-Extension-Cable/dp/B000BSLPZA



That's what I do if I'm feeling lazy or pinched for time. Usually I just build my own (I have a good supply of the pins & the molex crimp tool though). Albeit, that solution only works if your using a standard ATX power supply, and in the case of Bilbo's funky OEM psu's, they're pinned completely differently than the usual off the shelf types. Which would mean every time you swapped psu's, you'd have to re-pin the adaptor (or conversely the psu), to avoid shorting everything out. 


I built my own (using a UV reactive connector as to make plugging and unplugging in the dark easier) into my obelisk base, specifically for powering LED wash lights earlier this year, seen here: 












TL;DR version: Works perfectly for normal ATX psu's. Not for OEM versions.


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## Bilbo (Mar 8, 2007)

Raven's Hollow Cemetery said:


> Bilbo said:
> 
> 
> > Another idea... my wife has an old laptop AC adapter. It outputs 18.5V 4.9A. Would this run a wiper if I hooked it up to the slow pin?
> ...


My brain just blew up. I know very little about reading electrical schematics, I apologize. On the diagram you provided I can't even tell where the pos/neg power input would come from... 

I don't think I'm going to mess with running the LEDs off the laptop adapter just the wipers. Would I still need to have the complicated (for me) circuit to run one or both?

And of course the tealights don't seem to list the Vdrop anywhere... 

Oh, and I cannot tell you how much I appreciate all the help.


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## Raven's Hollow Cemetery (Jul 3, 2011)

Bilbo said:


> My brain just blew up.
> 
> I don't think I'm going to mess with running the LEDs off the laptop adapter just the wipers. Would I still need to have the complicated (for me) circuit to run one or both?
> 
> Oh, and I cannot tell you how much I appreciate all the help.



Lol! No problem at all, that's just what I do.  It's really not as difficult as it sounds/looks w/ the LED's. You can run an entire yard full of them on with the above circuit.  


To add something in that I completely skipped over while typing fast earlier (brain outran the fingers ). I would use the laptop power brick to power LED's, not the wipers, and this is why:

The wiper motor(s) _*should*_ be fine with 18-19 vdc, however, a power supply with a capability of more than 5A per motor is very desirable in case of a bind (strain), and so I'd only recommend running one motor on that laptop power adapter, maximum. They will run a bit faster than normal on that power brick. If you were intending to run them on the high speed setting, just reconnect power to the low speed wire to negate that increased speed. If you had connected to the low speed wire originally, well...


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## Bilbo (Mar 8, 2007)

I think I'm going to see if my wife's college has tossed any computers lately... they usually have working power supplies I can scavange.


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