Hot power supply

spoodie · Post by **spoodie** » July 14th, 2006, 9:14

I got a new power supply for my router yesterday as the last one stopped working. The previous one was very hot when I unplugged it and this new one is also running hot, enough to be painful if you put your hand on it for more than a few seconds. Not knowing much about electronics I'm asking, is this a bad thing? Could it cause a fire?

Post by **Dr. kitteny berk** » July 14th, 2006, 9:19

spoodie wrote:is this a bad thing?

not really, transformers are just very inefficient, so put out a lot of heat

spoodie wrote:Could it cause a fire?

*Very* unlikely. worst case you'll send some paper a bit yellow. (if you leave paper on the power brick)

Post by **ProfHawking** » July 14th, 2006, 9:20

is it an old style fat-transformer or is it a new style switchmode thing (noticable by smaller size and less weight)

The switchmodes seem to get hotter, but there isnt much in them to burn. They shoulnt be too hot to touch!
If an old style one is getting hot, its probably being overworked a bit, get one that can handle more current

Post by **Dog Pants** » July 14th, 2006, 9:21

It isn't good, that's for sure. Somethings do run quite hot and are fine, so it doesn't neccessarily mean it's dangerous, but if it's getting that hot it means it's drawing more power than it probably should be. It's possible that there's a fault with the equipment that's causing it to draw too much power and that's what burnt out the last power supply. Berk could probaby give you better advice than me though.

Post by **FatherJack** » July 14th, 2006, 9:22

I have a few devices that get this hot, I don't like it especially but they have never caught fire. While I won't say they never will, I think it's unlikely - the combustion point of paper, for instance is several hundred degrees - (your hand would burn instantly at that temperature).

Keeping it off carpets and clean of fluff and dust would be a good move though.

Post by **Dr. kitteny berk** » July 14th, 2006, 9:23

Dog Pants wrote:It isn't good, that's for sure. Somethings do run quite hot and are fine, so it doesn't neccessarily mean it's dangerous, but if it's getting that hot it means it's drawing more power than it probably should be. It's possible that there's a fault with the equipment that's causing it to draw too much power and that's what burnt out the last power supply. Berk could probaby give you better advice than me though.

this stuff.

i'm a bit tired atm.

got a linky for router, and info for power brick?

spoodie · Post by **spoodie** » July 14th, 2006, 10:08

The router is a Linksys WAG354G.
The power supply is a universal adapter I bought from Currys, something like this. It's definitely a Uniross one but I think it's 500mA rather than 300mA, the one that came with the router was 1000mA. I don't know if that makes any difference.

I've just noticed from the datasheet for the router that it's power req. is 12VDC 1A, would this explain a hot power supply that only does up to 500mA?

Post by **deject** » July 14th, 2006, 10:14

you need to get a 1A adapter ASAP. You're using an adapter that is only designed for half the power draw. This can only lead to disaster. if anything get one that's rated for more than 1A.

and in case you somehow don't know, 1000mA == 1A.

Post by **Dr. kitteny berk** » July 14th, 2006, 10:18

spoodie wrote:I've just noticed from the datasheet for the router that it's power req. is 12VDC 1A, would this explain a hot power supply that only does up to 500mA?

YES

Very bad, http://www.rapidonline.com/home.aspx

Code: Select all

AC/DC UNREG PTOP PSU 12V DC 1A RC

85-3915 

or

AC/DC UNREG PLUGTOP PSU 12V DC 1AMP RC	
  
85-2915

Should work.

basically, your router is trying to suck twice as much power as the wall-wart can provide, may result in badness.

edit:

deject wrote: if anything get one that's rated for more than 1A.

This. but i'd be impressed if you could find one, and you'll be better off sticking with 1A (for fear of overcooking the router)

spoodie · Post by **spoodie** » July 14th, 2006, 10:20

deject wrote:you need to get a 1A adapter ASAP. You're using an adapter that is only designed for half the power draw. This can only lead to disaster. if anything get one that's rated for more than 1A.

and in case you somehow don't know, 1000mA == 1A.

Well that's all just Super Ghey! Lucky it's the weekend tomorrow so I can go hunting for one.

It's all switched off now so won't be burning down my house in my absence

spoodie · Post by **spoodie** » July 14th, 2006, 10:43

I've ordered one from Rapid, thanks Berk. And thanks everyone for your help, makes a little more sense now.

Post by **Dr. kitteny berk** » July 14th, 2006, 10:44

rapid are generally pretty good, usually get stuff in a day or 2.

your 500w should be fine for a few days, but only use it while you need it, don't leave it on overnight etc. etc.

cashy · Post by **cashy** » July 14th, 2006, 12:26

has to make me wonder, did you get the old power supply with the router?

Post by **FatherJack** » July 14th, 2006, 12:29

cashy wrote:has to make me wonder, did you get the old power supply with the router?

Hmm, I have the non-ADSL version of that router, and it certainly came with one.

spoodie · Post by **spoodie** » July 14th, 2006, 13:23

cashy wrote:has to make me wonder, did you get the old power supply with the router?

Yes I did. It's Cisco branded and they own Linksys. It would be a bit annoying if you bought a device like this and didn't get a power supply.

spoodie · Post by **spoodie** » July 15th, 2006, 20:05

New power supply from Rapid arrived the day after I order it, now that's service. It's been running most of the day and it's still only warm.

5punk

Hot power supply

Hot power supply

Re: Hot power supply