Fried peltier powersupply

[ookabooka]

How you can fry your peltier power supply:
Turning it on and then connecting peltier, then boom!
http://www.theforumisdown.com/uploadfiles/0802/friedpsu.JPG

As you can see, both transistors are blown, while it may not look that bad, you can see taht the left leg on the left transistor has completely vaporized. And there is a chunk of the transistor sitting under the heatsink. Btw 300 volts was running through these transistors (that is how it is designed to work). What does that mean? Lets just say, the fireworks were amusing, and why sparks that crossed the room did so little damage boggles me. . .

[Diggrr]

Wow!
Any damage to anything else?

Sorry I missed it. I love a good indoor fireworks display!

[ookabooka]

no, as far as I can tell, the left transistor fried first, which kept constant power on the right one, cooking it nice and slowly. It doesn't seem to have damaged anythign else, except for possibly those orange capacitors. I can't tell if there are scorch marks on the circut board, or if the capacitors leaked. I will pick up some transistors tomarrow. Maybe radio shack? Where should I get them? I dunno. . .

[Warlord2]

haha I have no clue why all my psu's havent been fried by now, Ive shorted all of them out atleast 3 times by now. I guess its easyer for me just to reset the fuse thin to buy another psu.:D

[Since87]

Originally posted by ookabooka
no, as far as I can tell, the left transistor fried first, which kept constant power on the right one, cooking it nice and slowly. It doesn't seem to have damaged anythign else, except for possibly those orange capacitors. I can't tell if there are scorch marks on the circut board, or if the capacitors leaked. I will pick up some transistors tomarrow. Maybe radio shack? Where should I get them? I dunno. . .

There's a whole lot of variation to transistors. Unless you can read the part number off of them, I think you'll have a hard time replacing them with something that works. I think it's extremely unlikely that Radio Shack will have something useful.

Odds are fairly high that components other than those transistors went too.

I don't want to be discouraging, but I'd probably write that supply off.

However, if you can find part numbers for the parts I can probably track some down for you.

[ookabooka]

according to manufacturer:
"two TO-220-sized NPN transistors"
And it said I could replace them with any standard NPN sized transistors. I would like to go a step up it that is possible, so it is less likely to fry again. . .

[Since87]

Well, the manufacturere's information is a load of crap. But...

The only part listed on the Radio Shack website that matches that criteria is:

TIP3055 Transistor
$1.69
Catalog Number: 276-2020

That transistor is only rated at 15A, 60V. You said that "300 volts was running through these transistors". If so the Radio Shack transistors will fry almost immediately.

BTW voltage doesn't flow through things. Amperage (current) flows through things. Voltage can be thought of as the pressure which drives the current through a resistance. It would be more meaningful to say that the transistor had 300V across it.

I presume you live outside North America. Otherwise, it's very unlikely the transistors would have 300V across them. I'd strongly advise not messing with a 220/240V circuit if you don't know exactly what you are doing.

I've been shocked by 480V. In one hand, through my body and out the other hand. The only reason I'm alive is because I was standing at the time and fell away from the equipment. I couldn't let go, I couldn't yell. There were other people in the room and all they heard was a strange sound coming from my direction and then a crash. This was four year ago and I've still got clear scars on both hands to show for it.

This is not an area for amateurs to be messing with.

[ookabooka]

dam, ok. . . I will get another one then. . . The manufacturer said it was 300v only because the capacitors changed it that high, I know that volts is the driving force, by running through it, i meant it was unstoppable. Which is why it fried :)

[Ct. Strangelove]

hot dog, that is a awlsome pic. srry about you psu. i am running a pc psu for my peilter. now i will take even more precautions.

[ookabooka]

I was surprised too. . . The thing could supply 30 peak amps. . . I don't see how a 20 amp pelt could do that. . . I'm gonna talk to the manufacturer

[Since87]

If it was a quality supply it would have protected itself from a short on the output. Cheap supplies tend to be weak on protection circuitry.

[ookabooka]

Well, I am getting a replacement now. . . after talking with the manufacturer. What can I do to prevent this from happening again? Can I install a fuse on the red output line? Like a 25 amp fuse perhaps? Though it would suck to blow a fuse while on the comp. . .

[Paxmax]

Yup !

A fuse would help. Unless you cross the wires before the fuse ;)
It's wierd though, isn't there a fuse on the mains, inside your PS?
It should be, since the transistors were totally capable to switch them selves to death.
I'm glad I got built-in overcurrent protection in my PS.
I'm glad you got a replacement! Wow, how did you talk them into that ??? :)

Good luck with your new PS !!!

-Paul

----------------------
"Well... at best, faith is only hopeful ignorance."
-Guillermo del Toro

[Since87]

I'd go with a 30A fuse. It will give you enough margin for the pelt's operating point, and should still blow if the you put a dead short across the output.

I personally would never run a pelt without the ability to kill power to everything in the event that the coldplate got too hot. A thermal switch like Digi-Key (http://www.digikey.com/) part number 317-1080-ND could be used for that purpose.

[ookabooka]

well. . . . I did have to pay a "restocking" fee or something. was 20% of the cost of the unit :( still, its nice. I expected there to be some sort of protection, but it appears that there is, a 5 amp fuse on the input, so techinically you could short out the transistors using only the power in the capacitors. This is why I think a fuse on the output line would be necesary