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Electronics => Electronics => Topic started by: guncha on July 30, 2009, 09:02:45 PM

Title: how to tell if a chip has fried
Post by: guncha on July 30, 2009, 09:02:45 PM

Let's say I have an IC that I might have fried, but I'm not sure as I might not be using it correctly. How does one tell them apart ? I am quite sure it's possible to test it with a multimeter, but what is that EXACTLY happens in a chip when it fries from over voltage or too much current ? Does the resistance between pins and the ground go up or down ? Between neighboring pins ? What about current drain ?

This has been bugging me for a while and if I don't find out soon, I'll have no choice but to cook an atmega. In the name of science! :)

Title: Re: how to tell if a chip has fried
Post by: airman00 on July 30, 2009, 10:40:34 PM

Every scenario would be different, since the whole chip doesnt always fry, usually just  "systems" of the chip.

Title: Re: how to tell if a chip has fried
Post by: SmAsH on July 31, 2009, 01:39:10 AM

normally if it just doesn't work, its generally hard to tell from appearance which sucks...
ic's generally die silently... which sucks...

Title: Re: how to tell if a chip has fried
Post by: Joker94 on July 31, 2009, 05:51:30 PM

you should be able to use a continuity testor, and theoretically if it still is fine to use then some of the links between pins should light up.Not 100% sure for your chip but it worked on mine, i just tested it.

Title: Re: how to tell if a chip has fried
Post by: apc3161 on July 31, 2009, 11:55:03 PM

This is always an annoying problem. I once had JUST the ADC0 pin on my ATMega8 fry. I couldn't figure out what was wrong for so long. The chip was connecting correctly, I was able to upload code, and every other function seemed to work correctly. I spent literally days trying to figure out what was wrong. I eventually just replaced the chip and it worked fine.

lesson: No easy way to tell if a chip is partially fried.

Title: Re: how to tell if a chip has fried
Post by: Joker94 on August 01, 2009, 12:11:02 AM

if you are really desperate you can build a chip testing circuit and try it for your self

Title: Re: how to tell if a chip has fried
Post by: SmAsH on August 01, 2009, 03:21:00 AM

normally you can tell by the "try and program it" method, try programming it to turn on an led at each port... if it doesn't program properly the chip is useless... if its just a few I/O pins, its good.

Title: Re: how to tell if a chip has fried
Post by: Joker94 on August 01, 2009, 03:59:29 AM

nice idea smash, and simple

Title: Re: how to tell if a chip has fried
Post by: Truckstop on August 04, 2009, 05:04:01 AM

I like smash's idea however ic's can fail in other ways too, i had a basic stamp 2 ic that got over volted.. (yes my fault) and it still worked fine , however it did draw allot of current and get hot really fast. after awhile it would even freeze up but for a good few minuets it would work fine. make sure you check how hot your chip gets if it starts fouling up as this could be a sign of a fried ic