How to Judge Whether IC is Working Correctly in Electronic Circuit or Not

A week ago, my radio was broken and it wasn't work any more. I just felt so sad, and I decided to repaired it. However when I repaired it, I met a question , which was I didn't know how to judge whether IC was working correctly in electronic circuit or not. So I surfed it in the Internet. I read a lot of passages about it in kinds of website, like http://www.kynixsemiconductor.com/News/64.html. It describes some ways to judge whether IC is working correctly in electronic or not, but my question is I want a practical way which shows me directly how to operate it in radio instead of some theories.
Thanks in advance for your help.
-Jane

A general method is to measure the voltages in the pins of IC concerned.
Then you may deduce whether it is working or not.
You must have the pin diagram of the IC used, to find the fault.

Post your Radio IC type number.

Make sure your basic inputs to function the IC are given and proper like Supply, Clocks, Resets, default state of IOs etc.
After that try to measure any response from IC, like Output clocks (which makes sure PLL, clock conversion circuits are working), if any free running clocks, Voltages generated, RESET OUTs, any Outputs (I/Os) etc.
After that u can go for individual interfaces validation.

Always measure the impedances of important pins of IC's to make sure no shorts etc

When doing repairs, it may not be worth figuring out what chip is or is not working correctly. Sometimes it's easier just to replace all the active components and maybe any old aluminum electrolytic capacitors and cross your fingers. Or if you have any insight to how the thing works you can maybe narrow it down to a subset of all the active components. In a radio for example, if it turns on and appears to be tuning, but there is no sound, just try replacing the output drivers. They're usually what blows out in an audio circuit.

Hello j33pn,

In a radio for example, if it turns on and appears to be tuning, but there is no sound, just try replacing the output drivers. They're usually what blows out in an audio circuit.

Click to expand...

If its a tuning fault, you should still be getting something out audibly. Just normal hash at least, no matter how far off your tuning is.
You need to determine if you have an audio problem or not. Best way to determine that is to inject an audio signal into it, say at the
pre-amp stage, then work forward from there.
If you could provide a schematic diagram, it would make things easier for us to determine a possible fault location.

srizbf's suggestions are quite valid:

A general method is to measure the voltages in the pins of IC concerned.
Then you may deduce whether it is working or not.
You must have the pin diagram of the IC used, to find the fault.

Click to expand...

Regards,
Relayer

Without a schematic, you're pretty much out of luck. You have to know how it works and what is supposed to happen before you can analyze whether it is working. Basically, unless it is smoking when you power the system up, the way to test it is to look at each pin for the expected signal or state when it is in use.

Can you read a part number? If so, you can go to the manufacturer's site and look at application info to see if you can psyche out how it is being used in your circuit.

If it is socketed, replacing it would tell you if it's bad, or it may blow another good IC, depending on what caused the problem. If it is a complex part (CPU, controller, etc.) that is hard soldered to a board, and you don't have a lot of experience replacing them, I'm afraid you'll have to write it off or get some help. Since it's a mouse chip, I'm guessing that's what it is.

Beyond the science project value of trying to fix it, mice are so cheap that it isn't worth the effort to deal with it.