Does any one knows how to check an IC if it is working or not ?
I agree with Berk.....I am sure somebody does.
That's not very nice, is it, chaps?
Basic approach hasn't changed since vacuum tube days.
Begin by measuring voltage on each individual pin, write it down.
Then ask yourself "Does that make sense for this circuit?"
You'll have to know your IC's pinout and understand the circuit where it is used. Datasheet is a good place to start.
Always check power pins first.
You also need to be very careful not to short pins together when you are trying to measure the signals on the pins. It is not a trivial skill and you could find you have broken a perfectly good chip if you are clumsy with it.
On the IC there should be a chip number. Find that then google that number and look for a data sheet. Post that and we can better help you troubleshoot it.
If you are working on a piece of equipment with no circuit and obscure integrated circuits, don't assume the ICs are at fault.
ICs are usually very reliable.
However, if you find an IC with the same voltage on most of its pins or running very hot (or cold) you could start to get suspicious.
Realistically, though, if you reach the stage of changing ICs that are not in sockets, just in case they are faulty, you should give up.
It is much more likely that a faulty electrolytic capacitor will go faulty than an IC, so if you want to try a random fix, that is more likely to get a result.
I have seen TV repairs done like that. Change all the electros first and then diagnose if it still doesn't work.
If you have well known ICs in sockets and you have a spare one, you can substitute the spare if you remove the old one carefully. You might get lucky.
At least be sure you are in the right area of the circuit, though. If a signal goes into an IC but doesn't seem to come out anywhere, at least you are right to be suspicious.
Also - many ICs Datasheet shave some form of a test circuit shown - often related to testing the timing and response to inputs. If that circuit works - the IC should be fine.
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