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-   -   How do I test integrated circuits with a multimeter? (https://www.badcaps.net/forum/showthread.php?t=19216)

Koda 02-25-2012 06:33 AM

How do I test integrated circuits with a multimeter?
 
I know how to check other components but IC's are always a pain in the a**. I don't have any expensive equipment to test it with, only a multimeter. Also I'd like to know how to test smd resistors and capacitors without desoldering them off the board. Any help is greatly appreciated.

ratdude747 02-25-2012 07:33 AM

Re: How do I test integrated circuits with a multimeter?
 
you can't with the resistors and caps... they have to be out of circuit to be tested (otherwise you are testing the whole circuit, which often has other devices in parallel, messing up thee test)

as for ICs, depends on the IC. get a bench PSU, a solderless breadboard, and breadboard wires and build a sample circuit as per the device datasheet.

severach 02-25-2012 10:21 PM

Re: How do I test integrated circuits with a multimeter?
 
The best you can expect is to find shorts where they are not supposed to be. Get the datasheet and find out what the pins do. Some pins are supposed to be shorted. No shorts allowed between power and ground.

Koda 02-26-2012 06:07 AM

Re: How do I test integrated circuits with a multimeter?
 
This is going to be a bit of an effort for me but will give both approaches a go and see which one works better. Thanks for the suggestion guys. If anyone else has any more ideas I would like to hear them.

Tube_Dude 02-26-2012 06:24 AM

Re: How do I test integrated circuits with a multimeter?
 
With a multimeter, you can't do a really serious test about the IC, but if you have a good new IC, the same type of the suspect one, you can compare readings and maybe you can spot any significant difference...

Agent24 03-01-2012 04:26 PM

Re: How do I test integrated circuits with a multimeter?
 
There is no easy way to function test ICs except perhaps basic logic gates - of course you can check any IC for dead shorts, though.

Since they all have completely different designs and functions, the only real good test is in the circuit it was designed for, and verify by substitution.

Quote:

Originally Posted by Koda (Post 219664)
Also I'd like to know how to test smd resistors and capacitors without desoldering them off the board. Any help is greatly appreciated.

The same way to test a non-SMD part - you can measure it as long as it's not in parallel with anything else, or connected to any other circuitry that can throw off the measurements.

If in doubt, you still have to remove it and test out of circuit. There is no way around that.

Koda 03-02-2012 05:15 AM

Re: How do I test integrated circuits with a multimeter?
 
I hoped to avoid removing dozens of smd capacitors and resistors from boards to test them.

PlainBill 03-02-2012 06:34 AM

Re: How do I test integrated circuits with a multimeter?
 
Quote:

Originally Posted by Koda (Post 221279)
I hoped to avoid removing dozens of smd capacitors and resistors from boards to test them.

It's possible to do this if you have a schematic. Even without a schematic it may be possible to spot a gross problem. Part of the challenge is knowing what the circuit does.

With a schematic you can check the value of the resistors and capacitors and use a 'not less / greater than' rule. A good resistor in circuit will never read greater than it's true value because parallel resistances will reduce the resistance. A good capacitor in circuit will never read less than it's rated capacitance because any parallel capacitances will increase the capacitance.

PlainBill

Koda 03-03-2012 07:22 AM

Re: How do I test integrated circuits with a multimeter?
 
I guess I'm gonna have to learn how to read schematics. BTW can ic's be checked the same way?


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