Which reason powe ic is over heat

[razu]

Hy all tech friend......

past few days I have found a lot of power ic over heat problem.........

Tps 51225, Tps 51125

but there were no short on 3v and 5v rail..no short on LDo 3v, and 5V

I change Original ic from old motherboard. Why this happen.

I found some power Ic fault,some ldo short, Io bad, but this fault is rare.

Any one can help to find out this common problem...............out

Thank in advance

[mcplslg123]

Re: Which reason powe ic is over heat

If it is heating, there has to be some short. Need to check resistance to gnd on all pins of such ic. Always check whether ic becoming hot after removing SIO .

[razu]

Re: Which reason powe ic is over heat

Which pin of power ic is check................example

[mcplslg123]

Re: Which reason powe ic is over heat

For example tps 51125

first thing to check pin16-you have vin or not.
pin 8/17 for vreg3 and vreg5
pin23 for 3v/5v power ok signal.

If all of these signals are present-likeliness of short is almost slim.

Check resistance to gnd of those particular pins where you are not getting the desired voltage though i prefer measuring all pins