pc motherboard with inductor problem

[insomnia]

ok so i have this pc motherboard turn it on the fan spins for about 6 seconds the n cuts out so i was messing about seen a few swelled caps took them out replaced them but still have the same problem so i started checking the inductors by taking them out the last one i took out it had 6 coil turns on it after i took it out the board stays going with out shorting out now im thinking is the inductor or something on the trace of it why would it short out i know these store energy in magnetic field but cant picture whats going on

 

[Nigel Goodwin]

I would imagine it's VERY unlikley to be the inductor at fault, far more likely there's a short on the board somewhere, and disconnecting the inductor is isolating it.

I would presume that the duff capacitors have blown something?.

 

[insomnia]

thats what i thought also that very unlikely the inductor there is 6 capacitors in series that are after the inductor they are slightly sweld maybe best replace them also one question i have does the capacitor have to be sweld to be faulty

 

[mneary]

Capacitors do not have to be sweld to be faulty.

They are faulty when their internal function is not correct. Occasionally their outside appearance helps you find them.

 

[insomnia]

thanks for that i will go and change a few more and see how it goes are those esr meters any good

 

[Nigel Goodwin]

thanks for that i will go and change a few more and see how it goes are those esr meters any good

They are absolutely brilliant, and essential for doing repairs these days.

 

[insomnia]

thanks nigel would what would be a good one to go for i bought an oscilloscope but i think was moving to fast not ready for it yet its a hantek dso 1060 60 mhz so maybe a good esr meter would be beter for me can they also be used on smd components

 

[Nigel Goodwin]

thanks nigel would what would be a good one to go for i bought an oscilloscope but i think was moving to fast not ready for it yet its a hantek dso 1060 60 mhz so maybe a good esr meter would be beter for me can they also be used on smd components

Yes, but SMD electrolytics are relatively less common - mostly because they aren't very good

This is the one I bought at work the other year

Peak Electronic Design Limited - Atlas ESR - Equivalent Series Resistance Meter and Capacitor Analyser - Model ESR60

And there's a new higher spec version now as well

Peak Electronic Design Limited - Atlas ESR PLUS - Equivalent Series Resistance Meter and Capacitor Analyser with Audible Alerts - Model ESR70

 

[insomnia]

ye they look good have you had much success with your one as surprized fault finding

what do you think of this one would it be as good as the peak
**broken link removed**

 

[Nigel Goodwin]

ye they look good have you had much success with your one as surprized fault finding

Yes, it's pretty well used on a daily basis.

what do you think of this one would it be as good as the peak
**broken link removed**

No idea, I've never seen one - but it looks a bit pricey?.

 

[insomnia]

i will go with the one you have i also still havent found the short in this mother board stays on for about 6 seconds then goes out have check a good few caps have checked the voltage on mosfets seems to be good and also you were correct about the inductor i replaced it just to see but same result its isolating the short there is some smd components on the board thats what makes me feel like giving up lol

 

[Nigel Goodwin]

Electrolytics failing often cause far more damage to other components, as they normally fail as they are used in switch-miode supplies, a common result is the voltage increases until it kills sensitive chips.

 

[insomnia]

thanks for your tips the im running out of ideas as in what components to check there is still about 10 caps that have not been checked i hope it is one of them there is a few chips on the board i will take a picture later and show you the board

 

[Nigel Goodwin]

thanks for your tips the im running out of ideas as in what components to check there is still about 10 caps that have not been checked i hope it is one of them there is a few chips on the board i will take a picture later and show you the board

It's probably killed some nasty big chip, either SM or BGA - buy a new motherboard.

 

[insomnia]

i got a peak atlas esr meter just wondering is there an esr chart around or whats the best way of knowing were could be a possible failure

 

[Nigel Goodwin]

You don't need a chart, duff capacitors are always dead obvious, reading FAR higher than a good one should. Just check the reading of new capacitors for a comparison, or check the manufacturers datasheets.

 

[insomnia]

thanks nigel so the capacitance that the peak reads if its real high with no esr is what im looking for how do you find yours for reading in circut i got the latest one just wondering is it accurate in circuit

 

[Nigel Goodwin]

It's fine in-circuit, and depending what else is actually in-circuit it will warn you it's not 'happy' with the result.

 

[insomnia]

cool saves a lot of hassle been able to test in circuit if i get 0 esr in circuit is that a fail

 

[Nigel Goodwin]

cool saves a lot of hassle been able to test in circuit if i get 0 esr in circuit is that a fail

If you get zero it is, but it's more likely a shorted component somewhere. Good capacitors should give a low ESR and the correct capacitance reading (within tolerance).