Identifying and eliminating short in NB power line

[thanibee]

Hello,

I have a short in one of the G41 motherboard in the northbridge VTT power line. What voltage and current is normally used from external powersupply to identify the shorting component?

Thanks for any help.

[dicky96]

Re: Identifying and eliminating short in NB power line

Supply voltage would be about 1V or 1.1V but possibly the NB chip draws quite a bit of current so it is hard to find a short (for example capacitor on VTT) without removing the NB first - then if the short is still there you have a chance to locate it.

Problem of course then is resoldering or replacing the NB

[piernov]

Re: Identifying and eliminating short in NB power line

If the resistance to ground is very low then it's already a good indication there's a short to ground. If the resistance is high enough there's no reason to suspect a short to ground.
I don't know the typical resistance to ground for a G41, but I'd expect it to be higher than 20 ohms.

[SMDFlea]

Re: Identifying and eliminating short in NB power line

If the resistance to ground is very low then it's already a good indication there's a short to ground. If the resistance is high enough there's no reason to suspect a short to ground.
I don't know the typical resistance to ground for a G41, but I'd expect it to be higher than 20 ohms.

I measured FSB_VTT at 12 ohms on a Foxconn G41MX-K

[thanibee]

Re: Identifying and eliminating short in NB power line

Injected 0.9V with 3A limit and identified the shorted capacitor. Now the 1.2V VTT is generated. Still the board is having issues as it is not booting yet. Will get back with more questions.

Thanks for all the responses