Compaq Presario CQ61 - Fan spins, no display

[mcplslg123]

Re: Compaq Presario CQ61 - Fan spins, no display

Hi
To 99% it is GPU Problem
Do a mild Reflow on them and check if picture come

On this model with ati-not even 99%, its 100% bad gpu. Reflowing will be waste of time. You need to change the chip. However, reliable chip are very hard to find.

[piernov]

Re: Compaq Presario CQ61 - Fan spins, no display

Make sure you *don't reflow* and *don't use flux*… Just heat the northbridge die to 200°C max for a minute and a half and it'll come back to life. And it'll fail again a few days later, so it has to be replaced.

I've had luck with the RS880M from see-ic. Not saying they're 100% trustworthy (they aren't), but there's not much else you can do.

[WhiteWolfHellas]

Re: Compaq Presario CQ61 - Fan spins, no display

Make sure you *don't reflow* and *don't use flux*… Just heat the northbridge die to 200°C max for a minute and a half and it'll come back to life. And it'll fail again a few days later, so it has to be replaced.

I've had luck with the RS880M from see-ic. Not saying they're 100% trustworthy (they aren't), but there's not much else you can do.

Why not reflow and not use flux though? Isn't heating it up for a minute and a half called reflow?

[diif]

Re: Compaq Presario CQ61 - Fan spins, no display

Why not reflow and not use flux though? Isn't heating it up for a minute and a half called reflow?

It's failed internally rather than it being an external BGA failure.

[mcplslg123]

Re: Compaq Presario CQ61 - Fan spins, no display

Reflow is for bad solder joints under bga chip. In case of RS880M-more often its the internal die on top of the chip which fails. Perhaps, thats why piernov has asked just to heat the die on it and not reflow it. Hope that clears your query.

[WhiteWolfHellas]

Re: Compaq Presario CQ61 - Fan spins, no display

Reflow is for bad solder joints under bga chip. In case of RS880M-more often its the internal die on top of the chip which fails. Perhaps, thats why piernov has asked just to heat the die on it and not reflow it. Hope that clears your query.

Yes, thank you for the information.

I found a thermal pad with thermal paste on the gpu when I removed the heatsink. Isn't that wrong? I mean it is not how it leaves the factory, this was replaced by another technician, right?

[Duranitron]

Re: Compaq Presario CQ61 - Fan spins, no display

in my opinion using thermal pad is worst in dissipating heat that is why many gpu that uses it breakdown prematurely. i rather use an copper shim to directly transfer the heat to the gpu heat sink. i replaced a lot of defective bga gpu chip that uses thermal pad and i always placed copper shim to the new bga gpu and it lasted a lifetime... warning using copper shim that is too thick will kill the gpu.. i learned that the hard way... .

[piernov]

Re: Compaq Presario CQ61 - Fan spins, no display

In my opinion using copper shim is usually a bad idea. If the cooling system was designed with thermal pads in mind you risk damaging the die by using copper shim, or having alignment issue so the copper shim or the heatsink doesn't sit perfectly flat on the chip (so one side isn't properly conducting heat).
Also even laptop is designed with thermal paste (rather than pad) between GPU and heatsink, unreliable GPUs will end up failing anyway.