FS Amilo M3438G OS-CON replacement help

[KountZERO]

Re: FS Amilo M3438G OS-CON replacement help

They are ordered just not arrived yet, 2 other caps on board near battery management circuit are hard to get at. Components are densly packed around them and i cant see the values. They arnt os-cons tho, they are skinned in green plastic.

[PCBONEZ]

Re: FS Amilo M3438G OS-CON replacement help

I think it's very unlikely the OSCONs are bad.
Your laptop uses the nVidia 6800 'Go' series GPU.
Some of the 6xxx 'Go' and most of the 7xxx 'Go' laptop GPUs were defective.
.
If power is dumping through a bad GPU the power management circuits are likely to get hot.
.

[KountZERO]

Re: FS Amilo M3438G OS-CON replacement help

Been down the road of the bad 6600Go gfx card, was the first thing i tried. Its been baked, prodded and modded to death but tbh it wasnt needed as when the machine boots the gfx work perfectly anyway and runs nice and cool (i got rid of the crap heat pad and fitted a copper shim and arctic silver) Its been ran for 8 hours solid daily every day with no problems and its only issue is this cold booting phenomena. i get where you are comming from but as i said in my 1st post i tried many other things before focusing on the 2 caps. I borrowed an x700 card out of another laptop of a friend and it did the same thing, in fact i couldnt get it to power at all with that in it.

What i dont get is how a defect in the gfx card could be "cured" by warming 2 caps that are not even close to the MXM slot, doesnt make sence but hey who said it was meant to lol. The area seems related to the HDD but there is no issue with the sata hardware that has shown up. You guys are the experts and anything else i can try is always received gratefuly but as i said before ive tried loads of things before coming to this conclusion.

cheers

PS. the 2 other caps are Sanyo too, 100uf with green plastic skins

[kc8adu]

Re: FS Amilo M3438G OS-CON replacement help

if the cap replacement fixes it i will be surprised.cant ever remember a sanyo oscon failure but i did see a nippon chemi con os-con in a laptop that was badly bulged.

[PCBONEZ]

Re: FS Amilo M3438G OS-CON replacement help

Heating a GPU with the problem that's plaguing nVidia is more likely to cause more damage than to fix anything.
I know that problem 'sounds' the same as the chip-to-board BGA problem but it's really not. The problem with GPUs is more similar to the layers in a motherboard separating. Applying heat without pressure is more likely to cause more seperation than to fix anything -and- for it to work you'd have to melt the resins back together too, not just the solder. The get enough heat to 'weld' cured resin between layers you're pretty much talking smoke and charcoal on the outer layers.
.

Caps change uF, ESR, and leakage with temperature changes.

Parts aren't necessarily located near the circuit they are in. The boards have circuit traces that run between the layers that you can't see.

Other components change values with temp too.
When you heat/cool those caps you are also heating and cooling all the nearby SMD components and solder joints. One of those may be the problem.
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[KountZERO]

Re: FS Amilo M3438G OS-CON replacement help

So in essence what your saying is the fact the caps are getting hot is a symptom of another fault rather than the fault itself? Is it not possible that the caps have been over worked for an extended period? the machine has been used every day for 8 hours+ a day since new in 2006 thats over 10000 hours >< . I believe its on its second geforce go [it was my sis-in-laws b4 me and she says gfx died when it wasnt very old] the card was replaced under warranty when it failed.

I'm loath to think its the mobo at fault as it doesnt misbehave at all once its actualy booted up for the day. Ive ran pretty much every stress test possible at it and it laps them up and asks for more, i did that after doing the copper shim to the heatsink and flashing it with alienware bios [it has different fan profile] to see the difference.

The lappy is kind of a project i have ongoing and eventualy its going to get a different mobo thrown in it from an XI series, an ATI HD3*** ~GFX card and a 2nd hdd but till that point id like to fix the current issue, more for the challenge than anything else. So if there is an underlying issue with the power delivery to the MXM slot better to find it before i try forking out for a new GFX card, My mates x700 from his Amilo wouldnt post at all dont forget.

Caps havent arrived yet [coming from US to UK], but will strip it over the weekend again and rig it up on the workbench and see if i can trace any dry joints on the reverse side. I guess i should bite the bullet and get an ESR meter

Cheers again for all the advice

[PCBONEZ]

Re: FS Amilo M3438G OS-CON replacement help

>>> So in essence what your saying is the fact the caps are getting hot is a symptom of another fault rather than the fault itself? <<<
No. It could be either way.

Reactance is basically > resistance *AT SOME FREQUENCY*.
- It is in ohms. Ohm's law works using it.

Caps get hot two ways:
They absorb it from their surroundings.
They generate it internally based on volts, their reactance and the resulting current flow.

Reactance changes with frequency, temperature, aging, and defects.
If any of those things change the reactance changes, so the current changes, so the heat [watts] changes.

If voltage goes up then so will current even though Reactant doesn't change.
More current, more heat.

Very possible for some other fault to shift the frequency or voltage on the cap which could raise the current through it and it's temperature.

Also possible that a degraded cap has 'less than advertised' reactance which would allow current [and heat] to go up.

~~~
That said.
It is very VERY rare for OS-CON to go bad.
kc8adu said he's never seen one.
I've been in electronics [at one level or another] since 1981 and I've never seen one.
I don't even KNOW anyone that's seen a 'for sure' bad OS-CON.
-
If those are bad it might be something for the Guiness Book of World Records.
.

[KountZERO]

Re: FS Amilo M3438G OS-CON replacement help

Ok, i get your point, i always had been under impression that os-con's were bullet proof myself as well. Ill keep on down the dry joint route, as an after thought, what are the chances a ceramic chip smd cap is the root of it [not a dry joint] and would heat effect those in the same way?

[PCBONEZ]

Re: FS Amilo M3438G OS-CON replacement help

It's not -impossible- the OS-CON are bad. Just REAL unlikely.

I'm not sure how much ceramic chip type change with temp.
I imagine not much, but I dunno.

So far as heat failures AFAIK ceramic chip smd caps have a lot less problems and are very reliable like OS-CON.
They are however small, so I could see a moderate voltage spike knocking one out, or out of spec.
.
.

[KountZERO]

Re: FS Amilo M3438G OS-CON replacement help

Update lol. I changed out the caps for Pana FC's. The result is a brighter battery led [woot =/ ] pulse than before and it now takes anywhere from 10 seconds to 5 minutes of button pressing to get it to power on [it used to be 30mins to an hour before] It also wakes from sleep a lot easier now, 8 out of 10 wake ups being successful.

My reasoning now is in line with yours PCBONES, that the GFX card is drawing too much current at power on and the mobo is thinking there is a short and stopping the post. There is a double inductor that ticks once when u press power on and pulses when u hold the button down. It doesnt do this on a successful power up.

It looks like im probably going to have to relent and get an ATI HD3650 for it for now and look to getting an xi series amilo off ebay to canibalise a bit sooner than i anticipated.

Thanks for all the help so far, at least its a bit easier to live with atm.