[Newbie Assistance] Toshiba C850 LED Blinking

[DanFen]

Hey everyone.

Newbie here and requires assistance. I have a Toshiba C850 on the bench that does not power on. The only think I'm having is a constant LED blink on power LED. No fan spin, no nothing.

First thing I noticed is that it was FULL of dust, fan clogged and everything dusty. I've checked the DC IN just in case, even though, I think this is not a symptom of DC IN.

However, I don't know how to proceed. The only piece of information I've got is this thread:

https://www.badcaps.net/forum/showth...highlight=c850

I was wondering if it's the CPU or the chipset, considering that probably the cooling system was not functioning as it should.

It's easy to get a cheapo (probably refurbished) motherboard from China, but it would be even better to go through some troubleshooting with some of you guys.

Thanks!

[jiroy]

Re: [Newbie Assistance] Toshiba C850 LED Blinking

If the fan was totally clogged , forming a carpet-dust like , the Cpu is 99% fried . In few cases , the Cpu thermo sensors may prevent its normal operation , So you have to do some serious cleaning .

Anyway , try cleaning the Laptop first from dust with an air gun , re-seating and cleaning Rams and connectors , looking for rust and humidity damages . Put new Thermal paste on the CPU , and try booting again .

[DanFen]

Re: [Newbie Assistance] Toshiba C850 LED Blinking

Hi

Really appreciate your reply. That's done already, first thing I did is clean the fan and the rest from the dust, visually inspected the board. In the process RAM and connectors were removed, even tried to power on without one memory module, different slots, no connections at all, and all that stuff. None worked and symptoms remained the same, that of flashing white LED.

To be honest, there seems to be some hint of corrosion on the external card readers connectors. I will post a photo of this.

CPU can be found second hand from China for as little as 10 USD. Might be worth trying if you also think the CPU might have got fried.

[jiroy]

Re: [Newbie Assistance] Toshiba C850 LED Blinking

Hi

Really appreciate your reply. That's done already, first thing I did is clean the fan and the rest from the dust, visually inspected the board. In the process RAM and connectors were removed, even tried to power on without one memory module, different slots, no connections at all, and all that stuff. None worked and symptoms remained the same, that of flashing white LED.

To be honest, there seems to be some hint of corrosion on the external card readers connectors. I will post a photo of this.

CPU can be found second hand from China for as little as 10 USD. Might be worth trying if you also think the CPU might have got fried.

Welcome ..
If you're sure you did a thorough visual inspection of the board , better with a magnifier , and didn't find any unusuals , then try to remove the Cmos battery for like 1 minute . Testing it also isn't bad at this time . Anything under 2.5 volts may prevent booting .

Next , you can try a dump Bios .
Next , you can try to reflow the board (many Youtube videos would help ) ..

And finally , you can order a Cpu .

[DanFen]

Re: [Newbie Assistance] Toshiba C850 LED Blinking

CMOS battery is fine, and tried removing that already even tried a new one.

I gave it another inspection with my precious hand magnifier. I'm putting links for the photos of the external card reader area and the other side of the motherboard. Just links so to retain a good resolution.

http://i67.tinypic.com/348k3y8.jpg
http://i64.tinypic.com/efj4ux.jpg

[jiroy]

Re: [Newbie Assistance] Toshiba C850 LED Blinking

CMOS battery is fine, and tried removing that already even tried a new one.

I gave it another inspection with my precious hand magnifier. I'm putting links for the photos of the external card reader area and the other side of the motherboard. Just links so to retain a good resolution.

http://i67.tinypic.com/348k3y8.jpg
http://i64.tinypic.com/efj4ux.jpg

Baoooo , man , you said you cleaned the mess .. Now that's what i call an earthquake , lol .

[DanFen]

Re: [Newbie Assistance] Toshiba C850 LED Blinking

Ahahaha... yeah, I've disappointed there!

Anyway, I cleaned the area as much as a could with alcohol... stuff on the card reader lines is really difficult to remove (in fact, it's still highly visible without a magnet). The other side is much better, but I'm not sure if there's damage or not. Also it's difficult to identify what type of mosfet is that (at leats for me as a beginner).

Shall I attempt to put is some flux on the card reader lines and reflow the soldering? Or maybe eliminate it completely...

Baoooo , man , you said you cleaned the mess .. Now that's what i call an earthquake , lol .

[jiroy]

Re: [Newbie Assistance] Toshiba C850 LED Blinking

Ahahaha... yeah, I've disappointed there!

Anyway, I cleaned the area as much as a could with alcohol... stuff on the card reader lines is really difficult to remove (in fact, it's still highly visible without a magnet). The other side is much better, but I'm not sure if there's damage or not. Also it's difficult to identify what type of mosfet is that (at leats for me as a beginner).

Shall I attempt to put is some flux on the card reader lines and reflow the soldering? Or maybe eliminate it completely...

Due to multi-layers in boards , i hope the corrosion didn't do deeper damages , but that's my friend give me the no choice but to advise a re-flow first .

Do what you see fit , and next , we may help with schematics and other stuff

[DanFen]

Re: [Newbie Assistance] Toshiba C850 LED Blinking

I removed the card reader all together. It was a mess underneath it. Soldering tip was getting stuck, and it was like steering jam rather than solder.

I've also removed the mosfet that looks corroded, cleaned the area properly and put it back in place.

However, still the same.

Due to multi-layers in boards , i hope the corrosion didn't do deeper damages , but that's my friend give me the no choice but to advise a re-flow first .

Do what you see fit , and next , we may help with schematics and other stuff

[jiroy]

Re: [Newbie Assistance] Toshiba C850 LED Blinking

I removed the card reader all together. It was a mess underneath it. Soldering tip was getting stuck, and it was like steering jam rather than solder.

I've also removed the mosfet that looks corroded, cleaned the area properly and put it back in place.

However, still the same.

If I were in your place , I would re-flow , only re-flowing can reach the inner multilayers , and then i would try a dump bios .

Yet , the cpu for 10 $ isn't bad at all , although used .

[alvin24705]

Re: [Newbie Assistance] Toshiba C850 LED Blinking

Hey everyone.

Newbie here and requires assistance. I have a Toshiba C850 on the bench that does not power on. The only think I'm having is a constant LED blink on power LED. No fan spin, no nothing.

First thing I noticed is that it was FULL of dust, fan clogged and everything dusty. I've checked the DC IN just in case, even though, I think this is not a symptom of DC IN.

However, I don't know how to proceed. The only piece of information I've got is this thread:

https://www.badcaps.net/forum/showth...highlight=c850

I was wondering if it's the CPU or the chipset, considering that probably the cooling system was not functioning as it should.

It's easy to get a cheapo (probably refurbished) motherboard from China, but it would be even better to go through some troubleshooting with some of you guys.

Thanks!

hi..

first u must be check the power standby 3v, 5v, Power button (3v), than u check ic for hibernate, u must be use the schematic....

im not recomen for reflow BGA first. so first time u must be check the power input to standby...

i hope my answered can helpfull

[jiroy]

Re: [Newbie Assistance] Toshiba C850 LED Blinking

hi..

first u must be check the power standby 3v, 5v, Power button (3v), than u check ic for hibernate, u must be use the schematic....

im not recomen for reflow BGA first. so first time u must be check the power input to standby...

i hope my answered can helpfull

I Wasn't talking about BGA re-flow , I was talking about the whole board re-flow :


http://i67.tinypic.com/348k3y8.jpg
http://i64.tinypic.com/efj4ux.jpg