Toshiba C660 no power

[diif]

Hello, i have a Toshiba C660 with motherboard LA-6842P.
There's no lights or fan when i power with my bench supply.
No voltage at the power switch, but i have tested it is working.
I can find 18.90v around the charging section but no 3v or 5v.
18.9v is also present at PQ21 and PQ22 but there are no other voltages.
Is that suggesting PU6 ?
Any other suggestions ?
Thanks.

[rievax_60]

Re: Toshiba C660 no power

First check the rails for shorts to ground. PU6 could be faulty or many other things around it. Download it's data PDF to discover things to check.
pin13 needs to see 2.4v or higher.
Also check for any movement on the rails as you apply power. I had a fault in a Samsung that was causing the ALW5v to go higher than 5v at power on, then drop back to 0v, all in a few milliseconds. Need a CRO to catch this.

[diif]

Re: Toshiba C660 no power

Thanks rievax, i only get 1.7v on pin 13 of PU6.

[rievax_60]

Re: Toshiba C660 no power

There could be a fault with the resistor divider. Also check for 19v on VIN pin16. avoid measuring this directly at the IC pin. If your probe shorts to an adjacent pin, you will have more trouble.

[diif]

Re: Toshiba C660 no power

Yes, there is 18.9v on pin 16.

[diif]

Re: Toshiba C660 no power

Can you advise me where to check for 3v and 5v ? I am unsure which component/s convert the 19v down to the lower voltages.

[rievax_60]

Re: Toshiba C660 no power

Did you see the data PDF for the UP6182? There are 2 sets of regulators, linear 3.3v and 5v, and SMPS 3.3v and 5v. When power is applied and before the power button is pressed, the 2 linear regulators, pin8 and pin17 should be up. When the power button is pressed, the 2 SMPS rails are supposed to come up. These can be found at the 2 coils, PL4 and PL5.
pin13 EN needs to see 2.4v or more before anything else can work.

[diif]

Re: Toshiba C660 no power

Thanks rievax, i'm fairly new to diagnosing and reading diagrams.
I have downloaded the pdf and now understand a little better.
I only have 1.7v on pin 13 can you tell me where that feed comes from ?

[ktmmotocross]

Re: Toshiba C660 no power

check resistance and voltage on both pins of PR87

[diif]

Re: Toshiba C660 no power

Well, I cleaned up the area around PU6 with some ipa and have measured again. I am now getting 3.14v and the power LED.
I have connected up the screen and it's booting. I shall reassemble and report back.
Thanks again for your help.

[diif]

Re: Toshiba C660 no power

Hello again, i'm back with this one.
It seems that it has has some liquid enter at some point judging by the stain on the back of the keyboard.
All is working well apart from sound. The device is installed and shows in Windows. The sound driver installs ok, however there is a pop sound on turning on the laptop and then again as the screen goes black before the windows desktop.

I've tried headphones and alternative speakers and still the same pop

I'm not sure what to look for but i have checked some voltages on the ALC259Q chip.

Pin1 3.3v
Pin25 5.15v
Pin38 5.15v

As always your knowledge is gratefully received. What do i need to check ?

[reaper57]

Re: Toshiba C660 no power

If it's popping it's trying to do something, but there seems to be something stopping it from outputting sound. Do you have sound with external speakers? And what happens when you unplug the build in ones and plug in only external ones or headphones?

[diif]

Re: Toshiba C660 no power

No sound with any combination of speakers or headphones.
Nothing happens when i unplug the built in speakers, or plug them back in.

[diif]

Re: Toshiba C660 no power

Any ideas what i can check please ?

[dj_ricoh]

Re: Toshiba C660 no power

you need a scope on the chip.
you can check the output

[diif]

Re: Toshiba C660 no power

Would a simple scope like a DS201 be suitable ricoh ?

[dj_ricoh]

Re: Toshiba C660 no power

Would a simple scope like a DS201 be suitable ricoh ?

yeee
i got this ! i fix headphones, all types of audio ports;
i had a asus that non of the out work i check on the chip; nothing show but when i inserted a jack in front the internal speakers power up check on the chip , there was a short with the jacks so i left the short in jack to activate the internal speakers. the guys was happy me happy moved on.

it will do the trick!
the main thing i use it for is to see if BIOS chips active before power button press

[diif]

Re: Toshiba C660 no power

Cheers, i shall work out how to work this thing and i'll test to see if i get any ouputs from the chip.

[diif]

Re: Toshiba C660 no power

I bought an identical faulty board to swap components from to try and fix this.
On power PU6 gets red hot instantly so i was going to replace.
It is marked 51125A although the schematic indicates a UP6182.
I've done a search on here, that indicates they are compatible, is one better than the other ?

[meritosari]

Re: Toshiba C660 no power

yes you can change with that. i think its same quality