Toshiba C660 -1MK Completely dead, no lights at all.

[Andreasbest]

Hello.
I have a C660 and i order a replacement motherboard from Australia,the motherboard i received is completely dead,no power,no lights at all, i tried battery and charger nothing at all.
I get voltages on both fuses (19V) and also 3,3V on power button flex connector but no response when i press it/short circuit it.
The schematic is not helping me to understand where the 3.3V from power switch should end to power on the laptop.
I have the schematics here, if someone can give me any idea before i ask my money back it will be great.
Thanks in advance in case i forgot to thank someone...

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

When you press the power button, it pulls that line down to 0V, which is detected by the EC (also known as the KBC or SIO). That's U19 in the schematic.

The 19V from the AC adapter goes through the input MOSFETs PQ203 and PQ204. You are getting 3V on the power button so you don't need to measure these.

From there, the 19V goes many places. One important place is PU330. That's the 3V/5V chip and it is always one of the first things to check when the board won't power up.

Measure VREG3, VREG5, LL1, and LL2 (that's pins 8, 17, 20, and 11) for shorts to ground. Unplug the motherboard, then put a multimeter in diode mode and place the red probe on ground and the black probe on each of those pins. A short circuit will normally read as less than 100mV.

If there are no shorts, then the next thing is to place the multimeter in DC volts mode and then plug in the AC adapter. Measure those 4 pins again. Make sure you get 3V on two of them and 5V on the other two.

We already know you are getting the 3V from VREG3 (pin 8), but it's still a good to get in the habit of checking the whole chip.

If the 3V/5V chip is okay, and if nothing on the board is obviously shorted and getting too hot or something, then things start getting more complicated.

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Hello and thank you for the help.
I did all you said and here are the results :
1) No shorts at all on PU330 (multimeter in diode mode,motherboard disconnected from DC,Black to ground and measure with red)
2) I get 5v at 17 pin and 3.3 at 8, the 11 and 20 pins have no voltage.
3) The U330 is getting a little hot but i check it on my old, gpu faulty, same motherboard and is getting the same hot too, so no problem.

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

I recommend the opposite: put red on ground and measure with black. It gives a more accurate short/no-short reading.

But either way, there's something wrong with the main 3V and 5V rails. Pin 11 should have 3V and pin 11 should have 5V. Either the chip is bad, the outputs are being wrongly disabled, or there are short circuits on those rails.

I am concerned that the chip is getting warm enough to mention. That chip shouldn't feel like anything special. It should feel basically the same temperature as the board around it. You should also be able to hold your finger on it all day without any discomfort. Anything like that is a sign of a short. Sometimes it's difficult to find the short when the power is off because parts of the circuit are disconnected until the power is on.

Did you move any parts from the old board to the new one? Remove anything that can be removed (e.g. CPU, WLAN card, LCD, etc.) and then try testing the voltages again.

Also, inspect the USB ports and other ports and look for damaged/bent/shorted pins.

If those steps don't find anything, then you may want to get your money back. The next steps will probably require desoldering things. Or at least measuring a lot more voltages.

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

The board was working before the shipment, so i'm highly suspicious that something broken during transport (a solder, a line perhaps) that's a small evidence.
USB not shortcircuited also nothing is connected to both boards (wifi,cpu,ram,hdd etc are disconnected)
Another evidence is the the 11 and 20 pind both take voltage from PQ331-PQ332 and PQ351-PQ352 so i'm thinking that perhaps a voltage from the FET's is missing?
What do you thing?

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

The rail that powers the MOSFETs is the same one that powers PU330 itself, so that seems unlikely. You can check if the chip is being told to turn on the outputs though. Measure the voltage on pins 1 and 6. A reading of 0V means "turn off" and something higher (e.g. 1.5V) means "turn on".

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

PQ331 and PQ351 have only the 19V DC on one side, no other voltages.
The PQ332 and PQ352 have no voltages at all.

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

I meant check pins 1 and 6 of PU330. The voltages on MOSFETs are correct (except for no output).

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

1 and 6 have both 1.66v
I don't understand why the PU330 doesn't have the 3.3 and 5v output to switch on PU332 and PU352.

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

PU332 and PU352 are controlled by PU330. They help create the output voltage (3V or 5V in this example). But since there is no output voltage, the only thing you will find is the 19V on one side of the top MOSFETs. (see attached image)

Search the web for "synchronous buck converter" tutorials if you want to learn more about how it all works.

1.66V is normal for pins 1 and 6. The outputs should be on. So that likely means PU330 is bad and/or there is a short on one of the outputs.

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

I believe that a voltage is missing from pu330,a voltage that gives the command "start" that's why it doesn't give 3.3 and 5v output to the FET to start either.Do you have any idea which is this pin to follow it and see where the voltage stops?
Remember we have the old board that is powering on correctly so we can get any measures from there if you want too.

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

That's pins 1 and 6. You have already tested those. 1.66V is normal/enabled. A bad chip or a short are still the most likely causes.

Look at page 41 of the schematic. The board doesn't allow the 3V and 5V to go everywhere right away. There are transistors (Q29, Q30, U46) that disconnect parts of the board until the power is plugged in (also known as "load switches" when used this way). If there is a short behind a load switch, you won't be able to detect it at PU330..

You need to test for shorts on the other side of those load switches. See the attached pic for the points to test (meter in diode mode, red on ground, black on pin to test). I don't think you will have all 3 of those switches though. Either your board will have Q29 & Q30 or it will just have U46.

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

No shorts on Q29 Q30 (no U46 on board) and also no voltages at all.Before them?

[cyberhack]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

PU330 pin 23 PGOOD is there? if not replace it if you to test shorts on 3v and 5v use a bench power supply

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

PGOOD indicates stable outputs. Since we already know the outputs have no voltage, this unfortunately provides no new information.

We have reached the end of what can be done easily without soldering. You might want to return the board to the seller. But if you want to continue, read on..

Isolating the 3V/5V outputs is incredibly easy on boards like this one. The separate power rails of the board are connected with solder jumpers. You will find them on page 42 of the schematic.

To disconnect the outputs of PU330 from the rest of the board, all you have to do is use some desoldering braid to remove the solder jumpers from PJ332, PJ352, and PJ333 (there is no solder jumper for VREG5). Now plug in the board and test the voltages on PU330 pins pins 8, 17, 20, and 11. They should all be either 3V or 5V. If not, then PU330 is probably bad.

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Pin 23 has no voltage at all.but we went way back to q29 and q30 that haven't voltage either,they start the pu330 to start the fet's.now I'm trying to found out from where the q29 and q30 get voltage from....

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Wow, posted at the same moment.

Just a clarification... Q29 and Q30 are on the outputs of PU330, not the inputs. But you don't have to worry about those anymore. If you want, follow the instructions in my previous post.

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Yes indeed same moment
I have disconnect them all.now still no voltage on 11 and 20 but I noticed the chip is much more cooler.perhaps I should try to jumper one by one the three jumpers and see from which one it's getting hot or it's irrevelant ?
Soldering is not big deal,replacing ic's etc is not big deal,hit me freely

[meritosari]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Don't forget to measure pin12 and pin19 on pu330, if high (4.96v) then DC/DC protect cause OVP (over voltage protection), see datasheet TPS51125, the bottom mosfet driver ON

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

If you can notice the temperature change, there might be a problem on the VREG3 rail (PJ333). But that still doesn't explain why you are not getting all the voltages now. Leave all the jumpers disconnected until we get PU330 working.

Now we know there is a problem at or near PU330. It might be the chip itself or one of the MOSFETs it controls. It is useful to measure the voltages on all the pins. There are only 20 so it's not too hard to do.