Toshiba satellite C850 all usb ports not working

[String2016]

I need help on this Toshiba Satellite C850-B907 BOARD ID:PLF/PLR/CSF/CSR UMA MB REV:2.1.The laptop works fine then suddenly all usb ports not working.so, i checked first all ports for voltage but there is no 5v on all usb ports.Can you help me on this please

[walupapz]

Re: Toshiba satellite C850 all usb ports not working

check usb driver ic

[String2016]

Re: Toshiba satellite C850 all usb ports not working

do you have a schematic diagram for this model please

[Dark_Raven]

Re: Toshiba satellite C850 all usb ports not working

same problem with my Toshiba Sat C850....any solution how to fix?

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

I can't find a free schematic for that board. But there is a switch IC next to the USB ports. It has 8 pins and the pinout is as follows:

1 - Ground
2,3 - Input voltage
4 - Enable signal (5V = enabled)
5 - Overcurrent signal (0V = overcurrent/overheating condition detected)
6,7,8 - Output voltage

When the EN signal is set high (3-5V), then voltage from the input pins is allowed to travel through to the output pins.

Check to make sure there is 5V on the input pins. Check to make sure the chip is getting the 3-5V enable signal. If both of those are true, and if 5V is not appearing on the output pins, then either the chip is bad or there is a short circuit on the output.

On the other hand, if there is no 5V on the input pins or if the enable signal is not 3-5V, then you need to investigate why.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

thanks for the response i found the chip and checked it, pin 234 have voltage of 5v but on the output pin 678 there is no voltage. could the chip be bad or there is a short circuit on the output?anyone please help

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

Measure the resistance between the output pins and ground. If it's close to 0 ohms, then there is a short. If not, then the chip is bad.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

its not short to ground it 2.7 ohms so the chip is bad?

[String2016]

Re: Toshiba satellite C850 all usb ports not working

and the chip written is AP211

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

That is a short. Ohm's Law: 5V/2.7ohms = 1.85A. That's way way more than this circuit should be drawing with no devices connected.

First, check to make sure there are no bent pins in a USB port causing the short or anything simple like that. Next, I would remove the chip and then test for a short again. If it's gone, then you know the chip has an internal short and is bad. Otherwise some other component is causing the short (e.g. a capacitor).

Your chip might be one of the parts in the attached PDF. But there are ICs from multiple companies that are compatible.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

thanks for the respone bluemidnight i double check again the written on the chip i was wrong sorry its AP2111.and checked again with beeping mode pin 678 not beeping to ground

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

It seems like there's an appropriate component for almost any marking heh. They are pretty common.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

i have attached the image of the chip.i checked with continuity from the output on pin 6 and 7 connected to two caps at 1 resistor with mark 0

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

Yeah, you're going to have to start removing components to isolate the short. There aren't that many possibilities, so it's the easiest way.

I'd start by removing the IC. If the short is gone, then just replace the IC with a new one.

But if the short is still there after removing it, remove the 0 ohm link resistor next. That will divide the 2 USB ports so you can see which one has the short. Then, you can check the capacitors on the shorted port.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

Thanks for the response ill try that.It is possible if i try to inject 5v on pin 6 or pin 7 in order to find the fault?

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

Yes you can do that. But I felt it was just as much work in this case because there are so few components. You might want to do that if you only have a soldering iron though, since it's much harder to remove components (without destroying them) that way. But if you have a hot air station, then it's easier to just use it.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

or i will remove first the chip then inject 5v to pin 6 or 7?

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

You can inject voltage at pin 6/7 (or at any spot connected to them) and see what gets hot, or you can remove components and see when the short goes away. Both ways will work. There's probably no reason to combine the techniques.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

update: i inject 5v on pin 6/7 of the chip no one getting hot or taking ampere but when i touch the pch chip display goes white and goes off, but when i plugged in again the charger boots fine.could it be the pch?

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

A few possibilities:

- You never touched the component that was getting hot (e.g. one of the little capacitors or something)
- The resistance changed while under load so that it was no longer 2.7 ohms. In that case it may not get hot at all. If it is staying at 2.7 ohms, then it should be dissipating 5V x 1.85A = 9.25W of heat.
- The short is located somewhere other than the switch IC and capacitors, and possibly somewhere that doesn't get hot easily (e.g. inside the USB port or other chip on the board).

The only connection between the output of the switch IC and the PCH is potentially the USB ports themselves. For example, the 5V pin could be shorted to a data pin. The data pins do go to the PCH. Whatever event damaged the USB power circuit could have damaged the PCH as well. But they could also be totally separate problems. I would concentrate on one problem at a time.

You can check resistance between the 5V pins on each USB port and the 2 center data pins to make sure there is no short within the ports themselves. If not, then go ahead and remove the switch IC and narrow down the problem that way.

You can also set your meter to diode mode and, with the board still unpowered, put the red lead on ground. Touch the black lead to the 5V pin on each USB port and to each pair of center data pins. All should read ~0.5V, which is the body diode voltage drop of the FETs inside the PCH and the switch IC. Since the resistance to ground on the 5V pin is low, there probably isn't a ~0.5V drop there, but the data pins should have it if they are okay.