Toshiba satellite C850 all usb ports not working

[String2016]

Re: Toshiba satellite C850 all usb ports not working

i checked resistance on each pin with red probe on the ground there is no short and also on the data pins no short.can i try remove this ap2111 ic and test voltage on pin 6 and 7?

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

I just need to clarify something. Terminology is important in this case. If you set your meter for diode mode, you aren't measuring resistance so much as you are measuring the voltage drop between the 2 probes of the meter when it outputs a tiny test current. We need to know if the voltage drop you measured on all those pins is approx. 0.5V. It should not be much lower and it should not be much higher.

Earlier, you measured 2.7 ohms from the 5V output pin to ground. Is that still true? If you are reading 0.5V in diode mode on the same pin, then that indicates there is no short. Try measuring the resistance in both directions and see if it's the same. If one direction reads 2.7 ohms and the other direction reads infinity, then there is no short after all. Instead, you might have a meter with an unusually high test voltage it uses in resistance mode. It might be enough to forward bias the body diode of the FET inside the switch IC, and therefore show a low resistance in one direction.

If there is no short, the IC is bad and must be replaced. If there is a short, then the IC should be remove to help find it. Either way, you may remove it now.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

thanks for the response bluemidnight, I checked again and measure the output on the chip in diode mode red probe to ground and black to pin 6 it shows 0.5v and on pin 7 0.5v also.Maybe this chip is bad,and also i check its usb port pins for bents but it is clear, and now i have problem i cannot find the same with this AP2111 chip on my scrapboard here available only G547E2 chip, Is it possible to replace with this?

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

Okay that's good. That means we know the chip is bad and you don't need to go chasing shorts.

You will need a chip that uses an active high enable signal. Unfortunately, the G547E2 uses an active low enable signal. You would need a G547E1 instead, or something from another manufacturer that performs the same function. The Richtek RT9711A would work. It has the same pinout, 2.5A max current, and an active high enable pin.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

ok thanks i will try to find the chip replacement you mentioned.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

i cannot find any chip replacement that you mentioned in my scrapboard here all have G547E2,but i have found different chip with 2061 markings could it be the same?

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

That appears to be a Texas Instruments TPS2061. Unfortunately, it won't work due to having an active low enable pin, and only a 1A current limit.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

ok thanks im still finding the right chip

[String2016]

Re: Toshiba satellite C850 all usb ports not working

I still cannot find the exact chip on my scrapboard , but i have found here its AP2301 but it has only 70mΩ resistance.

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

Looks like that one is active low also. The AP2311 is the active high version.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

i have here another scrapboard from acer it has a mark MM-G1 111581

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

I'm not sure what that one is. But another way of finding out would be to look at the schematic for that Acer board.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

still i cannot find the same chip or the other replacement all the same with low enable signal.Is there a way to bypass this?

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

It's possible to use one of those active low chips and connect a wire from pin 4 to ground. However, the USB ports will probably be powered at all times, as long as the notebook is plugged in or has a battery.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

ok thanks for the response ill that and feed back soon

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

Thinking about it.. an even better option may be to do the same thing except bend pin 4 up (and/or place an insulator underneath) so it doesn't even touch the pad when you connect the pin to ground. That way it doesn't matter what unknown circuitry might be at the other end driving that signal.

[JaroTech]

Re: Toshiba satellite C850 all usb ports not working

Why not invert the enable signal with a transistor and a resistor?

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

Why not invert the enable signal with a transistor and a resistor?

That's a good question. And I think it all comes sown to practicality. If someone wanted to go out and buy a part, they could just buy the correct IC in the first place. And if they want to check scrap boards for the perfect transistor, that's going to be a lot of work (trying to find datasheets for each one to see if they are appropriate). And then 2 resistors would have to be found for the biasing and current limiting. And then they would all have to be mounted to the board in some way. And either the trace would have to be cut or pin 4 would still have to be bent upward...

Impossible? No. But not as simple of a solution as it is on paper.

[String2016]

Re: Toshiba satellite C850 all usb ports not working

thanks for the response i still not do it because i'M hoping i can find the same chip, if not do you mean i will not soldered the pin 4 of the ic on the board and bend upward and connect a wire to the ground?

[BlueMidnight]

Re: Toshiba satellite C850 all usb ports not working

It's probably fine either way. But we don't have the schematic. So yes, the safest thing is to connect ground to pin 4, but bend the pin up carefully so it can't affect (or draw current from) the rest of the circuit.