Lenovo Yoga 7i blown USB port issue

[mon2]

Re: Lenovo Yoga 7i blown USB port issue

Suspecting that a high current / heavy drain USB device caused this load switch to fail. Perhaps one of the low current widgets advertised on TV like a USB car starter, coffee maker, back massager. Need to review the details of this component but yes, some monitor the D+/D- pins to determine how to charge the attached USB device. There is a whole specification on this topic alone. Each permutation defines different output current and/or voltage for the USB vbus line.

If interested, purchase a replacement to restore this USB port. Before doing this, as suggested above, check the resistance to ground of the vbus pin. I think it will be ok unless the USB connector is damaged and shorting.

[Rolin]

Re: Lenovo Yoga 7i blown USB port issue

"Did anyone here took a closer look to the power rail, so USB_VCCA itself? Resistance ton GND measurement?"

Checked UI2 Pin 12 (+USB_VCCA) a few times. Mostly get no continuity (autorange: OL on meter).. but sometimes did get around 5 M OHMs and climbing reading.

[Rolin]

Re: Lenovo Yoga 7i blown USB port issue

Mon2, I was told the owner did charge or power something in one of the ports - I suspected this as well because I've seen more than a few laptops come in for this reason. People should probably consider using a $10 adapter instead of their $1000 laptop - some laptop motherboards can be expensive!

You mentioned to purchase a replacement to restore the USB port - are you referring to the TPS2546 (boardview shows SN1702001RTER)? That has been replaced (but currently removed for testing). Sorry if I'm misunderstanding...

[Sephir0th]

Re: Lenovo Yoga 7i blown USB port issue

Time to check the differential pairs, not only on Port-side but also on PCH side. Then there is still a fpc-cable and a Sub-Board to rule out.

Also it wasn't any single picture shared so far. Neither from UI2 with surrounding components, nor of the fpc-cable, the subboard, and the USB-Port itself.

Last but not least I have a issue with your replacement. The Top marking between a SN1702001RTER and TPS2546 differ so it can be still the case that this part is the origin of your issue.

It is not easy to assist like that.

[mon2]

Re: Lenovo Yoga 7i blown USB port issue

The c2546 by TI is cited in the search engine under the alias of the other part number. Appears to be a jelly bean USB current limited and BC1.2 charger IC.

New Original SN1702001RTER printing C2546 2546 WQFN-16
https://a.aliexpress.com/_mrW1Eek

Can you post pics of the PCB pads without the IC where this chip was soldered?

Then again with the ic placed on the PCB pads. Do not solder it back but place onto the pads. Just wanting to confirm that pin #1 on the ic was aligned with pin #1 on the PCB pads.

Would you still have the original SN1702001RTER part that was on this board? If yes, post a pic of this original part with the bottom side pads of the ic pins showing to allow for a review.

[Rolin]

Re: Lenovo Yoga 7i blown USB port issue

Thanks Mon2 and Sephir0th for your suggestions. I'll upload the pictures in my next post,

As I mentioned, I'm not experienced at component level repair like this. But Mon2, you brought up a good thing to check - where is PIN1 on both the new and original chip? I soldered the new chip with the label on the chip pointing in the same direction as the original one - that appears to be a rookie mistake. Comparing both the new, I find the ground plate on the bottom has a corner missing indicating PIN1. But the missing corner on both the original and new chip do not match! So I now understand I installed the new chip with the wrong orientation.

Here's what's confusing: I have the same identical problem with the old chip (correct orientation) and the new chip (wrong orientation) - 1 of the USB ports not working and constant errors in Windows related to surges on the USB port. But when the chip is removed, the errors are gone.

Should I install the 2546 chip with the correct PIN1 alignment and see what happens? Or am I correct there is still some kind of problem elsewhere?

[Rolin]

Re: Lenovo Yoga 7i blown USB port issue

Here are the requested pictures:
1) Original and new chip side by side - top and bottom. (see my previous post - Chip label orientation and ground plate corner indicating Pin1 are different between both chips)
2) Original chip installed on the motherboard
3) both sides of the motherboard.
4) Picture of area with the chip removed

[Sephir0th]

Re: Lenovo Yoga 7i blown USB port issue

Thanks Mon2 and Sephir0th for your suggestions. I'll upload the pictures in my next post,

As I mentioned, I'm not experienced at component level repair like this. But Mon2, you brought up a good thing to check - where is PIN1 on both the new and original chip? I soldered the new chip with the label on the chip pointing in the same direction as the original one - that appears to be a rookie mistake. Comparing both the new, I find the ground plate on the bottom has a corner missing indicating PIN1. But the missing corner on both the original and new chip do not match! So I now understand I installed the new chip with the wrong orientation.

Here's what's confusing: I have the same identical problem with the old chip (correct orientation) and the new chip (wrong orientation) - 1 of the USB ports not working and constant errors in Windows related to surges on the USB port. But when the chip is removed, the errors are gone.

Should I install the 2546 chip with the correct PIN1 alignment and see what happens? Or am I correct there is still some kind of problem elsewhere?

See what magic can happen just from a few pictures shared.

Install the IC with the correct orientation. If still not working you need to order a replacement to rule out you have burned the IC by this mistake. And from there we can proceed then.

[Rolin]

Re: Lenovo Yoga 7i blown USB port issue

Sephir0th, When I ordered the chip from Digikey, I ordered 2 - so I have a spare. I'll solder a new (untouched) chip properly aligned to Pin1. I'll let you know how it goes!

[Rolin]

Re: Lenovo Yoga 7i blown USB port issue

Mon2 and Sephir0th, I truly appreciate your help and patience with me on this. In the end, it was my own mistake that caused this thread to continue needlessly.

I soldered the new TPS2546 correctly aligned to PIN1 this time (now that I know to check the ground plate on bottom of chip indicating PIN1). Everything works now - no more USB errors and all 4 ports work again - including the bad port from the original problem.

Again, I can't thank you both enough!