Dell Inspiron 7568 not turning on? Boardview anyone?

[roxboy1984]

Hi,


Does anyone possibly have the boardview file for this board. I have the Schematic already.
The IC labeled "53A8" is getting extremely hot. This seems to be a 5V voltage regulator.

18706-1
H3KD8

[mon2]

Post a few pics of the area of interest.

[roxboy1984]

Post a few pics of the area of interest.

This is the area and attached pic. The circled IC is getting very hot.

[m1ch43lzm]

It's a USB power distribution switch IC
APL3553A
Marking 53A*
Remove it, you'll lose power to the USB port it's connected to

Also check for shorts on the USB ports themselves

Afterwards you can replace it, many vendors offer pin compatible equivalent ICs

[roxboy1984]

It's a USB power distribution switch IC
APL3553A
Marking 53A*
Remove it, you'll lose power to the USB port it's connected to

Also check for shorts on the USB ports themselves

Afterwards you can replace it, many vendors offer pin compatible equivalent ICs

Thanks, I removed the IC and still no sign of life.
There is a mosfet that is getting a little warm but not super hot as you can see in the pic.

[m1ch43lzm]

Looks like one of the caps near the G946F11U-GP IC, it's --2.5v regulator for DDR4-- EDIT: Not actually, see below post
As the IC is to the left of keyboard connector, that cap looks below it


Found it on an schematic for another board, this one specifically, attached the relevant part for reference


EDIT: On your schematics it says APL5934 for 1D8V

[roxboy1984]

So my thermal cam has a bit of an offset ghosting affect to so it looks as though the hotspot isn't over the mosfet but it actually is.

[m1ch43lzm]

Got the schematic for your board, it's actually the 1.8v supply, on your schematics its listed as APL5934 for 1D8V_S5

2 things could cause it to get hot:
1. The IC itself
2. The output of the IC is shorted, may be PC5402, or something else in that rail

[mcplslg123]

After removal of usb load switch,resistance to gnd readings not shared on its pads.

Should stick to basics before jumping GUN.

[roxboy1984]

After removal of usb load switch,resistance to gnd readings not shared on its pads.

Should stick to basics before jumping GUN.

The resistance to ground on the pad for VOUT is 0.4ohms.

[mon2]

You have a shorted part on Vout. Flux and remove each part but one at a time on this trace till the defective part is found. Most likely a shorted bulk capacitor on the pin of the usb connector.

[roxboy1984]

You have a shorted part on Vout. Flux and remove each part but one at a time on this trace till the defective part is found. Most likely a shorted bulk capacitor on the pin of the usb connector.

Thanks Mon, by any chance do you know of an easy way of doing this? Or perhaps know where I can find a boardview?

could I possibly inject some voltage on the VOUT and see if anything gets hot?

apologies if my questions are dumb as I'm very much a noob still.

[mon2]

To confirm, this USB load switch is no longer on the board.

You are measuring a very low resistance to ground of 0R4 ohms on VOUT pin #1 of this SOT23-5 package on the PCB?

Test the resistance to ground of the brown capacitor that is just underneath the location of this USB load switch. What is the resistance to ground on each side of this capacitor? This may be the linked capacitor that is shorted.

Yes, you can inject say 1v onto the VOUT pin and see who is running hot to hunt down the shorted part. By USB spec, the VOUT pin will have a bulk capacitor that is mating with the USB connector's vbus pin.

[roxboy1984]

To confirm, this USB load switch is no longer on the board.

You are measuring a very low resistance to ground of 0R4 ohms on VOUT pin #1 of this SOT23-5 package on the PCB?

Test the resistance to ground of the brown capacitor that is just underneath the location of this USB load switch. What is the resistance to ground on each side of this capacitor? This may be the linked capacitor that is shorted.

Yes, you can inject say 1v onto the VOUT pin and see who is running hot to hunt down the shorted part. By USB spec, the VOUT pin will have a bulk capacitor that is mating with the USB connector's vbus pin.

That is correct. USB load switch is off the board. Please see attached pic of measurements.

am I correct in saying this cap is likely the problem and needs to be replaced and the usb load switch is probably still ok?

[m1ch43lzm]

This IC is marked U2502 on the board, and Dell actually used it to switch 3.3v, I didn't notice the silkscreen at first, I just went from the marking on the IC
Schematics says that it's SY6288C, "Low Loss Power Distribution Switch", actually the same thing, same pinout as a USB load switch with a different name, and Dell used the other part (APL3553A) as a substitute

The output of that ic goes to 3D3V_VCCDSW, 3D3V_S5_PCH and 3D3V_VCCPRIM, search those names on the schematics



The cap you're pointing to is on 3D3V_S0, near U7001, maybe your thermal camera misled you?
Measure resistance on that "USB load switch" itself from Vin to GND to confirm it's shorted

Tip: to confirm where a short actually is, once you located the approximate hot spot with thermal camera, add a drop of isopropyl alcohol and visually check where it evaporates
You can also use rosin vapor for that purpose

Schematics: https://www.badcaps.net/forum/troubl...-schematic-plz