820-000928-A Help Identify Location of this Capacitor

[sikocan]

Hi there,
I'm working on a A1707 Motherboard 820-000928-A and only boardview I can find it attached.

Both legs of this capacitor are shorted to ground, well 1 leg is, the other is obviously ground. I've injected 1V maximum and 1.3amps I can not find anything getting hot and I don't want to go further. From injection I can tell top is Ground, 0V and max amp taken, bottom leg is going somewhere as 1amp at 0.05v for example.

Could someone please let me know where this cap is going? The capacitor itself is good, test outside board is fine.

When the Finger print sensor is connected, board stays at 5V and no amps taken, when finger print sensor is taken out, it jumps to 20V and system boots fine without button.

[mon2]

Re: Help Identify Location of this Capacitor

What is the cap # ?

[sikocan]

Re: Help Identify Location of this Capacitor

It's not in the board view, but it's on the motherboard.

[mon2]

Re: Help Identify Location of this Capacitor

Can you zoom out on the picture? Having a hard time locating where you are referencing this cap.

Also, the 820-xxxx # is etched on your PCB and matches the boardview that is under review?

[sikocan]

Re: Help Identify Location of this Capacitor

Correct for boardview model number. It's located right under power button ribbon cable. I'll send more photos today.

[mon2]

Re: Help Identify Location of this Capacitor

I may have found the point of view - please see attached.

Do not see the missing cap.

[sikocan]

Re: Help Identify Location of this Capacitor

Sir I know that cap location, I don't know where it is on boardview.

[sikocan]

Re: Help Identify Location of this Capacitor

Sorry I couldn't explain myself properly. I need to know where that cap is in boardview. My cap is good, but it's location is Shorted.

[mon2]

Re: Help Identify Location of this Capacitor

See attached. Could not locate this cap on boardview either.

[mon2]

Re: Help Identify Location of this Capacitor

I think I see the difference. The boardview does not accurately match the pcb layout.

Perhaps there are more updated versions of this layout? the component placements are not matching the picture.

[sikocan]

Re: Help Identify Location of this Capacitor

Correct. I'm also confused.

[piernov]

Re: Help Identify Location of this Capacitor

Boardview file is for 820-00281 not 820-00928, so that's possibly one difference between the 2. Check if the other side looks identical between your board and the boardview.

[sikocan]

Re: Help Identify Location of this Capacitor

Hi Piernov,

I've packed up the unit, here's the video of all thermal scan of entire board 1.3amps at 1v, nothing gets hot. Even after removing metal shields. I'll see if I can have another go with that boardview.

https://youtu.be/Q1i9OiKGD7g

[sikocan]

Re: Help Identify Location of this Capacitor

I've looked at boardview files:
820-00928.brd
820-00928 A1707 Apple Macbook Pro 15'' Retina Touch.brd
Boardview_J80G_MLB.brd
2016-3072-820-00281-A-A1707 SCHEM MLB BAFFIN X363G.brd
None of them have that Capacitor location. So weird. I don't understand what's going on.

All these files on BadCaps Forum and also ERS Discord channel.

Any ideas anyone? I've uploaded a video showing thermal camera of entire board every detail on both sides, no where is getting any hot at 1.3amps at 1v.

It's related to power button/finger print.

[sikocan]

Re: Help Identify Location of this Capacitor

I've ordered an TS-30A, this one here https://s.click.aliexpress.com/e/_AbU1Pw and if it comes in enough time I'll try it on this board. TS-30A Short Killer

[piernov]

Re: Help Identify Location of this Capacitor

The 820-00928 boardview is not available in any case. https://logi.wiki/index.php/Schemati...in_Logic_Board

[gizaha]

Re: Help Identify Location of this Capacitor

I have exactly the same problem. There are also 2 capacitors on the rear side of this area that are not on boardview and they share the shortage of the line also.

I removed all 3 capacitors and the short is here. So tommorow i will search the rest of board.

[sikocan]

Re: 820-000928-A Help Identify Location of this Capacitor

Update me please

[mon2]

Re: 820-000928-A Help Identify Location of this Capacitor

TS-30A Short Killer

We have the same. Although the vendor sent us one with a dim display but we are 1/2 way across the world so cannot fire back a complaint...

To use, dial up a LOW voltage (always) - try 0v8 (yes < 1.0 volts). This is to protect any possible downstream shorted rails like the CPU which will get killed with a high voltage.

Then you apply the red probe to the cap / block of caps you suspect as shorted & black to ground.

You will see a small spark due to the low resistance of the shorted caps and the current will climb. This process will heat up the shorted part.

Suggest to apply with a Q-tip some IPA (alcohol; 70% or higher) onto the parts. The IPA will mist away with the heat. Locate and remove that shorted cap.

The above is a general process and there are very detailed videos on youtube on this topic that are must watch.

[gizaha]

Re: 820-000928-A Help Identify Location of this Capacitor

Sometimes a shorted cap will not heat. No alcohol, no freeze spray, no thermal cam will help you. A laser thermometer does not indicate even a 0.1C difference. Motherboard lines will absorve the amperage and there are thinner that the shorted part (so the part will not heat even with high amperage).

In this case i apply some safe voltage as mentioned with 1-2 amperes (never needed more) and check with multimeter all the suspicious parts that connect with the shorted line (using boardview). In the multimeter on the small voltage scale, you will see a small difference in your checks (let's say you will read 0.42v, 0.30v, 0.27v in 3 capacitors). The shortage is near the smaller voltage you will find, remove the around capacitors/parts and you found it.