Nvidia Shield TV 2017 Dead

[mmartell]

This is the one with the 19v supply with the proprietary connector. Looks like a USB-C but it is not. There are many complaints of this adapter failing. I cracked mine open and found a vapourized trace. After repair it puts out the required 19v.

When plugged in Q16 is heating quickly and shutting off and that cycle repeats. I can't tell if this ic is functioning as intended due to a short further down the line because I can't find information on it. It is labelled as 1054P I think.

Can anyone identify this chip ?

[CapLeaker]

Re: Nvidia Shield TV 2017 Dead

take q16 out and fire that thing up.

[mmartell]

Re: Nvidia Shield TV 2017 Dead

Will do!

[mmartell]

Re: Nvidia Shield TV 2017 Dead

With Q16 removed I have 19v on pad 4 and zero on the rest. A continuity test shows pads 1, 2, 5, and 6 shorted to ground.

[budm]

Re: Nvidia Shield TV 2017 Dead

I would check and see if any of the pin that shows shorted to GND to see if it is connected to any MLCC hoping for just shorted MLCC.

[mmartell]

Re: Nvidia Shield TV 2017 Dead

You can't see on the pics but those four pads that are shorted are all tied together. I didn't notice it myself until now. Q15 is a dual channel mosfet which I removed and does not test shorted.

There are three mlcc's that test short so I guess that's my next step. Thanks bud.

[mmartell]

Re: Nvidia Shield TV 2017 Dead

There are more shorted caps along the back of the board near the ports, too many to start removing them. There are no shorted caps in the other areas including the cpu/gpu.

Would it be ok to inject some voltage at the drain of the removed mosfet or at the large filter coil in pic 3 ?

[CapLeaker]

Re: Nvidia Shield TV 2017 Dead

I figured that there is something else short. With a CV CC bench psu set it to 3.3 or 5V and 1A, hook it up and wait 30 seconds, then feel around for heat or douse area of interest with 91% IPA and watch for bubbles. Dont crank the psu, just wait. A shorted MLCC will get hot. It only gets tricky when there are MLCC's in parallel.
Iam guessing it didn't boot with it disconnected? Are you sure you got a short there somewhere?

[mmartell]

Re: Nvidia Shield TV 2017 Dead

Some caps are shorted to ground, yes, there is a short somewhere.

No it didn't boot with the 1054P removed. That ic is some current sensing chip or was acting like one, resetting every half second or so.

[CapLeaker]

Re: Nvidia Shield TV 2017 Dead

there are 2 ways finding that short. Either inject power and wait for that offending part to heat up, or with very good ohm meter that can measure milli and micro ohms similar to a leakseeker 89 etc.

[mmartell]

Re: Nvidia Shield TV 2017 Dead

When using ohm meter method do you use a common ground or do you measure across a device, like both ends of a cap ?

[CapLeaker]

Re: Nvidia Shield TV 2017 Dead

that ohm meter trick doesn't work with any ohm meter. It would need to read 4 digits past the decimal point. Just measure from a point that you know is shorted and start measuring all caps on that rail and look for the least resistance.
A while back I fixed a PSU that didn't want to turn on. It ended up being a shorted MLCC in a parallel group of 3 or 4. I used the power feed and IPA method.
HERE: https://www.badcaps.net/forum/showthread.php?t=82995
another one I used that trick on:https://www.badcaps.net/forum/showthread.php?t=73826

[mmartell]

Re: Nvidia Shield TV 2017 Dead

My esr meter reads low ohms. I'm going to read up on the method.

[CapLeaker]

Re: Nvidia Shield TV 2017 Dead

low ohms on an esr isn't a bad thing, that doesn't mean there is a short. You have to look at the DCR for a short if you look with an ESR meter. IF your ESR meter has that function.

[mmartell]

Re: Nvidia Shield TV 2017 Dead

No, the esr meter also reads ohms when it doesn't detect capacitance. Since I'm checking a circuit with a short the caps don't charge up and it measures the resistance of the path to ground.

[mmartell]

Re: Nvidia Shield TV 2017 Dead

When using ohm meter method do you use a common ground or do you measure across a device, like both ends of a cap ?

So I thought more about this and for anyone having the same brain block as I was I've determined you can use ground anywhere on the board since the shortest path will always be through the shorted component and the return to your ground location will always be the same path.

[CapLeaker]

Re: Nvidia Shield TV 2017 Dead

That only works IF it is shorted to GND. If it isn't shorted to GND, then you have to fine the shorted line first.

[mmartell]

Re: Nvidia Shield TV 2017 Dead

Yes that's a very good point !

[mmartell]

Re: Nvidia Shield TV 2017 Dead

I found and removed a shorted mlcc under one of the shields. I still have a bank of shorted caps so still have a short somewhere else. Problem is I can't trace the vcc line because I can't see the traces and I can't identify the chips I've removed so I'm kind of at a loss where to inject voltage.

Help!

[mmartell]

Re: Nvidia Shield TV 2017 Dead

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