Dead Switch wont start, help with diagnostics

Can someone help with repair?
Got a switch thats not turning on. Dont have a usb voltmeter to get readings when charging.

Opened and measured some caps. All good and not shorted afaik. But one near the BQ Chip does not have a connection to ground at all. Even with removed BQ.

Measures 8mOhms on “ground” side

Some ideas where to look now for a fault?

https :// / tu7cn

Your “ground” is connected via the big 2R2 inductor direct to vsys. If vsys is shorted, you can hope that something is getting warm if 1V are injected. Otherwise there are many possible places for a short.

Okay so i have to measure the red spots for a short?

Edit. No short on none of the parts!

Did you meant 8 M(ega) Ohms?

Yes 8 MegaOhms. Weird thing is that other caps around are also measuring resistance with a mega value but on not ground side. But the value kinda changes? Measured the cap from above with 8 and measured now over 20megaohms.

Measured without BQ installed!

Dont know what that actually means

It’s not strange :slight_smile: you won’t typically measure ground on an inductor which I think is where your confusion is coming from afaict (unless it’s a negative rail, or some rare fringe circuit arrangement, or of course unless your have a short to ground on the indcutors respective rail ie: a fault) - your reading is normal :+1:

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Okay thank you. Ill get a new max, pi3usb and bq chip next week. Try to install back a new bq and change the m92 chip. Saw a video where alex from northridgefix had the same problem. No short where to start from but still no power. Was working after he changed the m92 chip

m = milli → 10^(-3)
M = Mega → 10^(6)

Slightly different. :laughing:

So you are reading not a short to ground at the vsys. As Severence wrote: This cap has no connection to ground in normal cases and reads ok.

The first things I would check:

  • is the usb c port looking ok and has no bend pins
  • is the usb c port soldered correct and in place on its pads on the pcb
  • are the 5V passing the fuse and reaching m92t36
  • are there shorted caps around m92t36

With og power ac i could read 15v after the fuse and 4v at battery connector with battery in place. And found no shorted cap on the board at all.

If you can read 15V, m92t36 is working in terms of communication with the charger.
Would be interesting to know the amps at the usb c during charging, to check if the SoC is started fully.

Just found this.

https: //www

Maybe this ic is also causing my boot Problem. Ic looks kinda discolored.

https: // / xKHT2

Just dont know where to find this ic.

Yep, could well be, it doesn’t look quite right. You could take the same measurments as mentioned in that topic too.

It’s mentioned in that very same topic :slight_smile:

Measured also 150k like in the thread. Ordered 5 chips on ali.

and the other measurments?

I wouldn’t trust them myself

Just measured oms. No voltage yet. I guess the ics come not preballed. Any idea how to get them in place without reballing them? Is that even possible?

Maybe clean board pads, add solder to pin and then heat up with chip in place?

I’ve made a few posts on this IC, you’ll wanna find them and ensure it’s providing the output (3.3V) and if not you’ll wanna check it’s being told to turn on (enable line is high ie. 1.8V at the points I’ve previously covered) - though you have to ensure the console has actually been prompted to boot prior to this either with the power button or by using USB (though careful here if you have USB or M92 issues unbeknownst to you in the latter scenario)

Maybe though this isn’t the reason why I wouldn’t trust them… often times the Chinese sellers are “recycling” these chips off other devices and either not reballing them at all or poorly reballing them and then they pack them up like new IC’s… who knows if the chip worked in the first place or if the chips are clones / fakes. Just buy them from a legit source such as digikey, mouser, farnell, element14 and then there is zero doubt and they are preballed for sure and the price is virtually identical anyway.

Not really, you cannot reliably place these IC’s on the board without properly reballing them and/or potentially causing permanent damage as a result of trying (for example bridging a 3.3V line to a 1.8V) so just don’t do it :slight_smile:

And what purpose would this serve? there has to be a reason for doing this in the first place :slight_smile: we don’t even know if the IC in your case is even at fault so I don’t see how this offers any clarification.

And what purpose would this serve? there has to be a reason for doing this in the first place :slight_smile: we don’t even know if the IC in your case is even at fault so I don’t see how this offers any clarification.

i thought of doing this instead of reball it. I meant to clean up the pins on the board, pre tin the pins unter the chip and then “reflow” it in place instead of reflow it with the reflowed balls under chip, with the hope it will also work

Yes but again, what would be the purpose of reballing it either? 1: when you don’t even know if there is anything wrong with it (which the procedures I told you about prior would confirm) and 2: if the chips is bad how is a reball / reflow going to fix the chip?

I’m really trying to drill the point down for you as it’s what a lot of beginners do, they have a lightbulb moment :bulb: and then proceed to make the problem needlessly worse :slight_smile: then before you know it they’ve had x10 lightbulb moments spread across other areas of the board and turned an easy fix in to one that isn’t at all

yep, don’t do any of this :+1: :smiley:

I think were talking about different things. :smiley:

My idea was it to “reball” the new chip if it will arrive without solder balls on it. I have no reball Equipment so my idea was it just to put sufficient solder on it and “reflow” the new chip in place on the cleaned board.

With the Hope hat the new arrived chip is full functional and it will work like imagined

Oh I see :slight_smile: yeah, if you verify the measurments earlier and it in turn brings you to the conclusion the IC is bad and if the replacement IC which arrives has not been reballed or properly reballed, then yeah you can tin the IC’s pads with your iron and then reball it with stencil and solder paste. Just to note though, you’ll want to lower your soldering iron quite a bit from what your used to as these chips have virtually no thermal mass on their own and on some IC’s (depending on the coating around the pads) you can in some cases strip the coating off if your soldering iron is too hot.

Nope, no good, as mentioned it’s dangerous and not worth the risk…

An alternative way of doing it, is to tin the chip, carefully and gently wick it and then manually place some solder balls on the pads and reflow them in place. Tin and wick the pads on the board and after place the chip.

Anyway, probably not worth worrying about this anyway, chances are the chips you ordered will be preballed (hopefully)

But again though, you haven’t even detemined if the chip which is on the board is even at fault yet. The issue I’m trying to avoid is you randomly replacing it (for no reason) only for you to cause a secondary problem (due to the install) unbeknownst to you or me, which might come a’knocking if the actual problem elsewhere is resolved… hope that makes sense, this is another lightbulb moment :wink:

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