Acer Nitro 5 AN517-52-56A5 - won't charge, shorts the AC adapter

[mon2]

Yes the removed mosfet is 100% defective.

The second mosfet also looks to be in trouble. Replace it as well. Measurements are too low.

[gleniu]

Thank you, so I need to order a replacement for it. Will SIS412DN be a good replacement for B09N03?

[mon2]

Can you confirm if the 2nd mosfet you have tested is @ PQB12 silkscreened area of the PCB? The body size of PQB12 should be smaller that the first DCin mosfet.

[gleniu]

Yes, it is definitely smaller and it is PQB12. I have just removed it. It seems to have 3x3mm in size.

[mon2]

The replacement is 50% lower current than the original. 12A vs 24A. Would you have other options? Otherwise the part is suitable and also 3*3mm.

[gleniu]

I probably have some other options, but honestly I'm lost as how to look for these I'm using AI for finding replacements, then I looked through the store where I'm about to order MDU1511. I probably ask for too much, but would you be able to take a look at this store offer to check if there is anything suitable?

https://mikrusy[dot]pl/szukaj.html/szukaj=chip

For some reason they name all the mosfets CHIP, which also doesn't make it easier to look for these.

I will try to look for replacement by myself as well. If I find something, I will post here.

I really appreciate your help. Thank you!

[mon2]

Can you order from Digikey (online)? If you are not in a rush, there is Aliexpress.

https://www.digikey.ca/en/products/d...N7318/11567446

The original part is AON7380.

https://www.aliexpress.com/w/wholesa....best.search.0

Always order spares of this and the other DCin mosfets.

[gleniu]

AON7380 did the trick - it is not sold by the store I'm about to order MDU1511 from, but I can order it for a little price from a different seller.

So, to sum up, I will order:
- AON7380 for PQB12
- MDU1511 for PQB11

I will do it now, when it arrives I will attempt a repair, hopefully the PC will boot. I will update the thread for sure. Thanks!

[mon2]

Yes, this combination should be fine to apply for this repair.

[gleniu]

Actually, I found a store (TME.eu) that has AON7380 in a very good price. They also have AON7318. Which one would you recommend?

I see that PQB11 is EMP21N03HC, which I was about to replace with MDU1511. That store doesn't sell MDU. Any replacement from AON? For example they have:
- AON6512
- AON6560
- AON6500

I only checked 115A and higher, because the datasheet I found for EMP21N03HC says that its drain current is 100A, but I'm not sure if that's true. They also sells lower currents from AON.

[mon2]

Select the part with the highest current. We are all seriously in trouble if the logic board truly consumes the peak current value but there is the brief in-rush current that is of concern for the selection process.

[mcplslg123]

Hold on guys before jumping to order these mosfets. have you checked the resistance to GND on CLR located just after these dc-in mosfets?

I beleive it'll show short to GND. Adapter is no more shorted 'coz you removed the mosfet.

So do check whether your 19v rail is still shorted or not. Else the new mosfet will get shorted again.

Usually whenever, +19V rail gets shorted, the dc-in mosfet also gets shorted. So i beleive your +19V rail is still shorted.

[gleniu]

Hi mcplslg123, thank you for your input.

I'm affraid you might be right. I've checked the resistance to the GND from PRB46 and it shows 0.1Ω (on both sides).

So probably MOSFETs got destroyed by a short caused by something else, just as you suspected.

Any noob-friendly step-by-step guide on how to try to find the shorting element?

[mon2]

Oh no

Thought the laptop worked on battery ok till it died.

Measure the resistance to ground of each inductor on the board. Start with the cpu area. Post the resistance values in ohms.

Next, measure the resistance from this main power rail to the inductor. We are testing if there is a high side mosfet short. If yes, the cpu may be dead.

[gleniu]

mon2, sorry for confusion. I thought that was the case - in fact this my son's notebook and this was his version. Lesson learnt - never trust kids

But back on topic - I don't think the measurements look good:

Inductors to GND:
- PLG1 - 7.4Ω
- PLZ1 to PLZ4 - 0.2Ω
- PLA1 - 0.1Ω
- PLH1 - 0.6Ω
- PL1001 - 14.2Ω

Inductors to main power rail (I used PRB46 as 19V contact point - hope that is ok):
- PLG1 - 7.4Ω
- PLZ1 to PLZ4 - 0.4Ω
- PLA1 - 0.1Ω
- PLH1 - 0.6Ω
- PL1001 - 15.2Ω

[mon2]

Any chance you have an adjustable power supply? The general approach here would be to inject 1v (max) onto this shorted rail. Then the component who is shorted will heat / crack under the pressure. A thermal camera of course is nice to have but IPA (alcohol) can also be used. Whichever part evaporates the IPA quickly, is the shorted component. Let me review the inductor readings.

[gleniu]

I don't have adjustable power supply, unfortunately. I might get one, because I need it more often than I'd expect. Any recommendations from Aliexpress?

For now - is it possible to use anything else for that? I guess using 1,5V AA battery for it is a stupid idea, isn't it?

[mcplslg123]

De-solder PLA1 along with mosfet connected to this coil and check whether short is gone or not on main rail?

[gleniu]

Thanks, I will try to find some time tomorrow to desolder PLA1 and PQA1 and will report back.

Also, it turns out that my colleague has a thermal camera, so I might end up getting an adjustable power supply and look for the element that gets hot.

[gleniu]

After I removed PLA1 only, main power rail (probe PRB46) showed 10,2Ω to ground.

When I removed PQA1 mosfet as well, the short was gone.

It still shows short to the PLA1 pin, the closer to CPU one.