Medion Akoya E6435 no power

[ezenia]

This is a long shot, but I thought I'd ask here since I'm quite stuck.

So today I tried to power up an old laptop of mine that has been sitting doing nothing for months. However, it did not power up at all. It was dead. Lifeless. I tried a bunch of basic fixes and nothing worked. I felt around the motherboard and noticed what felt like some heat (couldn't quite tell). I ended up stripping the entire thing and took the motherboard out of the laptop to inspect further.

When I plug in the charger without the battery connected and don't do anything, I notice that a chip on the laptop gets insanely hot. I attached a screenshot of the chip. It's the one with the "3F = 3L" markings. If I put my multi-meter on temperature mode and touch the chip with the temperature probe that came with the multi-meter, it reads around 60-70C (not sure how accurate it is).

Does anyone know what it is? I'm just curious. It's difficult to find information about this laptop model online.

[fzabkar]

RT6575BGQW, Richtek, Dual-Channel Synchronous DC/DC Step-Down Controller with 5V/3.3V LDOs, marking 3F=xx, WQFN-3x3-20L:
https://www.richtek.com/assets/product_file/RT6575A=RT6575B/DS6575AB-04.pdf

http://www.smdmark.com/en-US/search/code?id=3f%3D

Note that the chip may heat up if any of its outputs are overloaded. To this end I would measure the resistance between ground and each of PHASE1, PHASE2, LDO3 and LDO5.

FWIW, here are some schematics which use the RT6575A/B:

https://www.hisahtech.com/wp-content/uploads/2020/06/Lenovo-Ideapad-300S-14-Wistron-LT41-SKL-14292-1.pdf
http://files.pochinim42.ru/scheme/WISTRON/EA53-BM%20(4PD037010001%2014222-1%20REV%20-1%20-%20Acer%20Aspire%20ES1-512).pdf
https://www.hisahtech.com/wp-content/uploads/2020/04/Quanta-N91-schematic.pdf
https://novoselovvlad.ru/wp-content/uploads/2018/06/DA0X81MB6E0.pdf

One of the documents states that the Richtek part can be substituted with a TI TPS51275CRUKR-GP.

https://www.ti.com/lit/gpn/tps51275c

If you have trouble getting this part, you may be able to get a free sample from TI.

[ezenia]

Cheers for the info.

I decided to check some readouts on my multi-meter near the charging port area. I'm just wondering if it's normal to have one pin read 24V. There's 8 pins and 7 correctly show 19V.  I attached a screenshot of the chip. It's the bottom pin at the end (right side). Maybe it's normal, but thought I'd ask. I was expecting to see 19V and was surprised to see my multi-meter show 24V.

[Rasz]

measure what fzabkar said first

[ezenia]

It's been a while since I last posted. I kind of gave up troubleshooting since I am by no means skilled at this yet. I lack the knowledge to properly diagnose this issue. Despite this, I have this itch to keep trying to diagnose what has failed. I always keep coming back to the motherboard, probing around to see if I get anywhere (obviously not). This motherboard has become a board I play around with from time to time. I have removed two chips from the motherboard, the chip shown in this thread and the Super IO (the ITE8587 FXA chip). Now, I know that the motherboard won't power up without the Super IO chip. I'm not fussed about that since this motherboard is more a practice board now. If I end up eventually getting it working again, that'll be a bonus. I'm not expecting it though. I just want to try identify what has failed if that's possible.

I took the Super IO chip off because there's a cap, that goes into one of the pads where the Super IO was, that has continuity on both ends. My multi-meter beeps on this cap. Resistance on both sides is 0.003ohm. I just wanted to see if it'd go away without that chip on. It didn't. Typical rookie move I guess. This cap is larger than others around it and sits right next to the pad. I don't know if should beep on both sides. Maybe it's meant to, idk.

I also realised that I actually may have done more damage to the motherboard than I initially realised. To go back to what happened: my laptop was originally sitting idle (it probably was in sleep mode then naturally turned off from low battery) for several months in some suitcase. I one day decided to power it up. I got no response from the device. It wasn't powering up at all. There was no battery charger LED. It was completely dead. I did some basic troubleshooting. I first removed the battery and tried running off the charger. Still nothing. I then proceeded to remove the RAM. Still nothing (it should still power on without RAM, just won't pass POST). I then tried removing the SSD. Still nothing. As a last resort, I disconnected everything else that wasn't essential (such as speaker cables). Still nothing.

I checked the charger via a multi-meter to see the voltage reading. It correctly read 19V. I was not satisfied. I thought, "Well, it might be passing 19V, but maybe the charger itself is still faulty and the laptop detects this". So silly me, I took my charger from my gaming laptop. I connected it to the charging port and tried powering up. Nothing happened. I thought nothing of this initially. After all this, I gave up and concluded it was a motherboard fault.

Some research later, I learned about "polarity". I thought since the charger seemingly fit into the port, it must be compatible, right? How wrong was I... I saw the polarity was different on both chargers. So now I wonder: did my laptop have a simpler fault, or did I actually kill it further by connecting a charger with the wrong polarity? I know it didn't turn on and nothing blew up, but maybe that's why the chip I referred in the OP now gets excessively hot. The charger must've done further damage. Looking back, I wish I had not tried my gaming laptop charger on this board. I should've bought a charger with the correct polarity and then probed around the board if that failed. It's annoying I might've done more damage to it.

I'm trying to determine if this motherboard is fixable, or if I should turn it into a junk board that I can use to practice on. If it can be fixed eventually, it'd like to be able to. I'm in no rush to fix it, I'm just trying to determine if it's possible or one of those cases that should be written off due to extensive board damage.


I took some resistance measurements on the pads where the chip with the LDO3, LDO5, PHASE1 and PHASE2 pins connect to.

LDO5 - Starts off at some high numbers, rapidly drops and settles at around 06.20kohm
LDO3 - can't seem to get a stable figure. It seems most often start at like 0.600Mohm and then go down if I leave the probe on. I'm not really sure how to make sense of this.
PHASE1 - can't seem to get a stable figure here either. It mostly seems to hover around 0.800-0.900Mohm. It doesn't really settle at any figure. It seems to be rising slowly. Every time I touch my probe on the pad, it gradually rises.
PHASE2 - Seems to settle at around 06.25Kohm

I don't know if I did the probing right (I have black probe on ground and red probe where I want to measure), but given that there is no chip on the motherboard and my multi-meter probes are thin enough, I could see that the probes were properly touching the right pins. I tried multiple times on each of those pads to make sure I wasn't doing anything wrong.