this would be away to rule it out as a potential issue. Other than that, Lenovo is currently known for weird issues originating from badly soldered BGAs, usually the CPU. But this would be out of the league for most technicians. Even for me...
Sephir0th
FairRepair
Last Activity: 11-21-2024, 01:06 PM
Joined: 10-17-2020
Location: Apen, Lower Saxony
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How was it, was it possible to deactivate the dedicated GPU in the BIOS environment with those Lenovo gaming laptops?
this would be away to rule it out as a potential issue. Other than that, Lenovo is currently known for weird issues originating from badly soldered BGAs, usually the CPU. But this would be out of the league for most technicians. Even for me...
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This has nothing to do with the DC-IN Mosfets. They're simply switching the charger voltage to the main power rail. Nothing more, nothing less.Leave a comment:
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We can't do anything for the board anymore.Leave a comment:
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I am explicitly asking for resistance to GND of PLW1, so +FBVDDQ.
+VCC_CORE has nothing to do with the shorted VRAM and even PLV3 rather indirect at most.
+VCC_CORE, respectively the CPU might be fried now, caused by exceeding the maximum of 1 Volts while injecting... or maybe not. However, this would mean it was missed a second High-Side failure. We will see what we can do at this point after you share the requested measurement, but per 99,9% a donor board now.Last edited by Sephir0th; 07-22-2024, 06:56 AM.Leave a comment:
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Since P5VAUXON is asserted from U7490, you want to check whether P3V3_LDO is present. You can alternatively measure at U6100 Pin8. Voltage and resistance to GND.Leave a comment:
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...How much voltage was injected ? Still 16 Ohms on the Main power rail? Resistance to GND of PLW1 ?Last edited by Sephir0th; 07-21-2024, 10:46 PM.Leave a comment:
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You are likely on the wrong path here.
First counterargument: ACOK is not even used (left floating) on some devices, so basically inconclusive then.
Second counterargument: if ACOK is pulled up by a 3.3V rail instead of REGN, then it is inconclusive too, since without a working 3.3V, ACOK can't be HIGH.
Sounds logical, doesn't it?
If i have to bet, i'd say your embedded controller is either shorted or simply not powered with (the same) 3.3V.
EDIT: Did not look into the schematics, but regarding what mon2 shared, it seems you have...Last edited by Sephir0th; 07-21-2024, 01:14 PM.Leave a comment:
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I'd check voltage of U7100 ACIN, VDD, VDDP, SMB_RST_N too to have a more complete picture of the situation. And do you get ACOK by any chance?
Also resistance between CSIP and CSINLeave a comment:
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Interesting device. The first thing you want to check is whether the Main Power Rail voltage (typically 19V) reaches the display connector.Leave a comment:
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Try again to find a secondary ower rail which shows almost continuity (less than ~3 Ohms) with the Main power.
If you can't find one, you are allowed to raise the current/voltage in steps up to normal operating voltage while injecting into the Main Power rail.
But be aware that neither me nor someone else does take any responsibility if you missed the secondary power rail and therefore kill something caused by overvoltage sending into one of these secondary power rails.
Personally i'd prefer to have resistance to GND measurements of any single power rail...Last edited by Sephir0th; 07-21-2024, 03:24 AM.Leave a comment:
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Either way, what heats up is the culprit of the short circuit. So it's probably a dead end here, except you find something else heating up.Leave a comment:
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Heats comes from the smaller Die/Crystal?Leave a comment:
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If you have a thermal camera there might already something to spot.
And don't forget to remove the heatsink and to clean the CPU/PCH BGA package, since the PCH is a suspect too.
If you can't feel anything you're allowed to raise the voltage to 1.8 Volts max(!).Leave a comment:
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1 Volt is a good starting voltage. The taken current will tell us whether we have to raise the voltage or not.
Good luck...Leave a comment:
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Ok. You probably need to open the laptop to get a more clear symptom/sign of failure.
Like a (partial) shorted power rail for example.Leave a comment:
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The Classic 1.8VALW is supposed to read in KiloOhms.
Voltage injection is the next logical step.Leave a comment:
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You realized that 2.8 Ohms is a partial short-circuit on the 1.8V rail?Leave a comment:
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Read my advise again please. I have left detailed instructions what to do.Leave a comment:
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Does more look like a testpoint than a actual via. So there might be a chance that this has no relation to your issue.
Otherwise you just flip the board and check there for a corresponding via.Leave a comment:
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Check the Data Pins, the middle two in the row consisting of four, in diode mode. Black probe to data pin, red probe to GND.
When switch to Ohms mode, range 200 and measure the outer pins. One is supposed to be GND, one is supposed to be the 5V rail. Red probe to the pins, black probe to GND.
Share the readings here.
Edit: But seriously, i don't have much hope for your device....Leave a comment:
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