Any suggestion can be tested in the name of good experiment
This is what is it all about , to learn something
Lifeisfun
Member
Last Activity: 06-18-2025, 02:06 AM
Joined: 04-26-2025
Location: ONT
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Any suggestions what else to try?
Any suggestion can be tested in the name of good experiment
This is what is it all about , to learn something
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Thanks for reply!
The only thing I'm still thinking here is something wrong with the slot is because the LED are going on and off while massaging the slot while the tester is locked in it.
I tried press on the CPU it self and there is no change how the testing board is lit.
You said Lenovo used low melt solder, does this mean that the 370F temperature I used to bake it was sufficient to reflow the board?
Board is NM-C421
This is just a project, nothing crucial so I'm willing to try anything for good experiment
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Thanks for your reply as well!
I just posted pics when you posted, yes, that epoxy is seen on the memory socket as well.
I pick the temperature from ideas while goggling on the subject.
Check all the pins and didn't find any cracked....Leave a comment:
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Well, I did check it and don't see any problems with the socket but it is virtually impossible to see the underside contacts in the socket.
I ordered new slot and will replace it just for the fun of it I think the most difficult thing will be the old socket removal since one the left and right side (about 10 pins each side)
there is blob of some kind of glue, probably epoxy.
Reball of the CPU is probably not worth it.
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Thanks for reply!
The test module it self there isn't much to it, no active components on it and I did test the traces going to those LED's
Memory it self was tested and works fine.
What I find strange is how the LED blink moving the test module when it's locked in the memory slot
I also applied soldering paste around the CPU while it was baking.
What do you think about the time of the baking and temperature?
From experience how often do you se bad memory socket?
Thanks for your time! You are great!...Leave a comment:
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Trying to troubleshoot DDR4 SODIMM slot with slot tester
Hi folks!
I have some kind of memory problem on Lenovo laptop. I was initially able to install windows after several tries since the laptop did freeze in middle of those attempts.
Eventually I discovered that it was related to moving the laptop.
Later on it even stopped booting unless I pressed around the memory slot. (no keyboard LEDs only power button responds)
If I remove the RAM I get the beeps that RAM is missing. Inserting the RAM there is silence and it will not boot most of the time. No picture.
I removed the board got one of those memory slot testers... -
There was no sign of liquid damage anywhere, overall the laptop looks like new, never used, oh well, it was great learning experience!
I like to thank you and all the other contributors for helping me to find the cause.
You are great bunch of people!
Couldn't do it without you!...Leave a comment:
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Here are the results, I'm afraid it ain't good unless I see it wrong.
@3V the rail takes 120mA, and the only thing that I see slightly glowing is the PCH (pics before and after injecting voltage)
Makes me wonder what caused the damage, the EC chip was bad for sure since it was shoring the LDO 3V rail but why did it take out the PCH as well is beyond me.
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Thank you!
Will give it a shot today and report back...
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I did unsolder the PJ0502 jumper to separate the rail from the power supply, and yes the partial short is there.
What would be safe voltage and amperage to inject to find the problematic component?
This rail feeds lots of stuff incl. the PCH, I just hope the PCH is not partially shorted, that would be the end
Thanks...Leave a comment:
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The only hot thing glowing is the BQ chip at 59C all other smaller chips are under 30C, and the EC chip has no longer hot spot on it but it's evenly distributed 28C.
The replacement BQ chip should be here any day, I'll try to swap it to see if it will run cool.
Once again thanks for your time and knowledge!...Leave a comment:
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Thank you for the assessment!
I do have thermal cam, will look in to it!
Thanks!
EDIT
Interesting, this is the original problematic power supply where the LDO voltage to the EC chip was shorted, after replacement no longer shorted but perhaps some other issue...Leave a comment:
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Yes, you are correct the battery spec is NOM 11.1 / 4.08Ah
Just tried again and it will not power on with only battery connected, I have to have the USB-C power connected (it ramps up on connecting power to 20V and about 0.48A)
Tested again and now with battery connected the PL0202 coil has 9V with battery connected or disconnected.
CPU is warm
Only power button response is holding it for 10 seconds or so, on first attempt it will reboot and doing it second time it wit shut off but the board is still taking about 40mA.
I will start all over again.
Is...Leave a comment:
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Thank you very much for your time to respond!
There is something strange with the charging since the battery voltage is 11.35V but charging voltage is stuck on 12.4V and dropping.
Yes the coil is very hot when battery is connected but also warm without the battery when the voltage drops to the 9V range.
The BQ chip is also hot all the time.
There is no Caps LED lit and no response pressing the caps button (there is 3.3V on the keyboard)
I was all excited since I found YT video where someone is measuring resistance and voltages on this board but my happiness...Leave a comment:
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You are great with all the hints and advice!
Thanks, will do!...Leave a comment:
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Sorry, that was oversight on my part ( assumed and I was wrong)
It is actually very strange, since even the board view doesn't ID that coil or the larger mosfet to the left above it.
The PL0201 is not present and the jumper is in place (jumper is 49K to ground) Yes there is 20V on that jumper and 20V on pin 1 of the BQ chip.
PL0202 (I assume since is not marked anywhere) is the one getting hot when battery is connected and warm without battery. (1K to ground on that coil)
The BQ chip is slightly above it on the other side of the board (BQ chip is definitely...Leave a comment:
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That's awesome! Good for you!
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Hi there, I have similar problem with my E15, the VSYS15 is also only 9.3V
Did you get it working?
Thanks...Leave a comment:
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I have another question about the VSYS15 voltage.
Considering I get on the VSYS15 only 9.4V without battery connected and 12.4 with battery connected, is there any way to test if something is causing this drop?
Can I inject voltage on the VSYS15 rail and see if anything is getting hot? If so what would be safe Voltage and Amp limit?
The PR0201 coil is warm without battery and very hot with battery connected.
Thanks
UPDATE: Just tested VSYS15 resistance to ground and its about 5M+ so I presume there is no problem there....Leave a comment:
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Oh, OK, thanks for the explanation, yes, the 3,3V rail is fine.
Will swap the BQ chip and report back
THANK YOU!...Leave a comment:
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