Thank you for the tip. I can't find my heat tape, so ordered new one today. Will try then. I may post photo of the PCB before, though, just to make sure I am working on right parts.
Rudolf...
Rudolfl
Member
Last Activity: 02-28-2024, 01:39 AM
Joined: 12-04-2020
Location: Oakleigh South
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Yes, as per my original post -- memtest86 passed all tests...Leave a comment:
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An update.
Replaced SSD with one I had handy. Same problem.
Lifted the CPU heatsink, found thermal paste being dry. Cleaned it off and replaced with fresh, high performance one. Problem is still there.
Also tried to but Linux off USB. Same -- freezes after some time.
Really lost hereLeave a comment:
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Lenov Yoga C740-14IML laptop freezes
Hi all,
I am really lost on this one. Lenovo Yoga C740-14IML. Running W11. Machine freezes intermittently. It may work for hours, then suddenly freeze. Or it may freeze as soon as it starts and gets to lock screen.
Now, what was checked:
1. BIOS and all drivers are up to date. W11 was re-installed. No additional software is running. Naturally, no viruses, as it is a fresh install
2. RAM test passed with memtest86
3. SSD is tested and reports healthy status. It is a Samsung M2 SSD MZVLB5512HBJQ. Unfortunately, Samsung "magician" software is not supporting... -
Fixed.
DT7 was faulty. Also DT6 on the other side of the board. Both are ESD protectors on USB port. In addition, power adaptor was not producing enough current. Replaced diodes and got new adaptor, now all is OKLeave a comment:
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Another update
Battery circuit is OK. Battery charge light flashes if battery is connected.
It looks like a controller IC (Lenovo chip IT8386E-192 at position UE1 is not happy). It gets signal from button, turn on LED for few seconds, but I do not see EC_SYSON signal coming out from this IC. It is unchanged. As a result, rest of machine is not turning on.
I am not familiar with this chip, will try to find datasheet (if available) and try to see what it is unhappy about. Basic things like VCC and clock are working.
RudolfLeave a comment:
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Thank you foe replying.
DCin MOSFETS are OK. That was the first thing I tested. They measure fine and I can also see 20V coming through (MOSFETS are PQ106, PQ107).
Machine "starts", power LED goes on for 3 seconds, then it shuts down.
20V on is stable on MOSFET drains in both states (when in standby and when turn on).
I also have stable +5V and +3V supply in both states.
Charging chip is BQ24715RGRR. II can see charging circuit is working and there is an output from this IC that goes to battery.
Feels like machine is sensing...Leave a comment:
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Lenovo Yoga G740 -- camera removal
Hi all,
Can anyone share tips on how to remove camera PCB without breaking it?
Replacing screen and back cover on this one and need to move camera to a new back cover
Thanks,
Rudolf -
Lenovo Yoga 3 14 80JH shuts down
Hi all
When power button is pressed, power LED comes on for a few seconds, then shuts down again. Removed all peripherals and battery -- same.
All voltages seem to be normal.
Not really sure what can cause shutdown. Thinking of BIOS re-flashing, any other ideas? -
Hi all
My name is Rudolf Ladyzhenskii. 52 years young :-) from Australia
Thank you for accepting me.
R&D engineer was working on hardware and software development for years (embedded systems). Mainly in telecommunication systems. Was part of the team who developed 3G technology, first 3G phones and base station. Also worked with ISDN, IrDA, DSL SDR and other comms stuff.
Also run own electronics repair business for about 20 years. TVs, audio, etc.. As far as computers go, was fixing on "module" level. And, software, of course.
...Leave a comment:
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Actually, I managed to find the schematics (attached), but do need board view, if someone can share. Looks like there should be 20V, but can not find those elements on board.
[COLOR=#e74c3c][Mod. Edit] [/COLOR]Schematic link -> [URL]https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-laptops-tablets-and-mobile-devices/schematic-requests-only/3202700-lenovo-ideapad-5-pro-14acn6-compal-la-k483p-rev-1a-schematic[/URL]
[B][COLOR=#e74c3c]Reminder: rules and organization of this section[/COLOR][/B]
[URL]https://www...Last edited by Vesko356; 01-23-2024, 03:00 AM. Reason: Attached schematic removed and replaced with linkLeave a comment:
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Lenovo IdeaPad 5 Pro 14ACN6
Hi all,
Friend asked me to look at his Lenovo laptop that is completely dead. Upon inspection , I found faulty DT7 (protection diodes off USB connector). Chip had small hole in it. Replaced, but still no power. No obvious shorts further on the board. Small resistors and SMT fuse I found all measure OK.
Measuring voltages on large caps I can see 5V and 9V present on the board.
I tried to remove all peripherals and disconnected battery -- still same. With battery in or out, charging LED is always off.
Now, for the interesting part. Dead with original charger....
No activity results to display
Leave a comment: