M4800 Owner's Thread

Another user previously pointed out that the sensor is somewhere on the left side (near/around caps lock or tab key maybe?) so that is a starting point, maybe. I don't know where it is on the actual motherboard, and I suppose that it could actually be on the I/O daughterboard that hosts the left ports (headphone connector, etc.) which is over on that side. Looking at photos of the boards, nothing pops out at me... Maybe you can find a magnet to hover around and see where you have to hold it to trigger the screen close. It could be in the smartcard/expresscard assembly which is also on the left side. (I think that you can actually just disconnect that piece if there are no components in it that you use.)

I think that the simplest thing to do may be figure out which component hosts the sensor and just replace the whole thing, rather than trying to tamper with the sensor. These parts don't cost that much, motherboards are around $35 and the I/O board is around $10.

 

Thanks for your awesome tips. Yeah, the lid sensor is located on the left side of palm rest. Because my left hand triggers it.

I'll try to disable the express card slot first!

Other M4800 user had the same problem on his refurbished unit. I guess some refurbished units have this kind of hidden issues.

Btw, I paid only $190 (include shipping) for my M4800 with i7 4800MQ and FirePro M5100 lol

EDIT: I disabled express card slot but it still triggers lid close.
then I removed the dummy express card that came with M4800... and now It doesn't trigger lid close and sleep mode! I'll update if this completely fixes the problem.

I think maybe bad express card slot was causing this problem.

 

By different issues not related to the lid I have also disconnected the express card reader.
Getting a driver for the smart card reader is hard, it caused bsods on windows 10 so I unplugged the whole daughter board below the trackpad and express card.
And as a bonus I get rid of the nagging that a driver is not installed for this board, I don't need it so why have it plugged in, I just put some electrical tape to hold the flex cable in place so it won't flap around when carrying the computer and make noises.
I chose to keep it screwed in place but unplugged just to keep it where I know where it is and its so low weight you don't even notice its there..
But about the magnetic sensor, it is located on the daughter board which sits above the motherboard on the left side on the computer along with audio in/out, usb ports and some internal flex connectors for the volume controls etc etc.

I have a new daughter board in front of me that I will put in tomorrow and if I reference to the location where the magnet turns the screen off it must be the black chip that sits between the two usb ports above the 3.5mm audio in and out ports.
I am replacing it due to that the 3.5mm ports are now too loose after ware and tare and its easier to replace the whole board than replacing the port by soldering due to that the board is double sided (components mounted on both sides)
You could try to buy a new board and replace it to see if it might fix the issue, or replace the sensor itself if you feel comfortable soldering very small components.

Part number: 0JR8JJ LS-9771P

The magnetic sensor chip is labeled H64wC and sits at U6 on the board, but I can't find any datasheet for the board so it does not say much.
Other side has two transistors and other components for the audio so nothing there related to this.

Searching for "smd magnetic sensor" brings up identical chips that are rectangular with two legs on one side and one on the other side in the middle

https://www.aliexpress.com/item/10P...E-A3144E-SOT23-Sensor-Switch/32947763024.html

After some searching I found that the correct name for this component is "Linear Hall Effect Sensor"
https://en.wikipedia.org/wiki/Hall_effect_sensor

Searching for "Linear Hall Effect Sensor" brings up a list of components that are very similar to the H64wC
https://eu.mouser.com/Sensors/Magne...-Magnetic-Sensors/_/N-6g7qo?P=1y9nzhvZ1z0z7pt

 

Yes, I no longer see malfunctioning behavior after removing the dummy plastic express card.

That's so strange... how can the express card slot get this laptop into sleep mode?


Thanks for your info. I think I'll leave this laptop this way... everything else's working fine.

 

Perfect... So you could just replace the I/O board ($10). I suppose you could try to remove the detector (desolder, or just break it off) — but there's a chance that it could cause unexpected system behavior if it is missing (i.e. failure to boot or the system thinks it is always triggered) so I'd have an extra I/O board on hand anyway.

 

I guess express card driver and slot are too old for Windows 10 so they can cause strange problems. A good lesson learned.

 

Yes, there are no correct driver for those for Windows 10.
I wanted to set up a smart card HW key to complement my encryption but this is easier said than done from my experience..we have this at work so I know how it works but the built in reader in this computer is crap, no drivers either since WinXP that does work on W7 but not very well on Windows 10..and I could't find any proper documentation on the smartcard reader itself, only a small mentioning as an "option" in the owners manual and data specification
So the only reliable option is to buy a reader or combined reader/writer that plugs in to the usb port...but that defeats the purpose of having a laptop.
At work we have the keyboard/smartcard reader combo so you just put your id smartcard into the keyboard and login but that is not very practical with a laptop and I wanted to see if I could make use of the internal reader that I already have.
But the keyboard combo/internal reader on the laptop are only readers, I need a writer to write my private keys to the slot on the smart card and then import it into my authentication process to have it prompt to insert my card when I enter my password..which is too much work so I gave it up.
Its a good practice to have on your servers but not very fun configuring on a laptop.

The express card works good for me at least, or did, I have a usb 3 card in there to get two extra ports...it works fine for a few months until some error appears in Event viewer and I always end up disconnecting the reader altogether, and this time I removed the whole daughter board cable to get rid of it once and for all..
The other connectors are for the fingerprint sensor and nfc antenna if you have this palmrest, either the swipe fingerprint or full size fingerprint...there are many different palmrests to choose from..so that's why there are many empty flex cable slots on this little board if these options were not selected when the original owner ordered the laptop from Dell.

 

Yes, I don't think I'll ever use express card again.

I found the problem came back though. Now when I give more pressure to left side palm rest, it turns off laptop screen for 2 seconds.
The only thing I have underneath express card slot is 2nd HDD caddy running an SSD.
I think I'll check if 2nd caddy ssd connection is alright.

 

The left side palm rest is still triggering 'lid close' when it gets pressure.

Is there anything that can trigger this in left side palm rest?

Express card has been removed. its driver's disabled too.

When I press down left side palm rest, it turns off my laptop for 2 seconds.. normally that would put my laptop into sleep mode but I have disabled sleep mode in Win 10 settings so it can't get into sleep mode. It returns to normal screen after 2 seconds.
But this is still very disturbing.. .I hope there's a way to fix it.

 

The magnetic sensor that @unnoticed pointed out is what causes this. It is on the left I/O board in between the two USB ports. Check to see if there is anything pressing on the sensor. Consider replacing the I/O board.