Thinpad T400 wireless antenna ...where..?

[Ignorant]

I had once opened up a T400 but never located any antennas on the Main board or in LCD screen cover?.
Of course ,I end up enriching a engineer to put the screws back....
The wifi card is there and works...
I am curious....
T400,p8400,1400X900,8GB , SSD ,status lights all NOT working/Dead...

[Vopu]

Hi , have you checked HMM ? page 285 "Wireless LAN/WAN/USB antenna assembly" here
Vopu

[Ignorant]

yes,I had even printed this manual for repeat lookups.
It indicates that it is behind the white lcd panel.but I never noticed anything there.May be next time when some one opens it up for me I
will request them to explicitly show me.--I will have to wait for 3 months....i am planning to replace p8400 with a p9500.
thank you for your help.
I am using wifi with a usb 2.0 dongle (WIFI N, which does not require a antenna...so..??? .I get a max of 30 mbps from my mobile ISP in INDIA.
I got the dongle because the in built WIFI is generatig a lot of heat when I connect to the interet via a mbile Hot spot.

I presume I do not know what a antenna looks like?.Is it a flat plastic base?.
I am usinf wifi . Are antennas only for for some other type of signals?.AND optionally available?.

[Vopu]

have a look at this

[atagunov]

I had once opened up a T400 but never located any antennas on the Main board or in LCD screen cover?.

Antennas are in the screen indeed. Screen cable runs from the base of your Thinkpad into the screen. Some traces on that cable lead to WiFi antennas. We normally don't disassemble our screens so we normally don't see the antennas. But you should be able to see the WiFi card under the keyboard. It will have two wires pluged in. (Maybe three? But I think probably two). The number of those wires matches the number of antennas. I understand those wires ultimately connect to the traces on the display cable. You can unplug those wires, clean the sockets/plugs with spirits and plug them back if you have reason to suspect something is wrong. I don't think it's worth asking engineers to show the antennas since they probably are not going to open the screen up - it's a hassle of it's own.

[Ignorant]

Thank you .
You smean screen cable carries the antenna signals also?. What about the status lights?. They also go via this cable only?.
Why are the antenas required?.
My USB 2.0 dongle is a quarter matchbox size gadjet and says wifi N .Can be used with any USB 2.0 slot.
No antennas.

I just visited a VI Gallery.
Is it that there is provision for a SIM connect directly from the laptop?. Then where do I put the SIM.?.
....

[Vopu]

Yes you can use a WWAN module in T400, you will need this and this, see page 158 of HMM item#4 ( SIM card slot FRU 43Y965), also have a look at here

[Ignorant]

Aha!. so that is what that small white strip below 9 cell battery for. I dont think I ever had a card for that...Thakss for this information .
A decade back it was purchased in canada and given to me in India which did NOT even have mobile internet for every one then.It was then only a expensive 3G
service used via NOKIA Phones.No Android phones then.....

My puzzle for the antennas still unresolved. how do the wires go from the base board into the display panel ..if the wires are in deed there?
The pdf manual shows antenna wires going from the base board ito screen ...I dont observe any such wiring..?...
my status panel is also Non functional. .
currently it works nicely without the status lights. and is
p8400,w10,8GB,SSD 250GB, 1600 x 900 tubelight display....

[atagunov]

You smean screen cable carries the antenna signals also?. What about the status lights?. They also go via this cable only?

Yes indeed. Thinking logically how else would the status lights work?

The connector for screen cable in T60/T61 is TE 5353190-6 with 80 pins. It's well possible that it's the same in T400. I'd love to buy them new btw, but I can't find any
Between 80 pins there's plenty of opportunity to supply power, drive leds, provide signal to the screen matrix, control backlight brightness (pwm), connect camera (if any), ThinkLight if any, WiFi antennas, BlueTooth antennas (if any), Cellular (WWAN = SIM card thingie) antennas if any, get signal from lid closed sensor.. maybe I've forgotten something

Why are the antenas required?.

Interesting question. Think to provide better connection. The dongle sits outside, the built-in WiFi card would have had to work through the body of the laptop. Also the idea is to have good connection no matter which way you face, whether the lid is closed or open etc.

My USB 2.0 dongle is a quarter matchbox size gadjet and says wifi N .Can be used with any USB 2.0 slot.
No antennas.

Oh there is something that works as an antenna, it's just internal to the dongle.

Is it that there is provision for a SIM connect directly from the laptop?. Then where do I put the SIM.?.
....

There's a slot for these so-called WWAN cards. I heard they probably won't work well under Linux. Not sure about drivers for more recent versions of Windows. I don't trust these cards that much - but then I never had one. In fact I don't feel like paying for an extra mobile contract for that.. So what I do instead - I have a mobile contract that allows tethering - it seems these have become more common in the UK lately and when I need connection on the go I enable WiFi hotspot on my mobile and connect my laptop over WiFi to my phone. Works okay.

Also - I'm not 100% confident if your T400 would have antennas for WWAN or not.. In theory these are separate antennas also located in the lid (unless I'm mistaken).

[atagunov]

My puzzle for the antennas still unresolved. how do the wires go from the base board into the display panel ..if the wires are in deed there?

It's just one single flex cable. Plugs into 80-pin or so connector on the motherboard. I have a T60 display flex cable in my hands right now. It's covered in black plastic over the area that is constantly bent so you can't see the traces inside. But they are there. And other parts of the cable that you can't see right now have got a number of traces visible. Some of them seem to be forming "twisted pairs". These must be the pairs of traces that carry high-frequency signals. They're twisted to lessen influence of electro-magnetic noise on them. I think about 6 or 8 pairs of "twisted pair" traces carry LVDS signals - to drive screen pixels. And a couple of twisted pairs might be going there for each antenna. Though I'm less sure if they're twisted

[Ignorant]

thank you *2 ....
I had some 10 months back Before March 2020)got the T400 LID serviced for a broken Hinge.
I had opend the screen covers but never show any antennas as represented in the hardware pdf . may be after 2 months I may get a chance again to peep.
Your comment about USINg the in built SIM is much appreciated...Today only I came back from my ISP (Vodaphone) after living a lot of individuals at their help desk
puzzled about a SIM chip to be put inside a vintage working laptop.
Nice help...They told me to get my moneys worth via the smart phone....(Red Mi NOTE 9) ..and .The ISP provides me 8-12 mbps peak download speeds ..
good enough for me.(I dont need Netflix or Amazon Prime.
I will now explore the un coperative internal whispering sound speakers.

[atagunov]

I had opend the screen covers but never show any antennas as represented in the hardware pdf

Should be small pieces of metal, not as thin as cooking foil but probably as thin as a beer can. Should be located around the edges of the screen, probably along the top edge. If they're indeed missing that might explain why your built-in WiFi operates poorly and you need a dongle

[Ignorant]

No...The internal wifi gives better speed then the dongle..but the laptop becomes extremely HOT(the reason I switched over to a dongle).
I was even exploring just changing the wifi card but I was warned that the bios settings ,as they are ,will NOT allow change of card to work.
AND then I got the 4G secret iof my village,(mumbai,India). The mobile operators harp 4G,are mostly 4G lte and worse never give downloads more than 10
mbps consistently so it would be futile to expect any improvement by just change of card . I will wait for a couple of weeks for 5G to arrive.