GPS Antenna Contacts

I’ve been struggling with why my GPS quit seeing any satellites after the 9.4.2.11 update when I realized something looking at Anand’s teardown:

AnandTech - ASUS Eee Pad Transformer Prime Teardown

Perhaps the antenna connections are weak or have become slightly corroded. Based on his teardown the contacts are spring type “pogopins” which mate with the opposite face. With that thought in mind I decided to try and flex the tablet ever so slightly to clean the contacts. The idea being that the slight flex would cause the pins to scrape the contact surface rubbing a clean(er) spot.

Before the 9.4.2.11 update I had the typical poor performance from the GPS, getting locks but losing them on the move. I had given up on it [GPS] until this update which touted GPS improvements. After updating and wiping I tested the GPS again, but could not see even one satellite after letting it sit, more than once, for over an hour with Wi-Fi on and off.

I must stress I strongly suggest you do not try this on your tablet for fear of damaging it. I take no responsibly for damage to anyone’s tablet and am only reporting my actions.

After this procedure I am able to see several birds indoors, albeit with weak SNR. This has me convinced that part of the problem is related to these contacts, and may serve to explain some of the weak Wi-Fi reports. It may also help illustrate why only some users are seeing issues, and perhaps why some of the returns are functioning better. These contacts may be more robust in some units or possibly be able to be rectified via service.

I do understand there are other factors related to both the GPS and Wi-Fi, but this appears, at least to me, to be part of the bigger picture.

Please note that the amount of flex I’m talking about is next to nothing, enough to see a change in light bleed around the display, I was afraid to go too far.

*Mods, I'm not sure why this post was deleted before, please PM me if there is a problem with this post. I did not include the link.*

Guybor said:

No joke, I'm going to try the "squeeze" method. Just so I'm clear, the antennas are on the power button side (left side looking at face)?

Click to expand...

Click to collapse

January 26, 2011
AsusTEK
Taiwan

In response to numerous complaints regarding Wi-Fi performance with the newly introduced Transformer Prime, Asus is providing existing customers with a fix. All newly sold devices will have the fix included in the box at shipping. By simply applying the fix over the Wi-Fi antenna connection on the edge of the Transformer Prime, customers will see an immediate benefit. As always, Asus is constantly stiving to come up with new ways of improving the customer experience.

http://xdaforums.com/showpost.php?p=21489600&postcount=10

You can bypass the pogo pins by connecting a pigtail to the UF.L connector at the chip leadouts, then solder the other end to the antennae's copper pads. It should improve reception.

Have you seen the new evidence found? It was found out that Original Transformer actually uses the soldered type connection E.mote described. I was gonna start a thread but no use as this one is perfect for the new info.

FIRST here is the quote n pics from e.mote of the current Prime type of connection

e.mote said:

From looking at the Prime teardown, your wifi loss may be due to a loose connection. Instead of running a pigtail directly from the chip lead-out to the antenna, the Prime uses spring-loaded pogo pins (1st pic) as intermediate connectors.

Second pic shows the pogo pins for the main wifi and GPS antennae. The spring-loaded pins are pressed against the copper pads of the respective antenna (3rd pic). Suffice it to say, this isn't the most secure way to connect the antennae.

Aside from possible broken or intermittent connection, it also looks like a high-loss connection, and could contribute to attenuated signal reception. My guess is that this may be the main culprit of wifi/GPS woes, with the metal shell being a contributing factor.

The 4th pic below is a U.FL connector that's normally used for antenna pigtails. The lip has an outer overhang for a secure connection.

My guess is that the tablet was bumped and something shifted a bit, breaking the antenna connection.

This is FYI only, as the unit isn't user-serviceable. It does look like a simple fix, but you'd have to open the unit. Edit: You can try smacking the top edge of the tablet a few times and see if it will jar back into place. Worth a try.


Pogo pins used as intermediate connectors for wifi & GPS antennae

The two pogo pins for main wifi and GPS. The spring-loaded heads are pressed against the antennae's pads to make the connection.

The main wifi & GPS antenna, with copper pads to connect to the pins

U.FL connector, normally used for antenna connection

Click to expand...

Click to collapse

NOW here is the Original Prime teardown and type of connection


http://m.techrepublic.com/photos/cr...-transformer-tf101/6270147?seq=53#photo-frame

OG Transformer teardown pix



NOW HERE IS THE KICKER

clenz said:

that GPS/Wifi connection looks like a soldered wire and not pogo pin to me!

Click to expand...

Click to collapse

WHO said copy n paste n select text doesn't work well on the Prime? Lol I did this all from the Prime itself from various threads.

LOOOOONG before any of this was known, before tear downs and pogo pins and what not, you can find a post of mine - late December - where I reported I had so so GPS with nearly zero signal seen or locked on, and then I dropped my tablet while running a GPS test - picked it up and low and behold POW satellites and locks for days.

Ironic how that post might have been the first indicator of connector issues and none of us knew at the time of that post.