need help with a t41

[werejag]

my t41 (2374-258) was working fine. so i decided to buy a modem/bluetooth card and install a bt attena. after this my wifi card did not work.

removing the modem/bluetooth card and reinstalling the modem card didnt fix the issue. i left the attena in.

installing a non official wifi had the same effects (patched bios check)


im looking for any idea so i can get it working again

[RealBlackStuff]

You are probably shorting the BT antenna against a WiFi antenna. Check again inside the lid.

[werejag]

hmmm

ill pull out multi metter and check

it was hard to figure exactly how to lay out the bluetooth antena. so this is very pluasable thank you ill post my findings

[poshgeordie]

We get too many Thinkpads in where the owner has incorrectly routed the wi fi and bt aerial wires from the body into the lid, and the cables are squashed and damaged as a result.

The way they should go is under everything. Referring to the Hardware Maintenance Manual page 121, note that the cables go under the LCD connector and then behind it into the "notch" in the rear metal chassis.
Looking at the LH hinge there's a gap where the hinge sits on the chassis for the cables to run into the Display. Make sure they're all running up this gap and not being squashed by one of the hinge "legs".

We always arrange the wi fi and bt cables so they're next to each other and not bunched up, and that they "flow" smoothly under the lcd connector, out the back and then through the hinge gap.

You may want to also look at my doc T4x screws page3 LCD Assy second photo which shows how the cables going OVER the LCD connector (wrong!) but does show it going them going under the gap in the hinge.

Re checking the aerial cables for short circuits, I need to confirm this but I think the aerial stubs in the lid are connected to the ground. I'm an ex RF engineer and I think the stub works as a tuned impedance (resistance) at the wi fi frequencies but appears as a short when using a multimeter. I'll confirm tomorrow when at work.

[werejag]

testing all 3 antenas they all are shorted together. ( i didnt unscrew them if that matters)

poshgeordie if you can make a guide how they are suppose to be ROUTED in the lid and case. i haven't checked the damage yet on these 3 i expect ill have to rip them out and buy all 3 again.

thank you and RealBlackStuff for confirming what i kind of expected but never saw before

[poshgeordie]

Should have said this earlier - Welcome to the forums!

I'll get back to you later today with the actual construction of the antennae - ie if there is a short circuit at the aerials.

Regarding a how to - I'm just too busy to do one but the HMM is very clear in how the cables are routed so one is not really needed. If you look at the picture I suggested on the T4x screws doc, it tells the whole picture in how not to route the leads "over" the lcd connector. They should go UNDER and the rest is as per the picture.

Other clues on cable damage:

1. Is there any cable damage at the join between the end of the cable and the tiny connectors onto the cards?

2. Are any of the cables damaged / look squashed? Look around the lcd connector and LH hinge assembly.

Either of the above would indicate possible cable shorting.

[Bibin]

If you tested the antennas without unplugging them... aren't you testing the outer shielding, which should be common across all three?

[werejag]

all antenas were unpluged . i tested the metal connectors to each other. im supose to test the plastic sheilds?

[werejag]

took entire laptop apart and found one (gray colored) of the 3 cables squashed at the lcd henge. is this the cuase of my problem?

if so.... i cant fix this and should purchase new antennas?

[RealBlackStuff]

Gray is the MAIN antenna, black is AUX.
Connect only the black antenna wire to your wifi card (try both MAIN and AUX).
If wifi now works (but at lower capacity because 1 antenna is missing), then you found the culprit.
You'll have to take the LCD lid apart to replace the antenna wire.

[poshgeordie]

Visually checked the spare aerials we have in stock, and also did a continuity test on them using a multimeter set to ohms, and the aerial measures a short circuit. The construction also confirms this. The only checks you can do therefore are going to be visual to see if there's any damage to the cables or miniature coaxial connectors which fit onto the cards.