[miso25]

Thanks man. Obviously I have to open the card but good to know that is 2 options and the card can be repaired. I'm planning to open it these days with my father in law because he is a sort of electrician guy and got better view then men. I'll use your pictures for opening the card if you don't mind. When I have a result I'll post it here. Keep fingers cross to end everything well.

 

[miso25]

tomalamix,
I open the card and have this:
the coil = 94om; checked the battery connections = they look fine.To be sure I will re-solder them. Any other suggestion where I may have problem????

 

[2beers]

Hi. Having the "insert card"-issue, I am really glad to find this thread - thank you very much for the good work!

I opened my card but and can see that the coil needs to be re-soldered.
Unfortunately I accidentally cut the wire of the coil into seven different-sized pieces...
So I had to unwind the wire and are my results:
turns: 353
length: 15769 mm

With this length and the given resistance of 94Ω, I calculated the wire cross-section.

R = ρ· l / A
<=> A = ρ· l / R

ρ = 0.01678 Ω · mm²/m (specific electrical resistance of copper)
l = 15.769 m

A = (0.01678  Ω · mm²/m) · (15.769 m / 94 Ω)
<=> A = 0.00281493425531914893617021276596 mm²

The wire cross-section leads me to the diameter.

A = π · d² / 4
<=> d² = 4 · A / π
<=> d = sqrt(4 · A / π)

d = sqrt(4 · 0.00281493425531914893617021276596 mm²/ π)
<=> d = 0.05986723318896545927493082691573 mm

First I thought, this would be way too small, but the german wikipedia writes, a human hair's diamater is between 0.05mm and 0.07mm and I think this is a good comparison.
Here I found some 0.06mm solderable enamelled copper wire (sorry for another german website).

Now I'm going to order this wire and will try to rewind the coil.
Any suggestions, if I am on the right way to a working card?

Greetings from Cologne
2beers

 

[2beers]

After about 30 minutes rewinding the coil I have got the same problem as miso25.
The card is working if i put it into the slot, but that is not what I call "keyless entry and drive".
In fact it is a much better behaviour than before and I do have two more or less working cards.

My coil now has a resistance of 102,3 Ω - maybe I did not count all the turns I made...

I could try to unwind the coil in 5-turn steps, to come closer to 94 Ω.

Good idea? Bad idea? Any other ideas?

btw: my brain went to bed after about 200 turns and I am going to follow now...:yawn:

 

[2beers]

94.5 Ω and nothing changed... !@#$%^&*

 

[tomalamix]

94.5 Ω and nothing changed... !@#$%^&*

check with the multimeter the voltage that the coil produces when you put the card on the keycard slot. if it produces the 12v peak then the coil is not the problem...

 

[pitasoft]

My key was giving a not detected fault. I have found the coil is faulty beucase I am reading 56kohms. I am going to rewind it and hope to fix it

Thanks you all guys, I have not found it without your help.

 

[tomalamix]

im glad to help as far as i can. if the wire is cut in one or two points dont worry, just make sure to solder in together again without touching the solder joints each other, this way you will be able to recover the coil.

cheers

 

[MIC3]

Tomalmix,

Thank you very much for starting this thread i have a problem whereby my card does not seem to work at all in the card slot still says insert card will not open or close at all i have now opened my card using your guidance which was spot on where i am unsure, is how to identify what a cold solder is or dry one i have looked at my circuit board based on the areas to look for faults, only areas that seem to have an issue are the right handside of the board where the battery connectors are ,you dont show the connectors in your pics as you have removed the board but there are two solder blobs opposite each other and one rectangle one in the middle the two outer ones have a like limescale around them is this the dry solders you are refering ?

 

[fastevo1]

Just wanted to say a big thumbs up to the user who posted up this thread!!

Was at work today and when I left to go home I had the dreaded "please insert car" After calling the RAC to be told there is a 2 hrs wait I took it upon myself to find a Internet cafe and look up the problem. After finding this thread, buying a stanley knife, and a Soldering Iron from Wilko, I had it apart, re-soldered the two connectors on the coil, and started just before the RAC man turned up!!!!

Thanks again.

Anthony.

 

[pitasoft]

im glad to help as far as i can. if the wire is cut in one or two points dont worry, just make sure to solder in together again without touching the solder joints each other, this way you will be able to recover the coil.

cheers

I have just fixed it. A friend gave me a copper dust, which mixed with a solvent (like acetone) and applied to the coil fixed it. He says it was very common some years ago repairing watches. I am getting now 160 ohms instead of 94, but it works great.

Thank you so much for this thread and hope my little contribution helps.

 

[rickg]

Just found this thread. Well done Tomalamix, everyone on this forum owes you a big thank you.

One of my Laguna keycards has recently stopped opening and locking the doors and resetting the seat etc. When I put the card in the slot the engine starts and everything works fine.

I sent it to Keycard Repairs but it came back with the same fault. I emailed them and they replied that they had done everything they could and have refunded my money.

Do you think I should open the faulty card despite keycard Repairs already having looked at it?

 

[tomalamix]

Just found this thread. Well done Tomalamix, everyone on this forum owes you a big thank you.

One of my Laguna keycards has recently stopped opening and locking the doors and resetting the seat etc. When I put the card in the slot the engine starts and everything works fine.

I sent it to Keycard Repairs but it came back with the same fault. I emailed them and they replied that they had done everything they could and have refunded my money.

Do you think I should open the faulty card despite keycard Repairs already having looked at it?

If you have a 2nd keycard working flawlessly and are whiling to try out to repair it your self it wouldn't be a problem, but keep in mind there is no 100% warranty that the card can be repaired or you can damage further more if you dont do it carefully (the card will not start up the car anymore)

Despite this its your choice, i may onlytry to help you on the readings and the possible ways to fix.

cheers

 

[REDD]

Thanks to Tomalamix for the first post... managed to rip my card apart lastnight because the central locking stopped working. (Also have the 'Replace Card Battery' message)
My problem is different to the usual problems tho... it's one of the tiny resistors (or whatever they are) has snapped off !!!
Found it, but can't DIY as the only way to get it soldered is with a pin in the end of my soldering iron and it just won't get hot enough !!! (Even tried heating a pin over a candle flame but that didn't work either)

Anyone got any idea who I can turn to who will be able to solder it back in place (or test and replace the resistor if its knackered) ???
Doing my head in it is !!!
(I thought mobile phone repair shop but just my luck it went into liquidation 2 weeks ago!!!)

 

[spacecadet]

I sliced off a resistor when I did this repair too. Resistors are quite tough and if it doesn't look like toast it's probably OK.
If the ceramic body has actually broken you'll need a replacement. If the metal terminals have merely come off the board, you should be able to solder it back but you'll need a fine bit for the iron. It's a matter of practice but you need to press the terminal gently onto the contact on the board with the iron whilst applying a bit of solder if required.

 

[SCOLEYTE]

Hi Tolamix.
Many Many thanks for the brilliant post. I followed it precisely and got my key card working, now it will let me start the car. You are a bloody genious!!!!
One other thing and I'm wondering if you can help me out. The card will not operate the doors. When I opened the card it has some components missing which I assume I have either disturbed during disassembly although there were no sign of the components or have dried joints and come adrift after 7 years. I need to identify what they are and their values. There are 4 components surrounding the chip that control the rf sig. if I take a picture of the board can you help with identification and values? Cheers Many thanks steve

 

[SCOLEYTE]

If any-one has a keycard that is open and can help me identify 4 components surrounding the RF chip for the central locking I would be most grateful . In doing this repair with the aid of Tomalamix posts I will give a bill of of materials for all parts in the card and an indepth write up on how the card works. Just to give an heads up the card has two completely different functions electronically speaking. The coil that gives the most trouble has been designed to be the secondary winding of a transformer. When it is inserted into the card reader it provides power to the ID chip which then sends out its code. This is why if you remove the battery a good card will still be recognised by the reader but will not operate the central locking. I intend to add value to Tomalamix's excellent posts and get this card key issue sorted. Enough of the rip-off. Steve

 

[RobinSt]

I stumbled upon this thread when I was searching for some more technical information about the megane keycard (not that mine is broken, but just out of technical curiousity). I own a megane II since yesterday.

And I must say that Tomalamix has done a tremendous job with his analysis of the keycard , with very little resources and information.

I have studied the photos that Tomalamix took, and tried to make some sense out of them.

Since information is extreemly scarce I decided to share my findings and hope they are helpfull.
Judging from the photos and my electronic engineering background and my experiences with RFID/mifare design, I think that the keycard works in the following way (but could also be wrong):

The normal (not handsfree keycard):
On the top there is a inductor coil, that powers/communicates with the PCF.. chip (mid bottom), when inserted in the dash. On the bot right there is RF transmitter chip.

Datasheets on the chips are unobtainable since NXP shields them (security by obscurity). The PCF.. chip seems to be a custom chip designed for keyfob use for the automotive industrie. Looking at the circuit board it appears to have RFID like interface (with the large coil) for programming and start operation, key inputs and a code output for the 433 MHz transmitter chip.
If I am right about the RFID interface on the card, then this it explains why the coil is such a pain in the behind.
A RFID interface provides power to the circuit, through an RF field but also uses this same RF field to communicate (using load modulation).
For this to work the impendance (AC resistance) of the entire circuit needs to be exactly right. If its off then this will directly effect the power supplied to the card, and the quality of the data transmitted to and from the card.
Unfortunately impendance can not be measured using a normal multi meter, and requires special equipement.
The way the coil is (re-)wound is also something of great influence, even more than the wire diameter.

Before its gets to technical, I will stop for now.
I will look at the photo's and try to identify as much of the components I can. And I will post it in this thread.

Robin

 

[RobinSt]

As promised here by my view of the components (see image).
The resistor values can be read from the components. The tolerances are 5% (3 digit code) the first 2 digits represent the value, the 3rd the exponent. fi: 103 = 10 * 10E3 = 10k (10000) ohm 472 = 47 * 10E2 = 4k7 (4700) ohm

The capacitors can not be identified that easily, the only way to identify the values is to solder them out the circuit and measure it with a capacitance meter.
Unfortunately the value is only part of the solution, and voltage and materiaal are also very important.

The 2 parts marked with ? can be one of very many things.
The 6 pin version could be a switching voltage regulator as it has some R L and C's connected. But it could also be a microprocessor.
The 3 pin version could be a diode (matches with the regulator idea) or a FET.

This is the best I can do from a photo, and without any datasheets. Hope its usefull.

Robin

 

[RobinSt]

When searching the internet for some other info, I stumbelt upon a megane II service manual. (http://janit.iki.fi/****/megane/MR364MEGANE8.pdf) Section 82A contains some information about the card and immobiliser system.
According to this manual, the car has a 125khz RFID cardreader in the dash that powers and validates the card when starting the car. And the keycard has a keyfob that operates on 433 or 315 Mhz (depending on the country) using a hoppingcode.

Note: The link is not working due to a profanity filter.
the **** should be sh*t (fill in the *...:d)