How to: Fix your Red Key Button - Alfa Romeo Forum
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How to: Fix your Red Key Button

Hi all, Got fed up with locking my Bella manually, so I've decided to fix my key remote lock after 5 years of locking her with my key, (yes i did type 5 years)

The problem i have with both my main and spare Red Alfa key is the micro switch mounted to the keys PCB, the defected switch isn't a simple push button, but more of a squeeze type switch which depends on the black rubber to compress the micro switch (push inwards towards PCB).

Tools you'll need:

2 or 1 (depends on how many keys) momentary micro switches, i bought mine off eBay for little cost.

A GOOD soldering iron, with a clean small tip, (Hint: use a Brillo pad to clean a hot soldering iron)

A Pair of metal tweezers (they have to be metal to withstand the Irons heat)

I also used a reel of copper braid to 'soak up' the existing solder to detach old switch, but you can use a bare stranded stripped piece of wire (as long as something metallic can 'soak up' the old solder) you'll need to apply the braid over the old solder then the Iron on top.

Helping Hands

Old toothbrush + Isopropyl Alcohol Or switch contact cleaner (a chemical cleaner that can evaporate and leave no residue)

Prior to Step 1, disassemble your key by twisting a 1p coin in the front of the key between the join

Step 1: I used a PCB clamp called 'Helping hands' with a magnifying glass to hold the keys PCB in the crocodile clips (you can buy this online or at a good DIY shop for 5).

Step 2: with the soldering iron HOT, i got the copper braid, laid the braid over the micro switch solder joints and then placed the flat end of the iron on top to transfer the old solder on the PCB to the copper braid. Do this both sides, but don't let the PCB get too hot or you'll melt the existing switch as the body is plastic, and you'll make a mess, and a nasty smell.

Step 3: with your metal tweezers in one hand, and the iron in the other, heat the joint up whilst sliding the tweezers underneath to break the join, repeat this on the other side and the switch will come free.

Step 4: You'll now need to clean up the surface of the PCB where the old switch was with the copper braid, follow same procedure to transfer old solder to copper braid.

Step 5: with the new switch upside down, (the side that is flat against the tabs on the end) apply a teeny tiny amount of solder to the tab, (apply heat to tab with iron, induce solder, then pull both the iron and solder away quickly and at the same time)

Step 6: Now, this is important to getting the switch as flat as possible to the PCB. The side that you applied the solder to on the switch, apply the same amount of solder to the PCB join, corresponding to that same side as that on the switch. Pick up the switch with the tweezers (correct mounting side up) and place the switch on top of the PCB join. With the Iron in the other hand, press the iron to the join that is 'tinned' with solder to 'tack' that side of the switch to the PCB. If you've put just the right amount of solder on, it should be tidy.

Step 7: Apply heat first + solder to the 'Dry' join side, (tiny amount of solder)

Step 8: with some electrical contact cleaner and an old tooth brush, clean the solder joins to remove the flux residue (apply the contact cleaner to the brush, not direct to PCB) Let the cleaner dry/ evaporate and your done!

Step 9: Re-assemble your key, and try her out!

Last edited by Chris_gta; 28-08-13 at 17:48.
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Great guide! Do you by any chance have the measures of the switches?
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Originally Posted by redtop_68 View Post
Great guide! Do you by any chance have the measures of the switches?
I think these are what you seek

3 Micro Switch for Alfa Romeo Remote Key Fob | eBay
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Originally Posted by pendragonfalls View Post
No, those are for the folding blade FOB, measures 3x6x2.5mm and have the push button from above. The ones for the red key have the push button from the side. They are also all over Ebay, but I like to source them elsewhere and therefore I need the measures since I don't have a red key FOB in front of me to be able to measure myself.

There seems to be two different kind of circuit boards with different switches in the red key FOB:
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Last edited by redtop_68; 26-03-13 at 14:01.
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I have about 10 spare red keys.. so i might try and butcher one of them for the switch.. but not only am i manually opening my 156 atm.. but i can only do so from passengers side lol

Thanks for the guide but might be an idea to include all stages, including opening the key apart.. thats first hurdle im a bit worried about - so gonna try it on a spare first
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