How To Fix Half Lit Needles

lexusn1ce · March 9, 2010

hi all, i will keep it brief because i only just finished doing my needles and its very late er early.

my rev counter needle was half lit so i took the instruments out to have a look, to cut a long story short the little cathode tubes connect to their power supply by 2 coiled springs ie + and - these also act as dampers for the needles return to 0 (so now you understand a cathode tube must have + and - to illuminate correctly) its pretty clever how the needle can move and have power but anyway back to the problem, providing the springs have not broken your tube should lite right? well you may have noticed earlier that there must be a positive and negative, if you look at a tube it has an anode and cathode now you may be thinking where is it on a needle which has only one end? the answer is one end connects directly to a connector the other end has a coating on the back of the tube running part of its lengh which conducts electricity to the other end and to a connecter out of sight.

now if a tube only lights one end it means the other is not earthed, and what happens here on our tube is the layer of coating lifts and peels with age and no longer conducts to earth resulting in a half lite needle.

The Fix

what i do now is fully dissasemble the cluster so i held just the needle and its workings attached to it (do not try to remove the needle from the shaft) next being incredibly gentle take a sharp stanley and strip of the remaining conductor but not off the very end, next take one fine strand of copper wire and using a pair of tweesers wrap a coil around the end of the needle only 3-4 turns just to hold it (FAIRLY TIGHT)(BUT BE GENTLE OR YOU WILL BREAK THE TUBE) then paint the tip black to stick the wire and the obscure light as it was before, now run the wire down the back of the tube and then feed it round the first connecter (looks like a small clamp around the tube just under the plastic cover, then loop around it a few times to hold the wire then cut of the access, now you could carefully use some thin black paint to act as a light shield like the origional coating did, but do not use tape as it is too heavy and your gauge will read wrong.

now if you combine this fix with the post already around detailing which capacitors to change (for delay in lighting fault) you can now completely mend your display, this needle repair makes the needle fully lite and is not noticable if done carefully it is not a bodge you are just replacing the worn out conductor with a new tiny wire which is ran out of sight down the back, be warned if you are going to try this take care and be very gentle with the parts as they can be broken so easily, you may find that even the ones that fully light are starting to peel but unless you want to a would only do the ones that do not for fear of breaking somthing by chance.

well i hope this helps some of you that are good with this stuff to fix yours i know theres a guy who fixes these but its so simple just time consuming :D

SteveLS400 · March 9, 2010

Hi

Sounds like you have put a lot of effort in so thanks for posting.

ROYT · March 9, 2010

Interesting post!..where you used fine wire, would it work using conductive paint instead

as supplied to repair heated rear windows?

lexusn1ce · March 9, 2010

Interesting post!..where you used fine wire, would it work using conductive paint instead
as supplied to repair heated rear windows?

i would say its quite possible i just used what i had to hand but yeah anything that carrys electricity and is light enough should work, i guess even silver foil but it reflects so would show up on the dial face.

im sure there has been a better method as i cant see those that charge doing it the way i did it takes ages and is ever so fiddly.