Hi guys,

i've been trying to problem solve my tacho not working for awhile now and tried jumping the yellow/blue to the tach signal on the back of the cluster and also tried a bridge from ign on the board to the 12v on the tacho, i've also re soldered all the joints on the tach but still remains the same.

The tachometer sometimes works properly after the car warms up for 5 minutes or will normally bounce around abit before sitting on redline while at idle or driving. The tacho will also move to roughly 2k revs if i just turn on the key to accessories without starting the car.

Is there something else i can do to fix it or is my tacho gone and needs replacing?

The car is a series 8 fd and ive had the problem ever since owning it.

 

Time to replace your capacitors.

I've had similar issues in the past and replacing the capacitors fixed the issue for me.

 

If you search a little more, there is a wright up on how to fix it.

 

Unless the previous owner pulled the tachometer needle out for whatever reason and f'ed the spindle then as above its most likely the capacitors on the power board of the tachometer.

Usually you can visually see a dodgy capacitor, the silver top part will look swollen/bulgy when it's meant to be flat. Sometimes also from this area they leak a black substance which can be seen.

to replace them you need to remove the tacho board, locate the faulty ones....then desolder them for removal. You should replace them with the exact same rating as they have on them for example 50uF 10v....they will normally have a temperature rating too. Never buy one that goes under this rating....but it's ok to buy one that goes over. The wedge shaped ones you can't really tell so best to just change them to be sure.

also capacitors most of the time are polar specific so make sure you solder them in, in the correct orientation. Some smaller capacitors aren't but make sure you check.