Hi guys, a couple of months ago I posted a topic (that's since been deleted) about my Cartron (Carmate) Digital Tachometer not reading revs correctly, the majority of responses was to first clean up the crappy DIY soldering that was present on the circuit board, it has since been tidied up (original solder joints have been kept) but the problem still persists and now I have a small clip showing the problem.
https://instagram.com/p/5BdgH2FGD9/
In the video it shows the car being revved and held at 2000rpm the tacho reads 1600 but in brief instances flickers to 2000, then the engine is revved to 3000rpm 3-4 times and most of the time the tacho reads 400-800rpm as the car is revving up and when it is losing revs the reading will jump up and read correctly as the revs fall. Anything over 3000rpm will either flicker excessively or more commonly just won't read at all.
So with the description out of the way does anyone have any idea what the issue could be? I have uploaded images of the front and rear of the circuit board in the link below
http://imgur.com/a/ksNBi
Sorry for the excessive use of 'rev' and 'revving' by the way haha