Rev Counter Mystery

[Jon Green]

Hi Guys,

 

Anyone got any ideas? I have a VDO rev counter that works fine when stationary but when im driving it reads very high. The needle still goes up and down with the revs but off the scale when the engines doing about 5-6k. Its as if its picking up pulses from somewhere else aswel as the coil connection.

 

I've checked i've got all the connections right and tight so im at a bit of a loss.!!

 

Any wacky theories appreciated!

[Longboarder]

Had a similar problem with my VDO rev counter picking up false signals and lying to me. VDO said fit a 1n4001 diode in line (in series) between the coil neg and the rev counter. Its a piddly little thing from Maplins and costs pennies but it works. Can't remember which way round it goes but if you solder it in and it doesn't work just unsolder and turn it round.

 

Nigel

[Jon Green]

Cheers Nigel,

 

nice to know im not the only one!

 

Jon

[Jon Green]

Hi Nigel,

 

I've purchased the said component from maplin and installed it (the wrong way round first) and all seems fine almost. The rev counter has stopped its wild behavour and now responds predictably but i think its reading low now.

 

Did you use the calabration srew poteniometer thingy on the back of the gauge or was yours a true reading?

 

Cheers

 

Jon.

[Longboarder]

Didn't find the screw calibration. Just fitted the diode, the readings stabilised and sound about right by ear so just said whoopee and left it.

 

Nigel