VDO Tachometer

[superheat6k]

One of the original 80mm VDO tachos on Boadicea has been replaced with a smaller 52mm, also VDO.

At Netley Boat Jumble I picked up for a few quid a new in box and unused VDO 80mm tacho, but the connections are different.

The older smaller 52mm tacho has: 1 - no connector; 2 (W to Alternator pickup); + ; -

The newer 80mm tacho has: 1; 2 - no connector; + ; -

I tried connecting it with the alternator feed to terminal 1 but nothing happens.

VDO website simply says terminal 1 is not assigned but this tacho does not have a terminal 2 (or W).

There is also a selector switch, but I assume this is to set the pulse count to match the scaling.

Any ideas, or should I return it next boat jumble ?

Voltages for both are multi 9 - 32v.

 

[rogerthebodger]

One of the original 80mm VDO tachos on Boadicea has been replaced with a smaller 52mm, also VDO.

At Netley Boat Jumble I picked up for a few quid a new in box and unused VDO 80mm tacho, but the connections are different.

The older smaller 52mm tacho has: 1 - no connector; 2 (W to Alternator pickup); + ; -

The newer 80mm tacho has: 1; 2 - no connector; + ; -

I tried connecting it with the alternator feed to terminal 1 but nothing happens.

VDO website simply says terminal 1 is not assigned but this tacho does not have a terminal 2 (or W).

There is also a selector switch, but I assume this is to set the pulse count to match the scaling.

Any ideas, or should I return it next boat jumble ?

Voltages for both are multi 9 - 32v.

I have a 80mm VDO tach in my wheelhouse that is driven by a tachogenerator and does not connect to 12V
power or alternator.

It could be the same type.

Does it have a part number if so I may be able to get you details as VDO have various types and sizes of Tacho's

 

[pvb]

If you put the part number into this page, you can download the instruction sheet giving the correct connections and dip switch settings - https://www.vdo-gauges.com/searchproduct

 

[superheat6k]

If you put the part number into this page, you can download the instruction sheet giving the correct connections and dip switch settings - https://www.vdo-gauges.com/searchproduct

Thanks but I tried that earlier, it just doesn't recognise the VDO number written on the side of the tachos - neither old nor newer. I will check if the box has any other numbers on.

 

[burgundyben]

I have a 80mm VDO tach in my wheelhouse that is driven by a tachogenerator and does not connect to 12V
power or alternator.

It could be the same type.

Does it have a part number if so I may be able to get you details as VDO have various types and sizes of Tacho's

I reckon you might be right. As far as I know a tacho with only 2 wires is for connecting to a minigen.

 

[rogerthebodger]

I reckon you might be right. As far as I know a tacho with only 2 wires is for connecting to a minigen.

It says speedometer but the same setup is also used on a tachometer with the inductive sensor on a pulse gear.