Tacho wiring?

[burgundyben]

My old Perkins had a generator for the tacho with a pair of wires going to the tacho.

My new engines have a tacho signal wire coming off the alternator, I connected this to one tacho contact and the other tacho contact to ground.

No dice.

Its a VDO tacho. There's just 2 terminals on the tacho.

One of them shoots right round to FSD, the other doesn't move.

Thoughts?

 

[aquapower]

My old Perkins had a generator for the tacho with a pair of wires going to the tacho.

My new engines have a tacho signal wire coming off the alternator, I connected this to one tacho contact and the other tacho contact to ground.

No dice.

Its a VDO tacho. There's just 2 terminals on the tacho.

One of them shoots right round to FSD, the other doesn't move.

Thoughts?

The 2 wire tacho is for generator only, the alternator driven one has neg, pos and signal connections,

 

[superheat6k]

I think the tacho you require is a simply a pulse counter but it needs to match the mode of pulse generation to read correctly - e.g. pulse counter on a gear spur, as on my VP TAMD60C or pulses from the alternator, which are subject also to the pulley ratio. Sounds like your old set up actually produced a voltage proportional to the engine speed instead of pulses.

Suggest you ask the same question on the PBO forum, but I think you may require new tachos to match your alternators speed ratio to the engine.

If you want to pop round (NB will be out tonight) I have a couple of old tachos in my junk drawer you are welcome to try. Favour owed anyway for recent loan of your puller.

 

[burgundyben]

Ok, so when you buy one of these alternator sensing tacho's do you get to specify the pulley ratio?

I'll make some calls tomorrow mornign to Lancing/Furneax/ASAP etc.

 

[superheat6k]

Ok, so when you buy one of these alternator sensing tacho's do you get to specify the pulley ratio?

I'll make some calls tomorrow mornign to Lancing/Furneax/ASAP etc.

In a way I suppose - at some point, someone, somewhere decided how to answer that question for any individual boat / engine set up, but as a boat buyer not sure how far down the list of priorities the mode of tacho data feed figures. Fairly low on my list I must confess, but then most of us never change our engines no matter how much we bitch about them !

 

[burgundyben]

Just been reading the Furneaux Riddal website, they do a Wemo one that has a calibrate feature, you just check with a hand held and set accordingly.

 

[aquapower]

Ok, so when you buy one of these alternator sensing tacho's do you get to specify the pulley ratio?

I'll make some calls tomorrow mornign to Lancing/Furneax/ASAP etc.

Here's link to VDO manual, page 7 shows how to set up.

http://www.vdo.com/generator/www/co...chometer_drehzahlmesser_uv.pdf?redirect=false