where do i get a replacement rev counter/tachometer

[scottessery]

hi

 

my lister petter rev counter/tachometer has stopped working

 

i cant see how to get it apart so thought it easier to get a like 4 like replacement

 

can i find one anywhere... can i boot!

 

could anyone help or suggest anything i can do

 

many thanks

 

scott

[OldGoldy]

hi

 

my lister petter rev counter/tachometer has stopped working

 

i cant see how to get it apart so thought it easier to get a like 4 like replacement

 

can i find one anywhere... can i boot!

 

could anyone help or suggest anything i can do

 

many thanks

 

scott

 

Question has to be asked, before you accuse the tacho of being faulty.....IS it the tacho or is it the wiring/sensor?

 

............'devil's advocate' and all that!

[scottessery]

Question has to be asked, before you accuse the tacho of being faulty.....IS it the tacho or is it the wiring/sensor?

 

............'devil's advocate' and all that!

 

 

how can i tell / test it dave?

 

there is only one wire leading from the back to the altinator

[Tony Brooks]

how can i tell / test it dave?

 

there is only one wire leading from the back to the altinator

 

 

Which means it could be a diode faulty in the alternator!

 

Pull the wire off the alternator and set a multimeter to Hz or 20 Volts. Either should go up and down with engine revs but the Hz one should be more pronounced. The volt one will only rise to a certain level, but it should end up with several volts. mV is no good.

 

(From Sir N - thanks) connect the DC voltmeter between the main output terminal and the warning lamp terminal. Start and rev the engine. If the meter reads 1 volt or more with the engine reeving the alternator is faulty.

 

You should also do a maximum output check and regulated voltage check to be sure, but they are more complicated. At least make sure the alternator is delivering 14 volts or above after a good cruise.

 

If the alternator tests OK I would do a continuity check on the cable between the alternator and rev-counter - beep test if the meter has that facility.

 

Then stick a test lamp between the rev-counter's + and - terminal. With the ignition on it should light with normal brilliance. Using a bulb saves confusion caused by voltdrop that will not show up when using a meter.

 

Only then condemn the rev-counter.

 

First port of call for a new one - Marine Engine Services or Uxbridge.

[alan_fincher]

If it's one that is triggered by pulses from an alternator "W" terminal, as your last post implies, then any tacho of that type with a suitable maximum revs should be a good replacement.

 

Someone like ASAP supplies do loads, so you should be able to find a style that reasonably matches other instrumentation you have.

 

Generally these things need to be calibrated to give the correct RPM reading, and I suspect that might still be true even if you sourced an identical item to the one you are replacing.

 

If you are intent on a Lister Petter one, I assume you have talked to the usual suspects for Lister help ? "Baldock" on thius forum is a very obvious starting point, if you have not.

[n.b.Goldie]

hi

 

my lister petter rev counter/tachometer has stopped working

 

i cant see how to get it apart so thought it easier to get a like 4 like replacement

 

can i find one anywhere... can i boot!

 

could anyone help or suggest anything i can do

 

many thanks

 

scott

There is a 'multiplug' on the back of the alternator, you might well find that the smaller of the three spade connectors within it has become loose. This will affect the tachometer. Try to 'tighten' it if it seems loose, you could find your 'dud tacho starts working again just as mine (same engine) did.

 

I think the multiplug gets quite hot during use and the spade connectors loosen off so to speak. The two large spade connections carry the current and when the connections are 'iffy' is i think the heat source.

 

I took the two thick wires from the multiplug and re-connected them to the b+ terminal leaving only the small wire connected. The heat problem went away and the tacho now works great.

 

Talk it over first with Baldock or Peter Thompson of Marine Engine Services if you are unsure that your system is the same as mine.

 

All the best

 

Ditchdabbler