ISSPRO Diesel Tacho calibration

[bsw26]

Hi,

Just discovered this forum whilst Googling for info. on calibrating an ISSPRO tachometer in a narrowbaot I have just bought. Since these appear to have been fitted to all sorts of craft over the years I hope someone can help.

The boat / engine are about 18 years old but the alternator is not the original and it appears that whoever fitted it did not re-calibrate the tacho. so it now reads about 50% fast i.e 1400 rpm shows as 2100 rpm. Obviously knowing that I can manage but it would be nice to have it right.

I cannot find a model number on the guage except for a paper label on the back with 645092 on it. There is also an 8 way DIP switch which I assume is used to calibrate it. Since there are 255 diferent combinations I'd rather not do it by trial and error.

Any thoughts anyone ?

TIA

bsw26

 

[bsw26]

I've found the answer to my question and thought I'd post it here in case anyone else has the same problem.

I tracked down the UK agent for ISSPRO (Technisol) and the chap there (David Morgan) was very heplful and sent me the instructions.

First you need to find the Pulses per Rev (PPR) by doing the following calculation: (Number of Poles on Alternator / 2) X ( Diameter of Crank Pulley / Diameter of Alternator Pulley)

Next convert the whole part of this number to it's Binary format and apply that to the DIP switch.

For example my PPR was 15, in binary this is 1111000 so the first 4 switches are set to on and the last 4 set to off.

Very easy and now the Tacho is spot on.

I would think that other brands of tachometer that have the 8 way DIP switch would operate in the same manner.

Hope someone finds this useful.

bsw

 

[Jegs]

Info re tach.

Useful post & response!

Thank you,

John G

 

[earlybird]

What's the easiest way of determining the number of poles on the alternator?
Are they typically a particular number?
Anyone know?