Volvo Penta Rev & Hours Counter

[Vulcan]

I have a Volvo Penta combined Rev Counter and Hours Meter. The Rev Counter is an analogue display and the hours meter a digital display. Part No is VP 873660. 4 terminals on the back for S+, S-, +, and -. The hours meter was intermittant. Does anybody know if the hours meter works off just the +12V and 0V terminals or does it need the S+ & S- as well.

 

[alan]

I'm pretty sure that the S+ and S- are the connections from the alternator for the rev counter. The hour meter shopuld just need the + and - .

If you want I will check the circuit tomorrow in my hand book (unless someone else replies first).

Alan.
Nettuno, Italy.

 

[Robin]

Is your question related to losing the display of engine hours from time to time or to actually failing to record the hours? Volvo Rev counter displays are notorious for not liking cold and damp, the Engine Hours are still counted and stored in memory but the display fades away. If that is the case with yours, then remove the unit and dry it in front of a fan heater or put in the airing cupboard, either will get it going (until it gets damp again) and it will display the correct hours run.

 

[Vulcan]

Thanks Alan, I already have the circuit. Thanks Robin, exactly as you describe! I will try drying it out and see if the display comes back.

 

[Robin]

We had one on our last boat a W33 we put an MD22L into. I used to set the rev counter in front of the on board fan heater for maybe 30 minutes, turning occasionally at Gas Mk3 (sorry 1KW setting). Usually it would be a bit flickery at first then settle down after 5 minutes or so and read OK.

 

[Vulcan]

Excellent, thank you! Dried it out overnight and now works OK. I wonder how many new units get sold each year because of this.

 

[bonny]

I had the same problem with mine (MD2030) 2000. The hour display started to fade, dissapear re-appear and then went completely after about 3.5 years. The hours do keep counting as previously stated.

Phoned Volvo to price a new unit, somewhere around £270, can't rememer if that's plus VAT (does it matter). The Volvo guy admitted that this is a common problem and that it's caused by damp. he advised me to dry it out in an airing cupboard for a month or so. It worked.

I used to be a component approvals engineer and we used to perform damp heat testing on electronic components. This was normally performed at 85 deg C, 85% RH (Relative Humidity) to force moisture through the plastic (which is porous) and aggravate corrosion. At 30-40 deg C in an airing cupboard it will take many weeks to dry out fully, the higher the temp the better but don't go above 70 deg C. Some of the components will have a max storage temp of 80 deg C.