The VOLVO PENTA Tachometer and Tach-Hourmeters are a common marine fitment, finding their way onto many vessels, in single and dual engine configurations.

The Units were made by VDO and use similar internals to the VISION Range of automotive instruments.

The marine units have a corrosion barrier lacquer applied to the printed circuit board and most units are double glazed with two plastic lenses and double seals to prevent ingress of water or condensation on the cold outer lens. 

Some of the VDO Sumlog units also share the same internals and construction.

Unlike their automotive counterparts the marine units suffer from more extreme environmental conditions with a greater dependence on the information that they provide. The LCD screen is often exposed to direct sunlight and temperatures can soar inside the plastic case, This puts the other electronic components under duress, especially if it’s followed by a sudden drop in temperature as night falls.

Another common failure is the memory where calibration and hours data is stored. A memory failure can cause dashes to appear on screen in place of the hours and the pointer will sometimes step up and down the dial scale or in the case of corrupted data, will display the incorrect hours or will exhibit some shift in the accuracy of its RPM readings.   

The signal that drives these units is often taken from the ‘W’ terminal of the alternator, however some configurations use an inductive or variable reluctance sensor reading the teeth of the starter ring. In both cases it is worth confirming continuity of the wiring before condemning the unit as faulty, especially if the unit is only unresponsive to RPM.

Ryan Linley Restoration is able to fully repair your Penta and Sumlog units, We can often recover lost hours data using our purpose made equipment and can program your unit to display the required hours or zero. The calibration is reprogrammed as factory and full setup instructions are supplied. 

We renew all common failure components including the memory and offer a rapid turnaround service.