weird problem with rev counter

[Chris G]

I just cannot work this out.
No light in my rev counter, so I changed the bulb. Bulb lights so I put it back in the rev counter. I can see light behind the panel in the head. So far so good. Look at my instruments and light in them all...except rev counter. Look again behind the panel and there is light in the bulb...but the light does not come through to the face of the rev counter. Rev counter works fine...just no light.
Swapped bulb and bulb holder with fuel gauge and I get light in the fuel gauge but still no light in the rev counter. So I have eliminated all possible options, right?
As I said, the rev counter works fine. Can there be something stopping the light coming through? Something melted or fallen out of place?
I have the original Volvo Penta MD17 and gauges.

Any suggestions or is it time for the Exorcist

[WillieC]

Bee’s nest in socket? Oh the fun we have with these old boats!

[DCatSea]

If all else fails you might remove the rev counter and hit it with a shot from a compressed gas aerosol of the kind used for cleaning computer keyboards.
That said, I like the suggestions of either bees or spiritual intervention. Worst case scenario - SPIDERS.

[DesertAlbin736]

Worst case scenario - SPIDERS.

...or Gremlins


By 'rev counter' I assume we're talking about "tachometer', or 'tach' for short? Questions: a) what make of engine & instrument panel are we dealing with here, b) is this an analog pointer style meter or digital LED or LCD, and c) when it did work if ever where did the light shine, through the face of the meter or around the edges? Most Albins have or came with Volvos, so each panel is a little different depending on what engine you have.

Our Yanmar panel looks like this. It has a little toggle switch below the row of warning (aka "idiot") lights, above the starter button, & between the ignition key & warning buzzer speaker. When the light is on, and in this case the only gauge there is to light up is the tachometer, it shines around the edges. If bulb and switch are working then the cause of the problem must be dirt or debris inside the tach that's blocking the light. The only other thing I could thing of is a grounding issue where the bulb socket plugs into the back of the rev counter. Does it make any difference whether the ignition key is switched '"On" or "Off"?

yanmar panel.jpg

[Chris G]

DesertAlbin:
Thanks for the reply. It is a Volvo Penta md17 from 1976. Tachometer is analog. It worked before. Light from around the edges. Ignition on.
Ny next move is to shine a “pencil” type mini flashlight into the hole that the bulb fits in, thus eliminating or confirming the dirt theory.
The next is to rule out the grounding theory. But I’m thinking that a bad ground is not the problem, as I can see light from the rear, when the bulb and holder are in place.
Will give you an update after my next visit to the boat within the next few days. The boat is on land now for the winter and it is minus 4 degrees C with snow on the way. So I’ve got a few months to solve the problem