Yes.http://classicaquasport.com/smf/index.php?topic=8752.msg85496#msg85496I believe the lamp is listed as a "grain of wheat" type. Google should help you locate the bulb once you have it out.Good luck.
First, let me say that IMHO the LCD screen in your gauge has seen better days.I'm fuzzy on why you prefer not to have the gauge(s) wired to the panel such that under low/no light conditions (running at night) that a single switch would illuminate all your panel gauges (assuming they have that capability). It's your choice of course so we'll move on.Your tach LCD is comprised of a pc board with electronic gizmos with an LCD screen mounted on top. The screen is sandwiched between two sheets of polarized film material with the back sheet covered with a reflective film. When energized it looks like this.http://classicaquasport.com/smf/index.php?topic=8752.msg81923#msg81923There was no "back light/display light" on at the time that pic was taken. Under normal lighting conditions during the day (direct sunlight will hamper/fade viewing) the gauge is clearly visible with no aid from the "back light/display light. It is again only intended to be used during low/no light conditions to give the LCD contrast and make it visible. The back/display light is one in the same. There is only one lamp in the gauge.Reading the "manual" you posted, it states that if you wire the blue and yellow together the back light will be illuminated constantly while switched power is being used. That is due to the fact that the yellow wire supplies 12 volt power to the gauge itself. By connecting to the blue, you are now supplying 12v to the back light It also states that if you wire the blue to your Nav. lights, it will again illuminate when they are in use (switched on thus supplying 12v to the lamp). This allows illumination only when needed. You normally run your Nav. lights in a low/no light condition.Illuminating the LCD screen in daylight will not increase the visibility of the screen. That is why I wire the gauge illumination to a panel light switch which allows me to turn on all my gauges both LCD and analog when it gets dark. There is just no need to illuminate the tach during daylight operation. So then why do they have that option? I can only assume it would be used in an instance where the gauge is mounted in a low lit area or the vessel is used only at night. UV radiation breaks down the polarized film sandwiching the LCD display and renders the LCD screen unreadable over time. The yellowing is one sign of UV breakdown (like 3M 5200) but the screen can fail while still appearing "normal". I'm guessing yours is giving up the ghost.Good luck.
The gauge goes through a systems check when first energized, then should display the rpm if the motor has started. Sounds like a dying gauge. Though yellowed, mine still functioned normally.Finding the older gauges (pre 1994) can be frustrating. The 1994 and up are easier to locate. I'm certain that is what Rick used (though his originals were from 1992) and the newer gauge (prior to the current generation) should be what you have for your year motor. rebuilding (replacement of the polarized film) appears to be a stimulating DIY project. Myself, I chose to tract down the old style gauges on eBay to replace mine.Good luck.
