Monster tach trouble shooting
Thread Starter
Joined: Jun 2005
Posts: 5,221
Likes: 1
From: Skiatook, OK
Monster tach trouble shooting Ok, so I picked up a used 5" autometer Autogauge tach from a friend. I got it all wired up & reading properly. So I know I have a solid power, ground & tach signal.
Now on to illumination. This is where I'm trouble shooting. I ran the wire down & piggy backed off my HVAC lighting which is also piggy backed to my Humount. All the illumination for the Humount & HVAC controls works perfect. So I know it's a good source.
This tach has "around the dial" lighting instead of "thru the dial" so there is a little bulb holder on the face of the tach. I have pulled this out & checked the bulb. filament is good still. Tried flipping the bulb around, tried flipping the bulb holder around & tried a LED bulb. Nothing has worked. I cannot get this thing to illuminate at all.
Has anyone else running one of these had this problem. I already did a search & everyone with issues had it hooked up wrong from the beginning. But this doesn't seem to be the case on my install. I'm wondering if something in the socket itself is messed up. I see there is 2 tiny screws on the face holding the little black piece on that houses the **** to set the shift light & the bulb for illumination. I was thinking about removing it to see if the wires are all still ok goin to the bulb socket.
I'm open to any idea anyone might have or info if anyone has had this same issue. I'm very happy with the tach during the day but I want it to illuminate at night so I can read the damn thing. I can definetly vouch the stock tach is way off on a solid H/C car now.
Now on to illumination. This is where I'm trouble shooting. I ran the wire down & piggy backed off my HVAC lighting which is also piggy backed to my Humount. All the illumination for the Humount & HVAC controls works perfect. So I know it's a good source.
This tach has "around the dial" lighting instead of "thru the dial" so there is a little bulb holder on the face of the tach. I have pulled this out & checked the bulb. filament is good still. Tried flipping the bulb around, tried flipping the bulb holder around & tried a LED bulb. Nothing has worked. I cannot get this thing to illuminate at all.
Has anyone else running one of these had this problem. I already did a search & everyone with issues had it hooked up wrong from the beginning. But this doesn't seem to be the case on my install. I'm wondering if something in the socket itself is messed up. I see there is 2 tiny screws on the face holding the little black piece on that houses the **** to set the shift light & the bulb for illumination. I was thinking about removing it to see if the wires are all still ok goin to the bulb socket.
I'm open to any idea anyone might have or info if anyone has had this same issue. I'm very happy with the tach during the day but I want it to illuminate at night so I can read the damn thing. I can definetly vouch the stock tach is way off on a solid H/C car now.
The HVAC signal you have may be a pulse width type that needs to drive a buffer interface for your bulb.
There are chips that take care of this:
http://www.scribd.com/doc/24073/7407
Depending on how much current the lamp requires, a transistor buffer may be required. (Very simple)
There are chips that take care of this:
http://www.scribd.com/doc/24073/7407
Depending on how much current the lamp requires, a transistor buffer may be required. (Very simple)
Joined: Nov 2003
Posts: 11,330
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
No, the HVAC illumination is just a pair of #74 bulbs wired to power and ground. The dimming is controlled by a simple rheostat. There is no pulse width modulation.
http://offroaders.com/tech/Autogage-Tachometer.htm
Then he should be able to hook up the illumination wire to +12 and the thing should light up.
Or run a small bulb from the spliced HVAC illumination wire and see if it is lightable and dimable.
One is funky.
Then he should be able to hook up the illumination wire to +12 and the thing should light up.
Or run a small bulb from the spliced HVAC illumination wire and see if it is lightable and dimable.
One is funky.
Thread Starter
Joined: Jun 2005
Posts: 5,221
Likes: 1
From: Skiatook, OK
Well the HVAC should be a 12v source. It worked fine for splicing in my Humount illumination. And whats got me is that the HVAC & Humount still illuminate just fine. But the tach doesn't at all. I don't even use the dimmer b/c I have all LEd interior & they don't dim. They are either on or off.
I'm gonna try splicing the illumination into the power for the tach just to see if it'll light up with straight power source. If it doesn't then I know something is wrong inside the tach.
I'm gonna try splicing the illumination into the power for the tach just to see if it'll light up with straight power source. If it doesn't then I know something is wrong inside the tach.
