Hey all..

I have an 87 Volvo 240DL and this is what happened... sometime ago I replaced the large clock in the instrument panel for a large tachometer. This installation worked fine and the tach had been running great until a few days ago that I decided to buy one of those small clocks that connects with the tachometer and install it. The problem is that when i installed the clock, it worked fine but it caused some kind of short in the tachometer and started when I turned on the car, the tach started smoking and it stopped working. The thing is that the tach works if I connect together the black and green wires that go to the clock but when I turn the lights on the tach dies again. Can I fix the tach? I dont understand the circuit but I know voltage isnt getting to the tach and that is why it isnt working and for some reason when I put the black and green cable together they give the tach power. I dismounted the tach and opened it to see if I saw any burned component like a capacitor or a resistor but I dont see anything burned..it does smell burnt though.. how can I fix this? it's as if it wasnt getting power from the instrument panel.

Another fact is that when using a tester with the car on and the lights of..the black and green wire together produce +12Volts (black being positive and green being the negative) but with the lights on the black and green wire are both grounded... the red wire always produces 12V