S1 Smiths tachometer problem
Posted: Tue Mar 11, 2008 4:25 pm
Hi all
I wonder if there are any electronic wizards out there that could offer a clue to the tachometer problem on my S1:
If the weather is cold, below about 25 degrees (F), when I turn on the ignition, the tachometer slams around to full pin. If I warm the tach up a bit with an electric heater before energizing it, it works fine. If the ambient temperature is above 25 to 30 degrees it works fine.
Looking at a circuit schematic that I obtained from the forum I see two transistors, one of which is in a position to apply full voltage to the meter if it is turned on. There is also a capacitor which, if shorted, will turn this transistor on. Can anyone tell me if capacitors or transistors get to be temperature sensitive in their old age? Might this problem be due to something else?
I wonder if there are any electronic wizards out there that could offer a clue to the tachometer problem on my S1:
If the weather is cold, below about 25 degrees (F), when I turn on the ignition, the tachometer slams around to full pin. If I warm the tach up a bit with an electric heater before energizing it, it works fine. If the ambient temperature is above 25 to 30 degrees it works fine.
Looking at a circuit schematic that I obtained from the forum I see two transistors, one of which is in a position to apply full voltage to the meter if it is turned on. There is also a capacitor which, if shorted, will turn this transistor on. Can anyone tell me if capacitors or transistors get to be temperature sensitive in their old age? Might this problem be due to something else?