I have a tachometer from a Chevy El Camino or Monte Carlo. When power is applied the needle spins and stops at the 6 o'clock position and will never move.
I'll attach the schematic and explain what I have done so far. I'll also attach the data sheet on the IC.
1. I measured the resistance of both meter coils at 200 ohms each (to common)
2. I replaced the LM1819 with no change in operation
3. I measured all the resistors and diodes
4. Using a signal generator connected to the 'coil' input I see pulses on pin 9, R8-9, and to the top of the .0068 cap. Nothing on pin 5, 6,or 8.
5. I replaced the .0068 cap with no change noted
6. 8.5 volts on pin 11, 13.8 volts on pin 13, and 5.1 volts on pin 1.
7. I forget which, but one coil of the tach meter has 0.0 volts and the other has 10 volts. Common has 5.1 volts.
8. The 1N4007 on the 13.8 volt input gets hot, so does the 20 ohm resistor. I'm guessing tach meter is probably bad?
I'll attach the schematic and explain what I have done so far. I'll also attach the data sheet on the IC.
1. I measured the resistance of both meter coils at 200 ohms each (to common)
2. I replaced the LM1819 with no change in operation
3. I measured all the resistors and diodes
4. Using a signal generator connected to the 'coil' input I see pulses on pin 9, R8-9, and to the top of the .0068 cap. Nothing on pin 5, 6,or 8.
5. I replaced the .0068 cap with no change noted
6. 8.5 volts on pin 11, 13.8 volts on pin 13, and 5.1 volts on pin 1.
7. I forget which, but one coil of the tach meter has 0.0 volts and the other has 10 volts. Common has 5.1 volts.
8. The 1N4007 on the 13.8 volt input gets hot, so does the 20 ohm resistor. I'm guessing tach meter is probably bad?
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