Tach not working
in General Tech Discussion
6 years ago
Hellow Rotax lovers!
Got an issue that have me buffle. I got a 912UL older type engine with the fixed coil type (no Adjustment), I had issues with my tach readings to the point that my UMA Tach stop working. I did an OHMs check on my RPM wires coming from the pick coil and got a reading of 126 ohms. Thinking that was a bad thach, got another Uma tach, and set it as instruction. (Cables from Uma Tach) Red wire to 12 volts, white cable to one cable from the rpm pick coil, Black cable to the other cable from the rpm pick coil plus connected to plane frame ground and the yellow I do not have use for it. After cranking the engine, the needle move from dead center at 6 oclock (normal point of needle when off) to the 0 cero mark on the tach. The needle moves but not the reading I want to see. I called Uma support and told me to check all wires connections (Idid 4 times just to be sure its ok) and also to check ac voltage from the RPM pick coil unit. This are the readings: engine running aprox, 1600rpm 0.011 volts ac, then around or above 2500 rpms was 0.034 volts ac but still not tach reading as expected. Then I called Lockwood aviation for 912 support and the tech told me to cut the frame ground, That is not needed due engine own ground and now the tach needle do not move, dead at 6 oclock position. With the frame ground at least the neaddle move to 0 rpm position and now is not. The instrucions from uma called for an extra external ground connecton to the black conection to the black wire to the uma gauge.
Can some one tell me what is wrong with this. I can fligh my plane with out the tach but prefer it working.
Thanks to all and any info is xtremely appreciated. See athachments please!
Pastor Luis -Rans S6
Got an issue that have me buffle. I got a 912UL older type engine with the fixed coil type (no Adjustment), I had issues with my tach readings to the point that my UMA Tach stop working. I did an OHMs check on my RPM wires coming from the pick coil and got a reading of 126 ohms. Thinking that was a bad thach, got another Uma tach, and set it as instruction. (Cables from Uma Tach) Red wire to 12 volts, white cable to one cable from the rpm pick coil, Black cable to the other cable from the rpm pick coil plus connected to plane frame ground and the yellow I do not have use for it. After cranking the engine, the needle move from dead center at 6 oclock (normal point of needle when off) to the 0 cero mark on the tach. The needle moves but not the reading I want to see. I called Uma support and told me to check all wires connections (Idid 4 times just to be sure its ok) and also to check ac voltage from the RPM pick coil unit. This are the readings: engine running aprox, 1600rpm 0.011 volts ac, then around or above 2500 rpms was 0.034 volts ac but still not tach reading as expected. Then I called Lockwood aviation for 912 support and the tech told me to cut the frame ground, That is not needed due engine own ground and now the tach needle do not move, dead at 6 oclock position. With the frame ground at least the neaddle move to 0 rpm position and now is not. The instrucions from uma called for an extra external ground connecton to the black conection to the black wire to the uma gauge.
Can some one tell me what is wrong with this. I can fligh my plane with out the tach but prefer it working.
Thanks to all and any info is xtremely appreciated. See athachments please!
Pastor Luis -Rans S6
m_UmaTach.jpg (You do not have access to download this file.)
m_Umasetinstructions.jpg (You do not have access to download this file.)
