Greg_D Posted February 16, 2017 Report Share Posted February 16, 2017 I decided to do a complete overhaul on my magnetos. After putting them back on the engine everything tested great, with the exception that the tachometer is not working now. I hope it's a broken wire, but decided to look at replacing the hall sensor if I can't find a wiring problem. I almost fell over when I saw how much these things cost. The best price I could find was from Airpower and it is $1291.48. Does anyone know where a less expensive one can be found in case I need a new one? Quote Link to comment Share on other sites More sharing options...
carusoam Posted February 16, 2017 Report Share Posted February 16, 2017 Doing a search around here you should find a few ideas. This topic comes up at least once each year... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
kortopates Posted February 16, 2017 Report Share Posted February 16, 2017 (edited) Good chance it is a broken wire at the connector. But to the un-initiated those sensors are exceedingly delicate and easy to break when removing a mag. If its not a broken wire, given the TCM replacement cost, it sure looks like great incentive to go with a replacement EI RPM meter (depending on your OEM size meter) or put the $ into a JPI EDM 9xx. The EI rpm unit doesn't even use a hall effect sensor, (its wired to your ignition key) and the EDM Hall sensor is ~$400 for replacement the next time it needs replacing. Salvage yards are another option. Edited February 16, 2017 by kortopates Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted February 16, 2017 Report Share Posted February 16, 2017 That's crazy considering that the actual sensor costs about $1.00, the mill spec Honeywell ones are $3.50. My hangar ferries would probably repair it if it broke. Quote Link to comment Share on other sites More sharing options...
Greg_D Posted February 16, 2017 Author Report Share Posted February 16, 2017 It turned out to be a broken wire, right at the point where it enters the sensor. Not much chance of repairing that. I decided to go with the alternate unit from JPI for $255. I considered the EI tachometer as a replacement, but the STC does not cover Ovations. There's no way I'd consider a $10K EDM as an option at this point. Quote Link to comment Share on other sites More sharing options...
kortopates Posted February 17, 2017 Report Share Posted February 17, 2017 It turned out to be a broken wire, right at the point where it enters the sensor. Not much chance of repairing that. I decided to go with the alternate unit from JPI for $255. I considered the EI tachometer as a replacement, but the STC does not cover Ovations. There's no way I'd consider a $10K EDM as an option at this point. Great to hear JPI's sensor is compatible - was not aware. Considering the cost that really sounds like your best option too.Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
thinwing Posted February 17, 2017 Report Share Posted February 17, 2017 I bet the mag shop had one for free Quote Link to comment Share on other sites More sharing options...
kortopates Posted February 17, 2017 Report Share Posted February 17, 2017 I bet the mag shop had one for free Why? These don't even go to the mag shop - they shouldn't and it's getting rough with them when R&R'ing the mags that breaks them.Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
thinwing Posted February 18, 2017 Report Share Posted February 18, 2017 The sensors on Mags get left on all the time Quote Link to comment Share on other sites More sharing options...
Greg_D Posted February 23, 2017 Author Report Share Posted February 23, 2017 I can confirm that the less expensive JPI sensor does work, if you remember to reset the tach circuit breaker A side benefit is that the JPI unit comes with a Molex connector. Add the other side of the connector to the ship's wiring and you can easily disconnect the sensor when removing the mag in the future. I still don't like the immediate 90 degree turn the wire has to make when exiting the sensor fitting though. Quote Link to comment Share on other sites More sharing options...
Greg_D Posted February 23, 2017 Author Report Share Posted February 23, 2017 On 2/17/2017 at 9:53 PM, thinwing said: The sensors on Mags get left on all the time At $1300 a pop, that's an expensive mistake. Quote Link to comment Share on other sites More sharing options...
kortopates Posted February 23, 2017 Report Share Posted February 23, 2017 I can confirm that the less expensive JPI sensor does work, if you remember to reset the tach circuit breaker A side benefit is that the JPI unit comes with a Molex connector. Add the other side of the connector to the ship's wiring and you can easily disconnect the sensor when removing the mag in the future. I still don't like the immediate 90 degree turn the wire has to make when exiting the sensor fitting though. Sounds like you are describing the sensor on the pressurized mags? That's what I assumed because those are the fragile ones compared to the standard unpressurized ones - which are very different? but you never mentioned, nor if slick or bendix? Your previous one was just butt spliced into the aircraft wiring? Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
Greg_D Posted February 23, 2017 Author Report Share Posted February 23, 2017 1 minute ago, kortopates said: Sounds like you are describing the sensor on the pressurized mags? That's what I assumed because those are the fragile ones compared to the standard unpressurized ones - which are very different? but you never mentioned, nor if slick or bendix? Your previous one was just butt spliced into the aircraft wiring? Sent from my iPhone using Tapatalk These are non-pressurized mags on an Ovation (they are vented). The previous sensor's wiring was soldered to the wiring bundle just aft of the baffling. Not a good setup. I'm not sure if that's how it came from the factory or not. Quote Link to comment Share on other sites More sharing options...
kortopates Posted February 23, 2017 Report Share Posted February 23, 2017 These are non-pressurized mags on an Ovation (they are vented). The previous sensor's wiring was soldered to the wiring bundle just aft of the baffling. Not a good setup. I'm not sure if that's how it came from the factory or not. Most unusual, the factory usually uses Canon plugs. The non-pressurized units entirely replace vent on mags. The pressurized mag has a different vent with larger orifice. Never understood why rpm sensors for the pressurized mags didn't also use a similar vent replacing unit but they instead chose to use a washer that fits under the original vent. Then the soft metal wraps around the mag. It's much like CHT gasket probe and similarly fragile. You are much better off now! Sent from my iPhone using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.