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What to do with a broken 2.25" tachometer?

toto

By toto
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toto Grand Master

toto

Posted
Posted

Hi all -

I have a broken factory electronic tach that went from perfect to intermittent to completely dead in a day.  My A&P has determined that the problem is in the tach generator, and that it's no longer possible to buy a new replacement generator.  His recommendation is to buy the EI R-1 electronic tach as a drop-in replacement.  This would be something like $1100 installed.

I've read with great interest all of the various threads on tach replacement, and it seems that most people go with the EI unit for 2.25" applications.  I'm not wild about the EI units, which have a curious LED arc, and appear not to have been updated in the past 25 years (so I would be replacing a 25yo factory electronic tach with a third-party electronic tach of the same vintage).  I think that the LED format is odd, and replacing only the tach without doing MP and EGT would look particularly odd.

I do not have an engine monitor, and I think that my preference would be to install something like the EI CGR-30P unit that could replace the factory gauges.  EI is running a nice rebate offer right now for the CGR-30P, which would be 4x as expensive as the R-1 installed, with far more functionality.  But the CGR-30P is a 3" display, and would not fit in the 2.25" factory tach hole.  My understanding is that there isn't a 2.25" engine monitor that can replace the primary tach, and I don't have an available 3" hole unless I'm ready for major panel surgery.

Any advice?  Am I better off just buying the R-1 now?  Something else?  Would I still want the R-1 later after installing an engine monitor that's a primary replacement?  (Is having an electronic tach even useful in the event of an electrical failure?  Doesn't the tach die along with the engine monitor?)

Hope I'm not beating a dead horse with this thread - would appreciate any thoughts.

Guest

Guest

Posted
Posted
19 minutes ago, toto said:

 


M20J (201)

 

Here is some info from the maintenance manual.  No tach generator in a standard J model.

Clarence

image.jpg

Marauder Grand Master

Marauder

Posted
Posted
Hi all -

I have a broken factory electronic tach that went from perfect to intermittent to completely dead in a day.  My A&P has determined that the problem is in the tach generator, and that it's no longer possible to buy a new replacement generator.  His recommendation is to buy the EI R-1 electronic tach as a drop-in replacement.  This would be something like $1100 installed.

I've read with great interest all of the various threads on tach replacement, and it seems that most people go with the EI unit for 2.25" applications.  I'm not wild about the EI units, which have a curious LED arc, and appear not to have been updated in the past 25 years (so I would be replacing a 25yo factory electronic tach with a third-party electronic tach of the same vintage).  I think that the LED format is odd, and replacing only the tach without doing MP and EGT would look particularly odd.

I do not have an engine monitor, and I think that my preference would be to install something like the EI CGR-30P unit that could replace the factory gauges.  EI is running a nice rebate offer right now for the CGR-30P, which would be 4x as expensive as the R-1 installed, with far more functionality.  But the CGR-30P is a 3" display, and would not fit in the 2.25" factory tach hole.  My understanding is that there isn't a 2.25" engine monitor that can replace the primary tach, and I don't have an available 3" hole unless I'm ready for major panel surgery.

Any advice?  Am I better off just buying the R-1 now?  Something else?  Would I still want the R-1 later after installing an engine monitor that's a primary replacement?  (Is having an electronic tach even useful in the event of an electrical failure?  Doesn't the tach die along with the engine monitor?)

Hope I'm not beating a dead horse with this thread - would appreciate any thoughts.

I have the EI unit in my plane and love it. Mine was installed when an avionics shop replaced the mechanical tach cable with one that was too long and destroyed the tach.

I had to adapt from a 3" hole to accommodate the smaller size. I eventually replaced the panel and went with all EI.

The LED warning lights are fine since I am only concerned when any of the red LEDs come on. The digital format is easily readable and the backlights are excellent. It has other features like max RPM tracking, tach time and flight time. My FP-5L was installed in the mid 90s and has been problem free.

41d9b696a62ade3e251ebdb07f079371.jpg

Sent from my iPad using Tapatalk

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toto Grand Master

toto

Posted
  • Author
Posted


I have the EI unit in my plane and love it. Mine was installed when an avionics shop replaced the mechanical tach cable with one that was too long and destroyed the tach.

I had to adapt from a 3" hole to accommodate the smaller size. I eventually replaced the panel and went with all EI.

The LED warning lights are fine since I am only concerned when any of the red LEDs come on. The digital format is easily readily and the backlights are excellent. It has other features like max RPM tracking, tach time and flight time. My FP-5L was installed in the mid 90s and has been problem free.

41d9b696a62ade3e251ebdb07f079371.jpg


Sent from my iPad using Tapatalk



Your photo of the all-EI setup doesn't look bad to me. Was it strange to have the EI tach by itself before you replaced the MP and fuel flow gauges?

toto Grand Master

toto

Posted
  • Author
Posted
I think the instrument shop at KCHD can overhaul them. I saw them working on them once, it looked like they had the equipment for it. 


My A&P seemed to know where the generator could be sent for overhaul (not sure where). But he was concerned that it might take a while. The EI install could be done in a day.

I'll let him know about KCHD - might be the same place he was thinking of.
Marauder Grand Master

Marauder

Posted
Posted



Your photo of the all-EI setup doesn't look bad to me. Was it strange to have the EI tach by itself before you replaced the MP and fuel flow gauges?



I actually had the fuel totalizer mounted elsewhere in the panel first. Once I had the tach installed and found I liked it, I decided to remove the MP/fuel pressure gauge, go all digital and rebuilt the right side to accommodate the smaller sized gauges.

Later I installed a JPI 900 to get rid of all analog gauges and use digital versions for everything. The EIs and the JPI both are primary and both can be substituted for each other -- allowing redundancy I didn't have before.

02bcfc14c367fba044a734a6a199d991.jpg

Here is the mess I cleaned up on the right side:

ea45d81f6053900cb9b57cec8fddce41.jpg


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Marauder Grand Master

Marauder

Posted
Posted



For what it's worth, here's a shot of the affected 2.25" stack in my a/c.

e3cfd3585f8c6853eb6eaacc4a64cc64.jpg


The easiest thing would be to fix what you have. The cost is what I would be concerned with. If the cost to fix is high, if it were my plane I would toss in both the EI RPM and MP and be done with it.


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carusoam Grand Master

carusoam

Posted
Posted

Background...  Marauder is one of those electronics hardware gurus at work...  the instrument panel is where he demonstrates his skills...

If you go all in one device there are three manufacturers to choose from.  All are good...

Best regards,

-a-

Guest

Guest

Posted
Posted
8 hours ago, toto said:

 

 


For what it's worth, here's a shot of the affected 2.25" stack in my a/c.

e3cfd3585f8c6853eb6eaacc4a64cc64.jpg

 

 

That is standard factory installed instrumentation.  The tachometer is driven by a pair of signal wires connected to the magneto switch in the panel, or by a set of breaker points in the magneto depending on serial number.  See the excerpt from the manual I posted above.

Clarence

goncaloareia Contributor

goncaloareia

Posted
Posted

Hi

I have a spare RPM indicator like the one that failed on your mooney.

It was removed working fine from my 252 about a year ago and has been sitting on the shelf since then.

The rpm green and red marks are the same and I think that its the same part number.

I sell it surely cheaper than the Ei R1.

Send me a PM if you want.

Goncalo

toto Grand Master

toto

Posted
  • Author
Posted
That is standard factory installed instrumentation.  The tachometer is driven by a pair of signal wires connected to the magneto switch in the panel, or by a set of breaker points in the magneto depending on serial number.  See the excerpt from the manual I posted above.
Clarence


By serial number, my a/c should have the tach connected to the mag.

In either case, when the mechanic says that he has traced the problem back to the tach generator, what's he likely referring to?

I don't want to start replacing things if there's just a worn connector somewhere that needs to be tightened or resoldered.


Guest

Guest

Posted
Posted
1 hour ago, toto said:

 


By serial number, my a/c should have the tach connected to the mag.

In either case, when the mechanic says that he has traced the problem back to the tach generator, what's he likely referring to?

I don't want to start replacing things if there's just a worn connector somewhere that needs to be tightened or resoldered.

 

 

Buy him a set of manuals, he clearly doesn't have one.  It could be the wires, the points in the magneto or the actual tachometer.

Clarence

toto Grand Master

toto

Posted
  • Author
Posted
Buy him a set of manuals, he clearly doesn't have one.  It could be the wires, the points in the magneto or the actual tachometer.
Clarence



Ouch.

Apologies for missing the point of your original reply - I didn't make any distinction between an electronic tach and a tach that uses a generator.

I do have copies of the J mx manuals, but I'm obviously not a mechanic and certainly don't have the knowledge I would need to steer the shop in the right direction.

This mechanic has never touched the plane before, but I was hoping to avoid needing a ferry permit to a shop that I know, and I was assured that he had "plenty" of Mooney experience.
carusoam Grand Master

carusoam

Posted
Posted

Toto,

When you can, update your avatar data. It is difficult to know what plane you have without it...

In the early 90’s, Mooney started to use a hall(?) sensor in the mag to send a signal to the tach.  Not sure if the J went that way...

Good luck with the details.

Best regards,

-a-

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