JPI EDM 900 Install in an M20J

[0TreeLemur]

Tomorrow I'm taking our J model to my A&P to install a JPI EDM900 and a few other things to clean up the panel.  He's not installed one in a J.   I installed one in our C model, under the supervision of a A&P who has since flown west.

First question:  Where is the current shunt installed in an '83 J?   

Thanks,

Fred 

[jetdriven]

On the top side of the avionics shelf over against the right side forward cabin wall behind the instrument panel. Or, if you crawl underneath the copilot side and look out board of the heater box it's on top of that metal plate

[7.Mooney.Driver.0]

Sent from my iPhone using Tapatalk

[mhrivnak]

In my 1990 J, the circuit breaker panel and related enclosure was riveted in place, making that shunt a giant pain to access and replace. It was a slow exercise of blind contortions and patience. It might be better to drill out if you face the same.

When I did mine about 2 years ago, JPI did not include a tachometer cap for the engine, so check early to see if your mechanic has one. https://www.aircraftspruce.com/catalog/inpages/tachcap.php

The thermocouple wire they provided was just long enough to fish through the wing thinking it would work, but came up a bit short. I had to get a longer piece of thermocouple wire myself and pull that through using the one that was too short. So as you pull it through, watch the other end carefully to make sure it doesn't disappear! The zip ties inside my 1990 J wing were tight, which made pulling the old wire out and new wire through (twice...) challenging, but it's worth it to have the probe in the right spot. Don't let them talk you into putting the temp probe in an air vent or somewhere easier to access.

Lastly, I found this stuff made an excellent cover for odd shaped holes, like the hobbs meter and the engine instrument cluster: https://www.amazon.com/gp/product/B0049MWXM8/

[ArtVandelay]

Mine is on the engine side of the firewall.

[AIREMATT]

11 hours ago, 0TreeLemur said:

installed one in our C model, under the supervision of a A&P who has since flown west.

Any idea how long you spent installing in your C and if you have any tips to make it go easier?

Looking at doing that in mine.

Thanks Fred!

[Aerodon]

@0TreeLemur

In a 1983J it will be bolted onto the side of the panel that runs fore/aft on the LHS of the circuit breaker panel.

on the 1986 252 I am doing, I removed the whole CB panel - so that I can rearrange some of the CB's and change out the shunts etc.

Aerodon

 

 

[0TreeLemur]

13 hours ago, ArtVandelay said:

Mine is on the engine side of the firewall.

Not there in our J.

[ArtVandelay]

Not there in our J.

I should note, that’s where it is now, as I have 900 as well.

[0TreeLemur]

4 hours ago, AIREMATT said:

Any idea how long you spent installing in your C and if you have any tips to make it go easier?

Looking at doing that in mine.

Thanks Fred!

It took my wife and I about 50 hours to install it.   Our C had the original windshield, so we had access to the backside of the panel through the top, which was awesome.  In our C, the ammeter shunt was on the passenger side of the firewall like in the photo above, and easy to swap out with  the instrument bay panels removed.   If your C has the J style windshield with no access to the cabin side of the firewall from above, you will have a very different and more difficult experience.

My recollections from 2018:

1.  Getting all those thermocouple and transducer wires through the firewall using existing pass-throughs was tricky.   Thankfully, the Tefzel wire is pretty slippery. 

2.  The instructions from JPI state that the ground wire for the engine monitor should be on or very close to the engine, so that ground wire will need to pass through the firewall too.  Unfortunately, I noticed that step last.   Getting one more wire through the firewall in the space available was really challenging.  It's better to pull them all through at once if possible.

3.  The circuit breakers in our '67 C were the originals, I'm pretty sure.  They were brittle.   Putting a screwdriver on the screws, and pushing hard enough to turn them broke some of the breakers.   We wound up replacing all of them.  I'm using the royal we here, my wife did that part.   She tagged every wire before removing it from its' breaker.   That let her confidently reconnect them without us having to do any tracing.   She's smart.

Highly recommend the engine monitor!  Good luck.

Fred

 

 

[0TreeLemur]

6 hours ago, Aerodon said:

on the 1986 252 I am doing, I removed the whole CB panel - so that I can rearrange some of the CB's and change out the shunts etc.

Aerodon

That seems to be a fantastic idea to improve access to that area.

[carusoam]

The shunt locations kind of give themselves away…

The wires to and from the shunts are as large as possible, as they carry all of the electrons used by the plane.

There are also a pair of wires heading directly to it from the Ammeter…

Also when installing a new one… you get the opportunity to shield it from anything that gravity can make fall onto it… 

 

Screws, drill tailings, and other pieces of metal have been flash melted when they fell against the shunt…

They are typically not well insulated for good cooling, so live pretty high on the firewall to avoid catching junk….

 

+1 for Mrs Lemur’s involvement on this sized project! 

PP thoughts only, not an electrician…

Best regards,

-a-

[AIREMATT]

42 minutes ago, 0TreeLemur said:

It took my wife and I about 50 hours to install it.   Our C had the original windshield, so we had access to the backside of the panel through the top, which was awesome.  In our C, the ammeter shunt was on the passenger side of the firewall like in the photo above, and easy to swap out with  the instrument bay panels removed.   If your C has the J style windshield with no access to the cabin side of the firewall from above, you will have a very different and more difficult experience.

My recollections from 2018:

1.  Getting all those thermocouple and transducer wires through the firewall using existing pass-throughs was tricky.   Thankfully, the Tefzel wire is pretty slippery. 

2.  The instructions from JPI state that the ground wire for the engine monitor should be on or very close to the engine, so that ground wire will need to pass through the firewall too.  Unfortunately, I noticed that step last.   Getting one more wire through the firewall in the space available was really challenging.  It's better to pull them all through at once if possible.

3.  The circuit breakers in our '67 C were the originals, I'm pretty sure.  They were brittle.   Putting a screwdriver on the screws, and pushing hard enough to turn them broke some of the breakers.   We wound up replacing all of them.  I'm using the royal we here, my wife did that part.   She tagged every wire before removing it from its' breaker.   That let her confidently reconnect them without us having to do any tracing.   She's smart.

Highly recommend the engine monitor!  Good luck.

Fred

 

 

Thanks Fred! I still have the old windshield and avionics bay access doors.

Sounds like the best advice is to have Your wife help with it. She seems pretty smart!

[Fly Boomer]

6 hours ago, Aerodon said:

@0TreeLemur

In a 1983J it will be bolted onto the side of the panel that runs fore/aft on the LHS of the circuit breaker panel.

on the 1986 252 I am doing, I removed the whole CB panel - so that I can rearrange some of the CB's and change out the shunts etc.

Aerodon

 

 

On your 252, how did you pull the circuit breaker panel out?  When you pulled it out, how much wire slack did you have?

[Aerodon]

9 hours ago, Fly Boomer said:

On your 252, how did you pull the circuit breaker panel out?  When you pulled it out, how much wire slack did you have?

Not the best pictures, but the whole engine instrument / circuit breaker panel comes out, along with the shelf underneath and the side panel that the shunts are bolted too.   There are two screws from outside, in front of the door, a couple underneath, another few on top.  Most of the wires have a CPC connector, but there are a fw that are not.  Notably the battery and alternator wires that each in right to the bus bars.

I am doing a complete avionics makeover, so it was worth my while to remove.  I also got setup with proper CPC pins, crimpers, removal tools etc. so I can clean up the installation nicely.

It will be tedious, but I think you will be able to change the shunt from on top.  Also, do you have a 14 or 28V aircraft - check the shunt specs, it might be the same as the JPI shunt?

I was really tempted to leave the OEM ammeter in place and ignore the JPI ammeter part of the installation.

 

Aerodon

 

 

 

[0TreeLemur]

On 3/12/2023 at 5:53 AM, Aerodon said:

It will be tedious, but I think you will be able to change the shunt from on top.  Also, do you have a 14 or 28V aircraft - check the shunt specs, it might be the same as the JPI shunt?  I was really tempted to leave the OEM ammeter in place and ignore the JPI ammeter part of the installation.
 

Interesting idea.  Our J is 14V.   Problem is, I have plans for that 2-1/4" hole where the ammeter is.   An AV-30-S is going in there.  That would be great if the shunt is the same.  They have such small resistance not sure how to tell how similar they are.  I'll do some digging.

[ArtVandelay]

Interesting idea.  Our J is 14V.   Problem is, I have plans for that 2-1/4" hole where the ammeter is.   An AV-30-S is going in there.  That would be great if the shunt is the same.  They have such small resistance not sure how to tell how similar they are.  I'll do some digging.

You mean AV-20-S I think unless you’re going to make the hole bigger.

[0TreeLemur]

20 hours ago, ArtVandelay said:

You mean AV-20-S I think unless you’re going to make the hole bigger.

You are correct.  Long day.

[Aerodon]

Here are some more pictures, a later model 'narrow' circuit breaker panel, and a 'canted' M20K assembly.  Mooney used 50mV / 70A shunts, JPI uses 50mV/100A shunts.

[0TreeLemur]

JPI EDM900 install proceeding, albeit slowly.   My A&P has a day job. 

I have a question with reference to the attached pdf.    We connect the JPI EDM900 in place of the analog gauge.  Is it possible keep the connection to the "Low Fuel Level" indicators in the Annunciator in an '83 J, when connected as shown?

Thanks,

Fred

fuel_sender_wiring.pdf

Edited March 25, 2023 by 0TreeLemur
for clarity

[ArtVandelay]

Yes, it will warn you when fuel drops below a certain amount, I think it’s configurable.

[0TreeLemur]

8 hours ago, ArtVandelay said:

Yes, it will warn you when fuel drops below a certain amount, I think it’s configurable.

Tom, my question wasn't clear.   I had a JPI EDM900 in my C, so I know how those work.   My question is, if connected as shown with the JPI substituting for the analog fuel gauge, will the Low Fuel annunciator lights still work?

[ArtVandelay]

Tom, my question wasn't clear.   I had a JPI EDM900 in my C, so I know how those work.   My question is, if connected as shown with the JPI substituting for the analog fuel gauge, will the Low Fuel annunciator lights still work?

Don’t know, but I’m sure JPI (which was NOT certified with this in mind) will not want any other circuitry connected to the senders, be like connecting 1 speaker to 2 different stereos.

Proper way is to cap the annunciator wires and let the JPI provide the fuel warnings.

[0TreeLemur]

Plane has been in the shop 3+ weeks.  Shop is over 2-hour drive from home. My A&P has a day job does most of his work nights and Saturdays.   Aviation-related withdrawals are setting in.

[as350]

I am about to embark on this same install in a '67 E. I have the 201 windshield so I expect it to be a royal PIA. I plan on removing an EDM-700, the 6-pack, tach/fuel press and MP gauge. It should be worth the hassle as the instrument panel will be much cleaner once completed.