Jumpers and Avionics

[65eTurbo]

I have a JPI 800 installed that is not in an ideal location.  I bought an 830 head which is plug and play with the 800 harness, and I can make it work in the current location, but I'd rather have it in a different spot on the other side of the panel.  If this were a hobby car, I'd just make up a jumper harness, plug it into the existing harness, and jumper the unit to the new location.  Is this kind of thing legal in the aviation world?  Is it considered acceptable practice?  Why/why not?

[7.Mooney.Driver.0]

Yes this is a legal thing to do, just get yourself a few male and female D sub connectors and do a one to one harness... That being said since you are dealing with temperature probes i would contact JPI and get their opinion on it, specially on what type of wire to use. You might have to get chromel alumel wire for the extension except for power and grounds.. The note below is from the installation manual.


NOTE: Unlike most other EGT & CHT installations the probe wire length is not critical and should be trimmed to any length as required for a clean installation. Do not extend the thermocouple wire with copper wire.

Hope this is helps.


Sent from my iPhone using Tapatalk

[Aerodon]

I think JPI sell 3' extensions.  Or contact me at supercub180@gmail.com and I'll scratch through my box for short bits of wire that you could make one.

Aerodon

 

[carusoam]

It’s not as easy as it sounds... 

Look to see how much wire you have behind the panel. There is a good chance somebody left extra wire to move the display around...

Read up on thermocouple wires and how to extend them properly...

improper wire materials used will give you a hassle of bad data that will be memorable for a lifetime...

TC wires generate signals in microvolts...  a small mistake will have a big result.

Many new owners have found temp sensors not working right for similar reasons...

PP thoughts only, not a mechanic...

Best regards,

-a-

[MIm20c]

As @Aerodon mentioned JPI sells an extension that is legal to use on everything but the primary units (900, 930) iirc. 

[Niko182]

I'm pretty sure according to JPI you're supposed to keep some extra cabling behind there incase you want to move the display around.

[EricJ]

The thermocouple connections will likely be the issue.   Those are sensitive to configuration.   Generally you don't want to make those longer or shorter without knowing for certain how it will affect the system.

 

 

[Oldguy]

When I replaced my 800 with the 830, I got the extension cables from JPI. It made the relocation a non-event. Moved it from the right side panel to the left, and had enough cable to install it and be able to connect all of the cables from the front of the panel before mounting it. I think it took me - er, my mechanic - less than 2 hours.

[65eTurbo]

Thamks all.  Great stuff.

[squeaky.stow]

My EDM 830 was moved from the right side of the panel to the left some time well before I owned it with an extension harness made and installed by a now defunct avionics shop in (I believe) Florida.

I spent the first year of ownership trying to figure out why my OAT, CHTs and Oil Temp were grossly inaccurate. Eventually discovered that the extension was all made of standard  copper avionics wire which is an absolute no-no for thermocouple leads. Replaced it with a custom  extension from JPI and all was good. They will build you whatever length you want, with the right thermocouple leads and connectors and the price is quite reasonable. 

Mark

[N201MKTurbo]

You have to use the same thermocouple wire as your thermocouples, usually K type. Also make sure the male and female pins in the connectors are the same metal.

You will form a thermocouple at the connector pins. One on each side of the connector. They will oppose each other, so the only error will be caused by the temperature differential across the connector, which should be very small.