Today's Message Index:
----------------------
1. 02:37 AM - Re: Reverse Engineering JPI Engine Monitor Interfaces (Peter Pengilly)
2. 01:26 PM - Why CB on regulator field supply? (Voyager)
3. 03:11 PM - Re: Why CB on regulator field supply? (Charlie England)
Message 1
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| Subject: | Reverse Engineering JPI Engine Monitor Interfaces |
>From what I remember from an aeroplane I sold 15 years ago this is a
straight RS 232 interface but the serial to USB converter is key, not
all work. Don=99t forget to switch the Rx & Tx pins on the way to
the computer. I believe it is only a 2 wire interface, so I=99m
guessing the Rx (3) and Gnd (5) pins (at the computer end) are
connected?
See also
https://mooneyspace.com/topic/35740-jpi-700-cell-phone-serial-data-cable/
From: owner-aeroelectric-list-server@matronics.com
<owner-aeroelectric-list-server@matronics.com> On Behalf Of Jared Yates
Sent: 12 January 2022 02:36
Subject: AeroElectric-List: Reverse Engineering JPI Engine Monitor
Interfaces
I have purchased a plane that came with an old JPI EDM-700 engine
monitor. This is the one with the orange and black display that shows
bar graphs for EGT, CHT, etc. It has a data logging capability, but the
interface requires their cable, which I don't have:
https://www.jpinstruments.com/shop/pc-interface-cable-for-edm-700-edm-800
-and-edm-760/
This looks like something that I could make out of things I have laying
around the shop, vs spending $40 plus shipping. Does anyone have one
sitting around that they could do some continuity testing on? If the
little plug only has two conductors, I would guess that there must be
two pins on the serial end that they are connected to.
JPI also offers a box that takes the serial from that cable and writes
to a USB drive. They charge $200 for that box, and I'd love to see
what's in one of those.
Another option is to send the unit into JPI, where they will modify it
to have a USB interface for $300.
And of course there is always the option of just pretending like it
doesn't record data, but where's the fun in that?
Message 2
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| Subject: | Why CB on regulator field supply? |
I have two questions I have yet to find an answer to either through searches here
or in the AeroElectric Connection.
1. I follow Bobs logic on using fuses rather than breakers and am planning that
for my RANS S-21. However, his one exception seems to be on the supply for the
regulator (alternator field). I am assuming a CB is specified here either
to make testing the OC crowbar easier as the test is then nondestructive or because
of the time to trip characteristic of a CB compared to a fuse. Can someone
enlighten me as to the reason?
2. Peripherally related is the question as to why the FAA recommends higher rated
CBs than fuses on many conductor sizes in table 11-3 in AC43.13-1B? Anyone
explain that?
I assume both of those are explained somewhere, but Ive yet to stumble on the explanations.
Thanks,
Matt
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=505692#505692
Message 3
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| Subject: | Re: Why CB on regulator field supply? |
On Sun, Jan 16, 2022 at 3:31 PM Voyager <m.whiting@frontier.com> wrote:
m
> >
>
> I have two questions I have yet to find an answer to either through
> searches here or in the AeroElectric Connection.
>
> 1. I follow Bob=99s logic on using fuses rather than breakers and a
m
> planning that for my RANS S-21. However, his one exception seems to be o
n
> the supply for the regulator (alternator field). I am assuming a CB is
> specified here either to make testing the OC crowbar easier as the test i
s
> then nondestructive or because of the time to trip characteristic of a CB
> compared to a fuse. Can someone enlighten me as to the reason?
>
> 2. Peripherally related is the question as to why the FAA recommends
> higher rated CBs than fuses on many conductor sizes in table 11-3 in
> AC43.13-1B? Anyone explain that?
>
> I assume both of those are explained somewhere, but I=99ve yet to s
tumble on
> the explanations.
>
> Thanks,
> Matt
>
> I'd have to wonder if the AC43 table issue is tied to the 'conditions':
[image: image.png]
Wild guess, but perhaps the fuse milspec is for some slow-blow fuse. A
'generic' breaker will typically open much slower than a 'generic' fuse.
(Note the quotes....)
My understanding is that the roots of using a pullable breaker for the
field are (at least) two-fold: It gives the pilot a way to manually disable
a problem alternator, and it allows recovering from a 'nuisance trip' for
instance, a momentary 'spike' in voltage due to a load dump may cause the
OV protection to trip. A breaker gives you a chance to be sure that the OV
issue is real, and not a nuisance trip.
Charlie
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