Today's Message Index:
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1. 06:52 AM - Issue with Garmin GTX 330 XPDR ()
2. 09:13 AM - Questions about circuit protection ()
Message 1
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| Subject: | Issue with Garmin GTX 330 XPDR |
1/2/2010
Hello Don Morrisey, You wrote: "I later discovered that each time I activate
the Master SWitch the unit turns itself on even though I had left it powered
off via the "Off" button on the unit. I went back over the wiring and
nothing seems amiss??? Any idea why it would be doing this?"
This very topic is currently being discussed on the aeroelectric list. Read
the email exchanges below (last email is first).
Also if you go to this web site, download the GTX327 installation manual and
look at figure B4 on page 47 you will see the pins and notes that are being
discussed.
http://www.velocityxl.com/Downloads/GTX327Transponder_InstallationManual.pdf
OC
==========================================
Allen then wrote:
Actually I meant 327 rather than 337. I looked at the installation manual
pin out diagram and my Approach Systems engineer (Tim Hass) has pin 1 and
pin 15 jumpered. The drawing calls pin 1 "Avionics Master on which may be
the pin that I could unhook from power and make it work like we want.
I emailed Tim Hass at Approach Systems to ask for clarification on this
issue. I'll let you know what I find out.
Allen
=================================================
-----Original Message-----
From: bakerocb@cox.net [mailto:bakerocb@cox.net]
Sent: Friday, January 01, 2010 1:22 PM
Subject: GTX337 ON or OFF?
1/1/2010
Hello Allen Fullmer, You wrote:
"........skip.....I have also noticed that the GTX337 transponder cannot be
set to remain off when power is supplied. It will remain in the standby
position but, once again, when I am playing and fiddling around I just hate
to see it go up and down unnecessarily. Haven't decided on a switch for it
or not."
I also can not program my GTX327 to remain OFF when power is applied or
reapplied to the avionics buss.** But the GTX327 has some options on which
pins electrical power can be supplied to. If you pick the correct pin(s) the
box will remain OFF until you push the ON button on the face of the box.
I suspect that the GTX337 may be built the same way. So if you desire, and
have the capability, you could rewire your GTX337 so that it would remain
OFF until you pushed the ON button on the face of the box.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
**PS: I suspect that the person who wired my panel set it up that way so
that it would take a very deliberate OFF button action on my part in order
to take off with the transponder OFF. I am with you, I'd like to have total
ON - OFF control of the box with the buttons on the face of the box.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
==============================================
Time: 05:54:51 PM PST US
From: Don Morrisey <donmorrisey@hotmail.com>
Subject: Avionics-List: Issue with Garmin GTX 330 XPDR
Hello Listers
I have just been finishing up my panel and one of the last things in was my
transponder a Garmin GTX 330 . Very straightforward to install as I had a
wiring harness made for it. Anyway got it in and it powered right up and
does a self test etc. I later discovered that each time I activate the Ma
ster SWitch=2C the unit turns itself on=2C even though I had left it powere
d off via the "Off" button on the unit. I went back over the wiring and no
thing seems amiss???
Any idea why it would be doing this? I have no issues with any of my other
avionics that are connected to this wiring harness (SL40 and PMA 4000 Audi
o Panel).
Thanks. Don...
www.donsbushcaddy.com
Don Morrisey's Skunkworks
Message 2
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| Subject: | Questions about circuit protection |
1/2/2010
Hello Matthew Schumacher, You wrote: "I think I will just get fuse blocks
per your recommendation for the reasons you mention, but also because
problems with a fuse can be remedied in the air quickly and easily."
If you are thinking of replacing fuses in the air to trouble shoot and solve
an electrical problem please think again. There are several disadvantages.
Some are:
1) Your airplane's Operating Limitations (part of its airworthiness
certificate) will require you to equip the aircraft in accordance with 14
CFR 91.205 if you fly at night or IFR.
Paragraph 91.205 (c) (6) says: "One spare set of fuses, or three spare fuses
of each kind required, that are accessible to the pilot in flight."
This means that, by regulation, if you design your airplane so that you have
access to those fuse blocks in flight then you must also have available to
you all those spare fuses while in flight. Do you want to create that burden
/ nuisance / danger?
2) Trouble shooting an electrical system in flight by fumbling around to
locate and then insert the appropriate fuse is not a good idea, particularly
at night or IFR when you should be concentrating on flying the airplane.
So fuse blocks are a good idea, but where you locate them has some
operational and safety implications. Please read some more of Bob Nuckolls'
philosophy regarding electrical problems / failures in flight.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
========================================================
Time: 07:42:35 PM PST US
From: Matthew Schumacher <schu@schu.net>
Subject: Re: AeroElectric-List: Questions about circuit protection.
First, thank you very much for looking at my stuff Bob. I greatly
appreciate it and have donated to keep this list going...
...................................... big skip
......................................
I know that fuses/breakers/fuselinks protect the wiring, what I was
missing was the part about problems with one component spreading to
others instead of being isolated. I think I will just get fuse blocks
per your recommendation for the reasons you mention, but also because
problems with a fuse can be remedied in the air quickly and easily.
Thanks again,
schu
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