Of clocks and learning curves...

So I picked up this nifty Davtron digital electric clock/timer at Sun N Fun.
It's exactly the same model I had in my Warrior (Model 800), and I found a
good price for it. (Roughly 4 times what it's really worth -- a bargain in
aviation!) Our wind-up clock had become sporadic in cold weather, and I
kept forgetting to wind it anyway...

My A&P took one look at the box and said "This will be a snap to install!"
This should have set off warning alarms right away, but it didn't. We
decided to do it at the annual, when everything was already ripped apart
anyway.

So, after most of the annual was complete, Darryl (the junior A&P in our
2-man shop) dug into it. As expected, it turned out to be a real
son-of-a-bitch getting at the backside of the panel. I ended up standing on
my head under the panel, holding the clock in place with the very tips of my
fingers, while Darryl carefully dropped the tiny little retaining screws
onto my belly, over and over again. It was fun! Really!

Eventually, through sheer persistence, he got the damned screws threaded in.
Then the real fun began -- wiring! The directions clearly called for the
dimmer control wire to be connected to one of the panel lights, and the hot
lead to go directly to the battery. Unfortunately the battery was in the
way back of the plane -- not exactly handy -- so Darryl decided to wire it
into the hot side of the master switch.

This made sense to me -- which, again, should have set off warning bells in
my head, but didn't -- as the master switch was a heckuva lot closer than
the battery.

So I picked the plane up today, after reassembling the last little bits and
pieces. Everything looked great, the engine fired up easily, I taxied about
40 yards -- and the clock blinked out and died....

Immediately spinning the plane around, I shut the engine and master down --
and the clock came back to life! So, I turned the master switch back on,
and *poof* -- 15 seconds later, the clock went blank.

What the hell!?

Darryl was completely stumped, and a huddle of wise old airport bums
immediately assembled. It was obvious that hooking up to the "hot" side of
the master switch was NOT giving us continuous power -- but why?

No one knew, and I had to get back to the hotel. I took the plane back to
my hangar, and left the wise men standing there scratching their heads.

As soon as I got back to the inn, I called Davtron. Describing the symptoms
to them, they immediately knew the problem. Apparently the Piper master
switch -- on the hot side only -- "powers down" after 15 seconds! Some
solenoid somewhere gets thrown, grounding the circuit and killing power to
the hot side of the master switch.

They said I had two choices: 1) Run the power directly to the battery,
clear in the back of the plane, or 2) send the clock into Davtron, for free
installation of a battery back up. This battery allows the clock to be
connected to the avionics master, rather than a "hot" wire.

I immediately called Darryl, and gave him the options. He has agreed to
fix the problem on Monday, whatever it takes, free of charge. Rather than
take the thing out, send it to California, and reinstall it -- he's opted to
run the wire to the battery...

Live and learn -- who'd ever think that installing a gol-danged CLOCK would
be so hard?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay... I have a cheaper alternative.. I carry my "ships clock" on my wrist..

LOL
BT

"Jay Honeck" wrote in message
news:lEurc.36031$gr.3583857@attbi_s52...
So I picked up this nifty Davtron digital electric clock/timer at Sun N
Fun.
It's exactly the same model I had in my Warrior (Model 800), and I found a
good price for it. (Roughly 4 times what it's really worth -- a bargain
in
aviation!) Our wind-up clock had become sporadic in cold weather, and I
kept forgetting to wind it anyway...

My A&P took one look at the box and said "This will be a snap to install!"
This should have set off warning alarms right away, but it didn't. We
decided to do it at the annual, when everything was already ripped apart
anyway.

So, after most of the annual was complete, Darryl (the junior A&P in our
2-man shop) dug into it. As expected, it turned out to be a real
son-of-a-bitch getting at the backside of the panel. I ended up standing
on
my head under the panel, holding the clock in place with the very tips of
my
fingers, while Darryl carefully dropped the tiny little retaining screws
onto my belly, over and over again. It was fun! Really!

Eventually, through sheer persistence, he got the damned screws threaded
in.
Then the real fun began -- wiring! The directions clearly called for the
dimmer control wire to be connected to one of the panel lights, and the
hot
lead to go directly to the battery. Unfortunately the battery was in the
way back of the plane -- not exactly handy -- so Darryl decided to wire it
into the hot side of the master switch.

This made sense to me -- which, again, should have set off warning bells
in
my head, but didn't -- as the master switch was a heckuva lot closer than
the battery.

So I picked the plane up today, after reassembling the last little bits
and
pieces. Everything looked great, the engine fired up easily, I taxied
about
40 yards -- and the clock blinked out and died....

Immediately spinning the plane around, I shut the engine and master
down --
and the clock came back to life! So, I turned the master switch back on,
and *poof* -- 15 seconds later, the clock went blank.

What the hell!?

Darryl was completely stumped, and a huddle of wise old airport bums
immediately assembled. It was obvious that hooking up to the "hot" side
of
the master switch was NOT giving us continuous power -- but why?

No one knew, and I had to get back to the hotel. I took the plane back to
my hangar, and left the wise men standing there scratching their heads.

As soon as I got back to the inn, I called Davtron. Describing the
symptoms
to them, they immediately knew the problem. Apparently the Piper master
switch -- on the hot side only -- "powers down" after 15 seconds! Some
solenoid somewhere gets thrown, grounding the circuit and killing power to
the hot side of the master switch.

They said I had two choices: 1) Run the power directly to the battery,
clear in the back of the plane, or 2) send the clock into Davtron, for
free
installation of a battery back up. This battery allows the clock to be
connected to the avionics master, rather than a "hot" wire.

I immediately called Darryl, and gave him the options. He has agreed to
fix the problem on Monday, whatever it takes, free of charge. Rather
than
take the thing out, send it to California, and reinstall it -- he's opted
to
run the wire to the battery...

Live and learn -- who'd ever think that installing a gol-danged CLOCK
would
be so hard?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay... I have a cheaper alternative.. I carry my "ships clock" on my
wrist..

Funny, that's what one of the wise old heads on the field said, while Darryl
was poking around: "Why in HELL do you need an electric CLOCK, for
Chrissakes? Doncha got a WATCH?"

:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay wrote, "Apparently the Piper master switch -- on the hot side only --
"powers down" after 15 seconds! Some solenoid somewhere gets thrown,
grounding the circuit and killing power to the hot side of the master
switch."

What?! I'd love to see a diagram of that circuit.

Jon

Jon Woellhaf wrote:

Jay wrote, "Apparently the Piper master switch -- on the hot side only --
"powers down" after 15 seconds! Some solenoid somewhere gets thrown,
grounding the circuit and killing power to the hot side of the master
switch."

What?! I'd love to see a diagram of that circuit.

Me to.
That sounds like a bizzare system !

Probably has something to do with it being a low wing....

--
Jim Carter
"MC" wrote in message
...
Jon Woellhaf wrote:

Jay wrote, "Apparently the Piper master switch -- on the hot side
only --
"powers down" after 15 seconds! Some solenoid somewhere gets thrown,
grounding the circuit and killing power to the hot side of the master
switch."

What?! I'd love to see a diagram of that circuit.

Me to.
That sounds like a bizzare system !

Jon Woellhaf wrote:
: Jay wrote, "Apparently the Piper master switch -- on the hot side only --
: "powers down" after 15 seconds! Some solenoid somewhere gets thrown,
: grounding the circuit and killing power to the hot side of the master
: switch."

: What?! I'd love to see a diagram of that circuit.

The Piper master switch does no such thing. The piper master switch supplies
GROUND to the master solenoid. Whne the switch is off, no current is flowing
through the solenoid windings, and the master switch appears to have +12V
battery connected to it - which it does - through the solenoid windings.
When you flip the master on, it grounds the wire from the solenoid that
previously appeared to have +12V battery on it. (Just like the dome light
switch on every car except for Fords.)

ASCII schematic:

(+ Battery)---(solenoid)-----(master switch)-----(- battery)

--
Aaron Coolidge

"Jay Honeck" wrote in message
news:wRurc.92436$iF6.8041834@attbi_s02...
Jay... I have a cheaper alternative.. I carry my "ships clock" on my
wrist..

Funny, that's what one of the wise old heads on the field said, while
Darryl
was poking around: "Why in HELL do you need an electric CLOCK, for
Chrissakes? Doncha got a WATCH?"


I'm with Jay on this one. I had an old analog clock in my 152, it wasn't
working, and I tried using my watch for things, but I much prefer to have
the clock right up there in my scan. I installed the 800 Davtron as well,
which is pretty basic (wanted the one that had temperature and voltage as
well, but didn't like the additional $300 for it and who knows how much the
install would have been since there would be additional wiring) Just has
local time, GMT, and a timer but now that I have it and have flown with it
for a bit, I don't ever want to go back to that old analog clock or the
watch on my wrist.

--
Louis L. Perley III
N46000


:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

ASCII schematic:

(+ Battery)---(solenoid)-----(master switch)-----(- battery)

Thanks, Aaron.

For us electrical dimwits, can you explain the purpose of this circuit?

Also, why is there a 7-second delay after turning the master switch on?

Here's how it works:

1. The clock is connected to the "hot" side of the master.
2. It works fine with master "off"
3. Turn Master Switch "on" -- works fine for seven seconds.
4. At seven seconds, the clock goes out.
5. Turn Master Switch "off" and the clock comes back on.

What's going on? Why is this circuit set up to do this?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Sat, 22 May 2004 04:38:34 GMT, "Jay Honeck"
wrote:

ASCII schematic:

(+ Battery)---(solenoid)-----(master switch)-----(- battery)

Thanks, Aaron.

For us electrical dimwits, can you explain the purpose of this circuit?

Also, why is there a 7-second delay after turning the master switch on?

Here's how it works:

1. The clock is connected to the "hot" side of the master.
2. It works fine with master "off"
3. Turn Master Switch "on" -- works fine for seven seconds.
4. At seven seconds, the clock goes out.
5. Turn Master Switch "off" and the clock comes back on.

What's going on? Why is this circuit set up to do this?


I think this is whats going on Jay,
First, Aaron is right..the master switch is just a ground path for the
master solenoid.
The master solenoid has 12 volts going to it but dosen't work untill
the master switch is ON ..providing a ground path for it.
So with the master OFF, one side of the switch is at 12 volts (the 12
volts going thru the solenoid coil, and the other side is at ground.
Your clock must be hooked up to the hot side of the master switch, and
gets 12 volts thru the solenoid coil.
When you throw the master ON, BOTH sides of the master switch are now
at ground..and the master is now supplying a ground path to the
solenoid coil. Your clock power feed is now at ground and it croaks.
Why the 7 sec. delay?.... I bet you will find if you provide 12v to
the clock thru any source, then kill it..it will last for 7
sec..probably some capacitance built into the clock power circuits.