66' M20E Instrument Panel

[chriscalandro]

Also, you are going to have to shift things a bit it looks like, you need room to mount the new panel.

[Nukemzzz]

2 hours ago, chriscalandro said:

Also, you are going to have to shift things a bit it looks like, you need room to mount the new panel.

Fixed it!

 

[carusoam]

Nuke,

Remember to watch the 3D space available behind the panel, at the top...

The center post splits in an inverted Y...

Best regards,

-a-

[Nukemzzz]

I started the surgery today...

Does anyone have any hints about how to remove the haze from the glass of my Tach?  I can’t tell if it’s internal or external  

 

 

[carusoam]

Quite possibly a remove and wash kind of thing...

There isn’t much to the instrument’s container...

If nothing else... An instrument shop can handle the challenge... fifty cents worth of standard parts...

PP thoughts only, not an instrument tech...

Best regards,

-a-

[Nukemzzz]

45 minutes ago, carusoam said:

Quite possibly a remove and wash kind of thing...

There isn’t much to the instrument’s container...

If nothing else... An instrument shop can handle the challenge... fifty cents worth of standard parts...

PP thoughts only, not an instrument tech...

Best regards,

-a-

It did look like the glass jewel would pry off. I wonder if the inside is smudged because over 54 years the fumes from grease on the tach cable adhered to it.  

[carusoam]

Many instruments will suffer from the same smudge...

I thought the lenses were bad... after 50years.

It turns out, they just needed 50years worth of crud washed off...

At the back of the tach is an oiled cable... that cable is spinning a chain of gears attached to the needle...

When you pull the tach out... you will actually see an oil cup on the back... to be filled at annual...
 

The tach May have got updated with new graphics to indicate where the do not operate zone is...  My M20C has a piece of red tape stuck on the ‘glass’... which I’m pretty sure is a nice piece of molded plastic...

Best regards,

-a-

[Nukemzzz]

Ok, so now I'm trying to prepare for Transponder install by learning as much about what I have as possible.  I have two main questions:  1.  How to connect alt encoding.  2.  Where to put the GPS Antenna.

I crawled around under my dash again and found that the prior, ancient, transponder was using encoding direct from the altimeter and it was connected using what i would call a "Serial Port" plug (PC Language).  However, as with most things on this plane I'm confused a bit by what I see.  

There was a switch by the old transponder that said "Mode C". It was spliced into this connection between the altimeter and the transponder.  There are many other wires between the altimeter and the transponder, but this one has a spliced switch.  There is also a ground wire supplied to the transponder connector.  I've created a diagram below of what I see.  My best guess is this Red wire is the Gillman code wire, however, I don't understand why it also goes off somewhere else.  Note: there used to be a DME down in the direction that this wire heads.  Maybe this switch turned the old transponder from A to C by adding or subtracting the altitude data.  But then it's strange that it also switched the DME.  Maybe someone was to lazy to splice ahead of the switch.

So here is my high level question.  If I make this switch always closed (remove it) and plug it into the Appareo ESG, will it just work?  My guess is yes, but I don't want to let the smoke out of any of my boxes. lol

 

My second question is where to put the GPS Antenna.  The best place seems to be right where this Com antenna is located or right next to it.  However, the install manual says it needs to be 2 feet away from any Com antenna.  Where do you have your GPS Antenna located?

In the picture below:  The left most circle would require me to take the ceiling down and it's old enough that it likely won't go back together so I don't want to put it there.  The middle circle seems to be the best, but its too close to the antenna per the manual.  Further back might work but it would look funny I think and the rudder could shade it.

 

I'm really curious about what used to be here.  Either way, it would look stupid here.I 

And here we used to have something but its right on the top of the roof between pilot and co pilot heads and the surface looks too curved.  Again I would have to pull down the ceiling, it would look stupid here, and I would take a hit on aerodynamics:

Thoughts?

 

 

 

[chriscalandro]

I think you are going to have to pull down the ceiling unfortunately. My experience is that you really want that 2 feet. You likely don’t have to pull down the whole think and you can probably just get down what you need. If you go by the baggage door you can get away without taking down much. 
 

whatever that old wiring is, you shouldn’t need it. With what you have purchased you will need rg400 to the GPS antenna, a power, a ground, and a static line. 

Edited June 4, 2020 by chriscalandro

[Nukemzzz]

8 hours ago, chriscalandro said:

I think you are going to have to pull down the ceiling unfortunately. My experience is that you really want that 2 feet. You likely don’t have to pull down the whole think and you can probably just get down what you need. If you go by the baggage door you can get away without taking down much. 
 

whatever that old wiring is, you shouldn’t need it. With what you have purchased you will need rg400 to the GPS antenna, a power, a ground, and a static line. 

The wiring I'm discussing above is for the current Altimeter Encoder in the plane.  I'm hoping that this aspect of the install is just plug and play since it previously had Mode C.  I'm just confused by this switch and extra wire spliced into the connector.

[Nukemzzz]

8 hours ago, chriscalandro said:

I think you are going to have to pull down the ceiling unfortunately. My experience is that you really want that 2 feet. You likely don’t have to pull down the whole think and you can probably just get down what you need. If you go by the baggage door you can get away without taking down much. 
 

whatever that old wiring is, you shouldn’t need it. With what you have purchased you will need rg400 to the GPS antenna, a power, a ground, and a static line. 

It does look like my best option is above the baggage area.  hmm

[chriscalandro]

I have that part of my interior out. I’ll send you a picture of what it looks like

[Nukemzzz]

The old transponder was an EDO-AIRE RT-667.  I "think" I've found the plug schematic (trouble finding the manual for free).  If this is it, then my Altimeter is of the Serial type.  It also indicates that these additional two wires (red and black are simply power and ground for the unit.  So now I think the red line is power to the transponder and the same wire is switched to the altimeter encoder for power to it.  Opening this switch would disable the encoder but the transponder would still have power.  I guess sometimes the prior user didn't want to report altitude or Pre-Mode C systems couldn't handle the altitude transmission.

So now I just need to find the actual wiring diagram for either the EDO-AIRE or the Altimeter so I can confirm the encoder wiring.  

 

 

[markgrue]

That schematic is for a grey code encoding altimeter.  You will need all of the wires to provide altitude information to the transponder.  I have the same transponder and I put the gps antenna on the roof just in front of where the speaker is on the inside.  I removed the speaker and could fit my hand in the hole in the ceiling panel to feed the wire up through the hone in the top of the fuselage where the adf sense antenna was.  I also installed the doubler on the inside through the hole to buck the rivets to it.  I put nutplates on the doubler so I did not have to use nuts on the antenna hold down screws.  

 

Mark

[chriscalandro]

The side panel you should be able to loosen enough to work with without removing it all the way. 

[Nukemzzz]

1 hour ago, markgrue said:

That schematic is for a grey code encoding altimeter. 

I see, thanks for the clarification. I assumed the older Grey standard would be a single analog signal. I’m really curious as to why there are so many wires used for this.  Is it binary code with each wire able to show 1/0?  Perhaps used since analog signals are subject to interference?

[Nukemzzz]

45 minutes ago, chriscalandro said:

The side panel you should be able to loosen enough to work with without removing it all the way. 

Is that a GPS antenna? I thought They used coaxial cable. 

[chriscalandro]

Not the Dynon one.  The Dynon one is power and serial.  I wish it was Coax, then I could have reused the old antenna and saved a lot of trouble!

[carusoam]

see if this helps any...

Nice pic of the drain line too... one of those, while you are in there things... some have a piece of PVC tubing that goes bad over time....

-a-

[tmo]

7 hours ago, Nukemzzz said:

assumed the older Grey standard would be a single analog signal. I’m really curious as to why there are so many wires used for this.  Is it binary code with each wire able to show 1/0?  Perhaps used since analog signals are subject to interference?

You're not wrong when you say it is an analog representation of a binary encoding of sorts.

[markgrue]

23 hours ago, Nukemzzz said:

I see, thanks for the clarification. I assumed the older Grey standard would be a single analog signal. I’m really curious as to why there are so many wires used for this.  Is it binary code with each wire able to show 1/0?  Perhaps used since analog signals are subject to interference?

It is a form of binary.  Most new encoders use a serial bus but the older ones use the grey code.  Actually I have the stratus transponder.  I did not look close enough at your transponder.  It is a pretty much universal hook up though.

 

Mark

[Nukemzzz]

Update...

GPS antenna is in and wire ran. Panel blank arrived and I made a lexan version to locate the mounting holes. I’m putting rubberized washers above and blow it to isolate it. I have a friend making prints for the panel and someone ready to waterjet it. 

It looked like the t&b would fit in the open 2 1/4” hole on the pilot side so tied to put it there and it interferes with the yoke tube. Not sure what to do here. 

[Nukemzzz]

I don’t understand the ELT. There is a switch in front of the pilot and something down by the right side headset jack. I wonder if I need both...did someone update this and leave the old switch behind?

[Nukemzzz]

Lastly, does anyone know what diameter scat tubes these are?

[drapo]

On 5/28/2020 at 8:18 AM, Nukemzzz said:

Revision #2.  Thanks to Andy for the idea for moving EDM Closer.  Note that I think I want a Ram mount under the intercom so I can place my full size iPad on that side tilted towards me.  I'm not sure if I should put it above or below the audio panel.  I'll likely port the audio into the "ENT Input".  I've never tried that input, but I believe it is sound into the intercom...like music.  If so, it seems useful to have Foreflight sound piped into the intercom here as well.

 

 of m

Think about protecting your master avionics switch. Mine was located just about there also, and in turbulence, changing transponder code, I killed the avionics with my hands as it went down from a moderate bump... I installed a protective cover after that event