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Another 68C Panel Upgrade - N3964N MasterThread


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Well I started this project a few weeks ago, and I've had about a million questions I have been trying to get answered on the Facebook groups; it's always a hodgepodge set of responses, however, so I've decided to create a "master" thread here and document all my progress and questions so folks who have similar questions can find all this later. 

This is how the panel looked when I got the airplane.  Most things "worked," but the airplane was basically not flying for four years when I got it so things were temperamental.  After getting a fairly sizeable bonus, and landing on a good deal on some G5s and other parts, I set off on the upgrade process after both my Terra radios decided to crap out on me during a flight 4 weeks ago. 

39XVaMm.png

 

What I am going with:

  • PMA7000H (Got a good deal on it used)
  • Garmin 430W
  • Keeping one of the TN760D and TN200Ds and a TriNav for backup NAV.  (I got THREE of each with this airplane, and I have a solid one of each that work great).
  • Garmin 330 Transponder.
  • Replacing display on JPI-700.
  • Dual G5s.
  • Keeping the Britain as it works. 

This is what it looked like about 4 hours after landing with the bad radios:

oX3UjtZ.jpg

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So after I got in there, I found about TWENTY wires that went nowhere.  Some were not terminated and had bare wire floating around behind the panel.  After I got about 50% of that out, my first hiccup was figuring out what this was; turns out it is the over-voltage relay which was an option on the 68C.  They left it installed when they put in a Zeftronics generator controller but disconnected the light. 

7HNZSfD.jpg

I got my DC PSU and hooked it up (Battery disconnected and GEN breaker pulled of course)  - low and behold at 16V the relay opens and (when connected) the light comes on.... *not amused*  Yes the Zeftronics has its own built-in protection circuits, but either leave this in or remove it for gosh sake.  I'm going to leave it in since it WORKS and is just another level of protection while I have a generator.  

 

Edited by TCUDustoff
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Next thing to tackle was the nastiness of the lower "switch" panel.  I did some reading and found some brave souls that went to town with scotchbrite; low and behold, it appears to be working!  I started with green and worked my way finer with red and grey.  Still have some work to do on it, but its 80% there.  Out of curiosity, however, does anybody know how this was made from the factory?  Silk screen?

image.thumb.png.aed913cb40920ccf642b122c7ae7615f.png

 

Also, while I was removing the breakers I found the remains of what appears to be some sort of paper between the panel and the circuit breakers.  I asked the younger A&P on the field and he says he hasn't seen something like this before.  There was some residual on TOP of a few of the breakers, but it did not go far enough back to cover the load connectors or the bus bar.  What was this (paper?) and what was the purpose?  It's not on the 172 a few hangers down I have access to...went and checked! 

R4e75DB.png

More to follow.....

Edited by TCUDustoff
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17 minutes ago, TCUDustoff said:

Also, while I was removing the breakers I found the remains of what appears to be some sort of paper between the panel and the circuit breakers.  I asked the younger A&P on the field and he says he hasn't seen something like this before.  There was some residual on TOP of a few of the breakers, but it did not go far enough back to cover the load connectors or the bus bar.  What was this (paper?) and what was the purpose?  It's not on the 172 a few hangers down I have access to...went and checked! 

I'm guessing this is "fish paper"  https://www.digikey.com/en/products/detail/gc-electronics/560/257752  I'm not certain what the purpose was (prevent scratching of things, provide some sort of electrical insulation...not sure), but I've run into it a couple of places.  One is between the gear warning microswitch and the throttle cable bracket.

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Only twenty wires? You lucky!  

I recently got a new clock and was wondering how I was going to get an always hot wire to power it.  I noticed a dangling wire with a masking tape tag.  Clock.  I put the voltmeter on the bare end, yep, 12.7 volts with the master off.  Perfect.  Wonder how many years that bare end dangling wire was loose back there?

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21 hours ago, David Lloyd said:

Only twenty wires? You lucky!  

Was thinking the same thing.  Just got done cleaning out the extra wires under my instrument panel.  I removed disconnected wire after disconnected wire from behind my panel...  0.2 pound of wire (which is what the weight and balance change shows) seems small, but its really quite a mess of wires.

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So I'm 100% positive that the fish paper material was there from the factory.  I might end up getting some and fabricating a flap that covers both the bus bar and the breaker "load" attachments.  Thanks for the tip! 

And, when I was working for about an hour today before the cold got to me, I ended up removing about another 20 wires that were cut at various grounding points on the A/C.  It also looks like, at some point, they used what I "THINK" was the factory lighting terminal strip (behind pilot panel) as a grounding block.  *facepalm*  SOOO many cut wires attached to that! It's a wonder ANYTHING worked.  Now I'm trying to trace the factory wires and see what's left and what can be removed... *grumbles* 

 

image.thumb.png.4524198aa2a1dec8749d8e3c9597cdb0.png

 

One last question for the group in-case we survive this cold snap and I can work on the plane on Tuesday..... The two screws that hold the bushing for the control yoke.  Are there a ton of stacked washers in there b/w the panel and the bracket?  I wanted to take these screws out so I can better brush the Aluminium, but no way in heck I want to pull them out if its a stack of washers back there.  Thats what it looks like to me, at least, and I can't get my phone in there to take a pic.  

image.png.4a128949694a1f0e229202845cec30c9.png

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Way cool... Dustoff!  :)

With so many cut wires... it means you have a lot of upgrades!

My 65C was very original when I had it...

But, I don’t remember anything like the fish paper... which means... the 65 needed it... but didn’t get any until a few years later...  :)

You are going to know every detail down to wire numbers when you are done... that’s amazing..!

PP thoughts only, not a mechanic...

Best regards,

-a-

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Yes, there are stacks of small thin washers in between the plates that hold the socket.  They have to be there so that the ball can "float" and not bind the shaft.  You should be  able to loosen the nut at least enough to brush the aluminum and clean under/around the screw heads.  Definitely easier than trying to get the washers back in.

Your experience with the wires is fairly common.  Avionics shops make their money by selling and installing new equipment.  Removing components is easy, removing the wires that connect them is a time-consuming pain.  When a shop supervisor is trying to get his tech to work faster in order to bill the customer sooner, it's fastest to just cut the connector off the ends and let the next shop worry about the wires.  Not right, but not uncommon.

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yeah,

not surprised as my 67 F had some interesting "features":

There were (I believe) original wires routed to avionics stack that could be used for radios. All were protected (insulated) by sleeves and numbers were clearly visible on the insulation. 

Then there are abandoned wires with light sockets (3 of them) behind pilot's panel that I think were for marker beacon lights and disconnected when modern audio panel was installed. I and working on a G5 install now (while waiting for new engine to arrive) and have a chance to clean that one up.

The worst was what I found installing Engine monitor at the copilots panel. All of the avionics was run to one 35A Circuit breaker switch and connected by one screw and nut driven through all ring terminals (at the end of radios 14V+ wire) and then "insulated" with electrical tape! it was just floating behind the panel and done by avionic shop(s). Very disappointing! I've added CBs far all the radios (and future use) and recut a Al panel and did a correct wiring with Bus bars and such. At the same time, I replaced the original trip CBs Mooney installed in 60-is with modern pull type CBs.

 

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if I recall it was Klixon 7277-2-X where X is Amps rating.

I already had a couple installed when doing a mod so bought new ones of the same type. I left a stall warning CB original as it was very close to steel cage and I think new one would interfere and possibly touching it. There a Factory installed insulation (PVC tubing of some sort) to insulate that but I didn't want to rely on it.

 

13 hours ago, SSimpson77 said:

Igor, if you don’t mind me asking, which pull breakers did you go with? I have the trip type and soon to be doing a panel upgrade starting off with 900 and figure I’ll start my planning and layout design. 

 

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Igor, where did you add the extra circuit breakers?  I was going to add a new ~35A CB where the stock Radio CB is on the Primary Bus Bar and run a new 8 or 10 GA wire to a new Avionics Bus Bar and run all the breakers off that (That is sorta what they did, minus the running power to it correctly part). Right now I need something like 10 CBs with the G5 install, so they wont fit in one row on the Avionics Stack.  Thinking I might have to do it where the ADF used to be. 

In other news, things are going slow on the progress front with the winter weather we just had.  Plus, I found that my prop cable is shot and am going to have to remove that and get a replacement made.... what a PITA!  Anyways, I am happy with how the "brushing" came out compared to the yellow mess it was before.  Perfect? No.  But good enough! I'll touch up the flaking black on the bottom with a paint pen and call it a day! 

MXJ5K0t.jpg

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  • 5 months later...
On 2/21/2021 at 8:08 PM, TCUDustoff said:

Igor, where did you add the extra circuit breakers?  I was going to add a new ~35A CB where the stock Radio CB is on the Primary Bus Bar and run a new 8 or 10 GA wire to a new Avionics Bus Bar and run all the breakers off that (That is sorta what they did, minus the running power to it correctly part). Right now I need something like 10 CBs with the G5 install, so they wont fit in one row on the Avionics Stack.  Thinking I might have to do it where the ADF used to be. 

 

Sorry for 5 months delay but I just saw this post

I installed 10 new CB above originals on new  copilot panel. 
this is the picture before Autopilot was installed into the opening at the bottom 

A77ADF72-C1D3-4330-8407-7D08ED161988.jpeg

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