What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Transponder stripped ramping screw

R

Richard RG

Active Member
Having no luck searching the forums/internet for a solution to remove the stripped 3/16" allen key ramping screw that secures the Narco AT 150 Transponder to its mounting tray, am hoping someone else has come up with a solution to this same problem.
Recently the transponder has been working intermittently, so cleaned the antenna connection and also attempted to remove the transponder from the tray, planning to spray contact cleaner on the back side connections as well. The 3/16" allen key as per the Narco installation manual and a few other sizes of allen keys did not engage the ramping screw and peering up the tiny access hole to the ramping screw head revealed a very stripped allen head.
Having easy access to the backside of the transponder (RV3) can see a single threaded rod projecting from the backside of the tray that appears to be in alignment with the access hole for the ramping/retaining screw. Possibly a gentle clamping and turning of this threaded rod will assist at least loosening and partially backing out the screw from the backside of the transponder?
Any suggestions much appreciated.
 
Richard RG said:
Having no luck searching the forums/internet for a solution to remove the stripped 3/16" allen key ramping screw that secures the Narco AT 150 Transponder to its mounting tray, am hoping someone else has come up with a solution to this same problem.
Recently the transponder has been working intermittently, so cleaned the antenna connection and also attempted to remove the transponder from the tray, planning to spray contact cleaner on the back side connections as well. The 3/16" allen key as per the Narco installation manual and a few other sizes of allen keys did not engage the ramping screw and peering up the tiny access hole to the ramping screw head revealed a very stripped allen head.
Having easy access to the backside of the transponder (RV3) can see a single threaded rod projecting from the backside of the tray that appears to be in alignment with the access hole for the ramping/retaining screw. Possibly a gentle clamping and turning of this threaded rod will assist at least loosening and partially backing out the screw from the backside of the transponder?
Any suggestions much appreciated.
Click to expand...
Use a flat screwdriver, a little bit wider than 3/16", it will not fit in the ramping screw.
Then use a file to sharpen the edge of the screwdriver until it just fits in the ramping screw but without touching the bottom.
Put the screwdriver in the ramping screw and push firmly so the screwdriver engages and turn.
Good luck
 
Richard RG said:
Having no luck searching the forums/internet for a solution to remove the stripped 3/16" allen key ramping screw that secures the Narco AT 150 Transponder to its mounting tray, am hoping someone else has come up with a solution to this same problem.
Click to expand...
3/16" allen?

Most radio gear use 3/32" allen to secure.

There are tips on the internet to remove rounded allen head fasteners. One of them may work for you as typically radio get is not installed that tight.

I have had good luck using a Torx driver insead and also "friction drops" (aka: valve grinding compound) with larger fasteners.
 
Pull whatever is below the transponder, and look in and up. You should see the locking lever pointing down below the metal bottom. Use some tool to rotate it 90 deg, up above the bottom of the box. The whole thing should then pull out.
 
Thanks for the suggestions and will try all methods. I've got access to the underside of the transponder and with a enough rib lacerations may be able to lever the locking lever unlatched. It appears the ramping screw needs to be unscrewed in addition to unlatching the locking lever, so will first try the less painful method of filing a small flat blade screw driver and wedging it into the remnants of the allen head and hope that works.
Narco manual says to use a 3/16" allen wrench on the ramping screw to remove /install their transponder, but that size would be prior to the round hole modification that I am now dealing with. I'll report back what worked or if the transponder will forever remain in its tray.
 
Another "Possibility" ...

Would be to try a 4.5mm hex Allen wrench - just a bit smaller than a 3/16" (.177 to .188); and, it might (just might) have enough "purchase" to get the process started.

HFS -

I really can't imagine a 3/16 Allen wrench for that purpose; but, I too looked up the docs - and that's what they said.
 
Richard RG said:
Thanks for the suggestions and will try all methods. I've got access to the underside of the transponder and with a enough rib lacerations may be able to lever the locking lever unlatched. It appears the ramping screw needs to be unscrewed in addition to unlatching the locking lever, so will first try the less painful method of filing a small flat blade screw driver and wedging it into the remnants of the allen head and hope that works.
Narco manual says to use a 3/16" allen wrench on the ramping screw to remove /install their transponder, but that size would be prior to the round hole modification that I am now dealing with. I'll report back what worked or if the transponder will forever remain in its tray.
Click to expand...
Here are a couple links for extraction tools:

#1 https://www.amazon.com/Extractor-St...MIk9Wfpdz2hQMV2SCtBh1wEAEaEAQYAiABEgL5AvD_BwE

#2 https://www.jbtools.com/cal-van-too...MIk9Wfpdz2hQMV2SCtBh1wEAEaEAQYByABEgIzNfD_BwE

After you use Gorilla tactics to remove the Transponder - I politely suggest an UPGRADE.
 
  • Like
Reactions: HFS
Before going into Gorilla tactics - Try a 5/64" Allen. I just pulled a Narco COM 120 radio from my relic's repository and the 5/64" allen is an EXACT fit. These are the same vintage & family avionics & believe it may be correct. After ponder the manual & other's mentioning 3/16" Allen - it's wildly incorrect - likely a manual typo.
Good luck
 
You must log in or register to reply here.
Back
Top