What's new
Van's Air Force

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

Uncontrolled flip-flopping Terra 760

grantcarruthers

grantcarruthers

Well Known Member
It would seem the flip-flop button return spring/mechanism has gone south on my Terra 760. The button feels too flush to the face of the radio ie depressed and I get flip-flopping randomly several times a minute. Only solution so far has been to tune both windows to the same freq.

Soooooooo, anyone ever been inside this radio or similar?? Am I going to nuke it if I open it to examine the mechanism.

I'm not even remotely opposed to paying for a repair but for something so ?minor? I don't want to hassle with down time, shipping, and waiting as there's no radio shop here at home and I have a single comm panel??

Any recommendations on a radio shop for quick turn-around if this isn't a do-it-yourself project.

:confused::mad::(

Thanks

Grant
 
A little info here

One of my engineering crew used to work for Trimble (who assumed Terra for a while). I asked him about working on the Terras in idle conversation the other day. He said "They were all hand built out of discrete components. Tuning them was a challenge sometimes. Sometimes it took hrs. to tune the variable potentiometers and variable capacitors to get the things to work in spec."

So, Good news bad news maybe. The switch may be easy to access and fix but just don't touch anything else in the box! :D
 
DIY is possible

grantcarruthers said:
It would seem the flip-flop button return spring/mechanism has gone south on my Terra 760. The button feels too flush to the face of the radio ie depressed and I get flip-flopping randomly several times a minute. Only solution so far has been to tune both windows to the same freq.

Soooooooo, anyone ever been inside this radio or similar?? Am I going to nuke it if I open it to examine the mechanism.

I'm not even remotely opposed to paying for a repair but for something so ?minor? I don't want to hassle with down time, shipping, and waiting as there's no radio shop here at home and I have a single comm panel??

Any recommendations on a radio shop for quick turn-around if this isn't a do-it-yourself project.

:confused::mad::(

Thanks

Grant
Click to expand...

The white plastic thingey activates a small switch on a circuit board. If you have an older Terra (likely) apparently this switch had a poor reliablity, and the correct dealer fix is to upgrade the circuit board it is mounted upon. This was expensive when parts were around, and who knows if they are still available.

The switch appears to be an old keyboard switch, from the era when keyboards had seperate switches for each key.

It's a NO switch and can be replaced by a micro size push button switch with some lead bending and filing of the actuator to fit the back of the white plastic thingey...

You might (fingers crossed) just have some mechanical interference at the face plate, but I bet the switch is faulty.

The front end of the Terra comes apart quite easily, just watch for small screws and keep track of the bits....:)

It is fiddley, but is DIY fixable....:cool:

gil A

..guess how I found out....

PS ... all of the digital Terra units use the same front end boards, just different labels on the switches.
 
Switches

FOLLOW ON TO PREVIOUS POST....

The switch you need is something like this one (1/4 inch square base)...

G2340B.jpg


..but with a longer actuator bit. Then you need to file away the actuator so that it will fit the back of the Terra white push-button.

Before you do all this, you need to determine the height of the pushbutton above the circuit card.... use the height of the other button as a reference.

You could possibly epoxy an extension the the actuator of the type switch in the picture as an alternative.

The best bet is to remove the old switch and go to your best electronics parts store (not Radio shack...:)...) and get a couple of similar sized switches to play with.

gil A
 
FreeFlight used to have the service manual for the 760D available for download in a PDF file on their website, but I can't even get their homepage to respond tonight.

EDIT: Their website is responding, but slowly with timeouts.

The page http://www.freeflightsystems.net/documents.asp describes how to log onto their FTP server to get the PDF documents.

ftp://24.227.190.27/Publications/TerraByTrimble shows your the Terra files. The 760DIM.PDF and 760DMM.PDF are the install, and maintenance manuals.

I presume these files are free for the taking since their website tells you how to log in and access them.
 
Last edited:
Another idea to try is to remove or cut 2 legs on the switch. This will stop it jumping. You will loose flip/flop, but will stay on the one freq.
 
No....

Jamie Aust said:
Another idea to try is to remove or cut 2 legs on the switch. This will stop it jumping. You will loose flip/flop, but will stay on the one freq.
Click to expand...

Jamie... this won't work. You tune the "Standy-By" freq. with the knobs, and then use the flip-flop button to put it into the "Active" freq. Terra actually calls it a "Transfer" button.

Cut the switch out and no tuning....:eek:

...and, unfortunately, there is no external line available for a remote Transfer button....:mad:

gil A
 
Option B ?

az_gila said:
...and, unfortunately, there is no external line available for a remote Transfer button....:mad:
gil A
Click to expand...

Gil,
Obviously you have done surgery and I have not on this particular radio, but your "rant" :) makes me wonder if it would be easier remove the old switch (leaving the solder leads long), install extended wires and run them to a new jack (or through a grommet) on the back plane to an "external" flip flop switch. :cool:
 
I shouldn't post after i have had a beer or two !!! you are correct gil. VAF is just full of great help, no BS just what is needed.
 
Wires...

rzbill said:
Gil,
Obviously you have done surgery and I have not on this particular radio, but your "rant" :) makes me wonder if it would be easier remove the old switch (leaving the solder leads long), install extended wires and run them to a new jack (or through a grommet) on the back plane to an "external" flip flop switch. :cool:
Click to expand...

Bill... it might be possible, but the Terra, being a mainly discrete component design is pretty well stuffed inside the box.... and it also brings up a point on how much work should be done to keep an obsolete radio going...:)

But...along the lines you suggest, I would say remove the button, and bring the switch wires out through the button hole... then use the radio as a "hangar radio"....:D

gil A

PS ... I believe that the Terra was one of the earliest digital type radios, and I guess that nice, extra features were not yet developed.

My later (but not that much later) radios, a KY-97A and a GX-65 both have an external "flip-flop" capability. I intend to wire an extra stick switch (since I do not have electric aileron trim) to be a "flip-flop" and to wire it so that the COMM1/COMM2 select switch makes the active radio flip-flop...

PPS ...when you take the radio apart, you will notice how modular everything is, and it all plugs together either directly with header pins or short cables. The panel part in this discussion was designed to be remotely mounted and connected to the main body of the radio with a cable. Think of a "stick-on" control head less than 1 inch thick. This really would have been a neat feature for tight panels, but apparently they had the Trimble/move factory/FAA re-certification problems before it could be released.
 
Most likely you can find the switch in the C&K catalog.
http://www.ck-components.com/product-list-page,21093,en.html
Then either get a sample from C&K or order one from Newark or similar. Probably less than a buck. I probably have one in one of our sample kits.
This should be very DIY'able if you are fairly handy with a soldering iron. Tip: cut the leads off the old switch and desolder them one at a time to avoid buggering up the board.
 
All I can say is wow. You guys and this site are awesome. I'm a bit intimidated but if I can get up the courage I feel I have the info to move forward on it. Thanks to all of you.

Grant
 
You must log in or register to reply here.
Back
Top