Terra TX 760D display
Posted: Fri Feb 17, 2023 8:15 pm
by n502pd
One of my other hobbies is fixing things, and I found a nice looking Terra TX 760 radio, that has a defective display. The displays are not available anywhere I have found. My question here , has anyone found a source for these displays? Or, has anyone found a method that will convert the radio to another display type other than plasma discharge? Its a nice radio, which I want to convert to desk top radio for monitoring, with disabled transmitters. Any help with where to go would be appreciated.
Re: Terra TX 760D display
Posted: Sat Feb 18, 2023 10:53 am
by T41pilot
If you have a service manual, you could determine if the segments are lit by supplying vcc or pulling a ground to light the individual segments. You could build a separate display if that could be determined using a different voltage other than the plasma supply. 7 segment displays are still available in several configurations. Most now are LED. All in all a lot of work but a fun project if you enjoy electronics. However, I did a search for the service manual and found no source for it. Without it, this project would be difficult. A cheap option is to buy a SDR Dongle(software defined radio) and use your phone or a computer to monitor whatever frequencies you want with the appropriate software and antenna of course. The software is free and the dongles are 15 or 20 bucks. I was having trouble with no ADSB output on my plane and used one to determine when I finally got it running right.
Re: Terra TX 760D display
Posted: Sat Feb 18, 2023 10:03 pm
by racaldwell
Joe, I have a Terra 760 com that has the push buttons that you can have for the cost of shipping from FL. I don’t know if you can convert back to the buttons from digital.
I bought it used and used it a couple months in my One Design when I heard a loud POP and it no longer worked. It’s been in my junk cabinet since.
Rick Caldwell
Xenos 0057 CAMit 3300
Re: Terra TX 760D display
Posted: Sun Feb 19, 2023 4:48 pm
by n502pd
Hi Rick! thanks for the reply. I need the display, which isnt avaliable anymore. its 70’s…80’s tecknowlegy. i was looking for a conversion to a display that is more modern. most of the older gas discharge displays for this unit have failed. one question, tho, can you see the frequency numbers on your display, or is it blank?
Re: Terra TX 760D display
Posted: Sun Feb 19, 2023 4:57 pm
by n502pd
Hi Greg! yep, i have built a couple of displays as you describe in years past, and really want a schematic for the terra, and, as you have found, service manual isnt easy to find. So, i guess I dont want to play with my ‘stock’ of led displays without knowing more about the actual diagram for the terra. Ha, one guy on another blog said to take the terra up to 5000 ft, over the water, open the window, and send it on its way! maybe so, but i wont open the canopy un til the asi shows 0.00, and am on the ground!! but maybe that is the only recourse. Thanks again!!
Re: Terra TX 760D display
Posted: Sun Feb 19, 2023 6:02 pm
by racaldwell
Joe,
The display on my TX 760 is mechanical. The digits are on a wheel that the pushbutton rotates. One forward & one reverse pushbutton for each number in the freq. Black letters on a white background.
I also have a Terra TXN 960 Tri-Nav C that works well. It has been my backup comm over the years. I have used the comm function on multiple occasions when the comm in the airplane stops working, i.e. the TX 760 failure. The Tri-Nav is solid with comm, glideslope and loran. I don’t need it anymore since I have new GTR 200 in my aircraft. If somebody wants it, we can work out a deal.
Rick Caldwell
Xenos 0057
Re: Terra TX 760D display
Posted: Mon Feb 20, 2023 8:39 pm
by n502pd
ok! that is something i did not know about the plain ‘760’. the D version is the one that is a pain. finally found a led display that will physically fit, but have to find one more!! junk box didnt have enough!. I think I can utilize the existing driver when I elliminate the 90 v supply, and sub a 2.4 to 5 v supply for common anode displays. have yet to make mockup of display and driver to actually see if I can convert to led display vs old plasma style display.it keeps me busy, and out of the stiff crosswinds here all week it seems!! thanks much for your input and info!
Re: Terra TX 760D display
Posted: Tue Feb 21, 2023 9:02 am
by T41pilot
If you are just using this for a base station, then the display would not have to necessarily fit inside the radio. You could make an external one. Wire bundle through the side of the case to a separate circuit board for your display. Then you have the room you need to do whatever you want. Box up the display if you want it to look pretty. My Sonex has several DIY electronic projects installed. Fun, if you have the time to mess with it.
Re: Terra TX 760D display
Posted: Wed Feb 22, 2023 3:20 pm
by n502pd
I did find some mini 7 segments that would fit inside perfectaly. However, investigating further, I found that the chip that holds the data base appears completely dead…no activity. power is there, so I now think either the 1992 data base had a y2k end of life, or something catastrofic happened. the general reciever is present, but at reduced sensitivity, on one frequency only, that cant be changed, conpaired to another radio. So, the saga continues, as I have justthis am got notification of a service manual available, and have to see what it entails. I am thinking at discontinueing this project if I can confirm a dead data base. thanks much for the interest, and conversations!
Re: Terra TX 760D display
Posted: Thu Feb 23, 2023 12:37 pm
by n502pd
Well, the 760D plot advances…some! finally got a service manual, found that the data processor’s crystal was not sufficently attached to the pcb, and that was the reason I had gotten zero activity from the processor. that is a great leap forward. next is to figure out why one hv powersupply is at half value, as the gas discharge display needs both + and - power polses at the same relative value to operate, or no display at all. Maybe the display isnt defective at all, and my voyage into LED displays isnt needed, yet! Its all surface mount stuff, so its very slow going. there are 2 chips for hv drivers, one for the +, and a different one for the - supply. and of course, they are not easily available. so, I continue to continue!!
Re: Terra TX 760D display
Posted: Sat Feb 25, 2023 1:43 pm
by T41pilot
Congrats on finding a print for your radio. If you have a source for a Genave alpha 12 base station let me know. I have one of those collecting dust that could keep me busy.
Re: Terra TX 760D display
Posted: Sun Feb 26, 2023 1:33 pm
by n502pd
No I dont! but have you looked at ‘schematicsunlimited.com’? i have found a lot of schematics there when working as guitar amp repairs. send me a picture of the radio, it may spark ( no pun!) a menory!
Re: Terra TX 760D display
Posted: Sun Feb 26, 2023 1:39 pm
by n502pd
As to the print for thr 760D, not 100% accurate. may be slightly newer print, or maybe different rev, as some parts I dont see on PCB’s are shown on the prints. But, I do have a great bit of info on the display senario, and may gut the HV parts, and …maybe…get to doing the 7 seg led display. just not now, as several other tech councelor projects taking my time. I will update again as I get back involved on 760D again. TKS for the conversations! And, I do remember the T41’s based at KEND in Enid, OK when I was at Vance AFB!!