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Need help on Navaid AP1

A

Airparkguy

I'm New Here
Hello Forum,

I have a Navaid and it appears as though the servo unit is defective. I am a electronic tech and I have tested the head control unit and all is ok, but the servo is erratic. I have changed all the solid state chips and it still is not functioning properly. I also was able to connect my control head to a system in a RV8 and it works as good as the one that was in the plane, so I have confirmed there must be some other components in my servo that is the problem. Does anybody have a schematic of the servo? Or can I purchase a servo that will work with the AP1 control head?
Thanks
Earl
 
Airparkguy said:
Hello Forum,

I have a Navaid and it appears as though the servo unit is defective. I am a electronic tech and I have tested the head control unit and all is ok, but the servo is erratic. I have changed all the solid state chips and it still is not functioning properly. I also was able to connect my control head to a system in a RV8 and it works as good as the one that was in the plane, so I have confirmed there must be some other components in my servo that is the problem. Does anybody have a schematic of the servo? Or can I purchase a servo that will work with the AP1 control head?
Thanks
Earl
Click to expand...

Did you check the feedback pot?
 
I changed

my Navaid for a Trio unit 2 times. It is worth the investment. If the servo works in one plane, it should work in all.
Woodman
 
Gyro unit

Woodman,
Thanks for the reply, the gyro panel unit is OK. That is what I tried in the other
plane, I also connected the RV8'S wiring harness and using the panel gyro to my servo and it went erratic. The feedback pot shows to be ok. When I got this unit it was full of ants. I had to clean up the servo board. I looked at the control pulse from the gyro unit (square wave) on my oscilloscope and they are clean and change smoothly with the turn and trim knobs. This was done with servo NOT connected, when I plug the three pin connector to the servo the control pulse becomes erratic. I did talk to Trio and they were no help at all.
I will try again with Trio to see if their servo will work with the AP1 gyro unit
Thanks again guys
Earl:D
 
Airparkguy said:
Woodman,
Thanks for the reply, the gyro panel unit is OK. That is what I tried in the other
plane, I also connected the RV8'S wiring harness and using the panel gyro to my servo and it went erratic. The feedback pot shows to be ok. When I got this unit it was full of ants. I had to clean up the servo board. I looked at the control pulse from the gyro unit (square wave) on my oscilloscope and they are clean and change smoothly with the turn and trim knobs. This was done with servo NOT connected, when I plug the three pin connector to the servo the control pulse becomes erratic. I did talk to Trio and they were no help at all.
I will try again with Trio to see if their servo will work with the AP1 gyro unit
Thanks again guys
Earl:D
Click to expand...

ok, next thing I would check is the power line and see what it pulls down to with the servo connected vs. unconnected. Probably have a low impedance short to ground somewhere which is pulling down the power supply, causing the logic chips to act up. The Trio servo is going to be fairly expensive if you're thinking about replacing it.
 
Navaid Guys

Have not seen any comment on this but has anyone ever contacted the original Navaid guys or anyone that worked there to see if there is some little bit of knowledge left out there to share and not call it 'support' or anything they are trying to avoid? Would be nice rather than hoarding parts like I have with Navaid and Terra.... Fortuantely there is some Terra support left at Texas State Technical College Avionics Repair Station. Maybe they might be interested in playing with some Navaid equipment to add it to their program?
 
Im having some issues with my navaid in my (GASP) Varieze.

Everything was fine, until I changed out the servo with a new old stock unit that I bought years ago.

With the new servo, the stick continually shakes, even if you put some "load" on the stick, and when flying, it doesnt really do any better.

The worst part is I sold the old servo to a friend in Florida, so I cant even switch it back!

One of the electronics engineers at work said he will take a look at the servo to see what he thinks, and in the meantime, I'll take the scope out to the hanger and take a look at the output from the AP head to make sure the pulse widths look good.

Ive never tried contacting anyone from navaid though, it sure would be nice to have a schematic, and parts list!
 
Have a Navaid Srevo for sale

I'm replacing all of my avionic as we speak. I have a Navaid A/P head with me now. I'll have a Trio EZ-Pilot head as well as a Navaid servo from my avionics shop in about 2 weeks if you or anyone else is insterested. I'll also have many other things for sale later as well.
 
Hi Gents,

I was out at the hanger today, and I took the oscilloscope with me, and I have confirmed that all of the "jitter" issues are in the servo, the PWM signal that the control head outputs to the servo is rock solid, even when the servo is bouncing around.

Im going to have the electronics guy look over the servo this week, and hopefully fix it, he also mentioned to me he will be able to install a "dead band" adjustment pot that might assist in tuning it to a specific airplane.


Tom
 
The Navaid servos were pretty well proven and don't really need and new parts. These servos use Pulse Position Modulation. Sounds like you have a corroded feedback pot.
 
ezetom said:
Hi Gents,

I was out at the hanger today, and I took the oscilloscope with me, and I have confirmed that all of the "jitter" issues are in the servo, the PWM signal that the control head outputs to the servo is rock solid, even when the servo is bouncing around.

Im going to have the electronics guy look over the servo this week, and hopefully fix it, he also mentioned to me he will be able to install a "dead band" adjustment pot that might assist in tuning it to a specific airplane.


Tom
Click to expand...

Brantel said:
The Navaid servos were pretty well proven and don't really need and new parts. These servos use Pulse Position Modulation. Sounds like you have a corroded feedback pot.
Click to expand...

Yep, absolutely no need to add anything to the Navaid servo, just make sure it is working as designed. Even though it is sorta long in the tooth, the servo is an excellent design that formed the basis of the more advanced Trio Gold servo.

My Navaid servo has been in service for a dozen years with no maintenance, first with the Navaid head and for many years now with the Trio EZ-Pilot and Pro-Pilot heads. Unless there is something defective in your servo, most likely it just needs a careful tuneup.

I assume your are referring to jittering in the air. A bouncing servo on the ground is completely normal when there are no air loads preventing it from hunting around center.
 
No,,

not only does my servo jitter on the ground, it does in the air as well.

the stick forces on my varieze are soo light, it doesnt really make much difference.

I checked the feedback pot today, and its good, nice smooth resistance changes.

The only change I did was replace a worn out unit with a new one, that was "tight" and had no slop in the main shaft.

I'll keep you all posted!

-Tom
 
Feedback pot

Brantel said:
The Navaid servos were pretty well proven and don't really need and new parts. These servos use Pulse Position Modulation. Sounds like you have a corroded feedback pot.
Click to expand...
Brantel,
It looks as though you are right on! I checked my feedback pot and found it was wide open in certain positions. Also the pot was marked as 1000 ohm and mine was showing 1900 across the full pad. I then used a dremal to grind it open
and was surprised to see the carbon traces totally worn out! I found that MOUSER Electronics has it in stock. FYI : Spectrol model 157, here is Mouser
part # 594-15711102
Thanks for the heads up. I will report back after the new install.
Regards
Earl
 
Remaining Trio & Navaid

I've sold the Navaid A/P head unit. Still have the Navaid servo and Trio EZ-Pilot A/P head unit. I purchased the Trio EZ-Pilot in July 2009 from Mr. Sam Buchanan. In 2010 Trio Avionics updated the display screen & software. Unit works 100% as new. Taking offers on the Navaid servo & Trio EZ-Pilot head unit.
 
Trio EZ-Pilot Head Unit Sold

Last item available is the Navaid servo. Taking offers. I will have many items for sale in about (2) weeks. (Van's fuel gauges, Pegasus panel mount compass ,G-meter, Rocky mountain MicroMonitor, VSI, Panel mount Monroy Traffic Watch, Nulites..4 Large & 4 Small...I think, and more misc. items.)
 
Navaid AP1

Does anybody knows what is the model or PN of the control head and servo connectors on the Navaid system?
I need to buy the connectors, but since I couldn't find it at local shops here in Brazil, I'll have to buy it form US by Internet.
Thanks,

Fabricio
 
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