VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #11  
Old 09-15-2009, 07:53 PM
smokenjoe50 smokenjoe50 is offline
 
Join Date: Jul 2008
Location: corona california
Posts: 74
Default

I am having the same problem with mine. I called vans and they where little help. At first mine would not work then I hooked up a battery charger to bring the voltage up to 14v. I also adjusted the pot. My trim is now working but it sounds like it is surging or laboring.
Reply With Quote
  #12  
Old 09-15-2009, 08:09 PM
JBPILOT JBPILOT is offline
 
Join Date: Nov 2007
Location: Jesup, Iowa
Posts: 1,613
Default Welcome to the club

I spoke with Ray Allen again today. Mine has the same problem. The gear inside that turns around the threaded rod is not running true, and has a slight bind with each revolution around the threaded rod. The problem here is Van's is feeding low power to the servo to slow it down, which cause the speed up and slow down because of the internal binding. For likely most applications, it is not an issue. Van's wants us to set the timing for a full stroke at 25 - 30 seconds at 12 volts. That requires a lower voltage to get it to slow down. Ray Allen told me it was designed to full stroke in 8 seconds. That requires a serious reduction in power to achieve that. Hope this makes sense.

John Bender
Reply With Quote
  #13  
Old 09-15-2009, 08:22 PM
vernhendershott vernhendershott is offline
 
Join Date: Dec 2007
Location: Spruce Creek, FL
Posts: 370
Default

Hi JT,

It would be interesting to apply the 9 v. battery to the forward ends of the wire at the connector to the tunnel cable. If you apply 9 v. and the trim motor works like the 9 v. applied in the rear then the wire is OK and if the 9 v. applied to the front comes out 4 v. at the back you would know that you have an issue with the wires and my first guess would be that one of the connectors that is crimped on is not the best of connections, it will ring out but not carry any load.

Have a good day.

Best regards,
Vern
Reply With Quote
  #14  
Old 09-15-2009, 10:02 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 7,957
Default

Quote:
Originally Posted by JBPILOT View Post
Van's wants us to set the timing for a full stroke at 25 - 30 seconds at 12 volts. That requires a lower voltage to get it to slow down.
This is not correct.

A lower voltage is not used to slow down the trim on an RV-12.

It uses a PWM (pulse width modulation) circuit. It uses full voltage but pulses it on and off to make the motor move slowly. When the speed pot is turned, it is adjusting the amount of time the voltage is off versus on. This is a standard technique for moving DC motors slowly without losing much torque. The laboring sound is because the internal friction varies slightly while it is running, but it is normal (for the RV-12 at least)
__________________
Any opinions expressed in this message are my own and not necessarily those of my employer.

Scott McDaniels
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
Reply With Quote
  #15  
Old 09-15-2009, 10:59 PM
smokenjoe50 smokenjoe50 is offline
 
Join Date: Jul 2008
Location: corona california
Posts: 74
Default

Quote:
Originally Posted by JBPILOT View Post
I spoke with Ray Allen again today. Mine has the same problem. The gear inside that turns around the threaded rod is not running true, and has a slight bind with each revolution around the threaded rod. The problem here is Van's is feeding low power to the servo to slow it down, which cause the speed up and slow down because of the internal binding. For likely most applications, it is not an issue. Van's wants us to set the timing for a full stroke at 25 - 30 seconds at 12 volts. That requires a lower voltage to get it to slow down. Ray Allen told me it was designed to full stroke in 8 seconds. That requires a serious reduction in power to achieve that. Hope this makes sense.

John Bender
I think you have it right
Reply With Quote
  #16  
Old 09-15-2009, 11:01 PM
smokenjoe50 smokenjoe50 is offline
 
Join Date: Jul 2008
Location: corona california
Posts: 74
Default

Quote:
Originally Posted by rvbuilder2002 View Post
This is not correct.

A lower voltage is not used to slow down the trim on an RV-12.

It uses a PWM (pulse width modulation) circuit. It uses full voltage but pulses it on and off to make the motor move slowly. When the speed pot is turned, it is adjusting the amount of time the voltage is off versus on. This is a standard technique for moving DC motors slowly without losing much torque. The laboring sound is because the internal friction varies slightly while it is running, but it is normal (for the RV-12 at least)
If what you say is true then why does my trim require more than 12v to even make it operate.
Reply With Quote
  #17  
Old 09-16-2009, 08:00 AM
Peterk Peterk is offline
 
Join Date: Mar 2008
Location: Texas
Posts: 1,378
Default Trim

Quote:
Originally Posted by rvbuilder2002 View Post
This is not correct.

A lower voltage is not used to slow down the trim on an RV-12.

It uses a PWM (pulse width modulation) circuit. It uses full voltage but pulses it on and off to make the motor move slowly. When the speed pot is turned, it is adjusting the amount of time the voltage is off versus on. This is a standard technique for moving DC motors slowly without losing much torque. The laboring sound is because the internal friction varies slightly while it is running, but it is normal (for the RV-12 at least)
Scott,

Just wanted to mention that I really enjoy your explanations of some of the engineering thought processes behind this delightful machine. If you don't get too frustrated by us anxious builders please continue to offer the insight - sometimes its pretty fascinating...above for instance. Thanks.
Reply With Quote
  #18  
Old 09-16-2009, 08:00 AM
JBPILOT JBPILOT is offline
 
Join Date: Nov 2007
Location: Jesup, Iowa
Posts: 1,613
Default Scott M

I understand fully what you said about motor contolling. My statement was general. Less power is a term I choose. The issue is the servo has a bind internally that greatly affects the way it will go thru its cycle with "lower power" applied. As I was told, it was designed to go thru a full stroke in 8 seconds with 12v. Slowing that down causes the internal binding issue to be come serious. Very hard to get the motor to start when it may have stopped in a binding condition. They are sending me another one, with the understand that it needs to operate at the "lower power" settings called for.

John Bender
Reply With Quote
  #19  
Old 09-16-2009, 10:05 AM
Jaknjoan Jaknjoan is offline
 
Join Date: Jan 2005
Posts: 215
Default Summary of what I have done to trim and still no luck

I've been unsuccessful in making my trim servo function properly since this past weekend.

Here are the steps that I have taken that points to the wiring being okay, some power is getting back to the servo, but it appears in a reduced voltage that is insufficient for its operation.

1. All 5 pins from the 37 pin connector to the servo have been checked for continuity.
2. The Odyssey battery is new, but I have put on a battery minder to bring the battery to a maximum charge of about 13 volts when the charger is in place.
3. I disconnected the trim servo connector and ran it from a 9 volt Duracell battery and it works fine but slower due to 9 volts.
4. I then put 9 volts to pins 31 & 32 on the 37 pin Tunnel harness connector at AV Board (with the connector removed) and the servo worked about the same as putting the 9 volt directly to the two power conductors at the servo.
5. The potentiometer is turned all the way counter clockwise, with the connector attached to the Av board, and the battery charger on I get a very, very slow movement of the servo, that is almost undiscernible. With the pot turned clockwise, there is no movement.

I understand from Scott's post that there should always be 12 volts going to the servo, the pot merely pulsates to slow or speed up the servo depending on the setting on the pot.

I was able to measure just over 6 volts going back to the servo with the master on and the trim switch activated.

I understand that Steinair did not fabricate the Av Board, so who is the mystery fabricator of the board? I'm at a loss as to where I go from here other than to Van's to see if I can get a new board to try.

JT
Reply With Quote
  #20  
Old 09-16-2009, 10:50 AM
vernhendershott vernhendershott is offline
 
Join Date: Dec 2007
Location: Spruce Creek, FL
Posts: 370
Default

Hi JT,

Yes you should go to Van's during the support hours, but be prepared to hear that the good support people know very little about their "Magic Box". If you are unable to get solid help then we as a group may have to approach Mr. Green, Van's President, to get him to hire or provide an avionics person for the support staff as he is now in the avionics business and I for one feel that he should provide that support that is required to get these kits working properly. I am 13 days into a magnetometer problem and last night I received the first response from Van's asking me to check the voltage on one pin, which I will do when they have confirmed that I do understand the instructions correctly to be sure that we are doing the test correctly in the hope that we do no damage to the Dynon.

Best regards,
Vern
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 12:24 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.