7C - Servo neutral points shift at different throw settings.
09-20-2005 | 04:13 PM
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From: Sammamish,
WA
7C - Servo neutral points shift at different throw settings.
I just found a hidden "feature" on my 7CAP that I can't resolve. I have three different control surface throws programmed on the three position switch G. <edit> The airbrake function assigned to this switch by the internal TX programming is inhibited, and no other pmixes are assigned to this switch <edit>. The "DOWN" switch is set for 100% throws on CH1 (ailerons), CH2 (elevator), Ch4 (rudder). The switch "MIDDLE" position reduces all throws to 75%, and the "UP" position reduces further to 50%.
The anomaly is that when I move from 100% to 75% throws with stick untouched in neutral, both the ailerons and the elevators move slightly off center. The rudder, however, does not. When I go to 50% throws, the elevator and ailerons move a little further off center, but again there is no movement of the rudder. <edit> I tried different amounts of rate percentages, and the amount of movement appears to be inversely proportional to the rate percent programmed in. If I have 100% rates, there is no deflection, and if I have 0% rates, there is about 4 deg. deflection. Rates between these values fall proportionally in between. <edit>
These movements are small, but noticable not only visibly but also while flying (fortunately they are not severe enough to have caused a crash, but the plane is definitely out of trim when I toggle the throw settings. I tried putting throws on a different (2 position) switch, with no change. I tried moving my sub-trim settings to see if that changed the movement, and it did not. I then reset all the throws to 100% at all three switch positions, and the servos stay in the same neutral position at all switch positions. So, this is definitely linked to the throw percentages, but it doen't show up on the rudder channel. <edit> I tried different servos to see if they stayed put, and they did not. I swapped the servo connections on the RX for rudder and elevator, and the problem moved from elevator to rudder, so the RX is not part of the problem. These tests seem to confirm the TX is the root cause with something internal affecting only on CH 1 and Ch2 (aileron and elevator). <edit>
This behavior can't be normal (can it?). It also explains why I've had changing flight trims with different throws from day one with this transmitter... I just never found out why until now. If a trip to the shop is needed, will this be covered under warranty? <edit> I ordered the TX a year ago this month, early in the month, but never got to use it until the following month because I immediately sent it back for servicing of the throttle timer bug! <edit>.
p.s. While your at it, will you please answer the question on max. changing rate through the 7c TX charging plug posted [link=http://www.rcuniverse.com/forum/m_3193202/tm.htm]here[/link]?
The anomaly is that when I move from 100% to 75% throws with stick untouched in neutral, both the ailerons and the elevators move slightly off center. The rudder, however, does not. When I go to 50% throws, the elevator and ailerons move a little further off center, but again there is no movement of the rudder. <edit> I tried different amounts of rate percentages, and the amount of movement appears to be inversely proportional to the rate percent programmed in. If I have 100% rates, there is no deflection, and if I have 0% rates, there is about 4 deg. deflection. Rates between these values fall proportionally in between. <edit>
These movements are small, but noticable not only visibly but also while flying (fortunately they are not severe enough to have caused a crash, but the plane is definitely out of trim when I toggle the throw settings. I tried putting throws on a different (2 position) switch, with no change. I tried moving my sub-trim settings to see if that changed the movement, and it did not. I then reset all the throws to 100% at all three switch positions, and the servos stay in the same neutral position at all switch positions. So, this is definitely linked to the throw percentages, but it doen't show up on the rudder channel. <edit> I tried different servos to see if they stayed put, and they did not. I swapped the servo connections on the RX for rudder and elevator, and the problem moved from elevator to rudder, so the RX is not part of the problem. These tests seem to confirm the TX is the root cause with something internal affecting only on CH 1 and Ch2 (aileron and elevator). <edit>
This behavior can't be normal (can it?). It also explains why I've had changing flight trims with different throws from day one with this transmitter... I just never found out why until now. If a trip to the shop is needed, will this be covered under warranty? <edit> I ordered the TX a year ago this month, early in the month, but never got to use it until the following month because I immediately sent it back for servicing of the throttle timer bug! <edit>.
p.s. While your at it, will you please answer the question on max. changing rate through the 7c TX charging plug posted [link=http://www.rcuniverse.com/forum/m_3193202/tm.htm]here[/link]?
09-21-2005 | 02:08 PM
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From: Champaign, IL
RE: 7C - Servo neutral points shift at different throw settings.
Hi Tom,
Before doing anything I would suggest going into a blank model and setting this up to see if the problem still occurs, this will eliminate any other programming affecting this.
But from what you are describing it sounds as though it may be that the pots need recalibrated. And in that case you would need to send this in to us.
I hope you find this information helpful. You can also reach our Futaba support technical team at 217-398-8970, or via fax at 217-398-7721.
Sincerely,
Krysta
Lead Futaba Customer Service and Programming Technician
Before doing anything I would suggest going into a blank model and setting this up to see if the problem still occurs, this will eliminate any other programming affecting this.
But from what you are describing it sounds as though it may be that the pots need recalibrated. And in that case you would need to send this in to us.
I hope you find this information helpful. You can also reach our Futaba support technical team at 217-398-8970, or via fax at 217-398-7721.
Sincerely,
Krysta
Lead Futaba Customer Service and Programming Technician
