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Old Apr 10, 2012, 07:59 PM
9958 gave me the toilet bowl
Proud Infidel's Avatar
United States, IL, Rockford
Joined Jan 2012
1,257 Posts
Quote:
Originally Posted by Ribble View Post
A new circuit board means unsoldering and soldering 6 miniature wires on miniature circuit boards, that may be different revisions.

You really need a replacement V911 helicopter.
You're right. Few people are able to mess with solder points that small. I was a mechanic for 6 years. I didn't have to deal with anything so minute (small)
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Old Apr 10, 2012, 09:25 PM
Master CP
United States, TX, Burleson
Joined Feb 2012
389 Posts
Just got done with an incredible flight. Been watching some messages about someone doing a front flip with a Xieda 9958 - so I wanted to try it with the V911.

First off, let me tell you, I was not successful

I did learn some interesting things though. I was taking my V911 up high enough that I really couldn't see the orientation well, but still could see a bit of it. I'm guessing about 150ft+ up. In the twitchy mode, full forward, in a full vertical dive, I realized it wasn't going to do it about 20 feet off the ground. I cut power and it did a free fall. Picked it up and saw there was no damage!

Repeated this a second time, but this time at 10 feet above ground I didn't cut power, but did full back on the stick. It freakin' stopped in midair maybe 2 feet lower than when I started. Unbelievable! I didn't even hear a flybar strike.

Repeated it a third time. Was much, much braver this time. Didn't pull the stick back or cut power, but just kept it going. It went straight into the ground. Picked it up. It was in two pieces...the copter and the blades. The blades were still together and one side was buried about 2 inches in the dirt/mud. Thought that I'd have to stop flying for the night, but I was wrong. Took 2 minutes to put it back together and get back outside and flying.

This copter is a beast!
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Old Apr 10, 2012, 10:13 PM
Registered User
Canada, ON, Ottawa
Joined Jun 2009
3,534 Posts
Quote:
Originally Posted by Proud Infidel View Post
You're right. Few people are able to mess with solder points that small. I was a mechanic for 6 years. I didn't have to deal with anything so minute (small)
If the servo operates and it only freezes occasionaly it does not look like an electronic issue. Hence no soldering should be required, just mechanical fix.

I suggest take a look at the gears inside first. Even if we find a broken tooth, we probably can turn it around to keep it working.

Mine was caused by some debris inside. It costed nothing to fix.

Only take 3 screws off and be careful not to lose any small parts.
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Last edited by Wasp09; Apr 11, 2012 at 12:36 AM.
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Old Apr 10, 2012, 11:40 PM
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Joined Sep 2007
480 Posts
Quote:
Originally Posted by Ribble View Post
Oddly, they put a pull-up resistor on the LED control. The IC shorts to ground to turn on the LED, A pull-up does nothing, They could have saved two resistors. OK, there could be another function for the resistors, I doubt it. I almost got the iron hot to remove a resistor and see what happens. And there were other parts that I would not have put on, like other pullups and capacitors. The Chinese don't skimp on parts.
The pullup is very important.

An LED might be speced at 10mA.
It might have a typical forward voltage between 1.3v(Red) and 2.7V(Green).
Beyond that voltage they are very non-linear and will draw way too much current.

The series resistor helps turn things back into a linear circuit.

Assume 5V.
At 10mA, a 330 Ohm resistor has 3.3V across it.
Leaving 1.7 for the LED>
If the LED starts to draw more current (as it gets hot), the resistor will sap more voltage and tone things down.

Put an LED (anything but white) across 5V and your asking for a brief bright flash.

Now if you're thinking, that microprocessor pin can't sink more than 20mA, so I don't need no stinking resistor, you're kind of right.
They spec at least 20mA. They could have improved. would your LED like 50mA?
You're also causing a single tiny transistor in the IC to dissipate a lot of power.

Resistors work, and they are cheap.
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Old Apr 10, 2012, 11:48 PM
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Quote:
Originally Posted by bobepine View Post
I'm beyond trying to use a pot. Just trying to get transistors to work with a switch like my other V911 TX. It's not working. At this point, I have retired that TX.

Chris
Can you post a schematic of what you're trying to accomplish?
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Old Apr 10, 2012, 11:53 PM
Crash and learn
United States, PA
Joined Dec 2011
1,605 Posts
V911 Dual Battery Charger Diagrams

Quote:
Originally Posted by RicksterRC View Post
Resistors work, and they are cheap.
No, this is a pull-up resistor. Like you would put on an open-collector output.

A series circuit .......

+5v --- LED ---- series resistor ------ driver.

Driver shorts to ground, LED turns on.

The added pull-up resistor pulls the driver output up to +5 volts.
----

Series Resistor = 1K = LED current less than 5ma, likely 2.5ma
Pullup Resistor = 10K

.XC6802 Series
http://www.torex.co.jp/english/produ...ata/XC6802.pdf
.
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Old Apr 11, 2012, 12:32 AM
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Canada, ON, Ottawa
Joined Jun 2009
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Quote:
Originally Posted by RicksterRC View Post
Can you post a schematic of what you're trying to accomplish?
And picture of what you did?

If you remove all the mod would it be back to normal?
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Old Apr 11, 2012, 12:35 AM
Registered User
Canada, ON, Ottawa
Joined Jun 2009
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Quote:
Originally Posted by Ribble View Post
No, this is a pull-up resistor. Like you would put on an open-collector output.

A series circuit .......

+5v --- LED ---- series resistor ------ driver.

Driver shorts to ground, LED turns on.

The added pull-up resistor pulls the driver output up to +5 volts.
----


+5v on left. LED on Top. Driver on bottom, SeriesResistor Right
----- PullupResister on left to +5V

.
Can you circle the pull-up resistor in the piture on the left?
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Old Apr 11, 2012, 01:09 AM
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Joined Jan 2012
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Hey you guys its been awhile but I have been having a blast w/my 911s,Ihave taken a time out on following this forum because of my other heli projects(and 1 planker)but just got the E-Hirobo monthly newsletter and they have the 911 RTF for $40.99 in white w/a cool looking canopy as of today,hope this helps somebody/Cant say enough about my favorite micro
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Old Apr 11, 2012, 01:10 AM
Crash and learn
United States, PA
Joined Dec 2011
1,605 Posts
Quote:
Originally Posted by Wasp09 View Post
Can you circle the pull-up resistor in the piture on the left?
I can circle on my copy, but I can not make it stick.

I get carried away with circuits. Nobody cares anyway, except the designer who put the pullup resistors in the circuit.

EDIT:
Series Resistor = 1K = LED current less than 5ma, likely 2.5ma
Pullup Resistor = 10K

XC6802 Series
http://www.torex.co.jp/english/produ...ata/XC6802.pdf
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Last edited by Ribble; Apr 11, 2012 at 03:44 AM.
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Old Apr 11, 2012, 02:09 AM
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robbynaish's Avatar
Rome
Joined Oct 2003
103 Posts
@Proud Infidel
@Ribble
Wasp09


Many thanks to all.

I wrote a PM at Aaron qin as you suggested explaining my problem (my v911 arrived only yesterday).
Normally he answer fast? Is necessary write to banggood too?

DO u think is better i dont touch the servo till he dosenet answer me? Im afarid if i open smt than they can say they cant send me a replacement anymore.

thanks

Ale
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Old Apr 11, 2012, 02:13 AM
Crash and learn
United States, PA
Joined Dec 2011
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Quote:
Originally Posted by robbynaish View Post
@Proud Infidel
@Ribble
Wasp09
Many thanks to all.
I wrote a PM at Aaron qin as you suggested explaining my problem (my v911 arrived only yesterday).
Normally he answer fast? Is necessary write to banggood too?

DO u think is better i dont touch the servo till he dosenet answer me? Im afarid if i open smt than they can say they cant send me a replacement anymore.
Ale
You open it, you buy it. Don't open the servo.

Copy your message to Banggood. It won't hurt.
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Old Apr 11, 2012, 04:00 AM
Aaron qin's Avatar
China, Guangdong
Joined Oct 2011
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Quote:
Originally Posted by robbynaish View Post
thanks for yr fast replay... yr "good luck" make me feel that the thing to do is no so so easy :'(

Is it a suspect or u know its happened and its the solution?

thnks

Ale
Could you please attach some photos or a short video to make the problem more easy to understand?
a little hard to understand for a nonEnglish speaker,LOL
You know there are many master hand here,maybe they can help you solve the issue?
If they all can not,of course we would definitely do something for you.
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Last edited by Aaron qin; Apr 11, 2012 at 04:07 AM.
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Old Apr 11, 2012, 04:42 AM
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Joined Nov 2011
299 Posts
How do you get the paddle mod stable? Mine is wandering around and very floaty. Every movement I try to correct will overcompensate and make it worse. Do I need more weight in the end of the paddles? My paddle mod is a bit under 2g, with msr paddles.
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Old Apr 11, 2012, 05:53 AM
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robbynaish's Avatar
Rome
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103 Posts
Quote:
Originally Posted by Aaron qin View Post
Could you please attach some photos or a short video to make the problem more easy to understand?
a little hard to understand for a nonEnglish speaker,LOL
You know there are many master hand here,maybe they can help you solve the issue?
If they all can not,of course we would definitely do something for you.
Hi,

i tried do a small video, i think it explain good what is the problem

V911 with Faulty Servo (0 min 20 sec)


What do you think?

PS: i sent u PM, but i get an automatic answer yr Pm box is full and u sent me email, that i didnt get

Many thanks

Ale
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