Search for Replacement 9x Potentiometers!

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Flaps 30
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Re: Search for Replacement 9x Potentiometers!

Post by Flaps 30 »

That's a shame Mike. The link works okay here.. This is another link of roughly the same thing using the Allegro 1302 -----> http://simhq.com/forum/ubbthreads.php/t ... ensor.html

What did you have in mind with regard to the magnetic encoder?
rperkins wrote:I like that hall effect idea. While researching the hall effect idea noticed that those aurora9 gimbals at lynxmotion.com are back in stock
Just checked. They are out of stock now.

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Re: Search for Replacement 9x Potentiometers!

Post by rperkins »

hmm. maybe i got the wrong ones or you gotta actually checkout to determine the stock status. sorry
http://www.lynxmotion.com/p-839-aurora-9-gimbal.aspx
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Re: Search for Replacement 9x Potentiometers!

Post by bob195558 »

In the photo you will observed three small holes which I had hand drilled with a Pin-Vise in which I tried to make the
connection between the Red wire Eyelet connector and the Resistant Element Surfaces.
I then wove some single strands of copper wire in and out of the holes, But when I checked for a better connection it did not work very well.
After removing the strands of copper wire, I had worse continuity connection then I had before.
But I think this was because of the large hole down steam from the Eyelet connector that it made the area of the Resistant Element Surfaces much narrower and/or less conductive.

I then went to the Conductive Silver Ink: CAIG CircuitWriter Pen Silver Ink, that RadioShack has.
This is made from Silver dust with an acrylic binder and is used to make conductivity traces on circuit boards, repair defective traces, make jumpers and shield electronics, design prototype circuits and repair electronic devices, like our 9X Radio's Potentiometers.
You can see where I applied the CAIG Silver Ink and I waited over night for it to dry and in the morning I reassembled my 9X throttle Potentiometer.
I then checked it out for conductive and now it has solid conductivity like it should have.
And when I tried it in my FlySky 9x Radio, it works great now.
I have the feelings that it is 100% more reliable then it was before.

I think the Number One Problem with our 9x Radio Potentiometers is this Weak Connection (inside the Potentiometer) between the Positive Input 5 volt Red Wire Eyelet Connector
to the Resistant Element Surfaces.
And the best solution to repair this Weak Connection is to remove the Resistant Element Surfaces back plate and use the Conductive Silver Ink Pen to repair this the fragile connection.
I used the CAIG CircuitWriter Pen Silver Ink, that I found at RadioShack.
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Last edited by bob195558 on Fri Nov 22, 2013 11:35 pm, edited 1 time in total.
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Re: Search for Replacement 9x Potentiometers!

Post by bob195558 »

The Ohms resistant readings of my 9x Potentiometer were as follows:

With my Digital Multimeter set to 20K Ohms and connecting the red cable to the
Positive 5 volt input Red Wire and the black cable to the Negative Ground Black Wire.

I get the reading of total Ohms Resistant to be: 6.7.5 Ohms.

Next I moved the black cable to the Output Single White Wire and left the red cable connected to the Positive 5 volt input Red Wire.

The readings are as follows:

Potentiometer Shaft Rotation when Installed into the Gimbals
Low Shaft Rotation: 0.7.4 Ohms Resistant
Center Shaft Rotation: 3.9.0 Ohms Resistant
High Shaft Rotation: 6.6.4 Ohms Resistant

The extra decimal point ? I did not understand also.
But comparing with a different Multimeter it looks like its carrying one more decimal point and so it is more precise in its reading then most other Multimeter.
The Multimeter was purchased from Walmart (INNOVA 3300) and may have something wrong with it but a closer look at it may show why the extra decimal point .
Using a different Digital Multimeter GE2524 it dose not have the extra decimal point, but it is rounds the reading up and/or down.
If I had a reading of 2.5.8 Ohms with the INNOVA 3300 Multimeter, the other Digital Multimeter GE2524 will round the same reading up to 2.6 Ohms.
So you could round my reading up or down and drop the extra decimal point from the right, But the reading will be less accurate.
The other Multimeter is less accurate, but look more correct with out the added decimal point.



With my different attempts in repair this 9x Potentiometer, the resistant values may have changed.
If there is still a weak connection somewhere, it may raise the Resistant values.
But it dose seem much more solid with it's readings now then it did before the Conductive Silver Ink repair.
The INNOVA 3300 Multimeter has an extra decimal point and is more accurate when it is used connected to
the Input 5 volts + Red Wire and and the Output Single White Wire.


.
Attachments
Multimeter is set to the 20K Ohms position and is connected to the Potentiometers <br />Input 5 volts + Red Wire and to the Ground Black Wire which gives a total resistant reading of 6.7.5 Ohms.<br />Using INNOVA 3300 Multimeter<br /><br />...........................................................................................................................................................................<br /><br />...........................................................................................................................................................................
Multimeter is set to the 20K Ohms position and is connected to the Potentiometers
Input 5 volts + Red Wire and to the Ground Black Wire which gives a total resistant reading of 6.7.5 Ohms.
Using INNOVA 3300 Multimeter

...........................................................................................................................................................................

...........................................................................................................................................................................
Low Stick Position<br />Potentiometer Shaft Rotation is at Low Stick Position: 0.7.4 Ohms Resistant<br />Using INNOVA 3300 Multimeter which is connected to the Input 5 volts + Red Wire and and the Output Single White Wire. <br /><br />.......
Low Stick Position
Potentiometer Shaft Rotation is at Low Stick Position: 0.7.4 Ohms Resistant
Using INNOVA 3300 Multimeter which is connected to the Input 5 volts + Red Wire and and the Output Single White Wire.

.......
Center Stick Position<br />Potentiometer Shaft Rotation is at Center Stick Position: 3.9.0 Ohms Resistant<br />Using INNOVA 3300 Multimeter which is connected to the Input 5 volts + Red Wire and and the Output Single White Wire. <br /><br />.......
Center Stick Position
Potentiometer Shaft Rotation is at Center Stick Position: 3.9.0 Ohms Resistant
Using INNOVA 3300 Multimeter which is connected to the Input 5 volts + Red Wire and and the Output Single White Wire.

.......
High Stick Position<br />Potentiometer Shaft Rotation is at High Stick Position: 6.6.4 Ohms Resistant<br />Using INNOVA 3300 Multimeter which is connected to the Input 5 volts + Red Wire and and the Output Single White Wire. <br /><br />............................................................................................................................................................................
High Stick Position
Potentiometer Shaft Rotation is at High Stick Position: 6.6.4 Ohms Resistant
Using INNOVA 3300 Multimeter which is connected to the Input 5 volts + Red Wire and and the Output Single White Wire.

............................................................................................................................................................................
Last edited by bob195558 on Mon Apr 01, 2013 1:26 am, edited 2 times in total.
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Re: Search for Replacement 9x Potentiometers!

Post by ShowMaster »

Good pictures.
I'm confused by the ohm readings having so many decimal points?
Using the 20K scale I would expect something like else?
Of the pots are still connected to the + and - busses that should maybe be 6 5K pots in parallel. 5K decided by 6 pots could equal 833 ohms you could measure. I'd have to open my tx to make this measurement.
The best way to do a comparison is to disconnect the two end pit wires on a good pot and a repaired one and compare the resistance. You should read 5000 ohms across the outside pot sites and around 2.5 k when centered. Then compare the rate of change between the two pots when the stick is moved it's normal range.
You could also leave everything connected as normal and with power on, measure the rate of change voltage from + to the center wiper and then gr - to the center. The meter hopefully will track good enough to make this test work. If you had a scope or scope program for your computer you could measure the PPM pulse changes or maybe a servo in a good pot channel compared to a repaired one.
I'm still confused by the 6.6.4 and 3.9.0 type readings on your meters 20k range scale?
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Re: Search for Replacement 9x Potentiometers!

Post by gohsthb »

Looks like there is some problem with his meter. It sounds reasonable to ignore the second period. Then he has 0.74k, 6.64k, and 3.9k.
-Gohst

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Re: Search for Replacement 9x Potentiometers!

Post by Promix »

hehe. That`s a funny thing ! :D
I just come across this thread and I remember that I have done a working pod mod with hall sensor to one of my 9x. It was designated as a temporary prototype for test. But it works so nice for more than six month now, so I forgot it completely :shock: :lol:

I am pretty sure it will going to work beyond the life time of the radio.
8-)
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Re: Search for Replacement 9x Potentiometers!

Post by jhsa »

Nice.. would you mind sharing more details? like which sensor did you use? and magnet and how did you place it?
Shame on you for hidding this from us ;) :mrgreen: :mrgreen:

I can smell more mods coming :mrgreen:

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Re: Search for Replacement 9x Potentiometers!

Post by Flaps 30 »

+1 on the hall effect device. Nice work there Promix. More information would be great. :)

João - Yes this would make a good modification to do if you are unhappy with the pots as they are, or you are having troubles with existing ones.
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Re: Search for Replacement 9x Potentiometers!

Post by ShowMaster »

gohsthb wrote:Looks like there is some problem with his meter. It sounds reasonable to ignore the second period. Then he has 0.74k, 6.64k, and 3.9k.
-Gohst

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I've never seen that meter display so I'm going to look up that model.
Even ignoring the second period those values seem wrong? Unless his repair has added a lot of resistance to the element and assuming it's not connected to all the others, 6.64k is real high for a 5k pot. That would mean that his repair isn't working out well.
Hopefully he'll do the same measurements on a good working pot so we have something to compare his reading to using his meter scale.
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Re: Search for Replacement 9x Potentiometers!

Post by ShowMaster »

Hall effect pot. Got to read up on this one. If Frsky's new tx does what rumors say it will and if Frsky offers replacement parts, I'm in!
I would like to upgrade my 9x pots in any case if a better one come along.
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Re: Search for Replacement 9x Potentiometers!

Post by ReSt »

The absolute resistance of the pot is not so important as it works as a voltage divider. The really important thing is, how much voltage range does he get with full stick movement. If it is in the range of 4 volt out of 5 volt total, than it's good as new.


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Re: Search for Replacement 9x Potentiometers!

Post by Promix »

@Joao
Yeah, shame on me. I think I`m getting old ............ :shock: :lol:

Anyway, here are some details about my podmod.
I use the Honeywell hall sensor device SS495B http://sccatalog.honeywell.com/imc/prin ... &PN=SS495B

The advantage is that it works directly with 5V with a linear output. And it can be used as a direct replacement for the stock pot. Except it is now important to connect the leads to the correct direction of plus and minus !
The magnet is a neodymium type of 2mm, cube or cylindric shape. You can get them from ebay or somewhere else. I put the magnet in place with a drop of superglue and after that I put some very little epoxy around. To make life easier I am going to build a little positioner tool for it.
Oh yes....., without it was a mess to fiddle around with this little tiny things to find the correct position and distance and on top of this the pot housing is made of iron sheet metal and it loves little tiny magnets. :evil:
However, it is very important to position everything correctly for center and voltage range to get the full resolution out of stick travel.
It would be much easier just to glue magnet and sensor in a raw position and use a little smd opamp board to make the fine adjustment just before doing calibration by the firmware.

I made some scale CAD drawings of all parts and will post them when I have revised and updated.

I hijacked the nice picture from bob195558 and make some ugly drawings on it to show vaguely how it is assembled now.
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Re: Search for Replacement 9x Potentiometers!

Post by mpjf01 »

There seems to be a demand for a replacement for the pots for both the 9x and the 9xr. There would possibly be some merit in finding an eBay supplier of a pot that fits mechanically, standardise on that and then accomodate the differences for that choice in the firmware. Is that sensible or practical?
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Re: Search for Replacement 9x Potentiometers!

Post by Flaps 30 »

I would have thought that the Allegro A1302 hall effect device might do for the job. It is more sensitive than the Honeywell device. So no doubt some messing around with the positioning of the sensor distance from the magnet would be required to get the voltage swing needed.

Promix - Did you have to play with the sensor distance with your setup? Just another thought here. If a more sensitive hall effect device is used, is there a chance that the magnet could be attached to the shaft assembly as you have done, then have the sensor glued to the outside of the disc (which could be some thin fibreglass board) and in doing so make adjusting if the final position easier?

2mm diameter by 1mm thick magnets along with the Allegro A1302's are available on Ebay at reasonable prices.
Last edited by Flaps 30 on Sat Mar 30, 2013 12:16 am, edited 1 time in total.
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Re: Search for Replacement 9x Potentiometers!

Post by jhsa »

I might get some just to play with it.. :)
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Re: Search for Replacement 9x Potentiometers!

Post by Flaps 30 »

Go ahead João. It will keep you off the street for a while longer. :)
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Re: Search for Replacement 9x Potentiometers!

Post by jhsa »

There's plenty of stuff around here keeping me off the street... :) I love my bunker anyway.. :D
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Re: Search for Replacement 9x Potentiometers!

Post by Promix »

The sensitivity is not critical. These little magnets are strong enough anyway. I played allot with distance and position to learn how it works best.
No doubt that the Allegro device may do the job like the Honey one. But whichever device will win the cup at the end it needs an opamp circuit for fine adjustment.
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Re: Search for Replacement 9x Potentiometers!

Post by Flaps 30 »

Thanks Promix. :)

My thought of mounting the hall effect device on the outside of the plate (made out of thin fibreglass board) would allow you to position the sensor to get the required range, along with the correct centre voltage, without having to go back inside the assembly. Wouldn't that be enough to negate any requirement of an op amp? Doing the standard calibration removes the need to get the range and the centre voltage exact IMO.
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Re: Search for Replacement 9x Potentiometers!

Post by Promix »

No, you really need the full voltage range. Anything less will reduce the ADC resolution instantly. You can`t compensate this by standard calibration, it only expand or reduce whatever range is present at the ADC port with the cost of resolution or resulting in dead band.
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Re: Search for Replacement 9x Potentiometers!

Post by jhsa »

Maybe you already said it and I missed it.. but did you use an opamp?
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Re: Search for Replacement 9x Potentiometers!

Post by Promix »

No, I was nerdy enough to find the only one fixed point. :ugeek: :mrgreen:
Well,...after that I was pooped and unable to hold a cup of coffee steady :lol:
So I would`d do that for all the remaining 7 pots .... :)

EDIT
I have 2 radios .... :roll: ;)
Last edited by Promix on Sat Mar 30, 2013 1:35 am, edited 1 time in total.
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Re: Search for Replacement 9x Potentiometers!

Post by jhsa »

wel, if it works good..... why not changing the other 3?? :D ;)
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Re: Search for Replacement 9x Potentiometers!

Post by Rob Thomson »

Any of these of use?


http://www.potentiometers.com/select_hall.cfm


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Re: Search for Replacement 9x Potentiometers!

Post by Promix »

No, I don`t think so. They are too big and don`t ask for the price. I`ll bet for each of them you can buy a complete radio. Then you will have at least 16 stock pots for spare :D
I was searching for those hall pots at a reasonable price for a while, but without luck.

IMHO the best way is to make it as DIY

( I can`t find the little op amp board which is already here. It was a board designed by Mike, I guess. Can someone point me to this thread please ? )
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Re: Search for Replacement 9x Potentiometers!

Post by jhsa »

Here, but it was designed by someone else I think. Mike fine tuned it .. But I could be wrong of course :D

http://openrcforums.com/forum/viewtopic ... uit#p19330

João

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Re: Search for Replacement 9x Potentiometers!

Post by Flaps 30 »

Promix wrote:No, you really need the full voltage range. Anything less will reduce the ADC resolution instantly. You can`t compensate this by standard calibration, it only expand or reduce whatever range is present at the ADC port with the cost of resolution or resulting in dead band.
Yes I understand that. You said in a later post that you spent a while finding the 'sweet spot' for the sensor. That is what I was trying to simplify by mounting the sensor on the outside of the potentiometer case. Hence the thin fibreglass (less than 1mm) board that will allow you to place the sensor anywhere to get the centre voltage and the range as it should be, without having to open up the pot again, or having limited space to move it if it was inside the case.

I haven't investigated how drastic the resolution would be reduced if the voltages where a few tenths of a volt or two off from where the pots would be. I suspect that you could easily get within tolerable limits that would cost you very little in resolution.

That is a fairly standard circuit João. Add a pot to set the offset voltage and another to change the gain (range) then you have it about right. The purists would insist on temperature compensation, along with additional circuitry to alter the symmetry, to correct for the sensor being off centre which would end up giving an asymetric output if not corrected.
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Re: Search for Replacement 9x Potentiometers!

Post by MikeB »

The MCP602 is good over temperature, offset voltage drift is only around 2.5uV per degree C. So over 40 degrees, only 100uV. With a gain of 4, this is only 0.4mV on the output, only 1 part in 10000 for a 4 volt swing. If the three resistors are the same type, they should have no significant effect on the gain. Adding pots for offset and gain could make things worse as their temperature coefficients are often much worse than fixed resistors.

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Re: Search for Replacement 9x Potentiometers!

Post by mpjf01 »

For the not so electronically literate, is there a relatively easy way to determine whether any particular pot or gymbal is or can be made suitable as a 9x replacement? Does one measure the resistance between the centre and one of the end terminals, or the two ends, or what, and what should the value be? Or do you measure something else (I see reference to voltage here but I have no idea how or where to apply a voltage source, what to use, etc). A simple guide explaining what to measure and how would really be appreciated. Sorry for the basic question, been flying for years but never had to learn about this type of thing before, just replaced faulty pots with those of the same value from the radio supplier's spares bin.

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