Replacing a potentiometer on a Commander

[66tbird]

I was about ready to show the AFPD game Commander the trash can and I thought I'd go for one last shot at a fix. I've sent it back twice already with eight week return times each time. Always the same failure after 20 hours. Jittery aileron in my case.

A simple Ohm meter test was all it took to verify the bad part. I'd tried tuner clean on the potentiometer but it didn't do anything. So then I whipped out a little tri-chlor from years ago and soaked (drowned) the part. Hey, it worked, for a while.

The part needs replaced. Anyone done this yet? Does it require a special pot? (i.e. odd ohm ranger) Or how about tacking a resistor in line and re-centering the pot? Maybe just grab another gimble from an old Tx and do the complete assembly?

I'm running these ideas past the board because where I live the weather is stupid hot and tinkering in the shop is out of the question. 118 in the shade, 125 in the shop and 181 in the car,, yea 181 :mad:

[66tbird]

Well I put the commander on the shelf, very disappointed in the product. Saw another unit on the bay with the same issue and sniped it cheap. I did it for the potentiometers. They are a little odd sized.

Plugged it in and sure enough same dead spot on the ele. So I pull the rudder pot, install it on my aileron and it works great,,,, for about an hour, Then the glitching starts, same channel. Pot now has a dead spot like it's brothers.

So I gather all the good potentiometers up and setup the ebay'd commander. Works great,,,,, for about an hour. it's the elevator, just like before. The seller had sent it back three time, nice overseas $40, 5 week trips :mad: Like me, but I only did it twice.

So I head down to the local guru (Circuit Central Dist. Inc.) and start going through their stuff. I find a couple military grade pieces that the guru says can handle anything that unit could put out with USB power. Great, I pop them in after a little shaft massaging and it does work,,,, for an hour or so.

Well, these little toys have just one more shot. I'm going to tack a cap across its terminals and see if that kills the spike thats killing the pot. If it don't, and there are no better ideas from this Sim forum, then these units will be parts of other projects and a better working simulator will be where my $ goes. You'd figure once the manufacturer has seen what is happening then a board swap instead of a pot swap would be the solution. Because I guess there are Units out there that still work :confused:

Yes, I know I could use the cord for my JR stuff, but I didn't get it for that. I got it to teach people the basics and not worry about messing up my real radios.

rant off, money lost, live, learn, tell others the truth, and move on.

[bilboa]

Why not just buy a better controller to use with your sim, rather than buy a different sim? The RealFlight controller is just as junky if you're at all picky about the stick movement being smooth around center. Reflex XTR's new iVol controller is supposedly higher quality, but for that price you could just use whatever sim software you want and buy a better controller separately.

[Malc C]

Not knowing the full ins and outs of the AFPD controller I would not of thought that the pot could be "burnt out" as the voltages and currents are so small. Generally these interfaces are based on micro-controllers such as the 16C745 and 18F2550 / 4550 types. Chances are that the pots on the gymbols are simply used to feed the analogue to digital convertors on these chips, ie the pot is across the supply (either 5 volts if powered from the USB socket or 9.6v if using the TX supply) with the wiper fed to the micro. The micro simply reads the voltage on from the wiper and converts this to a digital value which is then used in the programming and encoded into the data stream to the software.

If this is happening on the same pot each time, then try taking voltage readings across it and adjacent pots to see if it is being fed the same supply voltage. If there is excessive differences, try using a zenner diode or the like to regulate the voltage across the pots.

[BowerR64]

The problem is the design of the pot. The wipers rub against a graphite pad, this is what changes the resistance. After you use it a while (about an hour) the wipers sort of sand the graphite pad down inside the pot. The spikes your getting is the dust that is rubbed off the graphite pad. This is why it works for a while when you clean it.

One thing that can help is contact grease, what this does is collect the dust in the grease so that it doesnt get into the path of the wipers and cause these spikes.

I use to race this old old program called MCO and i used a wheel controler that was like an R/C controler, it was made by actsoft or somthing and it converted the analog signal to digital and then it came into the computer digitaly, it was the best control pot controler ive ever used. I never had any glitches, and it would eventualy fail when the pad would wear completly down to the fiberglass board the graphite was on. Ive never found anything since that worked like it.

Im sure there could be a program for these but no one but a select few have a problem with it. Its somthing that only a handful of people know this is not perfect but know it can be.

If there was a simple fix im sure it would of been thought of by now because guitars use these pots and they get noisy, amps use these pots, they get noisy

If there is a simple fix like a diode or a cap ide love to try it.

[66tbird]

Why not just buy a better controller to use with your sim

Good food for thought, I'll look into that. I need something light and USB powered. I have no idea what other controllers are compatible with this software

I would not of thought that the pot could be "burnt out" as the voltages and currents are so small. Generally these interfaces are based on micro-controllers such as the 16C745 and 18F2550 / 4550 types. Chances are that the pots on the gymbols are simply used to feed the analogue to digital convertors on these chips, ie the pot is across the supply (either 5 volts if powered from the USB socket or 9.6v if using the TX supply) with the wiper fed to the micro. The micro simply reads the voltage on from the wiper and converts this to a digital value which is then used in the programming and encoded into the data stream to the software.


I agree, then I read what I really suspected all along with what Bower said, Yet I have one unit that does it on the same channel only, or at least four times in a row, and another that has done that same on a different channel.

I'll do like you said Malc and test it in action and see what, or if anything my $1.99 mutli-meter can tell me.

I've got a few more pots. I'll test and clean and try again I guess. But if all systems work this way, or most, and I've had real radios for years that still work fine. Like my old Tower Gold system, lord that has to have hundreds of hours on it.

[Malc C]

Most cheap carbon track pots are expected to last a lot longer than you describe. I would suggest that rather than replace like for like (ie from another controller) you try and replace the actual pot with one of a similar value purchased from an electronics supplier (Digikey or mouser in the US, Rapid, RS or maplin in the UK). Most seem around 5K or 10K

If you can't replace the actual pots then look at a cheap TX to use with the interface, or as a donor and rip out the gymbals and use them

[BowerR64]

The first heli i bought used and it had some major damage to it, i got it in hopes i could use the controler as a sim controler to save me some money. I figured once i got good with the sim the heli would be there waiting to fly.

After some time i got the FMS working and i was doing pretty good, i noticed that if i pushed the right stick all the way down the model would go into a weird spin, full throttle and cyclic or somthing i could never recover from it. WHen i went into the calibration and did this move i could see all 4 chanels freak out some would go full and some would go minimum.

Since i was using a rig a maroo setup using the audio cable into the mic port, ppjoy yada yada i figure this was a glitch from all this junk i had to use to make it work.

After i bought a fe wmore helis i decided to try the controlers with them. guess what... they didnt have this glitch. The first controler had a bad pot in the full down position it was dead or somthing. If i had flown my heli with it in this condition it may cause a crash or some one hurt. I sprayed it with pot cleaner and the glitch is gone, for now.

So IMO, the sim is good for training, but its also good to test your controler. I mean the radio is the last thing you suspect to have problems. The heli i got crashed, it could of been because of this radio.

[Ledbetter]

66T,

Gotten any sim time in the last ten months? ;)

[66tbird]

66T,

Gotten any sim time in the last ten months? ;)

:D :D Hehehe,,, no,, afraid not. I sniped another controller on ebay and that even sat around for months.

Most cheap carbon track pots are expected to last a lot longer than you describe. I would suggest that rather than replace like for like (ie from another controller) you try and replace the actual pot with one of a similar value purchased from an electronics supplier (Digikey or mouser in the US, Rapid, RS or maplin in the UK). Most seem around 5K or 10K

yep, did that, mil grade sealed at $5 a pop. Got a few because I have other projects.