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admiralriker

Replacing Controller Potentiometers

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Hello everyone,

 

I have four controllers (two consoles). Out of the four controllers, three have an issue with potentiometers where they are constantly going to the right; I believe that these pots are totally dead. The buttons and flex circuits work just fine. I want to replace these three controllers pots.

 

Is there anywhere to get replacements?

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Before you give up on them, a couple questions:

 

1. Do you have a copy of Pete’s Test Cart and/or an AtariMax cart to run the binary so you can see the numerical values on each axis? 
2. Have you tried the calibration procedure for the stock controllers as described in the 5200 Field Service Manual?

 

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once you get them open you may find the pot arms are out of adjustment check them with a multimeter tone out the cord (harness)

 

before i took them apart i would use the ohm meter to check them out through the cord i think its pins 9-10 and 9-11 check a female plug diagram to find locations i use little paperclips in the holes

 

 

ps anyone wanting a controller adapter sorry its not that i am not making them anymore its just that i dont want to

 

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I never had trouble with the original 5200 controllers as far as the potentiometers going bad. I have repaired dozens that have the typical mylar flex circuit problem. The real problem is with the Wico 5200 joysticks. The potentiometers in them are horrible and it's very hard to find one of these joysticks that doesn't have a bad one. I have searched forever and have made many calls to electronic stores/ manufacturers with no success.

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Recently I took some measurements of the potentiometers in both the Atari controllers and the Wico joysticks.  The Atari controllers had a range of 0-1.4 M ohm while the Wico joystick had a range of 0-700 K ohm.  I'm assuming that the Atari controllers are not using the high end of the range.  Anyone know why the ranges are so different?

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Atari controllers are only using about half of the full wiper motion in the pots. Thats the main reason right there. In fact it isn't even quite half more like just over 1/3 of the full range.

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According to the service manual, the resistance on up/left should be less than 50k Ohms.

On the opposite direction (down/right)  the resistance should be at least 430k Ohms higher than the value measured on up/left.

Then, surely the controller does not use the full range of the potentiometer.

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It turns out that most of these potentiometers can be refurbished; its actually easier with very old pots. like in antique radios and amplifiers which had much higher quality solid-state parts.  We're talkin' 80s garbage here, but I think the same methodology can be applied:

 

Here's a post I found from a antique radio enthusiast ("Doug VanCleave"):

 

When I worked for ABL Electronic Service in the early '80s, we repaired only high end audio equipment. Our prices insured that.


We were required to use a 3-step technique to clean controls. First the pot was flooded with contact cleaner without a lubricant. The control was exercised from end to end while flushing out all debris.

Spray contact cleaner is cold and causes condensation. The control was warmed and dried with a hand held dryer to evaporate any condensation from the contact cleaner. The shaft was not moved at this point as not to scratch the dry carbon element.

Finally just a spirits of Channel Master Shield was sprayed into the control and worked in by again exercising the pot from end to end while the control was still warm. Oily contact cleaner bleeding all over the chassis and circuit boards was considered unprofessional and sloppy.

WD-40 is cutting oil. It is not a quality lubricant designed for carbon film potentiometers or turntable motor bearings.

 

I don't think "Channel Master:  Shield" is available anymore, which is a real shame.  I remember using this on some Lowrey organs. . . worked wonders.  Whatever substitution you choose, make sure it's an electronics lubricant; I'm pretty sure these controller pots. are conductive carbon (someone please correct me if this is not the case), so use an appropriate finishing lubricant.  I would recommend DeoxIT Fader Spray FN5S-2N.  It works for conductive plastic or carbon.  I hope this helps!

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3 hours ago, patroclus99 said:

It turns out that most of these potentiometers can be refurbished; its actually easier with very old pots. like in antique radios and amplifiers which had much higher quality solid-state parts.  We're talkin' 80s garbage here, but I think the same methodology can be applied:

 

Here's a post I found from a antique radio enthusiast ("Doug VanCleave"):

 

When I worked for ABL Electronic Service in the early '80s, we repaired only high end audio equipment. Our prices insured that.


We were required to use a 3-step technique to clean controls. First the pot was flooded with contact cleaner without a lubricant. The control was exercised from end to end while flushing out all debris.

Spray contact cleaner is cold and causes condensation. The control was warmed and dried with a hand held dryer to evaporate any condensation from the contact cleaner. The shaft was not moved at this point as not to scratch the dry carbon element.

Finally just a spirits of Channel Master Shield was sprayed into the control and worked in by again exercising the pot from end to end while the control was still warm. Oily contact cleaner bleeding all over the chassis and circuit boards was considered unprofessional and sloppy.

WD-40 is cutting oil. It is not a quality lubricant designed for carbon film potentiometers or turntable motor bearings.

 

I don't think "Channel Master:  Shield" is available anymore, which is a real shame.  I remember using this on some Lowrey organs. . . worked wonders.  Whatever substitution you choose, make sure it's an electronics lubricant; I'm pretty sure these controller pots. are conductive carbon (someone please correct me if this is not the case), so use an appropriate finishing lubricant.  I would recommend DeoxIT Fader Spray FN5S-2N.  It works for conductive plastic or carbon.  I hope this helps!

Yes they are carbon conductive pots. You can actually dissassemble them to better clean them up and I've done so in the past. But it isn't the most fun trying to do this. So what I do now is use contact cleaner and degreaser...then follow it up with contact cleaner and lubricant. I've got two separate cans each marked as I described. Then if I've able to do so, I will try and get some dielectric grease in there to help with preventing further debris or corrosion. The same thing is done with Vectrex power/volume knobs as well and works great. But the actual pots in these things are only using about a 1/3 of the entire wipe that is allowed. What determines which part or range of the entire wipe is used is the placement of the small white arm that is press fit onto the shaft of the pot. That arm can be turned separately from the shaft if you turn it to the extremes where it stops and keep pressing against the white arm, it will then slip and shift over. This is what I meant about calibrating the controller itself to match the console or to get the expected values that match per the service manual for proper controller activation. 

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6 hours ago, -^CrossBow^- said:

Yes they are carbon conductive pots. You can actually dissassemble them to better clean them up and I've done so in the past. But it isn't the most fun trying to do this. So what I do now is use contact cleaner and degreaser...then follow it up with contact cleaner and lubricant. I've got two separate cans each marked as I described. Then if I've able to do so, I will try and get some dielectric grease in there to help with preventing further debris or corrosion. The same thing is done with Vectrex power/volume knobs as well and works great. But the actual pots in these things are only using about a 1/3 of the entire wipe that is allowed. What determines which part or range of the entire wipe is used is the placement of the small white arm that is press fit onto the shaft of the pot. That arm can be turned separately from the shaft if you turn it to the extremes where it stops and keep pressing against the white arm, it will then slip and shift over. This is what I meant about calibrating the controller itself to match the console or to get the expected values that match per the service manual for proper controller activation. 

Oh. . . using that dielectric grease is a great idea!  I was always hesitant to use something like that, but really, I can't see why not in this particular situation.  I've also read some suggestions recommending lithium grease, but. . . I . . . dunnnno.

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On 1/19/2020 at 7:31 PM, homeboy said:

I never had trouble with the original 5200 controllers as far as the potentiometers going bad. I have repaired dozens that have the typical mylar flex circuit problem. The real problem is with the Wico 5200 joysticks. The potentiometers in them are horrible and it's very hard to find one of these joysticks that doesn't have a bad one. I have searched forever and have made many calls to electronic stores/ manufacturers with no success.

 

Do the Wicos use more standard - shall we say? - POTs or are they as rare/oddball these days as the ones Atari used in the CX52?

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The Wico joystick pots are no longer produced and are impossible to find.

 

Mitch

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On 5/14/2020 at 3:16 PM, Mitch said:

The Wico joystick pots are no longer produced and are impossible to find.

 

Mitch

 

Ah, so similar to the POTs Atari used then... 

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