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Old Dec 06, 2012, 10:49 PM
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HELP to modify JR X9503 Please

The JR X9503 has a small lever on each upper side of the case. The two levers are called right trim amd left trim. The levers operate over a range of about 70 deg rotation.
The 5K pot inside rotates maybe 120deg, but the lever mechanism limits the pot rotation. The change in R over the limited rotation range is only about 600ohms.
I want to change the levers to knobs that will rotate a full turn for more precise control. What R range does the radio have to see to put out the proper signal?
Is 5Kohm the necessary range, or is the radio looking only for a delta-R?
Any tips, clues, solutions very much appreciated.
Thanks,
Dan
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Old Dec 08, 2012, 06:32 AM
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Take the original 5k pot and add 20%. 6k ohms. Work from there. But you're not going to find a 6k pot, that's why they used a 5k, to keep it cost effective.
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Old Dec 11, 2012, 09:12 AM
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All newer radios are looking for valtages not Rs. So just measure the voltage at the output line at both endpoints and this is what you have to create agian.
You might use a 1k pot (or 500 Ohm) and 2 fixed Rs at the + and - lines, which reduce the voltage range to the range required.
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Old Dec 11, 2012, 08:40 PM
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Thank you.
I tried a 5K linear pot with 330 deg rotation and got a full range of output to the servo over the full range of the pot.
Previous rotation was only about 80deg, so I have the increased control deflection that I needed.
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