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York TV Servo Cycler / Tester V3.3


NOTE: If for any reason your YTV Servo Cycler does not perform as expected, you can reset all factory default values by doing the following: Remove the battery, press and HOLD the Center button, plug the battery back in, release the Center button. All factory values will now be restored. The most common reason to need to reset the YTV Servo Cycler is inadvertently setting sweep end points so close together that it seems to fail to sweep when the Up and Down buttons are pressed together.


Thanks for buying YTV’s Servo Tester. Here are your operating instructions. The YTV Servo Cycler comes ready to run. You will need to provide a power source of 4.8 – 7.5 volts. The intended use is with a 4 to 5 cell NiCad battery pack with standard R/C plug.


Pay close attention to the polarity on the servo and battery. Polarity is printed on the board. The YTV Servo Cycler uses the now standard pin polarity of signal and ground leads on the outside and power lead (b+) in the center. If you have an older battery or servo that uses the power lead (b+) on the outside, one of two measures need to be taken. Either move the pins in the housings or use a reverse adaptor found in R/C hobby shops. NEW: Futaba plugs will work in the pin housing. The fit will be a bit snug due to the extra blade on the side of their plugs, but this has not proven to be a problem.


The Servo Tester begins to run as soon as a battery is plugged in (Center Mode). It will continue to run so long as the battery is plugged in. There is no ‘on/off’ switch. When the Servo Tester is first powered on there will be a lit green LED light. This indicates that power is on and that the output signal is at 1.5ms (centered).

The 3 switches are used to set the modes of operation. The CENTER switch is used to reset the output to 1.5ms (R/C servo center). Note: Some Multiplex servos use 1.6ms centering. The operations are the same for them, but the centering will be off a bit. The two outer switches DOWN and UP are used to adjust the servo arm position, or the two outer switches are pressed together to start a sweep output. Once in the sweep mode, pressing the DOWN or UP will increase or slow the sweep speeds.


Default sweeps are made from .9ms to 2.1ms. in 9 speed ranges. The slowest of these sweep speeds will take 45+ seconds to complete a full cycle. The fastest sweep speed will be faster than most servos can keep up with. The location of the sweep end-points are adjustable. To enter a new end-point press the UP or DOWN buttons to the new end-point. WHILE still holding the UP or DOWN button, tap the center switch (this is kind of like marking the point on-the-fly while the servo is still slowly moving). The servo arm will return to center when you release all buttons IF the new end point was saved. Repeat the same for the opposite direction. Now when you enter the sweep mode, the sweep will be limited to between the new end-points. Your new end-points and sweep speeds will remain in memory even after removing the battery. To reset the end points and sweep speeds to the factory settings (full range sweep and mid speed), HOLD down the CENTER button when plugging in the battery. Once power is applied, release the CENTER button. The cycler will go to the center mode and the sweep endpoints and sweep speed will be restored to normal. Note that if the servo under test is already installed in the plane, it would be wise to set new end points before entering the sweep mode to avoid overdriving the servos mechanism.


There are two LED lights, one red and one green. The green LED functions to show that power is on when a battery is first plugged in, show when dead-center is being outputted and together with the red LED shows that the Servo Tester is in the sweep mode. The red LED shows when the output is not centered and it blinks when output is beyond the normal 1 to 2ms range. The green and red LED’s both lit shows when the Servo Tester is in the sweep mode. You always know you are centered when only the greed LED is lit.


One unusual feature if the YTV Servo Driver is that in the Offset Mode, the movement is paused for .75 seconds when adjustment range is at normal limits (1ms or 2ms). After this .75 second pause, further adjustments can be made outside the normal range (<1ms and >2ms) up to .9ms or 2.1ms. This process is to let you know when normal range has been reached and if the red LED is blinking this lets you know that you are beyond the normal range. When reversing the direction (in extended range) with the adjust up or down buttons, this .75 second pause is again used to let you know that you are at the normal limits. Once the pause is over, the red LED again is lit steady (blinking stops) as adjustments are made in the normal range.


The dual servo plug is simply a parallel connection between the two and both sets of plugs are also in parallel connection. The same polarity is used on both plugs, with the negative wire towards the edge of the board. 3 - 4 servos may be driven at the same time. Note that any of the pins sets can be used for battery and or servos.


The following is a description of the possible LED and servo drive conditions:









Center Mode


Servo holds center


Also, on initial power up (no switch pressed)



Sweep Mode

(.9 to 2.1ms)

Servo cycles back and forth

Press  DOWN and UP together




Offset Mode

(1 to 2ms)

Servo holds offset position

Press DOWN or UP

Tap for steps

Hold  for moving




Offset Mode Extended Range

(<1ms, >2ms)

Servo holds offset position

Press DOWN or UP

Tap for steps

Hold for moving


(ON after reset)


Rest Mode

Restores factory sweep

End points and speeds

Press and hold CENTER

While applying power

Release CENTER after power is applied



Set Sweep End Points

Program sweep end points (user defined) and store results in non-volatile memory

Press and hold UP or DOWN and tap CENTER when position is reached - Returns output to center confirming programming valid








York Electronics             

1005 S. Josey Ln., suite 208

Carrollton Texas 75006                        972-418-9000