Service Sheet 05

Servo Smoothers

Roundhouse locomotives have used two different types of servo smoother our locomotives over the years, the 'SAM-2' and the 'Sentinel'. Reproduced below are the instruction sheets that accompanied the models.


Supplimentary R/C Instructions for SAM-2
Radio Interference ('servo glitch') reduction

Under certain conditions, the radio control system fitted to this locomotive can be subject to interference. This can have a number of causes, which include outside signals from other transmitting devices, bounced signal (signal from your transmitter bounced by large metal structures nearby) or internally generated signals created by the movement of the locomotive. This will manifest itself as unwanted and un-requested movement of the servo(s), often known as 'servo glitch'. To reduce this phenomena, your model is fitted with a SAM-2 'servo smoother' that offers three levels (low, medium and high) of signal smoothing. The level of smoothing is set by placing the two control sticks on the transmitter in a set position at power on, so it is important to follow this procedure whenever you switch the radio control system on.
The default (recommended) level is achieved by setting the left hand control stick to the bottom (regulator closed) and the right hand control stick in the centre (mid gear) then switching on the transmitter followed by the receiver. This will give low smoothing on the regulator and medium smoothing on the reverser. If the transmitter is switched off at any time, the servo's will hold their position until it is switched on again and the level of smoothing is unchanged. If however the receiver is switched off, all settings are lost and the control sticks must be set to the desired position before power-up again.

A certain amount of servo 'twitching' is often present but it does not interfere with normal running of your locomotive. If however, with the above settings, your model is still affected by 'servo glitch' to such an extent that it makes control difficult, the unit can be adjusted to compensate. Be aware that as the smoothing level is increased, the speed of the servo decreases so, do not set the regulator smoothing any higher than necessary as response to speed and stop control will be delayed.

Before using higher levels of smoothing, you must first ensure that all other aspects of the radio control system are in good order i.e. the batteries in both the transmitter and locomotive have sufficient charge and there is not a problem with the ariel - see Trouble Shooting section in Owners Handbook .

Three levels of smoothing are available on each of the two channels independently and the default settings as above will give the minimum on the regulator and medium on the reverser.

The following control stick positions at power on will alter the level of smoothing as shown.

Left hand stick (regulator).

Bottom (default) - low smoothing, fast servo speed.
Centre - medium smoothing, medium servo speed.
Top - high smoothing, slow servo speed.

The right hand stick (reverser).

Left - low smoothing, fast servo speed.*
Centre (default) - medium smoothing, medium servo speed.
Right - high smoothing, slow servo speed*
*PLEASE NOTE - on certain models, the high and low settings for the right hand control stick will be reversed from that shown above but can be simply checked by watching the speed of movement of the reversing mechanism.

Once the control sticks are in the desired position, switch on the transmitter then the receiver. Remember that the higher the level of smoothing, the slower the response the servo's have to the transmitter so always go for the minimum smoothing setting that will overcome the major 'glitching'.

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Supplimentary R/C Instructions for Sentinel
Radio Interference ('servo glitch') reduction

Under certain conditions, the radio control system fitted to this locomotive can be subject to interference. This can have a number of causes, which include outside signals from other transmitting devices, bounced signal (signal from your transmitter bounced by large metal structures nearby) or internally generated signals created by the movement of the locomotive. This will manifest itself as unwanted and un-requested movement of the servo(s), often known as 'servo glitch'. To reduce this phenomena, your model is fitted with a 'servo smoother' that offers four levels of signal smoothing.

A certain amount of servo 'twitching' is often present but it does not interfere with normal running of your locomotive. If however your model is affected by 'servo glitch' to such an extent that it makes control difficult, the unit can be adjusted to compensate. Firstly, you must ensure that all other aspects of the radio control system are in good order i.e. the batteries in both the transmitter and locomotive have sufficient charge and there is not a problem with the ariel - see Trouble Shooting section in Owners Handbook.

Sentinel servo smoother
The 'servo smoother' (see picture above) is located in the tender and is adjusted by a bank of DIP switches on the front. Four levels of smoothing are available and the unit is factory set for the minimum required by your particular model. As the level of interference can vary locally, this factory setting may not always be sufficient and can usually be increased. For example, if your smoother is factory set to level 2 and still suffers 'servo glitch' on your railway, alter the DIP switches to set it to level 3. There are six small white slide switches in the DIP switch unit and these are moved up to set to ON or down to set to OFF and by a number of combinations of On or OFF, the different levels are set. Please note that the higher the level of smoothing, the slower the response the servo's have to the transmitter so always go for the minimum setting that will overcome the major 'glitching'. Use the blade of a small screwdriver to carefully slide the switches up or down, one at a time. The diagrams below show the switch settings for the four different levels of smoothing and a check box shows the factory setting for your model as a reminder.

Sentinel servo smoother


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