I just bought a L6 kit two weeks ago and had a problem when centering the servo. I have total seven servos: 1 HS-422, 4 HS-475HB, 2 HS-85BB. The HS-422 centers very slowly and makes a humming noise. The other six servos centers pretty quickly. Is my HS-422 not working properly? I don’t have a second HS-422 to compare and hence this newbie question. Thanks.
Are you sure it is the 422?
Have you tried switching channels?
Additionally, what type of power supply are you using?
Is the servo case heating up?
Is it under load during centering attempt? If so, take load off and see if humming reduces.
the 422 is one of the cheaper types with low torque - thus they are prone to hum. make sure it is not getting hot.
report back
It sure is 422. I started with the L6 base where the HS-422 is used.
For switching channels, did you mean changing channels on the ssc-32 board? I tried several channels for the 422 with same result. All other servos works just fine under same channel.
For power supply, I use the switching power supply bundled with the L6 kit. It is 6V 2A max.
There is no heating up on servo.
I have no load on the servo when centering the servo.
Thanks for your reply. I am ready to disassemble the servo to report any internal problem with the gears and motor.
I don’t think a 422 will be even close to functional on the base joint of the L6.
Are you using 2 of them? If you are, you need to be sure both are matched exactly.
According to the lynxmotion website, hs-422 should center quickly:
HS-422 (57 oz. in.) Standard Servo
Size = Standard
Servo Erector Set = Yes
Range = 180°
Voltage = 4.8 - 6.0vdc
Torque = 57 oz.-in.
Weight = 1.66 oz.
Speed = 0.16s / 60 degrees
So my 422 doesn’t seem working properly.
The servo speed posted is probably with it not connected to anything. Sounds like the servo may be under some strain. Try disconnecting it from the arm and see how well it moves. Is this the recomended servo for this application?
There is no load on 422 servo when I was trying to center it.
You are right that the rotation speed listed above is what the servo should do under no load.
Sounds like the servo might be binding internally. With out the servo connected to anything, can you carefully rotate the servo control horn with out unusual effort? Might be worth opening it up and checking the internals for problems.
No he means the base rotate, not the shoulder…
Sounds like the servo is defective. Contact us, or the distributor you bought from to get a replacement. Sorry…
Thanks robot dude.
Lynxmotion support seems pretty good. 
I too have some questions regarding centering servos. Per instructions on page 2 of Mid PosistionTutorial I clicked on All=1500 and all of my servos moved ~ an eigth of a rotation into what I thought was mid or neutral position. When I accidentally turned one of my servo’s white wheels (horns) I plugged it back into the SSC-32 board to re-center. It moved, but did not return to the position it was in before(?). I plugged in a couple of other servos which I had not disturbed and they too moved to a new position. So how exact is this “Mid Position”? I did not expect the undisturbed servos to move at all. Regarding mounting two servos on the C brackett, you suggest drilling 1/16" holes in the B servo horn to get alignment, but his will require very precise drilling. Wouldn’t it be better to remove the horn, being carefull not to rotate the servo drive shaft, and re-position the holes that way? Finally, which picture of the servos at mid position is correct, the one on page 4 with c-bracket at about 45 deg. to horz. or the one in the RIOS SSC-32 manual, page 3 that shows the shoulder 90 deg or normal to the horz.?
Ok, can you go into more detail as to how you are powering the VS and VL? What you are probably seeing is the SSC-32 resetting due to insufficent power. So the SSC-32 is telling the servos to move to center, they “turn on” and start to move. But because of a power problem yet to be defined they draw more power than the supply can deliver, and the SSC-32 “turns off” the servos. So the servos never actually made it to center position.
Center position is very accurate.
The assembly guide you are referring to has been redone. Please review this new guide.
lynxmotion.com/images/html/build118.htm
Also for more information on servo horns and mid position settings.
lynxmotion.com/images/html/build046.htm
Hope this helps! 
I also had this problem when I was using a single power supply for the ssc-32.
It was resetting the board because the current drain to the servos was large enough to drag the power from the microcontroller and reset it.
I just pluged in a 9v battery for the logic and had two power supplies (removing the jumper of course). It fixed the problem instantly.
Hope this helps.
Yes you may need a large current-peak if you start all servos moving at the same time (all 1500 with maximum speed). I use a large lead gel accu (8V/3.5Ah) and 7.5A regulators (LT1083CP-5) for my L5-arm. If you use a power supply I would recommend you minimum 6 Ampere and a large additional capacitor to get an extra peak of power!