old juddery locos

Hi Brendan

If you have made sure the contacts for the power pickups and wheels are clean. and the are decent brushes in the motor (also the commutator surface , that the brushes contact has no build up)
often oil gets into the brushes and makes them soft ,increasing resistance and causing bad running.
then the motor will need a good clean with solvent and a wash with alcohol (not the drinking kind)

CV's can be adjusted to give the motor some help if it needs a bit of help
increasing the start volts in CV2 to =20 or more will give it hand to move along from stop
Depending on decoder brand there are other adjustments to assist slow running
TCS decoders have "Dither" which is a super pulse power
ESU decoders have suggested values for different brands of motor and I found the suggested value for mine made it run beautifully

Hope this helps

Regards ZMil

QUOTE (Brendan11 @ 19 Nov 2008, 03:23) <{POST_SNAPBACK}>hiya group,

I've got a few older locos which I rarely run out as there a bit too jerky at lower/slow speeds, any advice on helping these run better by tinkering with cv values?

Many thx zmil & noggin for you advice on the CV3 & C4 values for my hornby 08 shunter, I tried a few values for accel and decel and it worked a treat. Shunter no longer stops dead but gently slows down before setting off in opposite direction - well chuffed.

thx

bren

***Hi

Presuming the running problem is motor cogging (older 3 pole motors) and not other issues, then try the following.

(advice presumes max setting for each CV is 255 - if not, ie with an ESU which has settings of ) to 64, then use 1/4 of the values shown for CV 5 and 6)

CV2 = 0 (especially if a back EMF decoder - but it won't help ths situation anyway so no adjustment yet)

CV3 = 20 (forward momentum) This isn't critical and can be higher of course, but some momentum is important for coggy locos

CV4 = 20 (reverse momentum) This isn't critical and can be higher of course, but some momentum is important for coggy locos

CV5 = 180 (V max) You can vary this, but should be appx 65% ~ 85% of max setting depending on the loco.

CV6 = 120 (V Mid) You can vary this, but should be appx 2/3 of whatever CV5 is set to.

The CV 5 and 6 changes will have the effect of compressing the speed step size especially in the zero to mid volts range, significantly smoothing slow speed running.

At this stage leave back EMF settings totally, and until this area is sorted don't worry about dither or any other adjustments including CV2.

we can sort that later

regards

Richard

Set speed steps to 128.