Loco going crazy!

[paul_garwood]

Please which CV is it that controls the speed, I have loco that's going far to fast, just thought if I could change the CV value to slow it down.

[P-Henny]

1. You will have to say which decoder it is.
2. Is it a new loco addition to your Railmaster roster (this includes an existing loco fitted with a new or replacement decoder).
3. But please also elaborate on your observations. Is it just that at maximum throttle it is too fast. OR is it a complete lack of speed control i.e it shoots of at full speed with just a small amount of throttle and there is no effective low speed control. These two speed control observations have different cause and effect in Railmaster. The second one (lack of speed control in general) is not a CV issue. If you have full range speed control but it is just the top speed you want to reduce, this can be done in Railmaster without writing to any CV. If that is what is needed, I can tell you how. It can also be done by a CV if supported by the decoder, hence question 1.

 

[paul_garwood]

Hello - It's a Hornby Sapphire Decoder, it starts off slowly but when I increase the speed it take off far to fast, I think it would burn out if I gave it full power. So yes it's the top speed I want to reduce.

[P-Henny]

If it is a very sudden jump from slow to full speed when the throttle slider is at a low setting and the speed is either slow OR fast with no mid-range control, then that was a very frequent reported issue in Railmaster and is not a CV adjustment issue.

Historically, this lack of speed control issue was reported weekly, but has not been reported very much in more recent times.

The cure is to completely delete the loco from the RM roster (throttle list) then add it again, but add it manually as a non-Hornby loco. The key thing in the fix is to not use the CV reading & writing screen to READ any CV value. The issue seems to be linked to an error creation in the RM loco database.

If your issue is as I described above in the first paragraph, then the 'step by step' cure detail is described in FAQ4 in the 'Railmaster FAQ' sticky thread. Previous members who have followed FAQ4 and then reported success, have also reported that they have sometimes had to do it 3 or 4 times before the fix sticks.

For the elimination of doubt, the FAQ4 fix is only applicable if there is a very sudden jump from slow to full speed as described in the first paragraph of this reply.

Note that if FAQ4 is adopted and followed, the Railmaster throttle may display 127 Speed Steps in a 'pink' background and not MPH in a 'green' background at the top of the throttle slider, this is totally normal and not editable. For the elimination of doubt, the 127 is not representing MPH and will display 127 whatever the max speed is set at.

Alternatively.

If the throttle gives smooth transition from slow to fast but over a small amount of throttle slider movement then that will be a different fix. This fix is only applicable if there is no noticable sudden jump in speed. That is to say the speed transition is smooth but just ends up too fast with say half the amount of throttle travel, then follow this guidance.

This fix does not require the loco to be placed on the 'programming track' as no CV is changed. The configuration change is stored within Railmaster.

Open the 'Locomotive Settings' screen for the loco with the Sapphire decoder. Click the 'Stop Watch' icon in the bottom tool bar to the right of the printer icon. A 'Speed Factor' configuration box will open.

I am assuming that the value boxes in this panel will be blank. In the top box enter a Max real life MPH value for the type and Class of loco containing the Sapphire decoder. For example a shunter might be 20MPH whilst an Express might be 80 MPH and a HST might be 125MPH. In the bottom box enter a value of 12 as the 'Time to travel 6.24M'. The value of 12 (seconds) is just an initial arbitrary 'stab in the dark' value. Save the loco changes and test the throttle response of the loco on the main track. If still too fast, go back and edit the 12 number to a lower value and test again. If too slow, go back and edit the 12 to a higher number. Then save the loco and test result again. Keep editing the 'Time' value up or down as appropriate and saving & testing until you get a throttle response you are happy with.

If all this still doesn't give you what you want, then as a last result consider editing the CV5 documented in the P.S.

P.S. CV5 is the max speed CV on a Sapphire. Valid range is 0 to 255 the default being 255 see decoder manual below.

R8245-Sapphire-Locomotive-Decoder.pdf

CV6 might also need an edit if CV5 is set to a very low value.