Change of address.

[Potrail2378]

Hi, probably a silly question but I have changed the address on a class 37 which I have converted from DC to DCC. Am I correct in assuming that I have lost any CV values that I have changed?

If so, can you please help me? The class 37 has been fitted with a Hornby sound decoder, a 'can' motor from Strathpeffer Junction, and a stay alive capacitor/resistor. It's very, very jerky while setting off and doesn't calm down and run smoothly until at least half speed. It also 'runs on' when I turn the power off. It was fine before I changed the address. Can someone please let me know what CV values I need to change? I have a Hornby Elite in the loft, and an upgraded Select in the workshop.

I shall also write them down and keep them safe. Thanks in advance.

[jane1707819582]

All you have changed is the address ,all other CV should remain the same .

Changing CV 150 to 1 is altering the motor pid control .

CV 153 and 154 can be adjusted to fine tune the motor .

If you stay with CV 150 at 0

CV 151 and 152 can be adjusted

If your decoder has gone gaga (it happens )

Then 8 to CV 8 should!d reset it losing any changes you have made .

CV 10 back emf could be turned off too ie CV 10 = 0

[96RAF]

To fit the stay alive it is presumed you soldered direct to the Hornby decoder and that your soldering skills are up to the task.

Be aware that having a stay alive fitted can prevent some decoders programming with certain controllers.

Try a reset of the decoder as suggested and as its a new motor type you may have to re-fiddle with those CVs Jane speaks about.

[Potrail2378]

Hi 96RAF, yes I've soldered the capacitor directly to the decoder and it worked fine. I will play with the CV settings later today when I get home.

Jane - hi and thanks for the info. I'll get back to you when I've changed some CV settings.

[Chrissaf]

Nobody so far seems to have picked up on your comment:

"It also 'runs on' when I turn the power off".

This is called 'DC Runaway' and is a common result of fitting a 'stay alive, as well as any other CV changes others have suggested, you would be advised to amend the value of CV29 to disable 'DC Operation'.

This website CV29 calculator will help.

DCC CV29 Calculator

[Fishmanoz]

Chris, might need to clarify Runaway. If it runs on a short distance with the power turned off at the wall, then stops, that is the stay-alive. If it takes off flat out and can only be stopped by turning off the power, that is DC Runaway.

seems to me it is likely the former given it is responding to the controller albeit jerkily.

I would start by only changing CV150 to 1. The other CVs mentioned are second order to CV150 and will only need adjustment if the CV150 change fails to fully fix the problem. There’s a separate thread on here explaining all of that more fully.

[Potrail2378]

Chrissaf - thanks for the link, I'll play around with the CV settings later today.

Fishmanoz - after playing (sorry, operating) the class 37, I turn the Hornby Elite off, and the loco 'jumps' forward about two or three inches.

[96RAF]

When the power is turned off the stay alive powers the decoder for a short period, but having lost the DCC signal the decoder reverts to DC operation hence the jump under DC runaway as Chris said.

[Fishmanoz]

Thanks Rob, and apologies Chris. Get it now - jerky when operating (change CV150 to 1), temporary Runaway when switching off, and fixed in CV29 as said.

[Potrail2378]

Hi all, and thanks for the info, links, etc. It now runs very, very smoothly. I have changed the following CV values as follows -

CV10 - 100

CV150 - 1

CV153 - 0

CV154 - 1

Start V - 5

Other Possibilities - 

CV3 - 75

CV4 - 20

CV10- 128

CV150 - 0

CV151 - 20

CV152 - 16

CV153 - 215

CV153 - 115