pendolino "chattering" at low speed

[jackbrad]

Hi,

I have just received a replacement from a supplier for my pendolino dcc ready.

I can't run a dc to it but fitted a chip to run it in.

It has the same fault as the first one. At slow forward speed it "Chatters"" as though it is jumping gears

 

or rattling along the sleepers. When it gets to about 1/4 max speed it runs well.

No problem in reverse.

I have changed the chip but it is still the same. I have also removed the capacitor but no difference!

Please help!

[Gregd99]

I have had "chattering" with some locos due to the decoder trying to respond to back-emf. my solution was to reduce the back emf cutout threshold. This is in CV10 of the 8249 and 8245 decoders.

 

the fact that it varies from forward to reverse indicates

 

that there is something physical happening as well. it might be worth checking lubrication (never too much and only specific model rail oil) or other mechanical issues.

[Rog RJ]

The Pendolino is well known for "grinding" at low speeds on DCC.

Fitting a higher quality decoder is said to eliminate the problem. I don't know whether a sapphire decoder would be good enough.

It doesn't happen on dc.

[jackbrad]

Hi, Thanks to you both. I will try the Back EMF first, and if that doesn't work I will try a new decoder.

[jackbrad]

Hi again, I tried to set CV10 to a lower number, but no change, until I set it to Zero - now running well!

 

Thanks very much. -Now to seek advice on it jumpinp the rails!