Odd motor behaviour, Soundtraxx Tsunami.

[w124bob]

An Ebay purchase, on reducing power to zero loco coasts almost to a stop then picksup speed for second or two. The distance travelled varies depending on on what the intail speed was. Removing the body reveals what I assume is a "stay alive" capacitor, CV's for the motor have been set by me to match a similar Tsunami equipped loco. I am assuming it's the "stay alive" causing the run on by discharging its saved power. Bit difficult to remove because it's a DIY hard wired conversion. As I payed about the price of a DC loco I might bin the entire sound system any way. Loco is an American Atlas ho C420.

Edited July 3, 2017 by w124bob

[geoff]

An Ebay purchase, on reducing power to zero loco coasts almost to a stop then picksup speed for second or two. The distance travelled varies depending on on what the intail speed was. Removing the body reveals what I assume is a "stay alive" capacitor, CV's for the motor have been set by me to match a similar Tsunami equipped loco. I am assuming it's the "stay alive" causing the run on by discharging its saved power. Bit difficult to remove because it's a DIY hard wired conversion. As I payed about the price of a DC loco I might bin the entire sound system any way. Loco is an American Atlas ho C420.

Ditching the sound system because the speed control is not as you want it seems a bit drastic. I stand to be corrected but I think the capacitor is part of the sound system not a keep alive. If you use decoder pro why not take a close look at the speed table settings. Three step or twenty eight?

 

Geoff

[10000]

As Geoff said it could be a factory fit capacitor. I have several Tsunamis, drop in boards and standard decoders many have a 'cap' dangling on 2 wires..

 

Have you tried a decoder reset? Put it back to factory defaults before adjusting settings. Also don't assume you need the same settings as a similar tsunami fitted loco. I have 2 Kato AC4400 but settings are different. Also its not just a case of changing the standard motor CV's and speed table, there are many other CV's that impact motor performance which is why I use Decoderpro to tune mine.

 

Edit:

 

you may find this useful

http://www.trainweb.org/gnw/BEMF%20Tuning.htm

Edited July 3, 2017 by 10000

[hobbyhorse]

I'd do a reset and start again, not knowing what cv,s have been fiddled with.

Simon

[flubrush]

I'd do a reset and start again, not knowing what cv,s have been fiddled with.

Simon

 

I would agree with that.  I've just spent a week,  on and off,  trying to get good slow speed running on a Tsunami fitted to an American Models S scale GP9.  I've downloaded all the "How To" articles I could find on the web and must have messed about with most of the CVs and got some very weird motor responses,  some not unlike the OPs loco.   I've used reset to default often to get back to a starting point which gives a fair performance with poor slow speed starting.   I might get a decent result sometime,  but I won't be using any Soundtraxx chips on the other locos I have to fit DCC sound to.

 

Jim.

[w124bob]

A factory reset solved the intial issue, however using JMRI to set various CV's still did not give any smooth stopping. Add poor sound and I gutted the thing, reinstalled a standard Atlas circuit board and dropped in a Lenz decoder. Silence but perfect running, this might seem extreme but the loco was not expensive to start with.