Loco doesn't stop

[Airbuspilot]

Hi

I have changed the two motors on an LGB Krokodil, one of the old motors ran with help and the other very slow. Both new motors are working well but when I set min position on the cab slider the loco continues to run at very slow speed (in both directions). I assume in its previous life the decoder was set to allow for old age? The only way I can stop the loco is to turn off track power, when turned back on with same loco selected the loco doesn't move.

Looking at "the dummies guide" could I assume the starting voltage (presumably a min voltage?) is set too high?

Thanks

Robin

 

[dunnyrail]

Hi

I have changed the two motors on an LGB Krokodil, one of the old motors ran with help and the other very slow. Both new motors are working well but when I set min position on the cab slider the loco continues to run at very slow speed (in both directions). I assume in its previous life the decoder was set to allow for old age? The only way I can stop the loco is to turn off track power, when turned back on with same loco selected the loco doesn't move.

Looking at "the dummies guide" could I assume the starting voltage (presumably a min voltage?) is set too high?

Thanks

Robin

To help it may be worthwhile stating (if you know) what kind of decoder is it?

 

[Airbuspilot]

I have no idea, there are two boards one on top of the other, the only marking is DMG2301L (larger board) which i have googled with no luck.

 

[dunnyrail]

I have no idea, there are two boards one on top of the other, the only marking is DMG2301L (larger board) which i have googled with no luck.

Oh, this may give someone a clue or better still a picture would tell all but I expect you have put it all back together now. Though the LGB number on the base sticker or box may give a clue. I am trying to see if this has a generic LGB fitted decoder board. The number is likely to be 234nn or something like that. The loco number on the side may help, most of the LGB decoder fitted ones appear be sound but a few non sound ones had 6/10 or Direct Decoder cable interface sockets on the board. Nothing is ever a simples with DCC as it appears. Though you could think checking CV4 braking time. The default for this is around 3 and if in the 255 range would mean that it could take an age to stop.

 

[Airbuspilot]

Sorry, I have two locos which were in pieces, the Krokodil and a Heidi steam loco, the code above is for the Heidi.

I took the top off the Krokodil and picture of decoder attached also the underside sticker which may be of help.

The loco is no 412, it does have a sound decoder.

 

[The Shed]

 

[dunnyrail]

Ok so we have a 25402. Crock with LGB on-board Sound Decoder production dating from 2004-2005. Shed has shown the CV values so be worthwhile checking out what values are for CV2,3,4,5 and possibly 29 if you can. That may give a better expert on DCC than me a possible clue to your issues. Write down the values next to the default and Max values a little bit like the table above, so easy to mix things up when changing them! Allow a couple of spare columns to show what you changed them to as well.

 

[Airbuspilot]

Thanks guys, that’s brilliant.

going over tomorrow morning so if all well I will try to list the existing CV’s first. Your table idea makes sense, this is all new to me and I am reluctant to change anything until I know that i’m not going to mess up something that’s working.

Robin

 

[Paul M]

Thanks guys, that’s brilliant.

going over tomorrow morning so if all well I will try to list the existing CV’s first. Your table idea makes sense, this is all new to me and I am reluctant to change anything until I know that i’m not going to mess up something that’s working.

Robin

Take pictures and notes as you go

 

[Airbuspilot]

Thanks, I discovered taking the Krokodil apart that a picture helps a lot. Removing the first motor was a nightmare.
Robin

 

[phils2um]

HI Robin - This is an LGB On-Board decoder with a separate factory sound decoder (the card with the big capacitor). You may have trouble reading CVs from the decoder - i did even though I was using a Massoth PC Module. The work-around for me was to unplug the sound card from the decoder. I could then read the decoder and change CVs without any trouble. If you find that you need to do this too, just remove the 4-conductor plug from the red socket of the decoder board. Make sure the power is off as a precaution. When you are done, just plug the sound board in again.

 

[Airbuspilot]

Hi Phil
Thanks for this. I tried to read CV's yesterday with no luck, I put it down to yet another DCC trick for new comers.

I will do as you say and try again tomorrow.

Robin

 

[Dan]

The red connector is the SUSI bus for the sound board. You should not have to disconnect the sound board to read CV values.
I would write CV 55 to 55 to do a decoder reset. This is LGB's on board digital decoder and was used in many 2 motor engines and even in the LGB Mogul (needed for the SUSI sound board).

 

[Airbuspilot]

Thanks Dan, I will give it a try tomorrow.

 

[Greg Elmassian]

Question, does this decoder board have separate output transistors for EACH motor, or do both motors connect to the same output stage.

Something seems fishy.

Greg

 

[Airbuspilot]

Greg is correct, something is fishy.

Went over today, normally Monday, the Krokodil is working perfectly it starts / runs / stops exactly as expected. I haven't changed anything, I put it on the programming track a couple of days ago and tried to read CV's without success. Ran the loco today and every thing is normal, very strange.

This loco has been idle for quite a while waiting for new motors. Was decoder slow to wake up, seems unlikely?

Robin

 

[Paul M]

Greg is correct, something is fishy.

Went over today, normally Monday, the Krokodil is working perfectly it starts / runs / stops exactly as expected. I haven't changed anything, I put it on the programming track a couple of days ago and tried to read CV's without success. Ran the loco today and every thing is normal, very strange.

This loco has been idle for quite a while waiting for new motors. Was decoder slow to wake up, seems unlikely?

Robin

Greg is correct, something is fishy. Yes Greg is a Dab hand at fishy things
Is it something to do with the programming track? If it works fine on the normal rails, there can't be much wrong

 

[Greg Elmassian]

Yes, if a motor was turning when the DCC decoder was at speed zero, scary. Any possibility that some wires to the motors are touching something they should not?

Any possible touching in the motor blocks, you said changing the motors was difficult. I'd trace all 4 motor leds and their paths to the decoder.

I would not feel comfortable until I had some evidence of what caused the issue, and that cause is gone...

Greg

 

[Airbuspilot]

I had no idea how to remove the motor block, the only information I had was the exploded diagram for part identification. The roof has been on one off so many times I should fit it with Velcro. As it happens taking the motor block out is fairly easy but only once you have demolished the loco several times and understand the logic.

Good point about wiring, I could easily have disturbed something along the way. I will take the roof and engine cover off AGAIN (is it a hood or a bonnet?) and check the wires.

Robin

 

[Greg Elmassian]

OK confused....

first post is you changed 2 motors in the Krok.... and this one is where one motor kept running... subject of this topic.

So did you open the motor blocks and change the motors (you said you changed motors) or did you buy entirely new blocks and change blocks not motors?

Greg