DCC loco perfect on DCC but has problems on DC

[beavercreek]

I am a very new wet behind the ears user of DCC and the following is probably a real 'no-brainer' for you experienced guys but here goes.....

I have a centrecab which has a Massoth XLS decoder . It works perfectly fine on DCC but will only work smoothly (motor, lights or sound) at higher voltages about 12 to 15 volts and up when on DC.
At lower voltages the lights, sound and motor keep on turning off and on. I have tried this with different DC powerpacks on extremely clean track....same problem whilst DCC remains perfect. All DCC functions operate absolutely fine.
I know that there has to be a 'wake-up' voltage but was not aware that it would be so high
There is no smoke unit
Does anyone have any ideas as to the cause?

 

[Gizzy]

I think that the wake up voltage can be set by CV.

Muns would know for sure though....

 

[Gizzy]

I think that the wake up voltage can be set by CV Mike.

Muns would know for sure though....

 

[beavercreek]

So good he said it twice!

Thanks Gizzy
I am not sure, of course, that it is to do with the wake-up voltage though...

 

[Philbahn]

It sounds like it to me as well

So good he said it twice!

Thanks Gizzy
I am not sure, of course, that it is to do with the wake-up voltage though...

 

[Cliff George]

Does anyone have any ideas as to the cause?

Not really. According to the manual it should work on analogue at greater than 5V.

I don't think there is a CV on Massoth to set the analogue starting voltage (there is on some other decoders such as ESU).

I see from the manual that the load control, CVs 60, 61 and 62 are effective in analogue mode so maybe playing with those will have some effect. Also maybe the acceleration, braking and top speed CVs could be played with as they too are effective in analogue mode (according to the XLS manual).

Do you have a power buffer attached? Does turning the sound off and on have any effect? Can you measure the current draw?

Sorry pure DCC here!

 

[beavercreek]

Do you have a power buffer attached? Does turning the sound off and on have any effect? Can you measure the current draw?

Sorry pure DCC here!

Hi Cliff
Would you be referring to an internal component put into the loco or one in the power supply chain?
Do not know about the power buffer as I bought the loco from another member. It is a small loco (Arist Centrecab) that has very limited space inside so not sure what size the power buffer would be and if it could fit inside with the decoder and speaker etc.

 

[Gizzy]

Have a look here Mike:

http://www.massoth.de/downloads/handbuch/emotion_xls_v120_en_letter.pdf

(Found using a Google search for Massoth XLS CV Settings.)

Page 20 shows that CV2 is for start up voltage (not sure though if this is DC or DCC) and the default is 2.

If you don't have the means to read the CVs, give Zerogee Jon a call as he has a Sprog unit....

 

[beavercreek]

Thanks Gizzy
I will give Jon a call.
I also have a Sprog, as yet unused, but will get it up an running.
Would the higher wake-up up voltage cause the sound, lights and motors to stutter?

 

[ntpntpntp]

I have a centrecab which has a Massoth XLS decoder . It works perfectly fine on DCC but will only work smoothly (motor, lights or sound) at higher voltages about 12 to 15 volts and up when on DC.
At lower voltages the lights, sound and motor keep on turning off and on.

As folk have said, these are the typical symptoms of being on the cusp of the decoder's "wake up" voltage, but 12V+ seems rather high - typically most decoders I've used wake up around 7v according to my bench power supply and are stable by another 2V or so. Might be the extra draw of the sound that makes it want a bit more voltage to be happy. I don't have an XLS myself so no first hand experience of this particular decoder.

I'm not aware of any CV that would affect the actual "wake up" voltage of a decoder (that's just down to the electronics), but as Gizzy says CV2 will affect the minimum applied to the motor to get it going at the first DCC speed step - with some decoders this also has some effect under DC.

Presence of a power buffer might have a determinental effect under DC. I have a vague memory of reading somewhere that Power Buffers and DC aren't a good mix.

 

[Cliff George]

Hello Gary,

CV2 is for DCC only (at least according to the manual). If you look at the page you quote there is no tick in the 'An' column. Maybe the manual is wrong, you could try fiddling with it Mike. The manual is contradictory in some places, for example page five seems to say that it is possible to define the starting voltage in analogue and digital mode! Some decoders such as the ESU ones have a CV separate from the standard NMRA ones to define the analogue starting voltage (I seem to remember it is CV 125 on ESU).

Hello Mike,

Yes I mean a power buffer as an internal component in the loco. They are quite big, so if there is little space I'd guess it does not have one.

I assume you have checked that analogue mode is not deactivated? CV 29 bit 2, however of it was I'd be surprised if it worked at all on DC.

Can you take the decoder out and see if the loco runs correctly on analogue without the decoder?

 

[Tony Walsham]

What sort of DC controllers are being used?
If they have a PWM component in the output to the track that PWM will play merry hell with DCC decoders.
Use only fully filtered linear DC.

 

[ntpntpntp]

What sort of DC controllers are being used?
If they have a PWM component in the output to the track that PWM will play merry hell with DCC decoders.
Use only fully filtered linear DC.

Good point Tony, and might explain why BeaverCreek reports an unusually high decoder "wake up" voltage (due to measuring PWM pulses of full track voltage)?

 

[beavercreek]

What sort of DC controllers are being used?
If they have a PWM component in the output to the track that PWM will play merry hell with DCC decoders.
Use only fully filtered linear DC.

Good point Tony, and might explain why BeaverCreek reports an unusually high decoder "wake up" voltage (due to measuring PWM pulses of full track voltage)?

Hi lads
As I said earlier I have tried the loco with three different powerpacks, all giving pure linear feed.
I may be new to DCC but I do know the detrimental effect that PWC has on a DCC decoder! .......ask me how I know.......:

 

[Tony Walsham]

I actually posed a question.
What sort of DC power controllers were being used?
Brand?

 

[steve parberry]

I think it will be worth reading out all the settings first as if someone has tried to set them using an lgb progammer then they could all be out as the main data screen does not match up with the massoth sound chips.


You can set them with the lgb unit but on a CV by CV basis (bottom left of sceen), and not using the lgb main data sceen.

 

[beavercreek]

I actually posed a question.
What sort of DC power controllers were being used?
Brand?

Tony
I have tested the loco on Train Engineer (linear setting using two different receivers being fed from a Crest 13 amp Elite power block).I use three TE receivers, one for each separate part of my layout.
I have also tested the loco using an LGB DC controller.
I have had other DCC decoder equiped locos operate absolutely fine on the TE set up.

I think it will be worth reading out all the settings first as if someone has tried to set them using an lgb progammer then they could all be out as the main data screen does not match up with the massoth sound chips.

Steve
I will check the CVs using a Sprog system, or even a Massoth 1200Z and Navigator. It is just getting my head around the CVs themselves.
The Sprog unit is really good for dullards like me who like their ICT to be user friendly and graphical.
I just have to know how things really work before I plough in and operate them.
I have been studying hard and now feel that I understand why and how CVs operate. The next step is making sure that I know how to change them when either using an MTS Universal remote, A Sprog, A Massoth Navigator. That will be a case of following instructions BUT they are quite easy to follow for Massoth, very good for Sprog but a little confusing for using the LGB Universal.