The importance of voltage on programming track

idlemarvel

idlemarvel

Neither idle nor a marvel
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I was trying to program a Massoth S sound decoder today (programming track). This was directly attached to the programming track so as not to interfere with the LGB motor decoder it is normally attached to. I kept getting unable to read decoder or other such error messages. Sometimes I could read a CV, sometimes not, sometimes I thought I had written a new value only to find it had not changed. I have programmed dozens of decoders in my time but this was thwarting me. I was about to throw in the towel when I suddenly thought "I wonder if it needs more juice?". I run my layout at 18v, don't ask me why, it has never been a problem in the past. Luckily I have a workbench power supply so I can just twiddle a knob to increase the supply voltage to the command station. I wound it up to 21v and hey presto everything worked! Read and write CVs with no problem.
Just relating this story in case it helps someone else. There was a discussion on another thread about what voltage to run your layout at, so this may be another factor if you run DCC. After I finished programming I set it back to 18v again.
 
What DCC system do you use? My system uses regulated voltage for the programming track, so the input voltage to the system makes no nevermind.

Also, the important thing that makes the programming track (NMRA Service Mode) safe is the limited current, and voltage only during programming.

The fact that your programming track worked better with a higher input voltage is disturbing.

Normally this is a current issue, not a voltage issue.

So, I'm really interested on what hardware you are using.

Greg
 
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Did you have a ballast load?
 
Apparently adding some resistance (often a light bulb) helps draw more current when reading back CV's and thus the DCC system can see more voltage on the track and more easily read the CV... seems counter intuitive to do this, adding load to make things better.

I believe this is what you are referring to Alan?

Upon more research on Lenz, the following advice from them:

"For best results in reading decoders that exhibit problems during the reading process use paged mode. If you receive an incorrect value of 0 you can often obtain the correct value by quickly perform a second read."

Greg
 
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Thanks Alan and Greg.
stockers stockers yes I had a 75 ohm resistor inline as per Massoth instructions

Greg Elmassian Greg Elmassian yes I have had to do second reads in the past, but in this case I was getting "decoder not found" messages
 
I thought I would do some more investigation by reducing the voltage to see when it stopped working properly. 20v fine, 19v fine, 18v fine. Huh? I can't explain it but it looks to be working at my "normal" 18v voltage setting again. I'll swear it wasn't yesterday, I spent half a day trying to read the decider until I upped the voltage. Weird. Just ignore this thread as the ramblings of an old man. :-(
 
In that case...
My guess would be a dodgy connection somewhere?? - Yes, I know you checked them all.

That, or alignment of phase of moon and 'another unexplained mystery of data-communications'.. :confused:;):rolleyes::rolleyes:
 
Who knows, but it sounds like a poor contact somewhere along the line.
 
Yes I guess so. I'll put it down to experience. I'll delete this thread to avoid any confusion for readers in the future.
 
It's obviously the combination of Science,




and Witchcraft....
 
No need to delete - all information is useful.
 
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