z21 and a booster

[PaulM381]

Hi
I'm having a few problems with my z21 start and a digitrax booster. I have for the last couple of years ran my layout using the z21 start connected to a Digitrax booster and had no problems at all. About 4 months ago we decided to move house so everything was packed up and boxed safely away ready for the move. We are now in the new house and I've put together a small layout to start building up and come across a really strange problem. For some reason my z21 will run certain locos with no problems at all. Then I have certain locos that won't run unless connected through the booster. Also I have a loco that runs well through the booster but I can't read or write CV's to. I have a couple of locos that run off without even being registered on the z21 and some other locos that behave really strangely running one way then the other stopping and starting whenever.. I've tried everything I can think of including trying to reset decoders on a programming track and also on the main layout. I'm also getting strange readings from some of the decoders that I am able to read ie. Reading CV 8 on some decoders giving back different results each time. I'm lost on what to try next. If it was one or two locos that were playing up then I would of thought it was the decoders and change them but this is happening to 7 different locos with different chips so I don't think it's the decoders. Anybody got any ideas why this is happening? Thanks

[Ironduke]

Locos may run off if they detect a DC component on the track. Possibly the output stage of the Roco z21 is running asymmetrically, but not so bad that the booster can't make sense of it? How is the booster connected? If it's using the B-bus, the output of that might be just fine.

[Bufferstop]

Peculiar problems with digital equipment are often down to the simplest of causes. Check the state of your connecting leads and the actual connectors. If they got twisted or squashed when they were packed away you may not be getting a good connection between the units and the track. Make sure of the connections and your supply to the track, before you start looking for problems with locos or decoders, you may find some of the problems have disappeared. You didn't have the problem before you moved, so what part of the moving process may have brought it on? Hence my suggestion to check the cables and connectors. Hope this helps.

[PaulM381]

Thanks guys for your answers.
The booster is connected via the bus B connection. It seems strange that some of the locos run fine then others are all over the place.
I've checked all wiring as well and can't see any problems with that side either. I've even done a test track on the dining table with a new piece of flexi track and now wires directly from the output of the z21 to the track and still get strange results. I've metered the track and get a steady voltage as well. I want to think that it's the output of the z21 which is causing it but then that wouldn't make sense as some of the locos run fine. But then if it was the chips why would so many have different problems. Strange???

[Bigmet]

The information you have provided suggests very strongly that the software that the z21 runs on is corrupted in some way. Does this system have a reset facility to bring it back to original status? I think you are on to the system support if that either makes no improvement or isn't an available option.

...I want to think that it's the output of the z21 which is causing it but then that wouldn't make sense as some of the locos run fine. But then if it was the chips why would so many have different problems. Strange???

Decoder designers are at liberty to design decoders to read the DCC signal any way they choose: which is another way of saying there is reliance on the DCC signal fully conforming to the NMRA specification. (Some may remember that Hornby's market entry to DCC was with a system with a non-conforming DCC signal, which worked Hornby's decoders; but was not acceptable for all the decoder designs then available, leading to anomalous results.)

[PaulM381]

Thanks for your reply. Yes I did think there was something wrong with the software as I did the update before I used the system after the move. I've messaged Roco to ask for support but not had anything back yet.

[Bufferstop]

I did the update before I used the system after the move.

Ah the vital piece of evidence!

[PaulM381]

Yes sorry forgot to mention that. But why some locos ok and others not? And how to roll back the software as it seems impossible to do through their update tool?

[Bufferstop]

You'll need to check out with their support line. If their update tool only goes forward then the only real option is to do a factory reset then apply all of the updates. It depends on how they handle the updates, and only the makers can tell you.
Each update might be a single patch to the software - this is the least likely and would be a real drag.
The updates might be cumulative in which case you may have to do one or two plus the latest,
or hopefully each update is an new version of the whole software which just means making sure you have a good copy of the update and applying it.
If they offer a software overhaul it might be worth sending it to them to do it. It's a similar process to updating the software in your router, or "flashing" the BIOS on your computer's motherboard. No matter how many times of done one I always end up holding my breath until I see it jump back into life.
Good luck and I hope it goes well.

[PaulM381]

Thanks Buffers too. Hopefully I'll get a reply from them soon. I messaged them over a week ago so might chase them and see what happens. Thanks for your help.

[Bigmet]

...I messaged them over a week ago so might chase them and see what happens...

I'd be in harass them daily mode! The product has failed thanks to your update, what's your plan to restore full capability by the end of the week at the latest? Squeaky wheels get the grease...

[Peterm]

That's the way to go.

[PaulM381]

Well I finally got a sort of reply but only after messaging them on Facebook. Apparently you can roll back the software using a previous version of the update maintenance tool. So I've tried that tonight and no joy.
Now the strange thing is that I've put a meter across the output of z21 and only getting a reading of 11.2 volts. I'm sure this should be higher. It would explain why I get a better result through using a booster as this generates a track voltage itself. Does anyone have any ideas why the voltage would be so low?
Thanks again for everyones help.

[Ironduke]

I suspect this is a hardware fault in the output stage of the controller. e.g. a blown power transistor.

[Mountain]

On my Lenz system one can alter the track voltage via internal switches if I remember correctly.
I am wondering if on your system the voltage can be changed a different way? Or when you did the upgrade, did you have to open the system up? Would you have accidently moved an internal switch? (If it works like my system does).

I maybe clutching at straws to think of possible answers... I am guessing that some more modern systems may alter the voltage via programming instead of internal switches? Just a guess as I only know my Lenz system. (I have used other systems but I never got to really explore them).