Flunter Posted September 17, 2020 Share Posted September 17, 2020 Hi all, first post here. I'm building my first layout (placed my order for track on the 17th July, still waiting for points, but that's a different story) and bought a second-hand Z21 unit from a well-known online auction site. While waiting for track to be delivered I've bought a couple of locos and attempted to get them setup on the Z21 on a small loop of Hornby set track I bought for the purpose. What I'm finding is that the unit seems to be blowing my decoders, I've popped 2 already and the 2 that haven't popped are performing really poorly and unpredictably, so much so that I daren't put the locos on the track again. Putting a multi-meter across the track the reading I'm getting is 25.1v, switching rails it shows 10.5v, is this normal, is the Z21 faulty? Yeah, I know, serves me right for buying second hand, lesson learned Thanks in advance. Phil. Link to post Share on other sites More sharing options...
Flunter Posted September 17, 2020 Author Share Posted September 17, 2020 Sorry, should have said, it's the Z21 black. Link to post Share on other sites More sharing options...
WIMorrison Posted September 17, 2020 Share Posted September 17, 2020 Download the Z21 maintenance application from Roco and set t output voltage to something reasonable such as 15v i would also advise you to reset the Z21 back to defaults, hold down the blue button for 30s or until if flashes ‘purple’ then let it go. Your track voltage will now be set at 18v 1 Link to post Share on other sites More sharing options...
Neils WRX Posted September 17, 2020 Share Posted September 17, 2020 Try updating the firmware of the Z21 using the Roco website. Never had an issue with it blowing decoders. Had a Z21 for a few years, its a great piece of kit !! Stay safe, Neil 1 Link to post Share on other sites More sharing options...
Flunter Posted September 17, 2020 Author Share Posted September 17, 2020 1 hour ago, WIMorrison said: Download the Z21 maintenance application from Roco and set t output voltage to something reasonable such as 15v I have already downloaded the Maintenance tool, completely forgot I'd got it, will give it a go. Appreciated. 49 minutes ago, Neils WRX said: Try updating the firmware of the Z21 using the Roco website I updated the firmware as soon as I received the unit, did a check yesterday and it still has the most current version installed. Thanks for the advise. Link to post Share on other sites More sharing options...
Flunter Posted September 17, 2020 Author Share Posted September 17, 2020 (edited) Well, I'm clearly doing something wrong, but I'm blowed if I know what! Apologies for the following essay. The first loco I bought was the Hornby Railroad Dean Single, I fit an 8 pin decoder myself and away we went, even after running-in it ran very jerky. Given the Z21 unit was secondhand I didn't want to assume it was faulty so I bought the Hornby Railroad Mallard with TTS sound and gave it a go. I setup all the sounds, changed the decoder address to 68 and it ran a treat.. for 45 minutes anyway. It stopped running and the Z21 was showing a short circuit, this was traced to the Mallard's tender so I'm assuming it was the decoder. I then bought the Hornby Ruston & Hornsby R&H 48DS 0-4-0 and fitted a 6 pin decoder myself. Before replacing the body I placed the motor on the track and almost instantly the decoder flashed and popped. I then bought the Class E1 No. 2173 in NER Lined Green livery 0-6-0 Tank Locomotive from Rails of Sheffield, this came DCC fitted. It appeared to setup correctly but didn't run well, the body was warm to the touch so I removed it straight away. Please remember that I'm still waiting for track to arrive, so all the above was done on a small oval of Hornby set track. I've just connected the Z21 to the Maintenance Tool, everything looks normal and the firmware up to date v1.33. Did a reset of the unit, still everything was normal. I've just fitted a new TTS sound decoder to the Mallard and given it a try. It sort-of ran but even after reducing the speed to zero the loco kept going, again, the decoder was very warm to the touch. Do I bite the bullet and fork out for a new Z21 unit, or has anyone any suggestions? Thanks in advance. Phil. Edited September 17, 2020 by Flunter Link to post Share on other sites More sharing options...
jpendle Posted September 17, 2020 Share Posted September 17, 2020 4 hours ago, Flunter said: Putting a multi-meter across the track the reading I'm getting is 25.1v, switching rails it shows 10.5v, is this normal, is the Z21 faulty? What do you mean by switching the rails? Also you can't measure a DCC voltage with a standard multimeter because of the way the DCC signal is transmitted. BUT the voltage you measure should be consistent. Regards, John P 1 Link to post Share on other sites More sharing options...
Flunter Posted September 17, 2020 Author Share Posted September 17, 2020 Just now, jpendle said: What do you mean by switching the rails? With the red multimeter probe on the outer track and the black on the inner it shows 25.1v, with the red multimeter probe on the inner track and the black on outer it shows 10.5v. 3 minutes ago, jpendle said: Also you can't measure a DCC voltage with a standard multimeter because of the way the DCC signal is transmitted. BUT the voltage you measure should be consistent. I am absolutely no electrical wizard and completely new to DCC, my last layout was 50 years ago when I was 10. Link to post Share on other sites More sharing options...
jpendle Posted September 17, 2020 Share Posted September 17, 2020 Just now, Flunter said: With the red multimeter probe on the outer track and the black on the inner it shows 25.1v, with the red multimeter probe on the inner track and the black on outer it shows 10.5v. I am absolutely no electrical wizard and completely new to DCC, my last layout was 50 years ago when I was 10. There's definitely something wrong there. When you swap the multimeter probes you should see +25V one way and -25V the other way, (or +10.5V & -10,5V). BTW are you using the Main Track output on the Z21 or the Prog Track output? Regards, John P 1 Link to post Share on other sites More sharing options...
Flunter Posted September 17, 2020 Author Share Posted September 17, 2020 3 minutes ago, jpendle said: BTW are you using the Main Track output on the Z21 or the Prog Track output? I've tested the voltage on the Main Track only. I used the Prog Track to programme the locos only, this was done by simply swapping the output on the back of the Z21 from Main to Prog. The unit is connected to my track using the old style Hornby power connector, the one that pushes into 2 slots between the rail and the sleeper. I do appreciate you trying to help. Link to post Share on other sites More sharing options...
jpendle Posted September 17, 2020 Share Posted September 17, 2020 FYI, you don't need to swap from Prog to Main for a simple test track, the Prog output acts like the main output as long as you aren't programming anything. It does sound like the Z21 may be faulty. What colour is the light on the Z21? It should be blue for normal operation, green for programming, and flashing red for a short OR for a power overload (where you have so many locos and accessories that you have exceeded the current capacity of the unit, not likely in your scenario). Regards, John P 1 Link to post Share on other sites More sharing options...
jpendle Posted September 17, 2020 Share Posted September 17, 2020 I forgot to say, I have a Z21 and it is a great piece of kit. Regards, John P 1 1 Link to post Share on other sites More sharing options...
BokStein Posted September 17, 2020 Share Posted September 17, 2020 (edited) 18 minutes ago, Flunter said: I've tested the voltage on the Main Track only. I used the Prog Track to programme the locos only, this was done by simply swapping the output on the back of the Z21 from Main to Prog. The unit is connected to my track using the old style Hornby power connector, the one that pushes into 2 slots between the rail and the sleeper. I do appreciate you trying to help. You said the old style Hornby connector? The R602? GET THAT AWAY FROM ANY DCC SYSTEM! Edited September 17, 2020 by BokStein 1 Link to post Share on other sites More sharing options...
Flunter Posted September 17, 2020 Author Share Posted September 17, 2020 5 minutes ago, jpendle said: What colour is the light on the Z21? It should be blue for normal operation, green for programming, and flashing red for a short All of the above applies. As said, I'm no electrical wizard but I do find it odd that the Maintenance tool is showing a steady 14.9v. 1 minute ago, BokStein said: You said the old style Hornby connector? The R602? GET THAT AWAY FROM ANY DCC SYSTEM! Is there a chance that could be causing problems? Link to post Share on other sites More sharing options...
BokStein Posted September 17, 2020 Share Posted September 17, 2020 It contains a capacitor which KILLS the DCC signal. BTW, I hope your voltage measurements are on your meter's AC scale? 1 Link to post Share on other sites More sharing options...
Flunter Posted September 17, 2020 Author Share Posted September 17, 2020 1 minute ago, BokStein said: BTW, I hope your voltage measurements are on your meter's AC scale? It is indeed. Just sitting down for tea then I'll get the soldering iron out and make a better connection, will report back shortly. Link to post Share on other sites More sharing options...
grriff Posted September 17, 2020 Share Posted September 17, 2020 One problem which causes decoders to blow up is a short between the track supply and motor wires. They must be electrically separate, there is no 'common' wire. It shouldn't happen with the way you have described fitting the decoders but before fitting a decoder make sure, with a multimeter set to resistance, that there is no connection between the track wires (which go to red and black on the decoder) and the wires which go to the motor (grey and orange on the decoder). if in doubt, check the wiring diagram which came with the decoder instructions. 1 Link to post Share on other sites More sharing options...
Flunter Posted September 17, 2020 Author Share Posted September 17, 2020 My faith in the Z21 has been restored, who would have thought that something so simple could have caused so many issues (and now cost me £££s in new decoders ). The Mallard is now running well, although the sound no longer works but I can live with that. The Dean Single is as jerky as it ever was, but still running. The Class E1 J72 will no longer run forwards, only backwards, and then it's all or nothing, so I guess a replacement decoder is called for. Because the Ruston & Hornsby 48DS 0-4-0 actually popped and flashed I haven't bothered trying it, safe to assume the decoder is cream-crackered. Thank you to everyone that contributed to getting my issue resolved Phil. Link to post Share on other sites More sharing options...
jpendle Posted September 17, 2020 Share Posted September 17, 2020 Hi, Glad you got things sorted. Re the decoders, a hard reset of the decoders might help, if not, the various Zimo non sound decoders for 20 pounds are extremely good value. They are not budget decoders, they used to be priced nearer the 35 pound mark, but Zimo reduced the prices on these a few years ago. Regards, John P 1 Link to post Share on other sites More sharing options...
Ron Ron Ron Posted September 18, 2020 Share Posted September 18, 2020 12 hours ago, Flunter said: My faith in the Z21 has been restored, who would have thought that something so simple could have caused so many issues (and now cost me £££s in new decoders ). ......Thank you to everyone that contributed to getting my issue resolved Phil. Just for confirmation, have you resolved the problem by removing the Hornby track connector ? . Link to post Share on other sites More sharing options...
Flunter Posted September 18, 2020 Author Share Posted September 18, 2020 33 minutes ago, Ron Ron Ron said: Just for confirmation, have you resolved the problem by removing the Hornby track connector ? Yep, the connector was the problem. Track power is now a steady 14.9 volts across the rails. Link to post Share on other sites More sharing options...
Michael Hodgson Posted September 18, 2020 Share Posted September 18, 2020 48 minutes ago, Flunter said: Yep, the connector was the problem. Not that I use them but it would never have occurred to me that a simple track connector could do that. It's not unreasonable to use a track connector for the purpose for which it was made, so I would have thought it ought to be subject of a warning in the manual (more meaningful than the usual health & safety "advice" such as don't plug a transformer in underwater or whatever). Link to post Share on other sites More sharing options...
Flunter Posted September 18, 2020 Author Share Posted September 18, 2020 Just now, Michael Hodgson said: Not that I use them but it would never have occurred to me that a simple track connector could do that. Me too. It came (several actually) with the Hornby set track I bought to test the Z21 while I'm waiting for track to be delivered, it seemed natural to me to make use of it. That tiny item has cost me the difference between my second-hand Z21 and a new one. That said, I'd still have used the connector with a new Z21, not knowing any different. Link to post Share on other sites More sharing options...
Flunter Posted September 18, 2020 Author Share Posted September 18, 2020 11 hours ago, jpendle said: a hard reset of the decoders might help How would I go about doing a hard reset? 11 hours ago, jpendle said: the various Zimo non sound decoders for 20 pounds are extremely good value Don't suppose you could point me to a supplier... I did say I was new to all this Link to post Share on other sites More sharing options...
WIMorrison Posted September 18, 2020 Share Posted September 18, 2020 https://www.dcctrainautomation.co.uk/ :) 1 1 Link to post Share on other sites More sharing options...
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