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The word is back from DCC Concepts (and it's not good!): "Decoder received and tested. All CVs are unable to be altered - all reading as 255 - including address, manufacturer ID, acceleration, deceleration etc. It will not do a decoder reset. This is one sign of a processor that's been fried with either voltage spike or incorrect connection. There's no sign of any overload/heating." They are very generously replacing the unit as the only person who could have caused this was me. Sadly I am still none the wiser as to what I did wrong. ​Anybody got any advice please? Remebering the question: ​I installed an 8 pin DCC socket with harness into an old Lima chassis and tested that everything worked on DC with a blanking plate. I put a generic DCC chip in and everything worked I put in a DCC Concepts Zen 360 8 pin direct chip and it worked well, better with adding a DCC-C stay alive and then changing CVs 2,6,5. Impressive slow crawl and good speed response. Removed the chip with stay alive attched so as to be able to cut off and replace the old tension lock couplings with NEM pockets (I use Kadees). There was a lot of cutting and sticking but no metal was involved - all plastic. I also eased the chassis to accept a Hornby body. Replaced Zen chip with it's stay alive still attached, and it wouldn't work again. Inserted generic chip and it worked. What could I have done before 5 that could have caused the problem and then between 5 and 6 reversed it? By the way the loco still runs on the generic chip - but not as well (as I would expect without a stay alive and no CV changing)

Are you SURE that the voltage is reduced or are you just repeating the commonly held view? There is no NMRA requirement that the voltage be reduced. Yes that's what I finally worked out too. I use PECO loco-lifts to do the lifting about in, but a separate track does seem to be a good idea. I am increasingly being drawn to the Sprog idea too (a better investment I am beginning to think than a decoder tester) and I have used JMRI in the past via an NCE USB adapter, its just freeing up a computer to dedicate to the job that is the pain.

Please don't be rude about us LEO dinosaurs we are a dying but proud bunch, without us you'd have no computers and no internet to ping or in my case no 2900 to grope

Thanks Ian. Mr Gurries would disagree with you https://sites.google.com/site/markgurries/home/technical-discussions/program-track/nmra-programming-track But I really do want to find the facts - since I don't want another damaged decoder. It wasn't the decoder that didn't work - it did when first inserted - so a decoder tester wouldn't really help me.

Look I am way out of my league here, so this may be a very silly question BUT surely all you have proved is that a certain amperage can be drawn and NOT what the PowerCab actually uses to write to a DCC decoder when in program track mode. I understand all would be revealed to me were I inclined to use Yahoo, but with respect I don't have a long enough spoon.

Please, it was my fault that I misunderstood you. However such action is not necessary. Please read Mr. Gurries at https://sites.google.com/site/markgurries/home/technical-discussions/program-track/nmra-programming-track I am pleased that you have not had problems with Yahoo. If you want to know what I am talking about try Googling "Yahoo security breach".

That sounds very sensible to me. When you say "insulated at both ends" do you mean you have an isolating section at both ends? I have heard it suggested that it is sensible to keep the main and the programming track isolated from each other, not just rail breaks. This is presumably to prevent accidental driving from one to the other when having program mode switched on. If you have a secure system of either one or the other the problem of course does not arise. I particularly agree with your point about lifting locos about. I have some sight problems so I always try to avoid using hands-on. I have some PECO loco lifts which I use to store and move my locos about. When fitting decoders though - needs must!

Thank you very much Mr. Cliffe, your assistance is as ever greatly appreciated. In my area of expertise we are very cautious of using services which have less than clear bills of health on user security. I and many others keep clear of Yahoo on that basis alone.

The PowerCab and PowerPro are two very different beasts - and this probably shows where the base system (the PowerCab) is a "cheap" starter system. The PowerCab has only ONE feed so it cannot of itself cut power to the main layout - an add-on (an auto switch) is provided should that be required. This is the problem with statements like NCE (or any other supplier) does X - I completely misunderstood and being fixated on my problem (which your system obviously doesn't have) I questioned your statement of fact.

I am sorry, but I don't believe that the statement is correct: see http://www.rmweb.co.uk/community/index.php?/topic/126071-i-think-i-just-fried-a-dcc-loco-chip-diagnosis-assistance-needed/ I absolutely agree with your point in using a programming track and the case for POM. I (and some others) use an entirely separate programming track - not connected to the layout in any way. I have a PCP attached to a piece of track and physically move my PowerCab handset. The NCE PowerCab does NOT reduce the voltage to the program track when "set Program Mode" is selected - well not for me anyway. I have 13.5v AC in both cases. I believe that what happens is that the commands are issued at a lower amperage and for only short bursts - but nobody seems to know for sure. The NMRA standards require that "service mode" (as they call it) operates at "limited energy". They go on to say "For the purposes of this STANDARD, limited energy is defined as 250 mA, sustained for more than 100 ms.". I do not believe that this or any other standard REQUIRES that track voltage be reduced. What the NCE PowerCab does as well is to test for a short circuit on the program track before it changes mode - another protection for a mis-wired decoder. Sadly none of this helped me - but it will help others if they understand exactly what is going on.

I apologise if I sounded scratchy. I am sure that you were helpful to people reading this thread who have one of the auto switches: that does not include me, nor does it answer the question which I really want an answer to. Sorry if I was being proprietorial about my problem.

Well, as far as I can see the power for the program track was taken off before the auto-switch for Rev A. But anyway all of this does not in any way indicate either whether the NCE Power Cab programs at "reduced energy" as defined by NMRA or whether (If it does not) the auto switch actually does anything to help. I believe 1) that the NCE PowerCab performs correctly and 2) the auto switch is what it says and contributes nothing to the process (or the argument for that matter). Given that obviously neither of us knows for a fact what the situation is this is all a bit pointless.

No it hasn't. My programming track is a piece of ST 604 on a piece of plywood. There is a red wire soldered to one rail and a black wire to the other (black to the back - my mantra as I wired the droppers on my main system). The 2 wires go to a piece of choc block. If I want DC I take my Gaugemaster Combi outputs and screw them colour coded into the chock bloc (I had thought of using the plug in style but I had run out). I then plug the wall wart output into the Combi and then the wall wart into the wall socket. I finally put the loco on the track. Hey presto a DC test bed. If I want DCC I take my box with an NCE PCP set into it and take the outputs (colour coded again) and screw them into the choc bloc - I won't bore you with the rest. It is of course possible to forget which is which - i.e. to set up a DC test and put a DCC loco on the rails. I am not aware of having done so - but I get old and frail.

Yes I think we are, but none the worse for that - we both seem to be finding out more as we go on. You may also have had the experience I have had, where having decided to use NCE mini-panels to automate my layout, I found the NCE documentation poor and confusing. This seems just another example. That's how I came across Mark Gurries originally: he had written some amendments for the manual. It seems that NCE are good engineers, but not good at documenting things (not unusual in my experience). So, having a lot of experience of using their stuff, and having read what you have read, I agree with you that it very probably does do what it should do - I just cannot prove it. Most of the other people posting on here seem also not to be able to prove things one way or another, or indeed explain what should happen in programming a DCC chip.

Thanks Nick, perfectly clear. This MAY be the cause of my fried chip, or may not. It's on it's way to DCC Concepts who will tell me the word in due course.

The error escapes me. I have been referred to information published by Mark Gurries, much of which I have already read with interest. You may wish to note that on: https://sites.google.com/site/markgurries/home/nce-info/nce-accessories/nce-autoswitch that the diagram is posted as a solution to a problem in the AutoSwitch - i.e.it switches off the main track power and bypasses the unit entirely for programming. Unfortunately I cannot find anything from him about the actual process of "programming". Sadly I won't be looking on Yahoo - its a jungle with unforeseeable consequences. I have has volts and amps etc explained gently to me in the past - usually with reference to water pipes.

Sorry Rob I didn't think I had? Lots of people keep telling me that there should be no voltage to the track in programming mode. I thought that was what I said. Also there is voltage to mine using a PowerCab and the NMRA doesn't say there shouldn't be - only that the instructions should be given with "limited energy" (their words not mine).

Not having an electronics background I don't understand what you did or what it proves or disproves. More explanation for an idiot please?

I am not sure what you find worrying? It seemed clear to me for a long time that the auto switch did nothing in particular, OTHER than what it was described as doing. Shutting off power to the main layout. Now I don't have one and don't want one, but there were lots of suggestions that such a thing would somehow make using a separate programming track with an NCE PowerCab "safer" or somehow make it comply with standards that all (most?) other systems complied with. I don't think it does anything of the sort.

If you have a separate programming track and an NCE PowerCab please don't go and buy an auto switch. It does NOTHING other than sense the pressing of the "set program track" menu option to switch power to the main off and power to the program track on. This is demonstrated by the attached official NCE diagram. The diagram shows the auto switch being used to simply switch the main OFF - the programming track is permanently powered. I can find nothing on the web that supports the idea that the programming track power should or must be off in what NMRA call Service Mode, or indeed of any particular voltage, however the NRMA states: "3) Service Mode operations should be performed in an environment with limited energy to prevent damage to decoders during programming. For the purposes of this STANDARD, limited energy is defined as 250 mA, sustained for more than 100 ms." I see no reason to believe that the NCE Power Cab does not issue programming commands in such a way, i.e. when the "set program track" option is selected then all the commands on the subsidiary menus are issued with lower energy and for short bursts as defined by NMRA. HOWEVER what for sure does happen is that full volts are permanently available AND when you "escape" from "set program track" it is possible to drive the loco as normal, if it's loco number has been selected. My problem was none of these things. A previously well behaved chip was removed during some work on a chassis, and then replaced. Placing that chassis on the separate programming track produced instantaneous run away, despite the loco number not being selected and the control wheel set at off. Auto-SW Live Program Track (1).pdf

This may have been the performance I observed. Thanks for the information.

Join the club! I have just tried experimenting with my NCE PowerCab on my separate PCP and I can find now way to make the voltage disappear, nor does It do so before or after any valid command I can give it. Maybe the special extra switch board actually does this? I don't know, and I don't really see the need in regular use. It MIGHT have helped in this case - I just don't know. I'm a simple man too. As you say, since the chassis works fine with another chip in it there must be a fault in the Zen one - but did I cause it, and if so how? I do want to continue with using Zen chips with their stay alive, I don't want to keep blowing them if that's what I did. Hopefully DCC Concepts will agree to examine the chip - they haven't yet.

Thank you for that warning. However in the present case I have also run it with a chip in the plug and it works. So that isn't the cause of my particular problems - though I will keep the warning in mind for other occasions.

DCC Concepts have just got in touch - my original emails seem to have gone walkabout so I have provided a copy. Hopefully I'll get some input from them later on. The other suggestions (for me) are moving off into the realm of fantasy. I'm not much of an electronic whizz, and certainly don't wish to get involved in building breadboard circuits. On the other hand there will be other readers to whom the information may be helpful so I am not suggesting that they stop - its just that I won't be joining in. I am about to do some experiments on finding how I get my separate piece of track to operate as a programming track like the above posts have suggested it should - i.e. with no AC to the rails except when commands are issued. I should point out that ideas of using DC in my case have already been dealt with - I put a blanking chip in and ran the chassis under DC to prove 1) that the conversion was indeed OK and 2) that the chassis still worked and has no faults. I had also programmed the Zen chip to get the speed/accelleration right and switched OFF DC working. The chassis in question now has a Hattons 8 pin direct chip in it and the Class 37 body properly fitted and is working OK. It ran six 6 coach trains in my timetable last night. The 55 which should have been doing the work sat forlornly on one side with no chip! The Zen with the stay alive had a much better working performance in the Class 37 than the Hattons does - and I have tentatively ordered another Zen 360 direct but I will not fit it until I get some reassurances from DCC-C that the chip will indeed handle an old Lima pancake.

Well I did the next best thing - see post #32 point 4. The wooden box actually holds my spare lumps of lead and steel. I backed off when the PowerCab said "short circuit detected" because I don't want to damage anything (well more than it is already). As Harold says, it would be best if DCC-C will take the chip in for testing. They will have better equipment than me and would be able to say quite quickly what was the matter and how it was caused (perhaps).