Bachy DMUs and decoder in trailing vehicles

[Dave at Honley Tank]

I've just fitted decoders to a Derby Lightweight and been able to prog'm the driving unit as a solo vehicle but the trailer gives "Error 2" which means that the decoder cannot be found.

I was informed that I needed to program both vehicles coupled as one but while this seems to work for the driving unit, the trailer still seems to be uneffected.

Everything works OK except the direction lights on the trailer are never on. As dc these changed colour with direction.

 

I'm unlikely to use the running lights because it shows up the fact that other trains don't have any that actually light up! However something is obviously not correct & I'd like to know why.

 

The decoders are the Bachmann recommended ones and fitted as per the instruction sheet which has no info about programming. The leaflet with the six pin decoder (trailer car) is very basic and it shows CV numbers and default values which indicate that it is a decoder suitable for loco control but the only comment about lights refers to FO switching running lights - it doesn't on mine!

 

What have I done wrong or do  have a duff decoder?

 

Dave

[10000]

Motor decoders normally need a load on to program which is why you need to do them together.

 

2 possibilities spring to mind 

 

1) Your dcc system can not do it ----  what are you using then maybe someone can advise.

 

2) Putting the trailer car back together maybe resulted in something not connecting properly - seems to be common issue when putting Bachmann dmus back together. When I did mine I always seemed end up reopening to adjust a contact for the lights.

[airwimp075]

Hi Dave,

I've had similar issues with their Class 105, i seem to recall reading somewhere to set up the decoder in the driving unit, transfer that to the non-driver, then set up the driving units decoder in the driving unit. I tried this but didn't succeed totally. It worked for a short period then stopped, i swapped the decoder with one of my steamers as it has no light functions, the new decoder worked fine in the driver, but stopped again after a couple of seconds in the trailing unit. So, what im getting at is, this method did work, but i think the non-driving units blowing my decoders ... so more invest into possible shorts when i have time.

 

I hope this is of some assistance,

Jason

[Dave at Honley Tank]

Motor decoders normally need a load on to program which is why you need to do them together.

 

2 possibilities spring to mind 

 

1) Your dcc system can not do it ----  what are you using then maybe someone can advise.

 

2) Putting the trailer car back together maybe resulted in something not connecting properly - seems to be common issue when putting Bachmann dmus back together. When I did mine I always seemed end up reopening to adjust a contact for the lights.

The DCC system I used was a Lenz 'Compact'.

Body  back on and on DC, direction lights work; Body off, decoder added, body back on - no direction lights.

All back to DC mode and body on, direction lights working again on analogue but not on digital.

In all cases the interior lighting worked so poor contact seems unlikely.

Dave

[Dave at Honley Tank]

Hi Dave,

I've had similar issues with their Class 105, i seem to recall reading somewhere to set up the decoder in the driving unit, transfer that to the non-driver, then set up the driving units decoder in the driving unit. I tried this but didn't succeed totally. It worked for a short period then stopped, i swapped the decoder with one of my steamers as it has no light functions, the new decoder worked fine in the driver, but stopped again after a couple of seconds in the trailing unit. So, what im getting at is, this method did work, but i think the non-driving units blowing my decoders ... so more invest into possible shorts when i have time.

 

I hope this is of some assistance,

Jason

My decoders are eight pin for driver and six pin for trailer so interchange is not possible is it?

Dave

[airwimp075]

Dave,

Sorry, my post is kind of redundant in this case, so I apologise. The only way around I can see this method working is if you had an 8 to 6 pin adapter or another 6 pin loco with light function (a wiser member may correct me as to wether lights are required in this instance) that you could programme the decoder with then swap it into the trailer unit.

I hope my previous post may assist someone else in the future if they stumble across this topic with similar issues.

Please do let us know how you resolve your issue.

Jason

[Dave at Honley Tank]

Dave,

Sorry, my post is kind of redundant in this case, so I apologise. The only way around I can see this method working is if you had an 8 to 6 pin adapter or another 6 pin loco with light function (a wiser member may correct me as to wether lights are required in this instance) that you could programme the decoder with then swap it into the trailer unit.

I hope my previous post may assist someone else in the future if they stumble across this topic with similar issues.

Please do let us know how you resolve your issue.

Jason

Thank you Jason.

Having a re-read of my wording in my last post, I hope you were not offended; - it was a question, not a sharp reply statement.

I think that a six pin decoder will fit in an eight pin socket but I' feel that such would risk totally useless or even dangerous(big bang) situation.

Perhaps if the six-pin, number one pin went in the eight-pin number one socket the six wires would indeed be correctly linked but I'm not sure. Anyone know?

 

Life used to be easier than this!!

Dave

[muddys-blues]

Hello - obvious daft question here, is the decoder plugged in the right way ? #1 pin in the correct socket hole ?

 

Best regards

Craig

[Dave at Honley Tank]

Hello - obvious daft question here, is the decoder plugged in the right way ? #1 pin in the correct socket hole ?

 

Best regards

Craig

Hi Craig,

I don't consider any question on here is daft, -  at best (or should that be "worst"?) it's a case of the questioner knows much less than the reader, and the boot can very easily be on the other foot!

 

Normally if you get no 1 in the wrong hole, every thing still works without danger but the loco direction may be reversed. 

 

 

in this case the offending decoder has been in both ways.

 

Thanks for your input

Dave

[airwimp075]

http://www.howesmodels.co.uk/product/Bachmann%206-pin%20socket%20with%208-pin%20plug

 

Something like this will make it safe to plug your 6 pin decoder into your 8 pin socket ... its one option, not quickest/cheapest and still wouldn't guarantee success. Hopefully a DCC expert will roll in with a real obvious answer ...

Jason

[Adrian Wintle]

Motor decoders normally need a load on to program which is why you need to do them together.

 

 

Actually, the load is only necessary for the feedback. The 'Error 2' means that the controller didn't see feedback pulses from the decoder (which can't happen because there is no motor load) but, assuming the decoder is installed correctly and is working, it should still program correctly.

 

Adrian

[Dave at Honley Tank]

Actually, the load is only necessary for the feedback. The 'Error 2' means that the controller didn't see feedback pulses from the decoder (which can't happen because there is no motor load) but, assuming the decoder is installed correctly and is working, it should still program correctly.

 

Adrian

That may well be true Adrian but, at least with the Lenz Compact, if you get "error2" then you can go no were.

I started with the trailer unit solo on the prog track and tried to change CV1 from 3. Calling up CV1 gives me "ER2" and then the only possibility is to go out of prog mode and back in again.

I've tried other CVs with exactly the same result; - always "ER2".

In short the programmer can't find the decoder.

 

Dave

.

[Nigelcliffe]

The problem is mostly in the Compact - its old, and has fairly limited capabilities, and its trying to be helpful by saying no loco detected (but failing to be helpful!).   The problem is the Compact is listening for the "ack" signal from the decoder, but that signal will only be generated if there is a modest load on the decoder, typically a motor or suitable resistor.  The LED lights are far too low current to generate the "ack" signal.   Hence the Compact doesn't see a signal, and goes to "error 2 = no loco detected".    It should be possible to make it work.  

 

 

Step 1 - find out if the lights work.   Do the lights respond on address 3 ?     If they do, at least you know the decoder is fitted correctly and working.  If the lights respond to speed control then the decoder is inserted upside down (lights are on the motor output, rather than lighting output), so turn decoder over and try again.    If it fails, then don't know whether decoder is OK and just reprogrammed to a different number, or decoder not working, or fundamental wiring problem in trailer car. 

 

 

Step 2 - programming the decoder.   If the Compact is the only option (ie. can't use someone else's kit), then you have to provide sufficient load on the decoder for the "ack" pulse to come back, and the Compact to proceed.    

Next two options are to introduce a motor load for the programming steps:

 -  The simpler ways to do this is a resistor (around 50 to 100 ohms) or a motor over the two terminals of the decoder for motor.   On a six-pin, that's pins 1 and 2.   Whether this is easier done on a bench, or in the decoder socket in the trailer car is really up to you to work out - I'd waggle a piece of rigid, but fine, wire into the sockets in the trailer and clip a resistor (or motor) to those, then slide the decoder in as well.  But you may not feel confident doing this.   

-  Alternatively to putting a resistor/motor temporarily in the trailer car, is using a wiring harness for a six-pin, and either connecting that to an 8-pin socket, or using the wiring harness to create your own test rig of two wires to programming track (red/black) and two wires to motor (orange/grey) for the purposes of programming.

 

 

- Nigel

[Dave at Honley Tank]

The problem is mostly in the Compact - its old, and has fairly limited capabilities, and its trying to be helpful by saying no loco detected (but failing to be helpful!).   The problem is the Compact is listening for the "ack" signal from the decoder, but that signal will only be generated if there is a modest load on the decoder, typically a motor or suitable resistor.  The LED lights are far too low current to generate the "ack" signal.   Hence the Compact doesn't see a signal, and goes to "error 2 = no loco detected".    It should be possible to make it work.  

 

 

Step 1 - find out if the lights work.   Do the lights respond on address 3 ?     If they do, at least you know the decoder is fitted correctly and working.  If the lights respond to speed control then the decoder is inserted upside down (lights are on the motor output, rather than lighting output), so turn decoder over and try again.    If it fails, then don't know whether decoder is OK and just reprogrammed to a different number, or decoder not working, or fundamental wiring problem in trailer car. 

 

 

Step 2 - programming the decoder.   If the Compact is the only option (ie. can't use someone else's kit), then you have to provide sufficient load on the decoder for the "ack" pulse to come back, and the Compact to proceed.    

Next two options are to introduce a motor load for the programming steps:

 -  The simpler ways to do this is a resistor (around 50 to 100 ohms) or a motor over the two terminals of the decoder for motor.   On a six-pin, that's pins 1 and 2.   Whether this is easier done on a bench, or in the decoder socket in the trailer car is really up to you to work out - I'd waggle a piece of rigid, but fine, wire into the sockets in the trailer and clip a resistor (or motor) to those, then slide the decoder in as well.  But you may not feel confident doing this.   

-  Alternatively to putting a resistor/motor temporarily in the trailer car, is using a wiring harness for a six-pin, and either connecting that to an 8-pin socket, or using the wiring harness to create your own test rig of two wires to programming track (red/black) and two wires to motor (orange/grey) for the purposes of programming.

 

 

- Nigel

Hello Nigel, nice to hear from you again.

If this had been a wire rather than a pinned decoder I'd have slapped a motor on orange & grey but this thing is all wrapped in heat-shrink so I don't know which pin is for which colour.

I also have 'PowerCab' by NCE but I have never tried to program with it; - I know the 'Compact' better and always use that.

I'll get out the manual for the 'PowerCab and teach myself how to program with it. Slow to learn now-days though !

That won't be today though; perhaps I'll be back here in a couple of days or so.

PS- sorry forgot to say the direction lights don't work with the decoder but OK with the shorting link & on DC. Driving car giving no probs.

 

Dave

[AMJ]

I found a similar situation.

 

If you reset the power car chip back to 03 address like the trailer.

 

My programming track is long enough to place whole train on and program both cars at same time.

 

I can also program the cars together on the main track.

 

Doing it by either of these fools the controller as there is a motor connected in one car.

[Izzy]

http://www.rmweb.co.uk/community/index.php?/topic/81418-which-way-round-for-Bachmann-6-pin-n-gauge-decoder/http://www.rmweb.co.uk/community/index.php?/topic/81418-which-way-round-for-Bachmann-6-pin-n-gauge-decoder/

Hello Nigel, nice to hear from you again.
If this had been a wire rather than a pinned decoder I'd have slapped a motor on orange & grey but this thing is all wrapped in heat-shrink so I don't know which pin is for which colour.
I also have 'PowerCab' by NCE but I have never tried to program with it; - I know the 'Compact' better and always use that.
I'll get out the manual for the 'PowerCab and teach myself how to program with it. Slow to learn now-days though !
That won't be today though; perhaps I'll be back here in a couple of days or so.
PS- sorry forgot to say the direction lights don't work with the decoder but OK with the shorting link & on DC. Driving car giving no probs.
 
Dave

If we are dealing with the standard Bachmann 6 pin decoder here - which I suspect is the case -then there are a couple of shots I posted in this thread

 

http://www.rmweb.co.uk/community/index.php?/topic/81418-which-way-round-for-Bachmann-6-pin-n-gauge-decoder/

which will show the pin orientation, or lets say you can work it out from them. You can then hook up connections to them. I have soldered wires to them in the past.

One thought though. With several 6 pins in order to get a good connection when inserted into the socket I have had to 'bend' the pins to ensure this. A quick tweak with pliers about half way along. If the dmu wiring isn't an issue this might be the reason why the blanking plate will work it all fine on DC but it's a no go with the decoder.

 

Izzy

[tarifa]

I dont think you can plug a 6 pin decoder into an 8 pin socket

 

6 Pin Wiring-8 Pin Wiring.docx

 

Mike

[Dave at Honley Tank]

I dont think you can plug a 6 pin decoder into an 8 pin socket

 

6 Pin Wiring-8 Pin Wiring.docx

 

Mike

Thanks Mike; link worked OK but my version of 'MSWord' is before .docx so I can't open the document.

Dave

[Dave at Honley Tank]

Hello and thanks so much to those who have tried to help ; the problem is now solved!!

 

Mr Cliffe, well done, you hit the nail on the head; my Lenz Compact was not good enough. Neither was my NCE PowerCab!

But Nigel's crafty -" stuff a thin, stiff wire in the socket at pins 1&2", allowed me to link up a spare motor and both systems then found the decoder.

I treated each vehicle separately, but simply gave each decoder the same address. From that point, everything worked as it should.

 

Nigel, you said "The problem is mostly in the Compact - its old, and has fairly limited capabilities, and its trying to be helpful by saying no loco detected (but failing to be helpful!).

Can I infer from that that the more expensive systems will find the decoder even with no motor? If that is so then am I also correct in assuming that the answer to this programming of a multi-decoder train ( i.e. DMU etc) is to put the whole train with its decoders fitted, onto the programming track and so give all the decoders the same address, but that most low end systems will find only the driving motor(s) decoder(s), meaning the lighting won't work because all other decoders stay at #3?

 

If there is general consensus as to the truth of my above summary then it seems fair and helpful to future sufferers that we make the last posting to this question, the definitive answer!

[Nigelcliffe]

Glad the decoder is now fixed.   With many things, being cunning and sidling up quietly before hitting with big stick is the solution :-)

 

 

Nigel, you said
 "The problem is mostly in the Compact - its old, and has fairly limited capabilities, and its trying to be helpful by saying no loco detected (but failing to be helpful!).
Can I infer from that that the more expensive systems will find the decoder even with no motor? If that is so then am I also correct in assuming that the answer to this programming of a multi-decoder train ( i.e. DMU etc) is to put the whole train with its decoders fitted, onto the programming track and so give all the decoders the same address, but that most low end systems will find only the driving motor(s) decoder(s), meaning the lighting won't work because all other decoders stay at #3?

 

No, sorry you can't infer....   The "helpful but failing" is down to the Compact insisting that it "reads" before it proceeds.    Other systems should be able to "write" and just get on with it (The PowerCab should do this, so I'm a little surprised you failed to make it work).   Also, other systems will have "Ops Mode" (Programming on Main), which will usually let you make an address change (again the PowerCab can do this,  the "usually" is because a few decoders make it difficult to make ops-mode changes to the decoder address. ).   Ops Mode will let you make any other changes to a decoder as it is running, such as changing the lighting brightness, or the function key which controls the lighting, etc...

 

 

The "read" mechanism of the DCC programming track relies on a bit of current coming back from the decoder - the "acknowledgement" or "ack" pulse.  This, in turn, needs a reasonable load on some of the decoder outputs.  Typically this is done with a motor, though a resistor of 50-100 ohms will work.   The current draw from a few LED lights is too small to register as current back from the decoder.   

The "ack" pulse is the ONLY thing a decoder sends back (yes, its that crude!). To perform a read, the command station has to go through a version of 20-questions (256 questions!), along the lines of "is the value of CV1=1",  "is the value of CV1=2", etc..   The decoder replies with "ack" when the answer matches. 

 

 

What should work, for any system, is placing an entire multiple unit on the track, and writing to all the decoders simultaneously.   The one with a motor will respond to "read" requests, the others will be silent.   That yours failed is a little surprising, and would need a bit of detailed digging to find out why it failed.  (I wonder if its an issue over "register", vs "paged", vs "direct" modes on the programming track,  that's where I'd start my first digging hole ). 

 

 

- Nigel

[10000]

 

 

 Neither was my NCE PowerCab!

Power cab will faIl if you do the trailing car on its own but should work with both on the programming track. Thats how I did my Derby Lightweight.

[MickD]

Hi,

Only thing with doing them at the same time is, will they be trying to go in opposite directions.? As you cannot tell one to go the other way as they will both respond ??.

Just a thought.

MickD.

[Phil S]

Phil: This is NOT a real problem 8-)

 

n ALL cases, the following should work:  Place the decoder-fitted units on the programming track***, and program them - adjusting the direction with CV29 if needed, to get the trailing car correct.

This programming makes use of the powered-car's motor to give the Ack feedback - whether using a programmer which 'reads' or not.

 

THEN REMOVE the trailing car, and reprogram the DRIVING (MOTORED) car as required to get its directional lighting correct - again using CV29 odd or even to change this as required.

Now, when using both parts together, it will operate correctly.

 

**If a LONG HST or similar, and a short programming section, the centre coaches are NOT needed at this stage

[Dave at Honley Tank]

Before I asked on here I tried Bachmann's web page but could do no better than send an e-mail via their page.

I've now got a reply, as follows:-

 

Dear Mr Booth

further to your enquiry: yes the DCC equipment would usually want to have some load to determine response from a decoder, and normally it will be fine if both cars are on the track together 

Regards


Service Team

Bachmann Europe plc

 

Not as helpful as on here!

 

I now have a Derby Lightweight running quite well and with its direction lights working correctly, thanks to enquireing on here.

I started by saying that using the running lights is extremely unlikely, so the exercise has really been a bit futile beyond gaining a bit more knowledge, and that's never time wasted.

Its a pity that we are unable to conclude with a diffinitive answer, but while it did not work for me, it would seem that the first step is to have both decoders connected to the programmer at the same time and then to progam as one.

I will try this at some time in the future, but for the time being I'm going to play trains with my new toy!

Very many thanks to all who responded.

 

Dave

 

[Dave at Honley Tank]

Gentlemen,

I'm old and increasingly forgetful and after all that's been said on here and my other sources of help I thought perhaps I had not actually tried to program the two as one on both my systems so I've done some more experiments.

First, I put both on the Lenz and tried to re-address as "3". -Result: driver now 3, trailer still 10.

Second, both on Lenz and address changed to 10 - Result both 10.

These tests were repeated on the NCE with exactly the same result.

 

So it appears that neither of my simple DCC systems can find a decoder with no load on its motor terminals.

I plan to visit the local Maplins to purchase a suitable resistor (50 - 100 ohms) which I will connect across pins 1 & 2 on the six pin socket of the trailer and leave same connected at all times.

 

This should allow me to do future progamming without hastle.

 

Once more, thanks for your help.

Dave