Bachy DMUs and decoder in trailing vehicles

[Grovenor]

 

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.

Be careful where you put that resistor, if you leave it in place it will be driven whenever you are running as if it is a motor, hence will get warm.

Keith

[Andy Reichert]

Be careful where you put that resistor, if you leave it in place it will be driven whenever you are running as if it is a motor, hence will get warm.

Keith

 

And turn off bemf.

 

120 ohm will pass 100 mA and dissipate 1.2 watts. So not merely warm if a typical 1/2 or 1/4 watt carbon resistor. You will need a higher power wire wound, or a much higher resistor value.

 

Andy

[Sir Topham Hatt]

I had endless problems with my class 105.  There are leds all over the units (running lamps, head codes, interior lighting etc) and they all seem to use separate contacts and, as said above, removing and replacing the coach tops can cause contacts to fail on DCC, though strangely they remain fine with DC! 

 

I seem to recall I followed the decoder fitting instructions, using 8 pin decoders on both cars and programming the unpowered unit in the powered unit first, then unplugging it and placing it in the unpowered unit.  You can of course use a cheap, basic decoder in the unpowered unit as you are only using the lighting switches.

 

When, by the way, I originally rang Bachmann to report the problems I was told that they had not heard of anyone else having experienced problems.  I suggested at the time they look in these forums - we all had problems!  They explained that if I had fitted the decoders myself they could not resolve the problem under warranty.  I explained that they were Bachmann decoders but that cut no ice.  I asked if they offered a decoder fitting service, but no, they didn't.  So I asked how a customer was able to fit a decoder to their DCC ready product without invalidating the warranty / customer support.  "Sorry, it's out policy"! 

 

This was over a year ago and things may have changed but I can remember when I called Bachmann some years ago to report that I'd bought a second hand but unused Peak loco and that the gears had become tight.  They asked me to post it to them and it was returned with a completely new gear set and no charge.  The guys in their service centre (as was) certainly understood customer service - but maybe had no business sense!!!  

[Dave at Honley Tank]

Thanks Keith &  Andy; actually after sending my last post I did some more thinking, along the lines of :-

Nigel's resistance range of 50 -100 ohms worked on programming but there is lower voltage or some form of excess current protection when programming.

A quick power check for 12v and 100 ohm showed that a 0.5W resistor would provide unwanted cab warming!

1kohm would be cool enough but would it give my Lenz Compact &/or my NEC PowerCab that required "ak" signal? Indeed could I use an even higher value resistor?

 

Does anybody know?

Or do I have to lash-up a test bed?

 

Dave

[Dave at Honley Tank]

I e-mailed Bachmann about the problemand their reply was:-

 

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

 

 

I replied with:-

 

 

Thank you but the “program together” has not programed my trailer decoder.

 

Do you not think that the information sheet included in the DMU packaging should have more information than simply which of your decoders is required by which car?

If you look on RMweb under “DCC Questions” you will quickly see that I am not alone with this programing of your DMU models.

 

Their reply to that was:-

 

Dear Mr Booth

further to your enquiry: I am sorry to read that you still have a problem. We have today tried a Derby Lightweight unit with both the simple E-Z Command control centre and also with Dynamis, and I can confirm both decoders have successfully readdressed together when using either equipment.

From time to time this particular equipment does get mentioned by users having problems and I presume that NCE may able to offer some suggestons to you as some DCC units do have some quirks from time to time
 
Regards

 

So it doesn't look as though the info sheet will change!

 

Ah well, one can but try.

 

Dave

[PaulCheffus]

 

I e-mailed Bachmann about the problemand their reply was:-

 

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

 

 

I replied with:-

 

 

Thank you but the “program together” has not programed my trailer decoder.

 

Do you not think that the information sheet included in the DMU packaging should have more information than simply which of your decoders is required by which car?

If you look on RMweb under “DCC Questions” you will quickly see that I am not alone with this programing of your DMU models.

 

Their reply to that was:-

 

Dear Mr Booth

 

further to your enquiry: I am sorry to read that you still have a problem. We have today tried a Derby Lightweight unit with both the simple E-Z Command control centre and also with Dynamis, and I can confirm both decoders have successfully readdressed together when using either equipment.

 

From time to time this particular equipment does get mentioned by users having problems and I presume that NCE may able to offer some suggestons to you as some DCC units do have some quirks from time to time

 

Regards

 

So it doesn't look as though the info sheet will change!

 

Ah well, one can but try.

 

Dave

 

Hi

 

I regularly program my DMUs this way by putting both on the programming track at the same time. I am using a Lenz set if it makes any difference.

 

Cheers

 

Paul

[Phil S]

As the trailing vehicle has no inbuilt 'acknowledge' device - and the controller is 'being made happy' with the acknowledge from the motor in the driven part ....

 

BUT the power Pickup for each vehicle is TOTALLY INDEPENDANT: I recommend:

 

1/  Ensuring BEFORE entering programming mode, that the lights are on ( eg Loco 3, lights on ) to ensure it is picking up power, and then...

2/ PUSH DOWN on the trailing car (which doesn't have the inbuilt weigth of the powered car) - to ENSURE GOOD CONTACT during Programming.

 

Then immediately test with the new number and 'lights on' command - and in the case of the DMUs. change direction to verfiy function (or redo with CV29 odd<>even)

 

(or, using a Roco Multimaus - I preselect the new address, before entering programming mode, enter programming mode and change CV29, and then select 'long', and it picks up the number I have already entered ... and automatically programs 17 then 18 as required .... then exit programming, and turn the lights on/off to verify ... remebering to Hold down the trailer as above during BOTH parts of programming.