question on a BD20


Bob Macionis
 

 I have an issue with a BD20 that is baffling me.  See file "macionis BD20 question".  I have a block running from point A to  point B that is being detected by a BD20 at B.  Originally all track from A thru B to C and thru E &F to G was on the same buss.  C to D (pink)  is a reversing section.  Everything worked ok.  The psx-ar reversed properly; the BD20 detected a loco entering the A - B block.  I decided the reversing section was too short, so I cut all the feeders  in B-E-F-C  (purple)  from the A - G buss (green) and added them to the reversing section.  Originally the only double gaps were at A , D and C  (G is a stub end).  So I needed to isolate the longer reversing section by cutting gaps at B, E and F.
    The psx-ar still works ok.  But the BD20 shows occupied all the time , whether a loco is there or not.  If I jumper the gaps at B (meaning the purple track is fed from both green and pink busses), the BD20 no longer shows false occupancy, and works normally .  I have seen many cases where a bd20 shows false occupancy because I added something to the block (such as powering an led from the buss), which I corrected by removing those wires.  But here all I did was remove the purple section from the green, and all of it is on the booster side of the bd20.   Cutting the gaps at B causes the bd20 to show false occupancy, and jumping the gaps closed allows the bd20 to work normally.  Can anyone explain this to me?  Thanks.


wirefordcc
 

Hi Bob,

Is your BD-20 before the PSX-AR?  If so, that is your problem.  The PSX-AR draws a little bit of power all the time and will cause the BD-20 to show the block as being occupied.

If you are using the same block detector for the reversing section as you are from B to C, you will not be able to do that unless you make the section from B to C part of your reversing section or use a separate BD-20 for the section from C to D.  In any event, the BD-20 has to go after the PSX-AR.

BTW,  Is your reversing section longer than the powered portion of your longest train?  It also needs to be longer than your longest train if all your cars have resistor wheels, your caboose is lit, or you have lighted passenger cars.

Allan Gartner
Wiring for DCC 


Bob Macionis
 

Thanks for the reply, Allan.  The reversing section and  A – G have separate busses going to different circuit breakers, a psx-ar and a psx. As far as I can tell, there is no electrical connection between them.  There is no block detector on the reversing section.  I did make my reversing section longer, by adding the purple track to the pink buss, instead of the green.  All green track goes to  the  psx; The purple and pink track go to the psx-ar. As I explained, everything worked- the BD20 detected perfectly, when all purple track was attached to the green buss, and there was no double gap at  B . (The reversing section was only the pink).   When I disconnected the purple track feeders from the green buss and attached them to the pink buss (negating the double gap at C) I had to cut gaps at B, E, and F to isolate the reversing section. Then, and only then, the BD20 always showed occupancy.  I added no new wiring; I deleted wiring and isolated the psx-ar  with those new gaps.  If I jump the gaps at B, allowing the psx-ar to leak into the green, the false occupancy disappears and the BD20 works perfectly. This I do not understand.

Bob

 

Sent from Mail for Windows

 

From: wirefordcc
Sent: Tuesday, September 28, 2021 3:43 PM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] question on a BD20

 

Hi Bob,

Is your BD-20 before the PSX-AR?  If so, that is your problem.  The PSX-AR draws a little bit of power all the time and will cause the BD-20 to show the block as being occupied.

If you are using the same block detector for the reversing section as you are from B to C, you will not be able to do that unless you make the section from B to C part of your reversing section or use a separate BD-20 for the section from C to D.  In any event, the BD-20 has to go after the PSX-AR.

BTW,  Is your reversing section longer than the powered portion of your longest train?  It also needs to be longer than your longest train if all your cars have resistor wheels, your caboose is lit, or you have lighted passenger cars.

Allan Gartner
Wiring for DCC 

 


wirefordcc
 

Bob,

 

It sounds like you have a bunch of things going on.  There are a number of things I recommend that very few people want to do.

 

  1. Double gap everything.  Electrically it USUALLY isn’t necessary; which is why people don’t want to do it.  But when you want to troubleshoot something, you will have an easier time.
  2. Hook up one wire or thing at a time.  STOP the instant your problem crops up.  Sounds like you did a number of things and then powered up.  You have so much going on, you may want to disconnect everything and start over.  I know, that doesn’t sound pretty, but you have a lot of things going on.  There is no telling where your problem is.  I’m also concerned you don’t have the wiring or gaps you think you have.  You might want to try disconnecting your various electronic modules and ohm out your track and wiring to make sure you have what you think.

 

I do these things on my own railroad.  I’m a big fan of double gapping and doing an incremental install.  When a problem crops up, I’m only a couple of minutes max from finding the problem.

 

Allan

 

From: w4dccqa@groups.io <w4dccqa@groups.io> On Behalf Of Bob Macionis via groups.io
Sent: Tuesday, September 28, 2021 5:10 PM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] question on a BD20

 

Thanks for the reply, Allan.  The reversing section and  A – G have separate busses going to different circuit breakers, a psx-ar and a psx. As far as I can tell, there is no electrical connection between them.  There is no block detector on the reversing section.  I did make my reversing section longer, by adding the purple track to the pink buss, instead of the green.  All green track goes to  the  psx; The purple and pink track go to the psx-ar. As I explained, everything worked- the BD20 detected perfectly, when all purple track was attached to the green buss, and there was no double gap at  B . (The reversing section was only the pink).   When I disconnected the purple track feeders from the green buss and attached them to the pink buss (negating the double gap at C) I had to cut gaps at B, E, and F to isolate the reversing section. Then, and only then, the BD20 always showed occupancy.  I added no new wiring; I deleted wiring and isolated the psx-ar  with those new gaps.  If I jump the gaps at B, allowing the psx-ar to leak into the green, the false occupancy disappears and the BD20 works perfectly. This I do not understand.

Bob

 

Sent from Mail for Windows

 

From: wirefordcc
Sent: Tuesday, September 28, 2021 3:43 PM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] question on a BD20

 

Hi Bob,

Is your BD-20 before the PSX-AR?  If so, that is your problem.  The PSX-AR draws a little bit of power all the time and will cause the BD-20 to show the block as being occupied.

If you are using the same block detector for the reversing section as you are from B to C, you will not be able to do that unless you make the section from B to C part of your reversing section or use a separate BD-20 for the section from C to D.  In any event, the BD-20 has to go after the PSX-AR.

BTW,  Is your reversing section longer than the powered portion of your longest train?  It also needs to be longer than your longest train if all your cars have resistor wheels, your caboose is lit, or you have lighted passenger cars.

Allan Gartner
Wiring for DCC