Hello i have my layout set up for DC block control using a atlas selector. Everything was going fine until now.some reason if turn block 1 on it controls block2 as well .the track has been gapped in both rails ive checked the gaps they are fine.i did get wet wallboard mud on the wires where they connect to the screws which is dried. Any ideas?
Thank you
A engine or passenger car with electrical pickup parked across one of the gaps will cause that to occur.
Hi as far as i can tell theres nothing crossing any gaps thank you
You said everything was going fine. Other than the wallboard mud did anything else get changed about the layout from when it was going fine? (Even removing and and then returning one wire is a “change” as I use the word.) Reasoning backwards is the first form of trouble shooting. If you were doing scenery for example, do you use wire screen and in some way could the screen or a nail or staple have somehow completed a circuit between A and B? Stranger things have happened.
I assume you have used common rail wiring which is the assumption behind the Atlas system. Is there a chance you swapped out the common rail to one block for example. Or (maybe more likely) from one power pack to the other?
And is this problem true for either cab, A or B, connected to block one? Or just one cab?
Remove the wires at the selector that go to blk 2 and set the button for 2 to center (off). Is blk 2 still getting controlled by the switch to block one?
Dave Nelson
Check the wires. They must be touching somewhere.
I hope this helps.
Disconnect the wire from block 2 at the selector. What happens?
Ok here is the status
All wires running from the selector to individual blocks have been removed.
Each block has both rails gapped with the right rail having a feeder going to a bus connected to the power pack
An engine is placed in all 3 blocks
Using a jumper i connected block 1 to the selector engines in block 1 and 3 turned on.
Using a jumper in block 2 only the engine in block 2 powered on.
Using a jumper on block 3 again the engines in block 1 and 3 powered on.
Obviously blocks 1 and 3 are now connected to each other and are being bridged.
Are the blocks adjacent to each other at any point on the layout? Look real close again at your gaps.
I am confused however as you originally mentioned blocks 1 and 2 were the issue. Now block 2 is isolated but 1 and 3 are connected.
Also, you mentioned one rail’s feeders are connected to a buss. This is typical for common rail.
However, that rail does not need to be gapped. Was it done for signaling?
Ahh yeh besides frustrated i was getting confused so took a break and started over and did the above status report. So the status report is accurate. Both rails are gapped using the non common rail method. When i used to use the common rail method i had problems when the engine crossed the gap other engines in other blocks lurched forward. I checked the gaps an ran a model knife thru them down to the plywood.nothing bridging the gaps that i can find. By the way thank you for the help.
It’s time for a track diagram. Show us where the gaps and feeders are. There is something you are not seeing and therefore not telling us about.
Thanks for the clearification. The lurching does not seem right however. 
Looking at the diagram above, lets assume one engine is parked on the siding which is block 2 and the selector for block 2 is in the center off position.
Now a second engine is traveling around the layout in blocks 1 and 3 using cab A.
The engine which is parked in block 2 should not move when the engine travels across the gaps between blocks 1 and 3.
This is why I am confused about the extra gaps you had to install to prevent the lurching.
Also, the engine in block 2 should be able to run using cab B when the selector is in the down position.
And again it should not be affected by the train moving from block 1 to block 3.
Did the layout ever run as described above?
If yes, then either the wires which run from the selector for blocks 1 and 3 are touching at some point.
Or a gap has been bridged. And Henry is correct, a diagram would be nice [I]
How do i post a diagram from a cell phone?
Ok the original problem has been solved at one point during the summer before i used any blocks i had ran a wire from would now be block 3 to what would now be block1.so i cut the wires all blocks work fine except block 4
Block 4 had no power.
So back at the power pack on the 2 track screws where i ran the wire to the selector i had disconnected the original wire
So i reconnected that wire so theres 2 wires on the screw ahh theres power in all the blocks but now the engines have no speed control they just go fast. To sum it up all blocks work but no speed control what did i do?
.w
Sounds like you have the input to the Selectors hooked to the fixed DC on the power pack, not the variable DC.
–Randy
What Randy said and glad you found the connection between blocks 1 and 3.
There is one set of screws labeled track dc the other set is variable ac.
On the track screws if i swapped the wires around would that hep?
How do i post a diagram from a cell phone?
Ok the original problem has been solved at one point during the summer before i used any blocks i had ran a wire from would now be block 3 to what would now be block1.so i cut the wires all blocks work fine except block 4
Block 4 had no power.
So back at the power pack on the 2 track screws where i ran the wire to the selector i had disconnected the original wire
So i reconnected that wire so theres 2 wires on the screw ahh theres power in all the blocks but now the engines have no speed control they just go fast. To sum it up all blocks work but no speed control what did i do?
.w
Connect your wires to the track DC screws. Make sure no part of them are touching the other screws.
I appreciate your help.the wires are connected to the track dc screws nothing is touching the other screws.
Connect another power pack, this one may not be capable of regulating the voltage.
The other power pack i have is an older bachmann trainset pack.
Could i have mess up the power pack when i had the 2 wires on one screw?