Large Scale Central

Engine not coming to a full stop with ABC

Electronics DCC
#1

I have an LGB 26194 Mogul with a Zimo 696V decoder. The Automatic Brake Control is not working fully on it. When the engine enters the block, it slows down but does not stop. It creeps along at a low speed step, with the brake squeal sounding, until it gets to the end of the block, where it resumes full speed. If I change CV 141 the distance where it comes to an almost complete stop changes, as it should, but the engine still will continue to travel.

None of my other engines have this problem.

I am pretty sure I have it wired correctly. I took the engine apart, to fix a separate problem, and rechecked the wiring. It looked ok to me.

Any suggestions?

#2

Did a decoder reset. Did not resolve the issue. Sometimes the engine blows right through the block without slowing at all, other times it will do as described above, and other times it seems like it starts to slow, then speeds up, then slows, then speeds back up. Almost as if it is getting an intermittent stop signal. But this is the only engine doing it. My other 3 stop as programmed.

I wonder if the decoder needs a software reset? I hope not.

#3

Would it be possible or worth the effort to swap a decoder from another engine to see if the problem is with the board?

#4

Unfortunately, the other engines don’t have the same board.

#5

My first suggestion is that some of us would appreciate a real name to address you by, in case we can be of assistance.

Thank you in advance for your kind co-operation.

Fred Mills

#6

Did you add the extra capacitor for dirty track? If so then try disconnecting it.

#7

Ok, I will try that when I get a chance. Thanks.

#8

Fred Mills. said:

My first suggestion is that some of us would appreciate a real name to address you by, in case we can be of assistance.

Thank you in advance for your kind co-operation.

Fred Mills

Friar Derailed ? Derailed Padre?

#9

I finally got around to removing the supercaps and running the train. The ABC seems to be working fine now. My other 3 engines are using the same supercaps with no issue. Could I be using the wrong ground wire?

Spoke too soon. Its still doing it. I guess I will have to take it apart again and cross fingers.

#10

What type decoders are in the working engines?

#11

two Zimo 696s in the Forney and older Mogul. 699lv in the Mikado.

Its almost as if there is an intermittent short in this engine. The engine slows down when it enters the block, then sometimes it seems as if it is getting a full track power signal for a second, overriding the ABC. Other times, it slows down but does not stop. Rarely it comes to a complete stop as it is supposed to.

I would suspect the diode array but the other 3 engines NEVER have an issue. Plus, it does this on both blocks which each have their own diode array.

I will take it apart one last time and triple check my wiring and add yet another layer of liquid tape to all the connections. If that doesn’t work, I will send the board back to be tested and reprogrammed.

it is supposed to rain all week so maybe I will be able to get to it.

#12

OK, I got her back together and ran it. Figured out that the problem only exists if I have the headlight/taillight and/or the smoke generator on. If the lights and smoke are off, it stops as it is supposed to. I know I have the wires wired correctly as they work in the correct direction with the lamp button on and the smoke works with F6 on. So what would cause this? The lamps are tied to the 10v using the CVs to drop the voltage.

thanks,
Dan

#13

This may not be part of the problem, however it could change your issue.

How did you program the smoke unit?

I tell the function key to ignore voltage dropping on smoke and then control the heater with cv 137-139. Also if using function 6 for smoke, I set cv114 to 128 to ignore voltage dropping on F6 plus i set CV 132 to 72 for steam smoke. Now you get 3 different heats for the smoke unit. Do remember to start with low values for cv 137-139 as no values would give 10 volts (read max volts from the wired power source).

CV137 is idle smoke, no fan if using a fan driven unit

CV138 is cruising smoke

CV139 is heavy load accelerating smoke

#14

The smoke is programmed to the above parameters that you suggested. They work fine. I can definitely see a difference in smoke volume, especially at idle vs acceleration. It is more difficult to tell when the engine is going full speed as the wind is blowing it. But it looks good. I believe the values set are 75. 100 and 130 respectively.

I can see that possibly the smoke is causing a too high current draw with the 10v, though my other engines have no issues. But I cant believe that one light bulb would cause such a fuss.

#15

The 10 volt source is tied to the internel computer and a current surge can cause a problem. You could try using the LM7809 tied to V+ for a voltage source for the smoke heater element. I use the engine weight for a heat sink.

#16

How do I set up the LM7809 circuit? Can I tie both the lamps and the smoke into this same circuit or will I need two?

#17

I use the LM7809, 1.5 amp. I do add .01uf ceramic caps for noise reduction. No other parts needed. Just remember the center lead (ground/neg reference) is tied to the metal tab.

Get the PDF by googling LM7809 pdf

THe LM units come in many voltages and in 100ma small transistor packages as well as t0220 at 1 or 1.5 amp.

Voltages available are 5, 6, 8 ,9, 12, 15 (number is the voltage). All are perfect for our train projects. And to simulate 4 batteries like the bubble car (6.8 volts ) I add a silicon diode to the center leg of the LM7806 and get 6.7 volts.

#18

I use the LM7809, 1.5 amp. I do add .01uf ceramic caps for noise reduction. No other parts needed. Just remember the center lead (ground/neg reference) is tied to the metal tab.

Get the PDF by googling LM7809 pdf

THe LM units come in many voltages and in 100ma small transistor packages as well as t0220 at 1 or 1.5 amp.

Voltages available are 5, 6, 8 ,9, 12, 15 (number is the voltage). All are perfect for our train projects. And to simulate 4 batteries like the bubble car (6.8 volts ) I add a silicon diode to the center leg of the LM7806 and get 6.7 volts.

#19

oops another double post

#20

To verify:

pos wire goes from the decoder’s +22v pin to the Pos lug of the 7809

Neg lug of the 7809 goes to the Pos/white wire of the smoke stack.

Gnd/black wire of smoke goes to the decoder F6 pin.

And I put one cap across the 7809 pos lug to grd lug, and one cap across the neg lug to gnd lug?