If you isolated the end loop at the bottom as I suggested, and you still get issues, then parhaps the to legs are not wired the same way - the track to the left of the bottom riught loop, both tracks, should have feeders in the same order.
If we take the bottom most track first, if you have a black feeder to the bottom most rail and a red feeder to the upper rail, then for the section of track at the top of the loop, the rail closest to the lower track should be black feeder, and the rail closest to the top would be the red. Both tracks in parallel to each other is how it works.
If the same thing is done with the upper loop - ignore the crossovers, the crossovers should be part of the 'shank' wiring - then you should be good to go. Make sure at no point along the 'shank' you have flipped the feeders, the order should be the same on both tracks all the way around, except for the isolated end loops.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I had to go back to the beginning of the thread to catch up.
In the very first post you said it shorted out in one direction (going from gap A to gap B) but not the other direction. The diagram that I posted for you does not clearly show which is gap A which is gap B.
Be that as it may, I recall you've tried 2 or 3 new MRC reversers without luck.
Did we establish that the length of your trains are shorter than the reversing section?
Henry
COB Potomac & Northern
Shenandoah Valley
Back again! I added a second AR at the bottom of the layout per previous suggestions in the second loop at the bottom of the layout, but the problem still exists when the loco(s) exits the first loop crossing the gap , the sparks fly and the locos stops... I'm so frustrated after a year I guess I will rework the loop so the complete layout is just a dogbone with no crossover... If I want the trains to return the opposite direction I will manually rotate the cars in the opposite direction, the locos can be turned on the turntable!
Thanks for the info Especially using the box method to describe where to place them! As this a new layout I have 3 available ARs from my previous layout! I will give it a try first snowy day! Which in Canada won't be too long from now! I will remove the second AR.and I will add the gaps and 1 AR in the box locations you mentioned! And Close gap 3... I will let you know later!
It is, in fact, completely opposite with DC compared to DCC. With DC, you keep the loop constant and change the polarity of the main before the train exits the loop. With DCC, you change the polarity (phase to be completely accurate) of the loop before the train exits back tot he main. And with DCC, you change it under the moving train with no effect, since the polarity of the signal on the rails has nothing to do with the direction the train travels.
The DC method can still work fine with DCC, but generally is not used with automatic reversing since that means the autoreverser has to carry the load of the entire layout sans the loops. Most are not designed to switch that kind of current. They expect to switch the current of one train on the reverse section, not the 4 or 5 other trains out on the rest of the layout.
The two gaps above and below the roundhouse are good, if that length of track is longer than the longest train. The second sets of gaps should be all the way down on the lower loop. Starting in the square ont he lower left, 3 squares up and 7 squares to the right, gap both rails. and 1 square up and 10 squares to teh right. If that section is about equal to the length of the top loop. No other reverse sections are needed.
The track plan is a dogbone with a crossover. Isolate the end loops and use 2 autoreversers, and you can have as many crossovers along the shank as you want with no futher autoreversers.
Agree on the second reversing section. I would move gap 3 to the divergent track of the turnout and put a second gap some distance on the divergent track and have the AR control that section. No gap where gap 3 is currently located
I can understand the complexity of some layouts needing Auto reverse loops.
I'm old school and only have one reverse loop on my layout that is very short. I will have a toggle switch on the fascia that can be flipped the direction the train is going. Even if I had three or four, I like to keep things simple. To me, I think paying attention and flipping a switch is part of the fun of the sport.
If I had a master computer controlling everything on my layout so I didn't have to do anything which I'm sure is very achievable on any layout. Why bother, at that point I would have nothing to do but watch
TF
Resurrecting this thread because the OP sent me a pic last month. I was moving the next day so I forgot about his email. He has added another gap and another Autoreverser, which, reading his old post, controls everything to the left of Gap 3.
He thinks it may have solved the problem, but has not fully tested it. I think he needs another gap.
As I understood the problem, he had one reversing loop around the turntable.
From the track plan, from the turnout at Gap 3 left and downward is a second reversing loop. I don't think Garry, the OP realizes that.
Hello All,
gregc(I)f there's a DCC bus from a command-station/booster with feeders to track, why wouldn't you connected the AR to the bus and from it to feeders in the rev section?
Absolutely!
rrinkerYes, you normally would connect the input of the AR to the main bus. MRC likes to 'simplify' their instructions, which can lead to consequences.
I concur!!
If the OP is following the printed directions there might be a flaw in the wiring schematic that I have found through my personal experience installing this exact same unit.
If the unit can be attached directly to the bus then to the isolated section that might be the easiest solution.
The caveat would be- -IS the OP using a bus with feeders to the track?
If they are using a single pair of wires from the command-station/booster to the track then powering from the track would be necessary. Unless the OP want's to run the power feed wires from the AR unit to the command-station/booster.
To repeat, ad nauseam: IF the OP can only use track power the feeder wires (Red) to the AR unit should attach to the track BEFORE the turnout, contrary to the printed instructions from MRC. The gaps to isolate the reversing section should be after the turnout on all four rails as diagramed by gregc.
IF the OP can attach the feeder wires directly to a bus then to the isolate reversing section that would be the optimum.
Regarding the size of the loop or train...
rrinker...this would mean the loco is sideswiping its own train, a bigger issue than shorting the gaps.
A valid concern for possibly another thread.
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
chenxue the metal railcar wheels short out the AR gap shutting down the loco(s) as it recognises a short... Can this not be cured with a bit of plastic in the gap? maybe just a couple thou proud to the inside to hold the wheel flange off? I think the wheels don't have to short the gap...
the metal railcar wheels short out the AR gap shutting down the loco(s) as it recognises a short...
Can this not be cured with a bit of plastic in the gap? maybe just a couple thou proud to the inside to hold the wheel flange off? I think the wheels don't have to short the gap...
This can only happen if the train is longer than the reversing section. In the case of a simple loop where the diverging side of the turnout loops back around to the straight route, this would mean the loco is sideswiping its own train, a bigger issue than shorting the gaps.
chenxueCan this not be cured with a bit of plastic in the gap? maybe just a couple thou proud to the inside to hold the wheel flange off? I think the wheels don't have to short the gap...
it sounds like the train is longer than the reversing section and was causing shorts at either end.
CPbuffI will try to figure how to post the track plan in the next few weeks for those who may be interested!
few weeks? a month?
it would be helpful if CPbuff could confirm that the diagrams I posted are accurate or describe inaccuracies
where is the 3rd gap?
greg - Philadelphia & Reading / Reading
Cid (Memphis, Tennessee)
Yes, you normally would connect the input of the AR to the main bus. MRC likes to 'simplify' their instructions, which can lead to consequences.
jjdamnitReferring back to the instruction sheet of the AD520 it shows the unit being powered- -both Red wires- -after the turnout but before the gapped rails on the straight section
if there's a DCC bus from a command-station/booster with feeders to track, why wouldn't you connected the AR to the bus and from it to feeders in the rev section?
just to summarize the problem:
it works fine in one direction, but in the other direction, the loco stops "when the loco goes over the gap (Gap B) to leave" (from this thread)
the other thread has other interesting comments (paragraph breaks and underlining added by me):
I have a problem with what essentially is a balloon track that I have an auto reverser on ...
the loco goes through the balloon track and passes the required gaps and loco continues on to the next gap (not related to the balloon track) and the loco has the front wheels passed the gap then if any of the following railcars trailing, cross the AR gap back in the balloon track , the metal railcar wheels short out the AR gap shutting down the loco(s) as it recognises a short...
Is this a call for another AR at the other gap not related to the balloon track or should I move this gap further out beyond where my longest train would be past the AR in the balloon track?
Yes, the loco does exit the loop and is across the third gap, when the following cars cross the gap between the wires of the AR when the wheels of the cars make the short...
The AR has switched the polarity to allow the loco to pass over safely a few seconds previously!
Yes the third section is a reversing loop also after goes away for a while to the rest of the layout...
If I run the loco by itself over this third gap it continues on because the polarity is correct at the third gap...
Its just the trailing cars that cause the shutdown...
We are out of the loop and its gaps when the problem occurs...
The loco and a couple of cars travel fine for a foot or so before reaching the third gap!
CPbuffno feeders required inside the loop as the AR supplies the power !
"3rd gap" and only one connection to the AR??
Thank you for the diagrams gregc.
After my experience of wiring this exact MRC AD520 unit to a wye I believe the culprit lies in where the AD is drawing power from- -Red Wires. (Wiring a Wye for DCC)
Referring back to the instruction sheet of the AD520 it shows the unit being powered- -both Red wires- -after the turnout but before the gapped rails on the straight section.
I submit that both the Red wires to power the AR should be attached before the turnout on the facing point end, NOT- -as the instructions show- -on the straight section on the trailing end before the gapped rails.
By powering the AR unit before the turnout this should remove the variable of the power routing of said turnout.
All the rails should be gapped per the first two examples in gregc's diagram.
The Yellow wires (polarity shifting) then can be attached to any point within the gapped (isolated) track (loop).
The addition of a second AR doesn't make sense IF indeed this is a simple loop or ballon as gregc has diagramed.
wjstix...assuming everything else in the track wiring etc. is OK.
That's a big assumption at this point.
BTW I believe the MRC reverser doesn't have an way to adjust the sensitivity, while others (like the Digitrax one) does. I've found using the Digitrax AR1s that it's very helpful to be able to adjust the sensitivity to get things working right. Could be switching to an AR1 reverser could solve the problem - assuming everything else in the track wiring etc. is OK.
is the 1st even needed with the 2nd in place?
I can't see why you would possibly need two ARs back to back like the second set of drawings, unless between the blue/orange and yellow/cyan section there are other turnouts that are not properly gapped and form a track shortcut to elsewhere within the yellow/cyan.
For example, two turnouts off the main, the diverging routes of which come together at a turnout in the loop, and then joins back to the main as a single track. Either the isolated loop section needs to be made shorter, or the diverging side of BOTH turnouts need gaps.
There is definitely more going on here than a simple loop if two ARs are needed to solve the problem.
can i suggest the following diagram until then
the top 2 loops illustrate a conventional reversing loop, one for each loop polarity. mainline polarity in red/green and corresponding loop polarity in yellow/cyan. with train moving counter-cockwise (CCW) thru loop, yellow and red polarity match on outer rail. as train exits loop in 2nd drawing, loop polarity switches, and outer rail polarity matches green and cyan.
bottom set of drawings (3, 4, 5) attempt to illustrate how 2 ARs are used, the 2nd AR illustrated in blue and orange
as train moves CCW thru loop, 2nd AR polarity matches mainline rails, red/orange and green/blue. rev section polarity is also shown as matching yellow/orange/red and cyan/blue/green.
drawing 4 illustrates when train exits loop, 2nd AR switches polarity, yellow/orange on outer rails and 1st AR remains unchanged.
drawing 5 illustrates trains returning to mainline. 2nd AR switches polarity, cyan matches green.
i would think the lengths of both rev sections need to be long enough for a train.
I for one, would be interested and need a track plan to understand this. Please show the gaps too. Atlas turnouts are not power routing so we can get rid of that red herring.It sounds like you are telling us you needed an auto reverser before the reversing loop.
pm sent, I will be happy to post your track plan
Thanks everyone for all your information (overload)... I beleive I may have figured it out ! Spent the last two rainy days gapping and measuring(VOM) and working on it...
Each time the loco went to leave the loop at Gap B , I finally saw the sparks fly as the loco crossed the gap (dull and dark made it easier to see) , shorted and then stopped!
What I ended up doing was adding an addition gap outside the reverser on the red (track power side) but the same short happened again and sparks flew so obviously the loco didnt like the wrong polarity so I added a second auto reverser just up the track from the first one but with two turnouts between them... So essentially I think I tricked the original AR into beleiving its getting track power on the red side when in fact its getting track power from other side (yellow)of the second reverser!
I will try to figure how to post the track plan in the next few weeks for those who may be interested!
Some other answers are: DCC, Atlas track and turnouts, happened to all locs, Prodigy Advanced system, no feeders required inside the loop as the AR supplies the power !
I didn't see where the OP told us what turnouts he was using.
He is not a prolific poster and if you read the original thread, people asked him to post a picture, offered to post a picture for him but the thread just ends with no more information.
Maybe he will get back to us in another year.
jjdamnit gregc it would be good to hear from the OP if the turnout to the reversing switch is power routed Seems we've been "ghosted" again !!! Hope this helped
gregc it would be good to hear from the OP if the turnout to the reversing switch is power routed
Seems we've been "ghosted" again !!!
Hope this helped
gregcwhat happens if the reversing section turnout frog and diverging rail up to the gap are powered and the turnout is not thrown correctly when exiting the reversing section
i wonder if the OP realized all his problems: trying 3 types of ARs and sending units back to the manufacturer -- were simply caused by a power routing tunout positioned incorrectly.
yes this might be embarassing, but we all make mistakes. knowing if this is the cause would solve the mystery and be a great learning experience for all of us
gregcit would be good to hear from the OP if the turnout to the reversing switch is power routed
it would be good to hear from the OP if the turnout to the reversing switch is power routed
Haha, I think that's exactly what I was worried about, jj
I think gregc was looking at more or less the same issue, or similar...
BigDaddyThe OP's original thread He is running a MRC Prodigy Advanced.
Thanks for the clarification, didn't see the original post.
In the MRC AD520 instruction sheet, it notes that both the Red (feeder) wires to the unit are connected to the track between the turnout and the gapped (insulated) rails on the straight section. The Yellow (polarity shift) wires go to the reversing section on the opposite side of the gapped (insulated) rails.
It doesn't matter which red or yellow wires go to which track polarity.
On the wye on my pike I originally put the feeder wires on the track between the two legs of the wye and attached the polarity shifting wires on the point end of the wye turnout.
The turnouts to the wye are #2 PECO insulfrog (unpowered) turnouts. When the points are thrown to the main power is not transmitted to the diverging line.
When the points are thrown to the diverging route both the main and diverging routes have power.
Both legs of the wye are gapped on all rails at the first joint past the diverging points of the turnouts.
This configuration didn't work.
I moved the feeder wires to the AR unit "outside" the legs of the wye and VIOLA! Success!!
For the OPs situation, a baloon track, I would move the feeder wires to the point end of the turnout, keep the gaps (insulated rail joiners) on the tailing ends.
My point...
If the feeder wires to the AD520 are between the turnout and reversing section on the diverging side, and the turnout is a power routing- -no power to the diverging route when the points are thrown to the straight section, then no power will get to the AR unit when entering through the straight track.
When the points are thrown to the diverging track (where the AR unit is fed from) then the power will energize the AR unit and the polarity successfully reversed.
Unfortunately, I am unable to post a diagram so a verbal description will have to suffice.
It's essentially the same thing. The main would be connected to the bus, so the input side of the AD520 needs to be powered from the main track, bus or some manner. Electrically it is the same. Main power in, the loop must be fed ONLY by the output side of the AD520.
Also, I notice in that AD520 manual, the bus connection is not to the main rails, but connected past the turnout toward the loop. This does not jive, to me, not quite sure why. Just not consistent between the entrance and the exit.