HI ALL.
I have a problem with my turntable actually it's my receiving tracks behind the turntable, before I wired my tracks all went well, my loco went from the main track to the bridge, it would turn around go my receiving track, now, I have wired my receiving tracks and now there is a short somewhere, I have disconnected the wires to my control, and I still have a short?!!, my turntable is a 130 ft Walthers Cornerstone Nscale I'm running my layout in DCC, I'm running the turntable in analog. I hope it's something simple that I just don't see, thanks for the help.
Happy Model railroading
Trainsrme1
Looks like some of these tracks aren't wired properly.Identify the faulty tracks and try reversing their polarity.I may be wrong,but since it's only since you wired them it would make sense.
I agree with Jactal. Where did you get the power to feed those tracks? One is probably crossed. If in fact it is a short and not a lack of power. That has been happening a lot on the Forums lately...some people are confusing short with lack of power/continuity.
Take Care!
Frank
jacktal and zstripe have given you some good replies.
We need to know more.
Take a photo and post it so we can see your setup and the location of the tracks.
It could be that you reversed the polarity of a pair of feeders.
Or, it could be the location of one of the tracks.
Why the location of one of the tracks? I can explain that after seeing the photo if there is a problem.
Rich
Alton Junction
Just to clarify, before you were able to use the turntable to turn the loco and there was no short?
Or you did NOT turn the loco on turntable, just moved it to another track and there was no short?
Keep in mind that when you turn a loco on a TT, it must be set up to reverse the track polarity just like any other reversing section. Some turntables handle this automatically. Is the Walthers TT able to do that? Or must you provide reversing apart from the TT?
Finally, you say the layout is DCC and the TT is "analog." Do you mean the TT is DC and controlled by a powerpack separate from the DCC system? Or just that it requires DC power to turn the TT, but the track power still comes from your DCC system?
Mike Lehman
Urbana, IL
The Walthers turntables have a sort of split ring setup to sense when the rotation would reverse the polarity. It is not an auto reverser per se, but the mechanism results in the same effect.
However, depending upon where you place the tracks, the mechanism may not effect a reversal of polarity, in which case, you could need to install a separate auto reverser.
Edit Note: jacktal's subsequent reply details what I was referring to in that 2nd paragraph.
The Walthers turntable has indeed the capability to self reverse the polarity of the "bridge" track so that it matches when turn half way around.But for this to work,the TT has to be positioned properly.
I checked mine (not yet installed) and I notice there are two "no track" areas,180 degrees apart...this is the polarity reversing point of the TT.This means that all the "approach" tracks have to be on the same 180 degree half of the TT while the "fan" tracks can be anywhere within the other 180 degree half.
My understanding is that both the "approach" and "fan" tracks have the same polarity and the TT does change the polarity during the rotation,that is providing the "no track" points are properly positioned.You can't have a mix of "approach" and "fan" tracks on the same 180 degree span in wich case the TT will not convert to correct polarity and shorts will definitely occur.
jacktal is exactly right. It happened to me. Check out this older thread.
http://cs.trains.com/mrr/f/744/t/181396.aspx
That's right Mike, my layout is DCC and the TT is operated by a DC powerpack.
Jacktal's latestt post if right on the mark. It is the "No Track" zones. This happened to me just last week. Locos were shorting out on two of my fan tracks. I rotated the pit about 90 degrees and re-programmed. All is well now.
Good luck!
On my layout, I couldn't move the track, so I needed to install an auto-reverser for that one track.
Rich,
Luckily I didn't have to move any track. I lifted the rail ends (twelve pair) off the rim of the pit, rotated the pit, then replaced the rails on the pit rim. Also, while the pit was out I had to cut a new notch in the underlayment to accomodate the sensor in the new location about 90 degrees from the earlier position.
Roger, you were more fortunate than me.
I have a double ended freight yard with a turntable approach track on each end. The location of the right hand approach track was on the other side of the NO TRACK zone. At the time, I had no idea of the problem that I had created. I did not understand what was wrong, so the only solution was to install an auto-reverser. It was too late and too difficult to relocate that approach track.
Incidentally, I recently removed that track entirely, some 10 years later, when I redesigned the yard and adjacent engine servicing facility.
Couldn't you just have rotated the whole turntable assembly a couple of degrees so the problem track was no longer in the "no track" zone?
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinker Couldn't you just have rotated the whole turntable assembly a couple of degrees so the problem track was no longer in the "no track" zone? --Randy
That track and the one above it wound up on an auto-reverser because they were both on the "wrong side" of the NO TRACK zone.
As it would be I'm having problems posting my pic of my TT!!! But if you look at richhotrain's pic, you can see that mine has a similar set up, ONLY I have just one main track going to the pit, and six recieving tracks on the other side, the sensor is facing from left to right, I hope this help's meanwhile I'm going to have my daughter show me how to post pic's AGAIN!!!....also time for a!!!!!
Transme1
Looking at the mounting template (at https://www.walthers.com/instructions/extras/0933/09330000002840a.pdf) the no track area is 90 degrees from the sensor.
Referring to Rich's photo, it looks to me that one would want to orient the pit such that the no track area would run from about two o'clock to eight o'clock, or from just to the right of the three tracks leading to/from the rectangular building to the area just camera side of the the garden tracks alongside the round house.
Keep in mind, though, that one of the pre-programmed, unchangeable tracks 1 and 2 will probably be in the middle of the round house fan tracks. I found these two factory set tracks to be a problem, eliminating my ability to number any of my tracks 1 or 2. I start with number 3 with the ficticious story that the original tracks 1 and 2 were removed years ago to make room for a workshop.
Frankly, I found the overall programming parameters quite difficult to work with. It took me four tries to "outsmart" the TT and get it programmed the way I wanted. But I don't know of an alternative TT that is better unless you spend much more.
richhotrain
I have a 90" Walthers HO DCC-friendly TT, and there must be something different about it compared to the installations in the above discussion. My approach track and a receiving track are on one side of the no-track zone and another receiving track is on the other side. All tracks are of the same polarity orientation. No problem, no short. And logically, there should not be a short because the bridge automatically changes polarity as it crosses the dead zone. Finally, there should be no difference between an approach track and a receiving track electrically.
Dante
Indeed the approach tracks and fan tracks should be wired the same polarity wise thus the need for the turntable to reverse the polarity of the rotating bridge as it turns.The 90' TT should be designed the same way...I can't see how it would work otherwise but then I'm opened to learning any time.
There's another way to void the whole discussion...simply feed the TT's track power through a reversing module like the AR1.
TrainsRMe1 That's right Mike, my layout is DCC and the TT is operated by a DC powerpack.
OK, I just wanted to make sure you weren't using DC for track power on the TT. Mixing DC and DCC track power is a sure way to let the smoke out. Using DC to turn the TT is OK.
dante I have a 90" Walthers HO DCC-friendly TT, and there must be something different about it compared to the installations in the above discussion. My approach track and a receiving track are on one side of the no-track zone and another receiving track is on the other side. All tracks are of the same polarity orientation. No problem, no short. And logically, there should not be a short because the bridge automatically changes polarity as it crosses the dead zone. Finally, there should be no difference between an approach track and a receiving track electrically. Dante
David Merrill explains the issue with great clarity.
I did read the linked thread and reread both threads this morning in case I had a case of brain fatigue last night; also, I reread my Walthers instructions. Before I go further, let me note that your threads deal with the pre-DCC Walthers TT; I have the newer DCC mode. As I said, there might be a difference between them that accounts for the problem/no problem contrast. But I don't believe so after rereading everything.
I cannot be sure because our TT models are different, but I believe if you had switched your B connections, you could have avoided the AR. If your table reverses polarity automatically, I believe that is all you needed. Delete the AR from the wiring diagram and note that the TT polarity will change as it rotates: all will be well.
As for track locations, my instructions say the same thing about the dead zone and suggests (not mandates) that "fan" tracks be placed 90 degrees from the "approach" tracks. But elsewhere, the instructions show 34 track positions (including the 0 position). It is a stretch without foundation to think that the 90 degree "suggestion" requires that approach and receiving tracks be on opposite sides of the dead zone. They can be 90 degrees apart and on the same side, obviously. Also, nothing is said in the instructions that "approach" tracks have to be on one side of the dead zone and "fan" or receiving tracks on the other. And there is no electrical reason for that to be a requirement. After all, there is no electrical difference between the two; the TT doesn't know what is an approach track and what is a receiving track! Additional evidence regarding the 90 degree issue is that my approach track and one receiving track are not only on the same side of the dead zone but are only 10 degrees apart.
Dante, you raise some interesting points.
At this point, the issue has become moot for me because after 7 years I removed that right side approach track when I reworked my adjacent engine servicing facility.
But for years after I installed the approach track and realized that only an auto reverser would remedy the problem, I wondered and wondered what caused the problem. Then along came that thread and Dave Merrill gave me the answer.
I think that part of the issue is with the design of the Walthers turntable. It does not include a true auto-reverser that detects reverse polarity. Rather, it keeps track of the degrees of rotation of the bridge track. So all of the tracks on one side must be wired the same way and all of the tracks on the other side must be wired the opposite way.
I believe the Walthers turntables are designed the same way,wether HO or N,or at least they should in my mind.And since they are to be used with either DC or DCC,they can't and don't have a polarity changing device.They rely on positional relationship between the rotating bridge and the outside tracks connected to them to achieve proper polarity.
The fact that the TT does reverse polarity at some point in its rotation tells me that the fan tracks (including the RH inside tracks) should be wired the same polarity as the approach tracks.If it wasn't so,the TT wouldn't work for DC.The problem though,as been said,can be bypassed with the use of a reversing module in DCC.As also been said,someone who'd want approch tracks coming from any direction wouldn't have a choice to use a reverser.
I have an Atlas N scale turntable on hand and it does exactly the same electrically...it does switch polarity around during its rotation.However,since only a degree or two are sufficient to achieve polarity reversing and the Atlas TT's track positioning is dictated by 15 degrees separated molded stalls,this one doesn't have any "no track" areas.But they still have a switching point that has to be positioned correctly.
Since the Walthers TT's can be programmed to stop at any position explains the "no track" stalls,where the rotating bridge is likely dead to avoid internal short to the TT and likely to the whole layout,should the bridge be stopped on one of these spots.At least,that's the way I see it.....
I well understand that you had resolved the issue for your situation, but I am curious if you ever tried reversing those B connections before installing the AR? Related, here is an excerpt from another and earlier forum thread:
I just hooked up the new 130' TT. I ran 4 feeder wires from the main DCC Power buss to the control box (2 each from each Buss). I have had no problem with power (Command Station is Zephyr Xtra - 3 AMP). The only thing I needed to change when I ran my first loco on the bridge was to switch leads at the control box because the loco would short going on the bridge. Once switched there were no issues. In other words:
Connections
1 & 4 originally attached to the Red Buss -- Switched to Black Buss
2 & 3 originally attached to the Black Buss -- Switched to Red Buss
My DCC system has 12VAC on the track when metered.
Hope this helps you."
As for the TT, I believe you are basically correct. The outer contact ring on the bridge pivot is split in half with insulating gaps at the 2 splits. One half of the ring must be one polarity and the other half vice-versa. Those insulating gaps produce the dead zone. There are 3 rings on the bridge post in addition to the outer split ring and 8 wipers on the pit pedestal. I assume that the 2 outboard wipers power the halves of the split ring and therefore, the bridge rails. The other rings must power the bridge drive motor via the circuit board. But what do I know ?!
Jacktal I believe the Walthers turntables are designed the same way,wether HO or N,or at least they should in my mind.And since they are to be used with either DC or DCC,they can't and don't have a polarity changing device.They rely on positional relationship between the rotating bridge and the outside tracks connected to them to achieve proper polarity.
I can't speak for the N table, but in the HO table, the bridge rail polarity has nothing to do directly with the outside or service tracks-they are not physically connected. As noted in my recent, I believe the polarity change for the bridge is strictly via the split ring contact. That is the polarity-changing "device," I believe. The power feeds to the service tracks and to the bridge must be consistent, as discussed before. If so, an AR should not be required.
P.S. All those little electrons spinning about make me dizzy!
dante Rich, I well understand that you had resolved the issue for your situation, but I am curious if you ever tried reversing those B connections before installing the AR?
I well understand that you had resolved the issue for your situation, but I am curious if you ever tried reversing those B connections before installing the AR?
The instructions said, to match radial tracks, "you can reverse polarity by interchanging the B1 and B2 wires" that power the bridge rails. But, that wasn't the problem since the bridge track rails already matched polarity with the left side approach track and all of the roundhouse tracks.
When I reversed the B1 and B2 wires, I solved the right side approach track but screwed up the left side approach track.
Here's the latest, I figured out that my fan tracks feeders are wired the same as the main track, they should be wired opposite of the main, I'll try that and let you guys know later!!!
TrainsRMe1 Here's the latest, I figured out that my fan tracks feeders are wired the same as the main track, they should be wired opposite of the main, I'll try that and let you guys know later!!!
Rather than guess and/or trial and error, send me the pic in JPG form or such, and I will post it for you.
Should I send you a PM with my email address?