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, have you read through the thread that I provided the link to?
David Merrill explains the issue with great clarity.
Rich
Rich,
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
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.
Rich
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…
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? Related, here is an excerpt from another and earlier forum thread:
"Posted by Curt Webb on Saturday, May 05, 2012 11:17 AM
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 ?!
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.
Dante
P.S. All those little electrons spinning about make me dizzy!
That was the first thing that I tried, but to no avail.
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.
Rich
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!!!
I know that you are having trouble posting pics but a photo would help.
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?
Rich
Just try 1 fan track as a test!
Dante
Yes Rich, that would be cool.
Sent you a PM
Rich
Here is a photo of the OP’s setup.
Rich
Thanks for posting the pic, like I said, I’m thinking about switching the feeder wires on the fan tracks, hope that works,
Picture isn’t helping since there’s no way to tell where the “no track” areas are.
It looks like the NO TRACK area is perpendicular to the approach track from markings on the layout surface. If that is the case, then the optical sensor is below the approach track.
Rich
If the TT is installed as believed it is (sensor below approach track),then the TT should operate fine.Then what I’d do is checking polarity of all tracks WITHOUT the rotating bridge in place.
1)Right rail of approaching track should match Right rail of ALL fan tracks (obviously same for Left side).If any number of the fan tracks don’t match,then the problem is elsewhere on the layout.Possibly a wiring error while wiring them OR may be that one or more are connected to a reverse loop on the layout.Sometimes,loops aren’t obvious so slow careful examination will tell if it’s the case.No need to go further until both approach and fan track polarities are matching.
2)Then install the rotating bridge.According to Walthers programming instructions,have the rotating bridge return to the ZERO point.Then,even if not aligned with them,the polarity of the bridge should match both the APPROACH and FAN track polarities.If it doesn’t,switch the DCC power wires to the TT’s control module.
3)Then,when polarities check OK at the ZERO point,rotate the bridge manually by holding the button (don’t care for programming at this point) a half turn (180 degrees).If the TT works right,then again all polarities should match.If they do,then the TT is properly installed and you can start programming.
BTW,I use a simple automotive 12V test lamp to check DCC polarity.One can get one at auto parts store for cheap or make himself one with a simple bulb and wires.
Great reply, jacktal.
Now, the OP should do just what you told him, step by step.
And then report back to us.
Rich
As soon as I get home from work, I will try that!! Thanks![:D]