46299 Motorized Turntable shorting during rotation.

[kpsdjs]

Hello all,
     I have recently aquired the Bachmann motorized turntable, and find that it "shorts out" as the rail rotates to it's own neighboring rail. While rotation continues faultlessly, it has none the less "shorted" long enough to reset my "E-Z Comand Controller" every time.
     I have a "relay patch" to cut power to the table's rails. However, I wonder if there is standard fix, or plane to engineer out the problem?
     The best fix would be to only allow the "contact fingers" power contact near "index". I quess this got overlooked at some level, but deserves attention, as it is otherwise an extreemly well made product.
Any Thoughts? kpsdjs

[Doneldon]

kp-

I'd also inspect both ends of the rails on the bridge and the various access, roundhouse and garden tracks to make sure you aren't getting a momentary contact/short there. If you find such a problem it will be a minor issue of filing the offending rails. I don't know how likely it is that this would be your problem but it's so easy to check and repair if necessary that I'd do it before looking deeper.
                                                                                                                                                     -- D

[kpsdjs]

Doneldon

     Thanks. But thats not it.

     This does remind me that the instruction never mention anything about "Polarity" at different positions. I had to run through all the positions one at a time and note "polarity". Otherwise bringing in more than one rail with power can cause catastrophic "Short Circuit" to entire layout!!

Thanks,
kpsdjs

[kpsdjs]

Doneldon, P.S.

     Just FYI. The problem is known exactly. It is an engineering error. The rail should not be allowered power while it rotates away from "Indexed" area!

Have a nice day, Doneldon

kpsdjs

[Jim Banner]

kpsdjs,

Don't keep us in suspense!  What exactly is the exactly known problem?  If not the rail ends, then what is shorting to what and where and when exactly is it happening?  If it is an engineering error, I am surprised that we have not heard from everybody who has bought one of these turntables.  If the problem occurs only occasionally, perhaps it is more of an assembly error.  If it occurs as the locomotive rolls off the bridge onto one or more approach tracks but not all of them, it is an installation error - the turntable may be forming part of a reversing track and requires a polarity reversing switch (dc) or a phase reversing autoreverse module (DCC.)  Alternately, the approach tracks may be wired at random with no regard to polarity or phase.

The idea of removing power from the bridge rails is not out of the question.  It could easily be done with a pcb switch.  But unpowered bridge rails would mean that the locomotive's headlight would be on/off/on/off/on/off... as the bridge turned.  One of the nicer scenes, both in the model world and in the real world, is watching a steam locomotive, all fired up and lit up, being turned.  This scene is particularly poignant just before sunup or soon after sunset.  Most of us go to great lengths to make sure our turntable bridges have a constant source of power as they turn.

Because I enjoy this scene so much, I am glad that this "engineering error" was included in every turntable I have ever seen or built.

Jim  

[kpsdjs]

Jim,
     Thanks for your reply. The problem is better understood if describe contact area's better.
First; When track is "indexed" It makes contact between the Bridge and Rails with Flexable copper contacts that are atached to the underside of the bridge rails. As rotation starts, these contacts move with the bridge and extend out to contact the next rail. Unfortunately, that next rail is it's own "other rail polarity"... and ZAAP! a momentary short causes reset of my E-Z Comand.
     The engineering fix would be to not allow power at that moment. I understand wanting all the lights and whistles, but they do alter polarity on some rails already, (as compared to main track power @ # 4pos.), causing momentary outages. Perhaps those contacts should "Drop away" slightly so they will "clear" unwanted rails while away from "index"? or?  I will re-engineer for $$. But I think they should do something to improve the product.

kpsdjs

[Jerrys HO]

kpsgjs
I have the same turntable and have no problems. The pit rail is powered and was designed that way. As the table turns it cuts power from one track and powers the next as it turns. The 4th track position is set up for the main track input from your controller.
Jerry

[kpsdjs]

Jerrys HO,

     Do you have an E-Z Comand DCC Controller? Or do you only run DC. Problem would not show up on DC systems. It keeps resetting my DCC system.

Thanks Jerry,
Please re-reply. I am very curious to hear about anyones experience with this turntable.

Thanx,
kpsdjs

[Jerrys HO]

kpsdjs,
      Yes I am running the ez command controller for now. I did not put the decoder in as I have the turntable hooked to separate power pack. With the separate power pack I can slow the turntable down to scale speed. I am using the 44212 power pack and controller. I plan on installing decoder when I replace my ez command to the zephyr.
Jerry

[vidguy069]

I recently acquired the afore mentioned turntable (happy b-day to me).  But my problem is a bit different.  I have the TT running DC on a separate power supply, and the rest of the layout is DCC with a MRC controller.  When everything is connected, and powered, the TT runs quite nicely.  The bad news is there is no power to the track.  I separated the terminal rerailer from the #4 index on the turntable, and the track had power.  I have no other 'powered' rails going to the turntable.  I have a couple of pieces of track on the 'other side' of the turntable so the locos have a place to sit, but that's it. 

My experience so far.

Vidguy069

[jward]

i will probably get into trouble for saying this, and i hope this is taken as the constructive criticism it is intended to be. bachmann needs to do a better job of providing documentation for their products. in the case of the turntable, atlas provides information on the polarity of each of the radial tracks. why doesn't bachmann? failure to provide this info sets up a situation where short circuits could damage the layout's electronic equipment. seeing as the polarity of the radial tracks is common to both the manula and motorized turntables, and the manual turntable is marketed to children in the thomas line (tidmouth sheds) you'd think explicit instructions would be provided.......

[Bucksco]

There is a possibility that the DC mode is not being "disabled". This would depend on the decoder being installed. When an NMRA 8 pin decoder is mounted into the socket it pushes down a small square button that switches the Turntable to "DCC" mode. If you are not mounting an 8 pin decoder into the socket the button will not be depressed which could be the problem.

[vidguy069]

This probably won't work for every one, but here is my solution.  Tested, once.
I put a piece of track (4.5 in) between the terminal rerailer and the turntable.  Locos and turnouts are DCC turntable is DC. Don't know or at this point care, but it seems to be working. Of course the loco did run off the end of the track because dumb-dumb here did not check the position of the switch, but that's a detail we won't didcuss.   

Vidguy069

[Jerrys HO]

vid,
   I did the same thing on my first attempt and it did the same thing. I removed the power rerailer and it is fine. I believe it has something to do with powering the tt with a dc controller but I could be wrong.(nah). I can't wait to post pics of my heljan roundhouse that I am converting to fit. I am just waiting on wall and roof matching panels from plastruct.
Jerry

[vidguy069]

Jerry;I actually got one loco on the the 'wait' track, then the turntable 'died'.  Frustrated, you bet.  But I will NOT give up.  Worst case scenario, I'll by the bloody decoder and have my LHS install it.  Everything else is DCC, why not this.

Good luck with the roundhouse.


Vidguy069