46299 Motorized Turntable shorting during rotation.

[kpsdjs]

Yardmaster, and All,

     My TT is DC, being controlled by my DC controller. The track @#4 has DCC on it. But the DC controller does not seem to mater, even if I unhook it, the DCC is still shorted!
     I can't get past the FACT thet when rotation starts, it Immediately shorts to it's own "other rail polarity". (which is DCC) Shuts down my DCC controller every time. This will be in ALL of these TTs!

Hope to hear more,
kpsdjs

[NarrowMinded]

I read through this and not having a Turn table or the diagram one thing jumps out at me and that is that you are using DC to power the table and DCC to run the rest of the layout. 

I'm curious if the drive is isolated from the track? i've read somewhere about powering track #4 is that how the turn table gets it's power? I'm just throwing questions for thought out there.

[kpsdjs]

NarrowMinded, and All

     Please re-read my last post. I think it answers you. Track #4 provides only power to the bridge. (At least in DC mode) The instructions show DC mode needs "seperate" power, but the DCC seems to show only "track" power is required.

I.e.; My TT is DC, being controlled by my DC controller. The track @#4 has DCC on it. But the DC controller does not seem to matter, even if I unhook it, the DCC is still shorted!
     I can't get past the FACT that when rotation starts, it Immediately shorts to it's own "other rail polarity". (which is DCC) Shuts down my DCC controller every time. This will be in ALL of these TTs!

Hope to hear more,
kpsdjs

[the Bach-man]

Dear KP,
In DCC mode, there is no power feed to the turntable other than the track. Address the turntable and control it like a locomotive, using your DCC command station. Do nor use the turntable controller...
Have fun!
the Bach-man

[kpsdjs]

Bach Man, and All,

     Even if I provided DCC module, the rail will still "short" as I rotate away from Index @#4!! Please... Do you have a real solution? Or just glaze?

THE #4 TRACK WILL ALWAYS (All-Ways) SHORT WHILE ROTATING AWAY FROM IT!!

Gimme something I can use.

Are there others out there with this table? I need to hear from as many as possible!

Thanx
kpsdjs

[Jim Banner]

kpsdjs

I think I understand what you all telling us.  But for that to cause a short circuit, the bridge would have to powered from somewhere other than just the contacts under the rails.  In that case, what are the contacts under the rails for??  Most (all?) turntables I have dealt with power the bridge in one of two ways and power all the approach tracks separately. 

The B-mann turn table is apparently different.  But it sounds like the bridge track is still powered up all the time.  It is were not, then the contact tab touching the wrong rail could not cause a short - it would just be touching an unconnected piece of metal.  You could check this very easily by connecting a 12 volt lamp (such as a grain of wheat bulb) across the bridge rails and see if it stays lit as the turn table turns. 

If I understand correctly about the B-mann turn table, the only power to the whole shebang is via track #4 and somehow that power gets to the bridge other than through the contact tabs.  Then when you turn the bridge, it powers up whichever other approach track it aligns with via those contacts.  What would happen if you slipped a piece of Scotch tape, sticky side up, under the ends of the rails of track #4?  Then the contacts would not be able to make contact with track #4 and there would be no short circuit. 

I suppose it is also possible that the bridge rails are supposed to be powered up by track #4 only when they are aligned with it but not otherwise.  In that case, you would have to look for some sort of "sneak path" carrying current to the bridge rails even when they are supposed to be dead.  This sneak path could be power applied to another set of rails or possibly by using the same power pack to power the trains and to turn the turntable.

Unfortunately, our local hobby shop does not have one of these turn tables in stock or I would ask to borrow it to solve this problem.  So I leave to it you to try the light bulb test and hope you will continue to let us know what you find.

Jim 

 

[kpsdjs]

Jim,

Way YES!! You hit it with this paraghaph;

If I understand correctly about the B-mann turn table, the only power to the whole shebang is via track #4 and somehow that power gets to the bridge other than through the contact tabs.  Then when you turn the bridge, it powers up whichever other approach track it aligns with via those contacts.  What would happen if you slipped a piece of Scotch tape, sticky side up, under the ends of the rails of track #4?  Then the contacts would not be able to make contact with track #4 and there would be no short circuit.

     That is absolutely the answer. Pos#4 does not NEED to contact the bridge, so the tape idea works perfectly. Another index # also has a DCC powered track coming in, so tape there also..WOOP.

     There is still a problem that does not bother me, but you had mentioned earlier. The power to the bridge is not constant...Blinking out as the bridge approches idexes that are polarized differently. So engine lights, etc. blink on/off/on as it rotates around.

Thank You Very Much Jim,
kpsdjs
Kelly

[Jerrys HO]

Kelly,
      There is still a problem that does not bother me, but you had mentioned earlier. The power to the bridge is not constant...Blinking out as the bridge approches idexes that are polarized differently. So engine lights, etc. blink on/off/on as it rotates around.
      I went and ran my MTH engine on my tt just to see,because it has all the bells and whistles you could ask for. Now as it sits in the pit and turns it does not lose power.all the lights and even crew talk stays going. The only time it shuts down is when I pull off to a separate index and turn the tt away from it.

Kelly and Jim and others
     Looking at the diagram that came with it which is not much info at all, shows #4 tracking has power feeding the tt thru a wire to the center rails which in turn should keep it powered. As the tt moves the brush like contacts connect with each approach rail and powers that rail. Your engine should not blink on and off. I also checked it with my bachmann engines as well.
     If you bought this new I would send it in to the service dept. and have it checked or replaced.
     When you say you lose power to the track does your ez controller blink and beep as it does when the rails are shorted or are you just losing power like if you unplugged your power pack from the wall.
    Jerry

[Jerrys HO]

Kelly,
    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?
    I don't understand the need for this relay patch if you care to explain? Matbe this is your problem?
Jerry

[kpsdjs]

To All,

     Problem is fixxed. Thank you very much to Jim Banner. His idea to isolate "Powered" track inputs with tape solves ALL. I don't need relay patch. Never installed it. I just knew that I could cut power to the bridge while rotating!
     The TT is not defective in any way. Just some fine tune at next run. The Lights DO blink on/off/on BECAUSE they engineered it that way, so that shorts occur less!
     My promlem was that I had more than 1 powered track comming into the TT. All these powered tracks need isolation from contacting the bridge. (Even if polarized correctly)
     I will, of course, not use tape. I will remove offending rail contacts and file away the Bottom 1/8" or so of those 2" lead-ins. If I ever want to change layout, I will just replace the 2" rails with new! Better yet, just insert isolating rail joiners. EXCEPT at #4 index, as it NEEDS to get bridge voltage from there.

Thank You Again Jim, a real Banner guy!
kpsdjs
Kelly

[richd286]

I have had the same issue after recently bring power up after a track change.  After reading everyones responses I think I have an answer...  I have a DCC powered arrangement with power coming into the TT from position 4.  I get a short when the turn table crosses polarity with another powered spur.  I have power coming out of the TT conflicting with a powered section.  If I remove the power to the spur, it will only be powered when the TT is aligned with it which can be OK if I want that spur dead when the TT is moved away from that position.  The other fix might be to put insulators between the spur and keep it powered.  My concern this the insulated track section is a possible short when an engine crosses the insulators and bridges the circuits.  I will test this tonight and get back to you.

[kpsdjs]

Rich,
     Putting isolators on the powered rails will fix UNLESS that piece of track is polarized wrong. Some TT positions are polarized one way, and others, opposite. I tested each track to find polarities.
     Going clockwise from pos. 1, rail 1 is "A", rail 2 on pos. 1 is "B" polarized. Pos. 2 is A-B, 3 is A-B, 4 is A-B. I.e.; 1-4 are alike. pos. 5-13 are B-A polarized, and 14-16 are A-B polarized.
     I.e; Pos. 1-4, and 14-16 are alike, but pos. 5-13 are opposite polarity!!
     You MUST isolate powered rails (except #4) to prevent shorts durring rotation!
Hope this helps. Maybe Bachmann will add this data next run?
Kelly