R070 Turntable

[A Law]

Hello all. I'm new to model railway forums, but reading through it seems that you have all the answers! I've just purchased the above TT and converted it to DCC. It's not yet fitted to the layout but connected to check that my soldering was ok. Looks like it was as the TT will rotate ok but only seems to move from one outlet to another and it will only do this if I "log on" to the decoder again for it to move, but only to the next outlet. As I'm only using the TT to turn the loco's through 180 deg this operation is going to be a real pain! Is this the way it's supposed to work? I'm using a NCE Power Cab controller and the lower line of the display shows No. 1. is this related to my problem. Hoping you can help.

Andy

 

[Yelrow]

Hi, Andrew and welcome to the forum. Your question, if i understand it, is you want the turntable in one movement to go 180 degrees. I dont think, it will do that. I have two, a hornby the same as yours on DC, and a Frestechci, on DCC. My hornby one when drive applied, goes to next rail, pauses, and carries on, which is what i think you want. However, the DCC one, only goes to next track, then stops. You have to click it again to move on, again only to the next track. you need my friend Stingray, for this, as he has the same TT, as you, and i am sure he will  post an answer. Unless i have programmed my DCC TT, wrongly, i cant make it do, what you want to do, athough it is no problem for hornby on DC. If you wait, i am sure others will come in, and   say whether i am  right. On my layouts, both do exactly what i want them to do. , so am quite content. john

[Rog RJ]

The Hornby R070 turntable has a Geneva gear drive which makes the movement pause at each outlet even though the motor continues to rotate.  There's nothing simple that you can do about the pauses, it's the way it's designed.

You can google Geneva drive to see how it works.

[St1ngr4y]

Hi Andrew,

Unless you are using Railmaster software, then the TT should be controllable from your DCC controller as if it were a loco. In other words, take it up to a cruise speed and let it go. The motor will operate continuously at that speed until you stop it with your controller, but the bridge will pause at each outlet. On the eighth pause, you will have rotated 180 degrees.

I'm afraid I'm not familiar with the NCE Powercab, so I don't know what is the significance of "the lower line of the display shows No. 1".

Ray

[St1ngr4y]

Hi, Andrew and welcome to the forum. Your question, if i understand it, is you want the turntable in one movement to go 180 degrees. I dont think, it will do that. I have two, a hornby the same as yours on DC, and a Frestechci, on DCC. My hornby one when drive applied, goes to next rail, pauses, and carries on, which is what i think you want. However, the DCC one, only goes to next track, then stops. You have to click it again to move on, again only to the next track. you need my friend Stingray, for this, as he has the same TT, as you, and i am sure he will  post an answer. Unless i have programmed my DCC TT, wrongly, i cant make it do, what you want to do, athough it is no problem for hornby on DC. If you wait, i am sure others will come in, and   say whether i am  right. On my layouts, both do exactly what i want them to do. , so am quite content. john

John,

When you say "You have to click it again to move on," do you mean the TT icon on your track diagram? If so, did you know that you can click the icon, say, 3 times in quick succession, to get the TT to move 3 places? Each time you click, a number will be incremented on the screen near the TT icon.

Ray

[Yelrow]

Hi, Ray, good to talk , i thought i was right about the hornby TT, as thats how i drive my DC one. I was aware that you could move bridge as you describe, but rather like its basic movement. I did try to drive it like a loco, as it is 022, but got into a muddle. Very happy now i have power on all 18 tracks, as have 3 loco sheds with self opening and closing doors , from which locos emurge. All i need now, are 14 moreDCC  locos, to fill up tracks. No problem with DC one, as have plenty. john

[Yelrow]

Rog, greetings, spent all my first post trying to remember the name of the drive, knew it had something swiss about it. john. Are you still talking to your trains. john

[Fishmanoz]

Suggest you stop trying to confuse poor Andrew with RM talk, he doesn't appear to have it as he only talks about Powercab. 

 

Andrew, Rog and Ray have it covered for you in their following posts above. Nothing more needs to be said. 

[A Law]

Gentlemen

Thank you all for your input. I was obviously impatient and setting the speed a little higher was able to move the TT through the full circle. Thanks for letting me know what type of gearing was used, very clever idea! The TT is now fitted and works as Hornby intended (including the conversion to DCC) 

[St1ngr4y]

Hi Andrew,

Have you catered for the DCC implications of providing power to the TT bridge?

Ray

[A Law]

Hi Andrew,

Have you catered for the DCC implications of providing power to the TT bridge?

Ray

Are you referring to the two wires on the underside running from the centre of the bridge?

No not yet, but I assume they should be connected to the track so that when the point gives access to the TT it also gives power to the bridge.

Andy

 

[St1ngr4y]

Hi Andrew,

Have you catered for the DCC implications of providing power to the TT bridge?

Ray

Are you referring to the two wires on the underside running from the centre of the bridge?

No not yet, but I assume they should be connected to the track so that when the point gives access to the TT it also gives power to the bridge.

Andy

 

The R070 was designed for use on analogue (DC), It has, on one of the inlet roads, a pair of brass connectors which make contact with the rails of the short approach rail. This approach rail then connects to the rest of the layout. On DC, it is via this approach rail that the TT bridge receives its power, thence through the two brass contacts, and the wire underneath which goes from these two contacts to the centre of the TT. At the end of the rails on the bridge itself, there are more brass contacts, and these come into contact with the other roads as the TT rotates. Under DC this method of operating is ok, because when the TT is rotating, there should be no (DC) power in the tracks. However, with DCC, there is always 16v AC in the tracks, and this means that when the TT rotates, there will come a point when one of the bridge rails makes contact with the "wrong" approach rail, causing a short circuit. 

Now, there have been one or two suggestions on how to overcome this problem. This is how I did it with mine....

Disconnect the wire from the brass contacts which leads from the centre of the TT, and connect these to your DCC supply (either the DCC bus if you use one or the track on the main line. This is the only tricky part - you need to connect these with the correct polarity. Then, wherever you have one of the small approach tracks connected, use plastic rail joiners to isolate these from the outlet sidings. Finally, wire up the outlet sidings which you use to the DCC bus, again being careful to get the polarity correct.

Ray

[Fishmanoz]

There is extensive coverage of DCC conversion of this TT in the forum but more than 12 months old now. A number of ways have been proposed.  You can do a search on turntable, TT or R070.

 

The first is proposed by Hornby and that is to remove the brass contacts at each end of the bridge and power all outlets. This method is generally considered a little crude as it means "butchering" the TT, along with all the wiring needed. 

 

The second is Ray's method. 

 

The third is to modify the inlet track by cutting a gap in each rail between the brass contacts and the TT end, and putting insulation in the gap. If any outlets are connect to DCC power, IRJs are used to avoid shorts when rotating, just like Ray's method. If they are just engine shed dead end sidings as outlets, nothing further needs to be done.  However these sidings are only powered when the TT bridge is turned to them so could be an issue for sound locos. The inventor of this method is Blackbird if I remember correctly, and he used to sell the modified gapped inlet track.  For me, this is the most elegant and requires the least wiring  

 

A fourth proposal was to just put insulation tape under the brass contacts to stop their contact. Not a long term solution I would suggest as the tape will wear away in not too long. 

 

A fifth way is to simply cut the power feed to the bridge and power all inlets/outlets.  Then the bridge is unpowered on rotation when not turned to a track and will be a problem with sound locos which will turn on and off.

 

You also need to take account of the fact that the slipring method of powering the bridge means that half the outlets are at reverse polarity to the other half. That means you have to be careful to make sure any powered outlets have the same polarity as the bridge when turned to them, else you'll get a short when a loco crosses. You can see more on this on Brian Lambert's extensive coverage of TTs in his DCC section. 

[Yelrow]

Gosh fishy, what a lot of detail. Glad i bought my Freteschi, complete with all track, decoder, etc, wires already fitted, complete with wiring diagram. I am not sure i could have got my head round all this. Mine was on a piece of board in Lille, too big to post, and came as DIY set. Fortunately, the seller, was very proficient, in his dcc knowledge. I had enough trouble, getting the sidings live, with my hornby DC one, again sorted, thanks to the forum. I had not realised about reverse polarity. Just set mine up in RM. and on schematic, gave decoder a number, and it all worked. Just think of all the posts i would have created, had it not worked. john

[A Law]

Gentlemen. I'm totally confused!

As I mentioned in my original post, I will only have one inlet/outlet, just using the TT turn turn the loco through 180 deg. I have removed the brass contacts as per Hornby's instructions, they state that " ensure any turnouts from the modified turntable are live in order for locomotives to operate".

This makes no mention of how to power the rails on the bridge in order for the loco to enter. I assumed this would be via the contacts on the inlet track to the centre. Hornby make no mention of any need to ensure correct polarity. 

[Fishmanoz]

Given that Andrew, you have nothing more to do. The bridge power goes via the brass contacts under the inlet track. Removing the contacts at the ends of the bridge ensures there are no shorts as it rotates. As you are not using any of the outlets, you have no worries about their polarity. 

 

Use and enjoy. 

 

John, not all TTs have reversed polarity on half their outlets, but the R070 does as it is a slip ring design.  No idea on the Freteschi.  Again, check out Brian Lambert. 

[Yelrow]

Fishy, mine works fine on all 18 tracks, so quite happy. john

[A Law]

 Fishmanoz.

Many thanks for your quick response. I've recessed my baseboard so that I don't need so much of an incline on the inlet track. Now to complete the wiring and get things working.

Andy

[St1ngr4y]

 Fishmanoz.

Many thanks for your quick response. I've recessed my baseboard so that I don't need so much of an incline on the inlet track. Now to complete the wiring and get things working.

Andy

If you find you do get a short circuit when rotating the bridge, it could be because one of the rails has slid and come into contact with the opposite rail of your inlet track.

Ray