Hornby Turntable - R070

[Fishmanoz]

Sorry Ray, my turn to not read properly. Yes, yours should work for you as long as you get all of your polarities correct.

 

RDS, if you use this method, which avoids having to gap the inlet, don't use IRJs on your sidings but do use them on your

 

inlet track.

[Fishmanoz]

Yep, apologies, was posting my retraction while you were insisting.

[St1ngr4y]

As I say, I'll give this a try tomorrow and let you know how I get on. Hope I can get the brass contacts back in easily!! :-(

[RDS]

@St1ngr4y

I look forward to hearing how you get on.

I am one of the 'one connection to the whole layout and NO DCC bus' school of thought.

I hope I can continue that way!

 

I am sure you will be able to get the brass contacts back in OK.

 

After all, they were originally installed on a Production line somewhere.

 

[RDS]

St1ngr4y said:

4) On dead-end tracks provide a DCC connection to the bus.
This will allow the contacts on the bridge to be left in place in order to provide power from the bridge to the X918's. It also means dead-end tracks will still

have constant DCC for sound loco's.
Ray

Just a thought .... I realise that you are intending to put IRJ's on all the X918's but will the wheels of the loco's not cause a 'short' when they cross from the X918 to the DCC powered dead-end tracks,

on those out-lets that have been subject to the 'swop'.

[Fishmanoz]

RDS, to compensate for the reversed polarity outlets, you also have to reverse the polarity of the bus connections to those sidings, which means the reversals cancel out and the polarity matches.

 

But if you are a single point connection man, gap

 

the inlet track and you will be right. Everything then works from that inlet connection - bridge and sidings when aligned.

[St1ngr4y]

RDS said:

Just a thought .... I realise that you are intending to put IRJ's on all the X918's but will the wheels of the loco's not cause a 'short' when they cross from the X918 to the DCC powered dead-end tracks, on those out-lets that have

been subject to the 'swop'.

@RDS
As Fishy says, you (or rather I) need to be aware of which outlets have their polarity reversed and connect these to the bus the other way around. I managed to replace the brass contacts which I had removed

from the ends of the bridge. Connecting the bridge to the DCC bus was even easier than I had thought it would be. On the underside of the turntable where the brass contacts of the inlet track are placed, the wires which run from the contacts to the centre

of the table are conveniently connected to the contacts by spade connectors, so they are easily disconnected. The wires to the centre are held in place by a strip of sticky-backed plastic. I removed about 2 inches of this from the outside so that I had about

4 inches of wires free which I could feed through two holes in the baseboard. I then found some 'male' spade connectors to fit into those on the wires from the turntable and from there connected to the bus. Everything works fine.
Ray

[RDS]

@Fishmanoz

Thank you for your post.

As you point out, I am a single point connection man, in fact earlier today I have counted up and quoted on a thread within the General Discussion area, called Hornby R965 > Multiple Outlets, the scenario I have

 

at the moment. This will get more fascinating when I add the turntable!

 

Sorry to be a nuisance but could you please be a little more specific though with your, Gap the inlet track ..... because I am still struggling to see how a short will be avoided

 

when the bridge first rotates away from the inlet track.

 

[RDS]

@St1ngr4y

Ray,

Thanks for reporting back. I am pleased your idea worked.

[St1ngr4y]

@RDS

I think what is meant is that you cut the rails on the X918 between the turntable end and where the brass contacts touch the underside of the inlet rail. This means that when the bridge isn't aligned with the inlet track, this small half-inch or

 

so up to the gap in the rails is electrically dead and only receives power when the bridge aligns and the brass contacts on the bridge make the circuit.

I achieved the same result by effectively removing the brass contacts from the underside of the rail

 

and having IRJ's on the X918 instead of cutting the rails.

Ray

[Fishmanoz]

Ray is right RDS. I posted more detail earlier in the thread and gave a link back to a post by Blackbird who was actually selling this a while ago.

 

To be specific here, on an X918 inlet track, cut both rails right through anywhere between where

 

the brass contacts touch the track and the turntable. Now fill the gaps left with an insulator. You could glue in and trim a piece of plasticard, or old credit card, or just use epoxy glue and trim it when cured. Make sure none is left on the track running

 

surface or protruding at the side where it can foul the wheel flange. Now the track is live up to the gap and the contacts under it will still power the bridge. But you won't get shorts when the bridge rotates as the last bit of track after the gap is dead

 

until the bridge is properly aligned and powers it.

[Blackbird]

Hi all,

After being away from this forum for some months, I was interested in seeing the debate on DCC operation of the Hornby R070 turntable still being topical. It seems that at least one member, @Fishmanoz, understands, and supports? the principle

 

of the 'Turntable DCC adaptor track'. Not the only solution, but a 'simple' method, negating the use of lots of additional wiring and reverse loop modules.

I'm still surprised that Hornby haven't picked up on this problem and produced a modified X918 track

 

themselves?, but still advocating mutilating the turntable to make it compatible? (with DCC).

There is one point raised in this current debate that I wish to correct; the under rail contacts have no influence or effect on the alignment of the rails. The

 

alignment is determined purely by the mechanical action of the (Geneva) gearing.

[RDS]

@Fishmanoz

That's great thank you.

I had not spotted the bit about the cutting the X918 between the Brass Contacts and the Bridge. It does look like I can maintain my one connection strategy!

 

I have just re-read your lengthy posting near

 

the start of this thread and it all becomes clear now.

Thanks again,

[RDS]

@St1ngr4y

Ray,

Thanks, As I have just stated in my post to Fishmanoz, I missed the fact that the in-let rail is cut between the bridge and the brass contacts.

It is good that we have a solution to cover either a one connection system like mine

 

or a DCC Bus solution like yours.

Thanks again,

 

[Fishmanoz]

Blackbird said:


There is one point raised in this current debate that I wish to correct; the under rail contacts have no influence or effect on the alignment of the rails. The alignment is determined purely by the mechanical action of

the (Geneva) gearing.

Blackbird, this topic has been dead quiet for ages then popped its head up again a few days ago in time for your return.

Just on your comment above, I think the reference was to the (end of) bridge rail contacts rather

than those under the inlet track.

[Fishmanoz]

Then rereading, maybe you meant those.

[Blackbird]

Can I add some further advise as there seems to be some confusion as the where to 'gap' the X918 rails.

They should be cut between the sleepers after the under-rail pickup points. Leaving the maximum length of track after the cut. It would also be

 

advisable to secure this track to the base with a very small amount of SG on the chair mounts, as there isn't much holding the track to the base after the cut. The protruding rails may need to be reduced in length by a small amount to ensure clearance with

 

the T/T rails, testing to be sure, but depends on how the rails were cut. For example; I used a 0.7mm diamond disc (set up in a jig on a milling M/C) and with a 1.0mm insulation insert, found that 0.3mm required filling from end,

but testing is required.

Hope

 

this is of help, but if required, I could post some photo's on another web site?

[Blackbird]

Just to reiterate, and referring to my previous (historic) posts.

The DCC Turntable Adaptor Track was designed (a modification of the standard X918 track) as a SIMPLE solution for the novice (or experienced) DCC railway enthusiast to incorporate the

 

R070 turntable into their DCC layout, without mutilating the turntable and the requirement of lots of addition (complex) wiring. There are, of course, many other ways of overcoming the T/T DCC shorting problem, but this is a basic and reliable method.

I

 

supplied these modified tracks for some years with over 70 satisfied recipient's, one comment: " does just what is say's on the tin!" The only caveat in the use was; that any additional outlet track attached the DCC system must have an additional DCC adaptor

 

track or IRJ's fitted. This was included in the installation instructions.

 

If Hornby read these posts, wish to expand DCC, and still incorporate the R070 turntable, why don't they take this information and market their own 'DCC Turntable Adaptor Track'

 

, supplied with the T/T, it could be classified as DCC compatible!

[St1ngr4y]

Blackbird said:

Can I add some further advise as there seems to be some confusion as the where to 'gap' the X918 rails.
They should be cut between the sleepers after the under-rail pickup points. Leaving the maximum length of track after

the cut.

Hi Blackbird,
Am I correct in saying that the only reason for cutting the rails is because you are still using this inlet to power the rails on the turntable? If you disconnect the wires from the under-rail pickups and connect these

wires directly to your DCC bus, then the under-rail pickups become redundant. IRJs can then be used to isolate that X918 from the main layout. In fact, this track then becomes identical, electrically, to all of the other X918s. Also, doing it this way means

that ANY of the tracks can be used as the connection to the main layout. Removing this restriction then means you can position the turntable so that the "polarity switch line" is placed so as to give the least disruption to power on the bridge during rotation,

so as not to affect locos with lights and/or sound.
Ray

[Fishmanoz]

Ray,you are of course quite correct. Blackbird did say there are many ways of achieving it.

 

One disadvantage of your method is that it is still necessary to modify the TT, this time by removing, insulating or isolating the under-rail pickups.

 

Also,

 

you can only completely avoid bridge supply interruption if you can arrange that all outlets and the inlet are within a 180 degree arc. If not, there will be interruption for a brief period when the slip rings pass through their break before make polarity

 

reversal. I agree you have a better chance then with the gapped inlet if they are within 180 degrees.

[St1ngr4y]

Fishmanoz said:

One disadvantage of your method is that it is still necessary to modify the TT, this time by removing, insulating or isolating the under-rail pickups.

I wouldn't have considered unplugging the wires from the

under-rail pickups to be such a major modification, Fishy. It's a lot easier than having to cut gaps in an X918 :-)

Ray

[RDS]

@Blackbird

I would like to see your pictures please, if possible.

[Blackbird]

St1ngr4y said:

Hi Blackbird,
Am I correct in saying that the only reason for cutting the rails is because you are still using this inlet to power the rails on the turntable? If you disconnect the wires from the under-rail pickups and connect

these wires directly to your DCC bus, then the under-rail pickups become redundant. IRJs can then be used to isolate that X918 from the main layout. In fact, this track then becomes identical, electrically, to all of the other X918s. Also, doing it this way

means that ANY of the tracks can be used as the connection to the main layout. Removing this restriction then means you can position the turntable so that the "polarity switch line" is placed so as to give the least disruption to power on the bridge during

rotation, so as not to affect locos with lights and/or sound.
Ray

Hi St1nray
Yes you are correct in your interpretation, it is the same principle; isolating the inlet rail to prevent the short circuit, whilst still supplying the T/T bridge

to allow it to supply the aligned outlet. Using the adaptor track is a SIMPLE method, making the adaptor track requires some 'expertise'. It all depends on your ability. I have supplied the details, and will shortly publish some 'photos as a guide, (as requested

by RDS)
I used to supply these modified tracks at £5, but with the difficulty of obtaining new X918 tracks, and when available, now @ about £3.50, it became uneconomic. If there is a 'demand' for these adaptor tracks, (and Hornby don't take them up?) I

will make them available again.

[RDS]

I intend to use the method described by blackbird, by gapping the inlet rail, just after the brass contacts. The turntable will be inside my inner loop.

However, even though I had not previously intended this, I am now considering connecting one of

 

the outlet tracks that has been subject to the 'voltage swop' back to the other side om inner loop. I would in effect be using the turntable in a reverse loop situation. I realise that I will need to 'gap' the relevant outlet rail.

Have I missed something

 

or will this be alright

[Fishmanoz]

You've missed the point slightly RDS. The only track that needs to be gapped is the inlet track because the isolation must be between the brass contacts and the TT. For any connected outlets, IRJs are all that is needed.

 

That said, I'm unclear

 

with what you mean for the connected outlet. Will it have the same polarity as the track it is connecting to, or will it be opposite? And if opposite, is it possible to rotate the whole TT to avoid this such that it is the same? The thing is, if it is is opposite,

 

you will need to use an RLM.

 

If polarity is a problem and can be avoided by rotating the whole TT, you may be going to ask me what about the inlet track and the brass contacts? The answer is to use Ray's method and connect directly to the bridge from

 

your DCC bus or track connection and not use the contacts at all. Then the inlet can be isolated by IRJs too.

 

Does that make sense?