Ruffnut Thorston Posted October 3, 2019 Share Posted October 3, 2019 Hi all. Has anyone done a conversion of the older, 1969s, early 70s, R.408 / R.408U turntable. I can forsee that the method of carrying power to the rails of the bridge will need changing, as otherwise opposite rails will contact each other as the ' table rotates. The power to the motor, which is attached to the bridge, is carried to the bridge by two wipers, running on circular tracks. Looking at one earlier, I was wondering if fitting a decoder to run the 'table motor actually on the bridge would allow the feed wires to convey the DCC track power to the bridge rails, as well as to the motor, via the decoder. That way the bridge rails would remain live. I would presume that something like a reverse loop module may be needed though, as the two rails would in effect swap sides when the 'table is rotated. As you can tell, the little grey cells are working at this... 😉 So, any ideas? Link to comment Share on other sites More sharing options...
Plumloco2 Posted October 5, 2019 Share Posted October 5, 2019 HiI have one of those Im going to use on a DCC layout. I have just checked the current draw. Turning the table its 0.55 amps, at the aligning stops it 0.3 of an amp. I dont think a standard hornby decoder would drive it. I'm going to wire it as it would be wired for DC and there wont be any problems, also a lot simpler. If you want the output tracks live at all times I would have insulated joiners after the turntable. RegardsDave Link to comment Share on other sites More sharing options...
Fishmanoz Posted October 5, 2019 Share Posted October 5, 2019 Sarah, from your description, the TT sounds very similar to the R070 for which a number of conversion methods have been described extensively on here. Do you have a service sheet we can look at? Is it an X03/04 motor (if so, Dave’s probably has weak a magnet needing re-magnetising)? And you will only need an RLM if outlets connected back to live parts of the layout and you can’t arrange them to connect with the correct polarity (phase) depending on which part of the slip ring they come from. Dave, I suggest you might look at the previous threads too. Sounds to me that you may not have dealt with shorts as the TT rotates yet? Link to comment Share on other sites More sharing options...
Plumloco2 Posted October 6, 2019 Share Posted October 6, 2019 The R408 turntable uses the XT60 motor from the early Lord of the Isles. I think the current draw when new was 0.43 Amps. I agree the magnet could be getting week and I might replace it with a neodymium. I know the issues with slip rings feeding to turntable tracks but the R408 has no slip rings for track supply. The way it works is the incoming track feeds power to the turntable track, the turntable track then feeds the 3 tracks coming off on the other side depending which its aligned with . Its all done with contacts. The slip ring is only for the turntable motor which is mounted on the rotating table. If you suppled the turntable motor with DCC and also the same feed to the track then yes there would be a problem with polarity. Below is pictures of R408, the contacts for the incoming track are on the left, outlet tracks on the right. /media/tinymce_upload/e6801cba00b432b6b423711fc46c9cec.jpg /media/tinymce_upload/87c0b4d04b5c6a32ee1bf6ea50a340d1.jpg RegardsDave Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted October 6, 2019 Author Share Posted October 6, 2019 This is the turntable. There was also one on the Blue Peter model railway in the later 1960s/ early 1970s./media/tinymce_upload/a25b92a403b7494352b74e52b31f64f3.jpgThere was no Service Sheet issued, I think that the instruction leaflet for the X.319 Turntable Conversion Unit is the closest. The current is supplied to the XT.60 (TT gauge and OO gauge 'Singles') motor via two complete rings on the turntable base, to two wipers that run on these rings./media/tinymce_upload/0f154c2fa6dd6e39b4173e87603ce7f5.jpg/media/tinymce_upload/0a77f0cbf5a26c24b853fc2ba0b38849.jpg The feed comes from a 12volts D.C. source via two wires, and a press button switch that can reverse the polarity, and thus the direction of rotation. Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted October 6, 2019 Author Share Posted October 6, 2019 Continued... The track power is conducted to the bridge rails from the input, single, track via two wipers on the underside of each end of the bridge. These pick up current from pairs of eyelets in the top of the trackway the bridge rotates upon.The input track is electrically connected to three sets of eyelets under the base. The output tracks, three, are each connected to a pair of eyelets. Therefore only the output track the bridge is aligned with is powered from the input track, via the bridge. /media/tinymce_upload/57b5594143affbd2db9bbf6124aa368b.jpgSome of the eyelets can be see as rings in the above illustration from the Tri-ang Railways X.319 instruction leaflet. /media/tinymce_upload/2056ccd6ae9f2666d6e1203e3b104350.jpgExtract from the Tri-ang Hornby Instruction sheet. Above... /media/tinymce_upload/86983ee58ec4151f8c2c93ea11d73497.jpgThe motor and gearing, mounted on one end of the bridge. Above... Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted October 6, 2019 Author Share Posted October 6, 2019 As can be seen from the above, the rails on the turntable bridge are only powered when the table is connected to the input/ output tracks. There is no feed to the bridge rails when it is rotating. For DCC, with continuous power to the track, there is a potential problem as the turntable stands. As the bridge rotates, first one, and then the other wiper contact on the end of the bridge will contact each eyelet. Now would this cause a short circuit, if there is no other DCC track feed other than the input track? The downside of the standard electric feed arrangements is that the outlet tracks would only be live when the bridge is aligned with them, and the bridge itself would be 'dead' while it is rotating. Maybe not too much of a problem, except for DCC sound, where the sound would cut out and restart.... Hence my trying to find a way of feeding all the sections all the time. Link to comment Share on other sites More sharing options...
Plumloco2 Posted October 7, 2019 Share Posted October 7, 2019 I hadnt thought of keeping the sound going on the turntable so I did some experimenting.The turntable takes 15 seconds to rotate and I have an A4 with TTS and a Laiss Stay Alive. When stationary the the loco chuffs for 35 seconds. I rigged it all up and it worked great. The turntable is a bit noisey but you can still hear the chuffs. Loco volume was about 60%.I did have a problem with the turntable pickups. The outer rails are made of aluminum and are rivited to the brass strips underneath. After 40 years there is corrosion between the two dissimilar metals and power was not getting through to the rotating table. I gave the riveting a wack with a centre punch while supporting the track on the other side and power was restored. I think for reliable power the DCC buss needs to go direct to the brass strips. All my locos dont have stayalive so your idea of power direct to the turntable with an autoreverse and a decoder on the drive is a good one. The wires from before the motor decoder could go under the table and connect directly to the table wipers out of sight and adding a decoder to the drive is easy. It would solve the problem with the rivets. Also the changes are reversible to return the turntable to orignal condition.l might give it a try.RegardsDave Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted October 7, 2019 Author Share Posted October 7, 2019 Hi Dave. It's always good to bounce ideas around. It may be some time before we get around to sorting out a DCC conversion, we are restoring the turntable first. We have all the parts now. It's interesting to note that the earlier version, with a maroon bridge, as in your photos, has brass gear wheels, these are the same as the drive gears in the locos with the X.04 motors. The later version, with a black bridge, has a modified base to take the fencing and lamps, and black plastic gears, as by this time the locos were fitted with black plastic gear wheels as well. Link to comment Share on other sites More sharing options...
Plumloco2 Posted October 7, 2019 Share Posted October 7, 2019 I have seen the version of turntables with the plastic gears. The one gear the should be made of brass is the pinion on the underside. I had one of these turntables in the 1970s and the pinion broke in half. I got back into old Triang, Hornby and Minic motorways a couple of years ago bought a turntable and suprise it had a broken pinion as well. So I drew one made it a bit stronger and had it 3d printed. Have you seen on Ebay in Ausy for sale the pinions part no S6307 for 11 pound for 3 . I bought 3 so I now have plenty of spares. RegardsDave Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted October 8, 2019 Author Share Posted October 8, 2019 Hi Dave. We had some of the drive pinions in the parts that we took over from a retired service dealer, and yes, the Ausy seller has some good parts, as well as the pinions. From the Mouldex factory it seems. The older pinions were moulded in the same red oxide colour as the turntable bridge.The first red oxide R.408 turntable we had came with the pinion in two pieces, maybe the red plastic isn't as strong? Our spares are all black, so must date from the later Hornby issues... Peters Spares has the wipers from under the turntable it seems...Hornby S3971 Turntable Deck Contacts (Pk2) Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted October 14, 2019 Author Share Posted October 14, 2019 Peters Spares has the wipers from under the turntable it seems...Hornby S3971 Turntable Deck Contacts (Pk2) The wipers are in fact those from the ends of the turntable bridge. The ones that connect to the rails. For some reason, all those that I received have a + cut out in them... It would be good if I could find a source for the motor pick up wipers, and the circular tracks... Oh for a supply of the motorisation kits! 😉 Link to comment Share on other sites More sharing options...
Plumloco2 Posted October 15, 2019 Share Posted October 15, 2019 If you can get the material and want to have a go at making them I can measure the bits up for you. The wipers are 0.006" thick x 0.250" phosphor broonze and the rings 0.010" thick brass. OD 1.400" Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted October 15, 2019 Author Share Posted October 15, 2019 Thanks. We may not have the tools to make the parts at the moment.Maybe a small market for such parts. The turntable was originally made in hand operated and motor driven versions. I wonder how many hand operated ones are still out there, that have not been motorised over the years? The hand operated version doesn't have any of the wiring, or the rings, of the electric version.... All these parts came in the motorising kit. Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now