LGB analogue reverse loop set not working :S

[Rob]

Hi,
since rebuilding my railway earlier this year the reverse loop set has become a bit annoying, only working intermittently, but when I went out to run a train yesterday and again today, its not working at all :wits:
A couple of weeks ago we had the same problem an opened both units up and they were full of water, so after a dry out and a clean they worked perfectly, but when I opened it up yesterday there was no water or dirt in there.
Can anybody advise me how i can find out whats up with them or fix them, or, find an alternative to them

Thanks,
Rob

 

[Neil Robinson]

Hi Rob.
As it seems to have be giving trouble on more than one occasion I'd be tempted to remove the LGB circuit board from the track with the arrow ( there shouldn't be any electronics in the other track in the set) and replace it with a diode bridge. These are easily and cheaply obtained from any electronic component supplier, get one with a current rating of at least twice that of the largest power supply you are likely to use.
The illustration shows a KPBC2504, rated at 25A 400V suitable for a 10 A supply and available for £2.11. from Maplins; maybe less from alternative suppliers. If you don't wish to solder the connections your supplier will doubtless be able to supply suitable crimp connectors, note the positive is identified by being at 90 degrees to the other three terminals.
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[don9GLC2]

Neil, that's a very clear diagram and an excellent suggestion, but is the polarity correct? I do not use analog so I may have got it wrong, but NMRA standard 9.0 states

II. CONTROLA. Direction control by polarity reversing shall be provided. Positive potential applied to the right hand rail shall produce forward motion. (3)

and note (3) states

(3) The term "right hand rail" as used herein means the rail to the right of the observer standing between the rails with their back to the front of the locomotive.

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If I understand that correctly you have the loop connections reversed, that is if LGB have followed the NMRA standard. I think the positive (red on your diagram) should go to the right hand rail, or else the rectifier will be shorted when the train bridges the insulating section.


Don

 

[Neil Robinson]

If I understand that correctly you have the loop connections reversed, that is if LGB have followed the NMRA standard. I think the positive (red on your diagram) should go to the right hand rail, or else the rectifier will be shorted when the train bridges the insulating section.
Don

Spot on Don.
My diagram is a straight replacement for the LGB reverse loop set as LGB locos are, and always have been, wired opposite to the NMRA standard. Indeed some Bachmann, and possibly other brand, locos have a changeover switch from "Large Scale" to "NMRA".

 

[dunnyrail]

This is very interesting or have I got the wrong end of the wire?

What you appear to be saying is that I can use one of these for an MTS Reverse Loop for less than £3.00 rather than paying around £77.00 for an LGB 55080 Reverse Loop Module (that is if you can get one). Oh plus the cost of 4 isolating fishplates. Can this really be true?
JonD

 

[dutchelm]

Can this really be true?
JonD

I'm afraid you missed the most important word in the thread title, ANALOGUE

 

[Rob]

Thanks Guys, thats a great help!

it really is good here innit

 

[dunnyrail]

Yup that's me, must try to get out of speed reading! Many thanks.

But what is wrong with just 4 diodes onto 2 isolating tracks? Or does this beastie allow circuits around the loop BOTH ways on the good old analogue? Sorry to ask what may appear to be silly questions.
JonD

 

[korm kormsen]

analogue as i know it:
the train enters the loop allways in the same direction. there is a length of track, that thanks to diodes allways has the current in the same direction. while the train travells this track, it hits a switch, that changes polarity for the whole track, save the "dioded" length.
the train does not even stop.

 

[Rob]

Not quite Korm, the train always has to go round the same way, as you said, but you have to stop the train and reverse the current, i.e. turn the controller the other way.

 

[Neil Robinson]

In

Not quite Korm, the train always has to go round the same way, as you said, but you have to stop the train and reverse the current, i.e. turn the controller the other way.

In my experience you are both correct. In Rob's case I presume he has a center off controller and with these I find it best to slow to a stop then gently accelerate with the controller in the opposite direction. Korm mentioned a switch, if this, or an automatically operated relay, is quick enough it can be reversed without any visible change in the train's motion.

 

[korm kormsen]

i am no friend of standing and steering trains.
i prefer to sit and watch them over the rim of a glas.
so it is automation for me.
when i had a single track with a loop at each end, i used:
1 loop set from LGB
1 homemade loop set (copied from the above)
2 electric turnouts
1 additional switch (the add-on for the turnout switches)
2 homemade copies of the 17100 reed-contacts
1 transformer/controller AC and DC

i put the loop-sets directly after and before the two arms of the turnouts.
so, thanks to the diodes the whole loops could be travelled in one direction only.
(as continental person i had the trains go to the right of a turnout and return into the left.)
far enough into the loop i had a reed-contact. (AC in - reed - diode or reversed diode - "DC" out)
the reed in the right loop did switch the right turnout to the left, and the left turnout to the right.
the reed in the left loop did just the oposite.
the power from the controller did not go directly to the track, but into the additional switch.
when the right turnout opened its left leg, the power was reversed. when it opened its right leg power went straight.
(supposing, that travel from left to right on the main line was forwards)
even at slower speeds it was hard to notice the short powerless moment, while the switch was moving.

that was simple.
(it became more complicated, when i included a siding in the mainline and a second loco with reversed polarity...)

edit: i did not let the trains slow down before stopping. (i hadn't learned the idea with the "slow-down" diodes yet)