Tortoise 16v AC circuit problems

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Julian Roberts
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Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 10:35 am

I wonder if anyone has had this problem with the third wiring system in the Tortoise instructions electrics diagram? - the 16v AC option.

I have found it works perfectly for one turnout motor but as soon as a second one is wired up (as per the diagram), the motor goes at half speed returning to its original position.

Then....

Taking a pair connected up to a Society lever frame: reverse one and it throws at its usual speed; reverse the second and that one throws at half speed. Now return either one to Normal and it goes at the proper speed; return the other to Normal and it goes half speed.

Add a third and the same pattern persists - reverse one and it goes at proper speed, the 2nd and 3rd go at half speed, return one to Normal and it goes at proper speed, then the other two go at half speed.

There are four operational turnouts and all seem to have the same behaviour.

Then...

Reverse all four at the same time and they all go at the proper speed, return to Normal simultaneously and they all move at the proper speed.

I have discounted any actual underboard wiring issues by connecting test leads directly.

There is no actual problem with a turnout moving half speed, except that it apparently shouldn't be working like that.

I've already asked some of the best brains in Scotland about this and not really expecting a short cut to actually taking the layout to one of them, but I'm posting this just in case! As may be inferred, I've pretty much zero electrical understanding beyond absolute basics.

Below, the wiring diagram with capacitors option added - but I have not done this.
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davebradwell
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Re: Tortoise 16v AC circuit problems

Postby davebradwell » Fri Mar 10, 2023 11:13 am

You must have an extra connection, then or one missing. Mine have worked for a long time.

Your diagram is a bit dodgy in mixing the conventions for wires crossing without making contact but can't see that this would cause the problem. The little bridges went out before my time in this country and we worked to the latest BS.

DaveB

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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Fri Mar 10, 2023 12:04 pm

Hi Julian,

Without the capacitors you are creating two unsmoothed half-wave supplies.

The Tortoise motors are stall motors -- meaning that when stationary they continue to draw current, in fact more current than when moving. And the more of them you have, the more continuous current is needed.

The problem you are finding is that a motor runs at normal speed when it is the only one on one of the supply lines, and at a lower speed when it is sharing the supply line with other motors.

This suggests that the 16vac supply is of too low a capacity to provide sufficient current without significant voltage drop, or the diodes are too small to pass sufficient current (and probably getting hot and unlikely to last long).

Is anything else sharing the 16vac supply? Is it from a multi-tapped transformer which is also supplying something else?

Martin.
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nigelcliffe
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Re: Tortoise 16v AC circuit problems

Postby nigelcliffe » Fri Mar 10, 2023 1:19 pm

As one of those who've tried to help from afar....

There are four or five tortoise motors, total current shouldn't be an isssue(*). They are rated at under 20mA, so 100mA the lot, even allowing 50% headroom, its not much power.
The diodes are 1A, substituted later for 3A.
(Capacitors were sent along with the diodes, but as things usually work on half-wave AC, they're not yet present ).
Switches are microswitches, fitted to a lever frame (typical Scalefour lever frame style).

The diagram comes from the Tortoise maker's website.

*note that the slow running is one direction, which direction depends how the other switches are set... all motors (bar the one moving) would be drawing stall current at all times, yet some combination of switches means the speed is reduced (and I assume the voltage being pulled down).

I've not yet found the fault (by emails).

- Nigel

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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 1:29 pm

Thank you both so much for your replies, Dave and Martin. Dave, I've (w?)racked my brains about the wiring and can't see any mistakes. The diagram is the same as comes with the Tortoise. Edit! - the Tortoise instructions diagram doesn't include the capacitors but is otherwise drawn identically!

Martin, I see the logic of what you're saying - but several people have said this shouldn't be happening. The diodes are 3 amp, and there is a separate output from a (new) Gaugemaster transformer specifically for this circuit. The Tortoises are new too - maybe they take more current when stalled than Dave's, and the others have assumed? I do have a state of the Ark meter that I've never learned how to use, maybe this is the time.

Two videos to hear rather than see the different motor speeds


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Last edited by Julian Roberts on Fri Mar 10, 2023 2:27 pm, edited 1 time in total.

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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 1:38 pm

Nigel thanks! - you replied as I was writing. The diodes aren't hot by the way.

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Re: Tortoise 16v AC circuit problems

Postby Dave Holt » Fri Mar 10, 2023 1:45 pm

Hi Julian.
Like Dave B, I've used this system on my layout, without experiencing the problems you describe. However, my arrangement does not include the capacitors, which are not shown on the Tortoise instructions that I have. In my case, the diodes are 1 amp, 50 v (only fed with 16 v AC) and there are two, in parallel, per half wave. So. 2 A capacity and each motor takes 16 mA, stalled, so that should power quite a few motors without being overloaded. In my case, the diodes are located in the control panel and there are two half-wave bus bars along the length of the layout with tappings to any local point switches and also to the control panel point switches (points operated from the signal box rather than by local hand levers).
In the case of cross-overs, both motors are fed from the same switch and move together. I haven't noticed any difference in operating speed compared with single motors.
Perhaps, as suggested, your supply isn't man enough or, perhaps, the capacitors are affecting the feed?
Hope you manage to sort it.

Dave.

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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Fri Mar 10, 2023 2:28 pm

Hi Julian,

Turn the switch on the meter to 50 VAC (right-hand side).

Plug the test probes into the 16vac supply alongside the existing wires. It doesn't matter which way round.

What is the reading with no motors moving? With a motor running fast? With a motor running slow?

Remove the existing wires so that only the test probes are connected. What is the reading now?

Have you fitted the capacitors? If so I think they would explain the effect you are seeing if they are not large enough. In effect the low speed is the normal speed, with the loaded capacitors charging to a lowish voltage. The fast speed is seen when an unloaded capacitor has charged to a higher voltage and a single motor is switched to it. Try fitting much larger capacitors, or not using them.

cheers,

Martin.
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 3:04 pm

Quick reply to Dave H and Martin - I haven't put in any capacitors! (I did say that on OP :) )

Thanks both and for the instructions Martin - will report the findings.

Oh and by the way Dave, this frame is for the four points in the yard where the crew would throw them. The main line will be as from a signal box and will control another 5 turnout motors and nine (sic) signals. Yes the proper wiring is from bus type wires under the layout - everything you can see here is a temporary lash up to prove the issue is not the below board wiring - the behaviour is just the same.

Here is the actual instructions diagram, apologies that I didn't have it to hand this morning
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 5:40 pm

Hi Martin I am posting this in case it throws any light although I may not have quite answered your questions.


Probes to (red and black) input wires from transformer

20230310_152825.jpg


Diodes set up, output yellow grey orange

20230310_153427.jpg



All turnouts normal

Probes on yellow and orange (yellow and grey the same result, orange and grey needle all the way to the left)

20230310_154033.jpg



While first turnout moves to reverse

20230310_154202.jpg



While 2nd turnout reverses

20230310_155655.jpg



While 3 reverses

20230310_155850.jpg



While 4 reverses

20230310_160141.jpg


All stationary reversed

20230310_160506.jpg


Dial does not move as I set each back to normal

Interrupted for a while. On return I find yellow and orange show no reading. Now orange and grey show 10.

20230310_164732.jpg


Reversing all 4 in turn, the needle doesn't move. Restoring one of them to normal -

20230310_165115.jpg


Each subsequent one shows higher (leftwards movement on dial) reading. All at Normal, reading is 10 (on grey and orange still, yellow and grey or orange is 1k on left)


From all Normal again

Probes on yellow and grey, pulling one lever

20230310_171753.jpg


At rest, lever still pulled off (reversed)

20230310_172039.jpg


Transformer wires removed needle all way to left.

If any of this makes no sense to you please say what and I'll test again.
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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Fri Mar 10, 2023 6:23 pm

Hi Julian,

You wrote: "orange and grey needle all the way to the left".

Please double check that. If the reading really is zero between orange and grey, it means the left-hand diode in you picture has failed, or is not connected properly.

Which makes it difficult to make sense of the other readings. But would explain why the circuit isn't working properly.

cheers,

Martin.
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 8:09 pm

OK Martin this is very kind of you - on first powering up again probes to orange and grey read 10, but to orange and yellow, and to grey and yellow, both needle to left.

Reverse all turnouts and same reading. Restore all and same reading. Still same motor behaviour.

It's just a dab of 140 solder to join the diodes.

Sorry if there is some contradiction here but I was sure I saw what I wrote.... There may be too many obstacles in terms of my lack of know how to solve this online.

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Re: Tortoise 16v AC circuit problems

Postby Tony Wilkins » Fri Mar 10, 2023 8:13 pm

Hi Julian.
There will be a reason for the problems you are experiencing. Just a matter of finding it.
First off check that the screws in the terminal block are done up tight as this is a common cause of high resistance problems.
Regards
Tony.
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Winander
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Re: Tortoise 16v AC circuit problems

Postby Winander » Fri Mar 10, 2023 8:23 pm

Hi Julian,

Are you sure that soldered connection between the two diodes on the black wire is OK? In the circumstances, I would make that mechanical.
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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Fri Mar 10, 2023 8:40 pm

Hi Julian,

This is getting confusing. Let's try ONE THING AT A TIME. First to test the diodes.

diodes.jpg


1. DISCONNECT the yellow and grey wires.

2. tighten all the screws as Tony suggests.

3. set the meter switch to 250 V on the left-hand DC side. This will prevent the meter being damaged if the probes are the wrong way round.

4. connect the probes to terminals 1 and 2 in the photo.

5. if the needle tries to move to the left, or seems not to move, swap the probes over.

6. if the needle moves a little to the right, change the meter switch to 50 V on the left hand DC side.

7. what is the reading?

8. swap to using the opposite probe on terminal 1 and connect the other probe to terminal 3.

9. what is the reading?

p.s. you have made bends in the diode wires too close to the body of the diode. This might cause a break in the internal connections in the diode. When fitting electronic components, hold the wire in narrow or pointed pliers close to the component while making the bend, so that there is no stress on the wire entering the component.

cheers,

Martin.
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Last edited by Martin Wynne on Fri Mar 10, 2023 8:56 pm, edited 1 time in total.
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grovenor-2685
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Re: Tortoise 16v AC circuit problems

Postby grovenor-2685 » Fri Mar 10, 2023 8:56 pm

OK so what we have is:
AC from transformer, Red and Black
DC (half wave) Common return, Orange
DC (half wave) +ve, Yellow
DC (half wave) -ve, Grey

The AC must be measured on the AC meter settings.
The DC (half wave) can be measured on either AC or DC meter settings.
There should be little or no change in these readings whether the motors are running or not as the load currents are very low. Highest load is with all motors stalled.

So start with the following measurements and report back:

AC 50V range, red - black = ?
" orange - yellow = ?
" orange - grey = ?
DC 50V range, orange - yellow = ? confirm positive is on yellow
" orange - grey = ? confirm positive is on orange
Regards
Keith
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 9:22 pm

Many thanks all!

One thing at a time!

Martin - question 1

20230310_211710.jpg


Question 2

20230310_211825.jpg
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 9:23 pm

I've put a big dollop of solder on the join and cleaned up the ends where they fix to the terminals

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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Fri Mar 10, 2023 9:38 pm

Hi Julian,

Are those with the meter switch set to 50 V DC? It's difficult to see the switch in the photo.

If it is, it is reading 7 volts, which is about right for half-wave, i.e. about 14 volts full wave plus a couple of volts dropped in the diode from 16 volts.

That's the open circuit voltage. Seems ok. Now to test it under load.

1. find a suitable load, such as 12 volt lamp bulb such as a grain of wheat bulb, spare car sidelight bulb, or maybe a 12 volt soldering iron.

2. repeat the above measurements while the bulb is connected to terminals 1 and 2, and then 1 and 3, at the same time as the probes.

The bulb should glow at about half-power. What is the reading while it is doing so?

cheers,

Martin.
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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Fri Mar 10, 2023 9:40 pm

Julian Roberts wrote:I've put a big dollop of solder on the join and cleaned up the ends where they fix to the terminals

That might have fixed the problem, so reconnect the yellow and grey wires and try it, before going any further. If not, disconnect them again.

Martin.
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 9:47 pm

grovenor-2685 wrote:OK so what we have is:
AC from transformer, Red and Black
DC (half wave) Common return, Orange
DC (half wave) +ve, Yellow
DC (half wave) -ve, Grey

The AC must be measured on the AC meter settings.
The DC (half wave) can be measured on either AC or DC meter settings.
There should be little or no change in these readings whether the motors are running or not as the load currents are very low. Highest load is with all motors stalled.

So start with the following measurements and report back:

AC 50V range, red - black = ? 10
" orange - yellow = ? 10
" orange - grey = ? No needle movement
DC 50V range, orange - yellow = ? confirm positive is on yellow
YES

20230310_214119.jpg



" orange - grey = ? Same reading as previous confirm positive is on orange

Yes



answers enclosed - don't know how to do different colour! Thanks Keith

These answers were with the diodes wired up, not as per Martin's preceding questions with them disconnected.
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Last edited by Julian Roberts on Fri Mar 10, 2023 9:59 pm, edited 1 time in total.

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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 9:48 pm

Martin Wynne wrote:
Julian Roberts wrote:I've put a big dollop of solder on the join and cleaned up the ends where they fix to the terminals

That might have fixed the problem, so reconnect the yellow and grey wires and try it, before going any further. If not, disconnect them again.

Martin.


Fraid it hasn't solved the issue Martin.

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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Fri Mar 10, 2023 10:24 pm

Hi Julian,

You are reading the numbers off the top black scale? Ignore that, it is for measuring resistance.

Read the numbers corresponding to the switch setting. So when on 50 v the scale is 0-10-20-30-40-50.

From which the meter is showing 7 volts in your photo.

You wrote " orange - grey = ? No needle movement". Is that correct? It conflicts with what you said in your previous answer to my questions. Maybe you had the probes the opposite way round?

cheers,

Martin.
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 10:35 pm

Martin Wynne wrote:Hi Julian,

You are reading the numbers off the top black scale? Ignore that, it is for measuring resistance.

Read the numbers corresponding to the switch setting. So when on 50 v the scale is 0-10-20-30-40-50.

From which the meter is showing 7 volts in your photo.

You wrote " orange - grey = ? No needle movement". Is that correct? It conflicts with what you said in your previous answer to my questions. Maybe you had the probes the opposite way round?

cheers,

Martin.



Hi Martin

Yes you're right I was reading the number at the top - hopefully Keith will see this.


I've just seen your previous post so I will answer that first

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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Fri Mar 10, 2023 10:49 pm

Martin Wynne wrote:Hi Julian,

Are those with the meter switch set to 50 V DC? It's difficult to see the switch in the photo.

If it is, it is reading 7 volts, which is about right for half-wave, i.e. about 14 volts full wave plus a couple of volts dropped in the diode from 16 volts.

That's the open circuit voltage. Seems ok. Now to test it under load.

1. find a suitable load, such as 12 volt lamp bulb such as a grain of wheat bulb, spare car sidelight bulb, or maybe a 12 volt soldering iron.

2. repeat the above measurements while the bulb is connected to terminals 1 and 2, and then 1 and 3, at the same time as the probes.

The bulb should glow at about half-power. What is the reading while it is doing so?

cheers,

Martin.


Hi Martin

Somehow didn't see this. Sorry!

I've got a test light. It glows brightly and the reading hardly moves on 1 and 2. Just a little to the left. Then on 1 and 3 the same (probes opposite way round)


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