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Offline sharples  
#1 Posted : 11 July 2020 06:43:38(UTC)
sharples

New Zealand   
Joined: 27/07/2019(UTC)
Posts: 26
Location: Manawatu-Wanganui, Palmerston North
Can someone please give me instructions on how to use my multimeter to detect and test the current running in my M track layout?

My meter is a SCA PLU: 4405 CODE DT8308

Specifically, what I need to know is were do I set the dial to.

Any advice greatly appreciated.
Offline JohnjeanB  
#2 Posted : 11 July 2020 13:05:41(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 3,084
Location: Paris, France
Hi
If I am not mistaken your multimeter looks like this
Multimeter.jpg
If this is the good one then:
- for current less than 10 A plug the red wire to the 10 A DC hole (one above where the red plug is on the picture)
- for current less than 200 mA (milli Ampère), leave the wires as on the picture
Then set the dial as shown on the picture
Cheers
Jean
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Offline cookee_nz  
#3 Posted : 11 July 2020 14:49:26(UTC)
cookee_nz

New Zealand   
Joined: 31/12/2010(UTC)
Posts: 3,949
Location: Paremata, Wellington
Originally Posted by: JohnjeanB Go to Quoted Post
Hi
If I am not mistaken your multimeter looks like this

If this is the good one then:
- for current less than 10 A plug the red wire to the 10 A DC hole (one above where the red plug is on the picture)
- for current less than 200 mA (milli Ampère), leave the wires as on the picture
Then set the dial as shown on the picture
Cheers
Jean


Just to add to Jean's advice, I'm not sure it's actually "current" (power consumption) that he wants to check, more likely I suspect it might be the Voltage?

I'd expect someone wanting to measure actual current would already know how to do it - but I could be wrong, so can you clarify Sharples (ps is that your actual name?)

Do you want to know how much power your layout is consuming, or just how much power (voltage) you have present at various places on the layout (usually for fault-finding)

It matters not only for the meter settings, but also how you connect the leads.

To read voltage we need to know whether you are running Analogue or Digital?

For analogue the Red Plug should remain where it is and turn the dial to the upper right V (AC) "200" setting (circled Green, and Red) - the left V setting is for DC (like from a battery).

The number you set the dial to is the maximum it can read, so in this case, 200 volts or below.

Because it's AC, polarity (+ / -) does not apply, but for the sake of some consistency, I'd put the Black lead to the Brown output ('O') (outer rails) and the Red lead to the red ('B') output (Center Rail)

You may prefer to test it first directly on your transformer?

If your transformer only has Brown and Yellow then Black to Brown and Red to Yellow and you should read anything from 16 - 20v (give or take)

If your transformer includes a controller (red speed knob) then you will connect red lead to red output but you will have to also turn up the speed control knob to get a reading. On a low setting it will probably show maybe 8v, up to 16-18v at full. And if you do a reverse pulse, it will jump to around 26v or maybe a bit higher for as long as you hold the control knob in the reverse mode.

But if you are running Digital, then you will actually get a reading on both the AC and DC setting, again typically around 14 - 16v but can vary. Don't let that confuse you for now.

AC is shown with a sine wive "~"

DC is show by the two lines, one solid and one broken underneath;

__
---

PS - If you have a 9v or any other small battery around, test those for some practice. For a Battery you need the DC setting. Black to the Negative or Minus side, and Red to Positive or Plus side and set the dial to the next level higher that whatever you are testing. So for a 9v battery, or a AA, AAA (1.5v) etc, set to 20v.

SCA_4405_hi-res.jpg
Cookee
Wellington
NZ image
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Offline marklin81  
#4 Posted : 11 July 2020 18:06:50(UTC)
marklin81

United States   
Joined: 19/03/2015(UTC)
Posts: 24
Location: Virginia
Originally Posted by: sharples Go to Quoted Post
Can someone please give me instructions on how to use my multimeter to detect and test the current running in my M track layout?

My meter is a SCA PLU: 4405 CODE DT8308

Specifically, what I need to know is were do I set the dial to.

Any advice greatly appreciated.


Going back to your original question: how to test current?

When measuring current, it is very important to place the meter "in series" with the circuit. In other words, without the meter in place, you would have an "open circuit" and current will not flow.

This is different from measuring voltage, where the meter is placed "in parallel" with the circuit.

The easiest way to measuring current in your layout is to take the red lead from the transformer and connect to the red probe on meter (with the meter set to 10 amp setting as detailed above). Then take the black lead from the meter and connect it to the red lead on your layout. At that point, current will continue to flow to your layout, and will be returned to the transformer via the brown lead.

All of this assumes you are using a Marklin transformer and conventional (analog) layout. See the image below (many like this on the internet). It details the different placement for the meter when used as a voltmeter (the V in the circle) or an ammeter (the A in the circle). Although it shows placement in a battery circuit, it will be the same for your transformer. Don't connect the meter "in parallel" when measuring current; you'll burn up the internal meter fuses.

Good luck!

ammeter and voltmeter.gif
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Offline DaleSchultz  
#5 Posted : 11 July 2020 20:29:20(UTC)
DaleSchultz

United States   
Joined: 10/02/2006(UTC)
Posts: 3,997
I suspect all you need is a coach with a lightbulb on it. If the light goes on you have power.

If you really want to measure current vs detect if your have power/voltage I suggest you read some pages on elementary electrical understanding so that you don't end up asking how to do things you are not trying to do.
Dale
Intellibox + own software, K-Track
My current layout: https://cabin-layout.mixmox.com
Arrival and Departure signs: https://remotesign.mixmox.com
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Offline sharples  
#6 Posted : 12 July 2020 16:22:56(UTC)
sharples

New Zealand   
Joined: 27/07/2019(UTC)
Posts: 26
Location: Manawatu-Wanganui, Palmerston North
Originally Posted by: cookee_nz Go to Quoted Post
Just to add to Jean's advice....


Thankyou for this very full reply! I'm running analogue - two tracks. The inner track is working fine, but the outer track is dead. I am just wanting to test to see if current (I suspect in my case voltage) is present anywhere around the track.

Edited by moderator 13 July 2020 01:33:45(UTC)  | Reason: Edit to remove entire post quoting

Offline marklin81  
#7 Posted : 12 July 2020 17:18:22(UTC)
marklin81

United States   
Joined: 19/03/2015(UTC)
Posts: 24
Location: Virginia
Sharples,

If you're just looking to see if any amount of current is present on the track, then Dale's suggestion (put a lighted coach or wagon on the track) will confirm.

You mention two loops. If they are connected, then check the center rail tabs (silver metal, easily bent up or down, at the end of each section of track). If they aren't touching, you won't have a complete circuit.

A few questions:
1. is there only one feeder track from the transformer?
2. if so, is it located on the inner loop (the one that has current)?

If the answer to both is "yes," then try swapping the inner loop feeder track to the outer loop. If the situation reverses itself (current on the outer loop, nothing on the inner loop), then you need to check those center tabs where the two loops connect.

Keep us posted!

Best of luck,
Pat
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Offline Bigdaddynz  
#8 Posted : 13 July 2020 01:39:13(UTC)
Bigdaddynz

New Zealand   
Joined: 17/09/2006(UTC)
Posts: 18,661
Location: New Zealand
Originally Posted by: sharples Go to Quoted Post
Thankyou for this very full reply! I'm running analogue - two tracks. The inner track is working fine, but the outer track is dead.


You're wanting to test for voltage on the track then. Use the AC 50V setting on your multimeter for that.

Dale's suggestion of using a coach with a light in it will also work.

If there is no voltage on the outer track at all, check that there is no isolation between the inner and outer tracks. If you have voltage in some places on the outer track but not others check that the centre tongue on each piece of track is making proper contact.

Offline mike c  
#9 Posted : 13 July 2020 05:00:26(UTC)
mike c

Canada   
Joined: 28/11/2007(UTC)
Posts: 7,880
Location: Montreal, QC
Originally Posted by: sharples Go to Quoted Post
Originally Posted by: cookee_nz Go to Quoted Post
Just to add to Jean's advice....


Thankyou for this very full reply! I'm running analogue - two tracks. The inner track is working fine, but the outer track is dead. I am just wanting to test to see if current (I suspect in my case voltage) is present anywhere around the track.


If you have a coach or car with lighting, that would be a good test.

Now a question about your set up...

How many transformers are you using?
1 for both tracks or 1 for each track?
How are the two tracks connected?
If more than one, is there some kind of insulation between the two tracks?

If you have a car with lights, roll it around the inner track. If the lights are on all the time, that means that there is power.
Now, run the car to the outer track. If the light stays on, then you have power. If the light goes off, take note of where the light went out.
If you can, swap out the track section where the lights stopped working. It could be that there is a contact issue in the centre rail.

Here is a second test...
If you are using a straight track power section, swap that section with a similar length section on the outer track.
Do the test with the car with lights again. If the issue is where the two tracks are connected, you should not have power on the outer track but no longer on the inner track. Then try replacing the tracks that connect the two tracks.

One last thing that you can try is to take apart and reverse the direction of the track pieces to see if that makes a difference.

Once we have your replies to these tests, we can better assess the issue.

I remember one setup where the builder had used the isolating section that came with a manual signal as a spacer track and it resulted in no power getting past that point.

Re: Multimeters, with a digital meter, it does not matter if you choose 50 or 200 volts. if the voltage is 16VAC, that is what will be displayed.

Regards

Mike C
Offline sharples  
#10 Posted : 14 July 2020 07:56:58(UTC)
sharples

New Zealand   
Joined: 27/07/2019(UTC)
Posts: 26
Location: Manawatu-Wanganui, Palmerston North
My multi-meter is exactly identical with the images posted above.

My layout consists of an inner track and an outer track. There are sidings branching off the outer track.


The two tracks are linked with two crossovers (insulated at the joints).

I have two transformers - one supplying power to the inner track, and the other supplying power to the outer track.

Earlier (before Covid19 lockdown) the layout was working perfectly. However, the other day when I was able to go to our clubrooms (NZ is out of lockdown now!) the inner track was fine, but I couldn't get any of my locomotives to run on the outer track.

The various replies on this forum have given me plenty of suggestions to follow up on - but I will have to wait until next weekend when I can go to our clubrooms again!

Thanks for your help!
Offline cookee_nz  
#11 Posted : 14 July 2020 09:15:22(UTC)
cookee_nz

New Zealand   
Joined: 31/12/2010(UTC)
Posts: 3,949
Location: Paremata, Wellington
Originally Posted by: sharples Go to Quoted Post
My multi-meter is exactly identical with the images posted above.

My layout consists of an inner track and an outer track. There are sidings branching off the outer track.


The two tracks are linked with two crossovers (insulated at the joints).

I have two transformers - one supplying power to the inner track, and the other supplying power to the outer track.

Earlier (before Covid19 lockdown) the layout was working perfectly. However, the other day when I was able to go to our clubrooms (NZ is out of lockdown now!) the inner track was fine, but I couldn't get any of my locomotives to run on the outer track.

The various replies on this forum have given me plenty of suggestions to follow up on - but I will have to wait until next weekend when I can go to our clubrooms again!

Thanks for your help!


From what you describe, I'd first suspect a wire has broken or come loose. But some sound trouble-shooting steps should lead you to the problem quickly.

"Divide and conquer" is best.

Always the first question to ask yourself, When was it working last, and, What may have changed since then.

But it's even simpler than that. You have two circuits of track, and two transformers. Swap the trafo's. Does the problem follow the trafo or does it remain with the track? That will quickly isolate whether one of the trafo's is faulty - it's unlikely because failures of those are rare.

But either way, you have either a break in the circuit (open circuit), or, you have a short-circuit.

A 'short-circuit' is where the Brown & Red have become joined. This can be as obvious as a de-railed loco or wagon. It may also be something metal lying on the track, a screw for example. These can be hard to spot, especially in turnouts.

You can check this by using the 'continuity' (resistance) function of your meter. Set the meter to the "200" setting shown (circled in Blue) and then touch the two test probes together. It should read "0". If it does, now try it on the 'Diode' setting next to it, with any luck it will sound a beep which is real useful for quick testing because you don't have to watch the display.

SCA_4405_hi-res.jpg

Now try it with a single strand of wire, or a nail, anything electrically conductive actually (even a teaspoon) - often this is done during science studies at school - testing various objects to learn what is a conductor, and what is an insulator.

You can now apply that same test to a section of wire on the layout. Or even between two sections of track.

What's between the trafo and the track? - ie is it a single unbroken length (pair) of wires or are there some joiners/connectors? - if there are any connectors between the trafo and the track, check those. Particularly if you have used the small coloured Marklin plugs and sockets. They can oxidise just through atmosphere and temperature changes and may simply require unplugging and replugging a couple of times to burnish them and restore a good connection.

This is also where you can use your meter much better than any wagon with a light. Meter the output from the Trafo to get a base start reading. Let's assume it correctly reads 16vac.

Next, go to the next connection point on the two wires leaving the Trafo. Measure it there. Should still be 16vac. And then the next connection, and so on. Repeat until you reach the track. Assuming you read 16vac at each connection then you should also read 16vac at the track. If you get a 0 reading at the track, or any point prior, your issue lies between where you got a good reading, and got the bad one. Easy peasy.

Sorry this is a bit rushed, dinner is ready. Please ask questions, lots of questions. We'll make a hobby electrician of you yet.

Or better still, come visit us one Friday clubnight in Upper Hutt and I/we can give you a crash-course. BigGrin
Cookee
Wellington
NZ image
Offline PMPeter  
#12 Posted : 14 July 2020 17:58:59(UTC)
PMPeter

Canada   
Joined: 04/04/2013(UTC)
Posts: 1,273
Location: Port Moody, BC
Just a quick safety caution. When using your multimeter to check continuity or resistance, make sure the power is off. When going back to testing Voltage make sure you change the dial settings on your multimeter and then obviously the power needs to be turned on.

Too many people have been hurt or destroyed their equipment by accidentally having their multimeter set for checking continuity and then putting their probes across live powered components.
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Offline sharples  
#13 Posted : 10 August 2020 19:17:43(UTC)
sharples

New Zealand   
Joined: 27/07/2019(UTC)
Posts: 26
Location: Manawatu-Wanganui, Palmerston North
Thanks to all the good advice, I am pleased to report that all is now functioning well on my layout, and I now have a better knowledge of how to use my multi-meter! Thankyou everyone!BigGrin BigGrin BigGrin
Offline dominator  
#14 Posted : 10 August 2020 23:34:24(UTC)
dominator

New Zealand   
Joined: 20/01/2015(UTC)
Posts: 1,195
Location: Kerikeri
What was wrong?
Northland. NZ REMEMBER 0228 for ä
Offline sharples  
#15 Posted : 11 August 2020 02:23:40(UTC)
sharples

New Zealand   
Joined: 27/07/2019(UTC)
Posts: 26
Location: Manawatu-Wanganui, Palmerston North
Basically, the track just had not been used for some time (Covid19), so really just a good cleaning of the track, and making sure track connections were all making proper contact!
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