Motor polarity

[Midnight-Freight]

I am currently running dc and my first loco was a Bachmann class 08. I have now added a dcc ready Bachmann class 66 but it is running the opposite direction to the 08 and against the direction of the controller switch. Obviously swapping the polarity of the wires to the rail has the opposite effect and has the 66 running correctly and the 08 opposite to the controller selection. Am I overlooking something or is the only possible cause that either one of the locos was wired incorrectly from the factory or has been tampered with? I've had the bodies off both and neither look like they've been messed about with. I'm guessing the 66 would be more complicated to do. Is there any way of checking which one isn't operating the way it should?

[royaloak]

Easiest way would be to try another loco, do you know anyone you can borrow one from.

 

Were both locos bought new?

If not I would say the second hand one was at fault, easiest way is to swap the connections on either the motor, might need to rotate the motor 180 degrees in its mount so the wires reach.

[DCB]

You need another loco to check which one is wrong, maybe take one or both to a friends layout or even an exhibition, but I have never had this issue with a new loco though I have often had to change the motor connections or swap magnets round to get second hand or scrap bin creations to perform. Most likely culprit would be a DCC blanking plate, easy to connect the wrong pair of wires, and easy to change back again.

[meil]

For DC operation the convention is right hand rail positive loco moves forward.

[kevinlms]

For DC operation the convention is right hand rail positive loco moves forward.

Agreed, but if the OP doesn't have a multimeter, there is another way to prove which is the correct way.

 

Disconnect the controller from the track & grab a 9 Volt battery. Put it across the track with the + sign on the right and the loco should move forward. Whichever one runs backwards, is the one that is wrong.

[Midnight-Freight]

Thanks for the replies. I'm glad it's not just me being an idiot!

 

Unfortunately both locos were bought secondhand. Having looked at the 08 again it's an earlier model with just two wires for the motor and one isn't long enough to reach over to the other motor connection from the pickup so I suspect the 66 to be the culprit. I don't currently have access to another loco for comparison so I'll have to investigate a bit more. 

[34theletterbetweenB&D]

...I'm guessing the 66 would be more complicated to do...

 Actually the 66 is very easy because the feeds from the pick up wipers just clip on both ends of the main board. As such it is also the more likely of the two to have been altered, especially if someone has had the bogies out, and there will be nothing to show that there has been alteration.

[Midnight-Freight]

Actually the 66 is very easy because the feeds from the pick up wipers just clip on both ends of the main board. As such it is also the more likely of the two to have been altered, especially if someone has had the bogies out, and there will be nothing to show that there has been alteration.

Thanks, so this is how it looks. The pickups are connected to the corresponding right and left connections on the pcb. Would it be as simple as swapping the M+ and M- connections on the top right?

[Finsbury]

Yes, but you may then need to fiddle with the light wires.

ETA the trouble being that the next dcc ready loco you get will need the same treatment ad infinitum.

Go with the above suggestion of pos to the RH rail wrt forward movement, that'll tell you which one is playing silly beggars.

Edited June 17, 2018 by Finsbury

[newbryford]

Thanks, so this is how it looks. The pickups are connected to the corresponding right and left connections on the pcb. Would it be as simple as swapping the M+ and M- connections on the top right?

 

 

Yes, but you may then need to fiddle with the light wires

 

The light wires are soldered so unlikely to have been fiddled with.

The likely culprit is either the M+/M- wires, or the L and R bogie pickups - grey and red wires that may have been swapped at some point.

[kevinlms]

Thanks for the replies. I'm glad it's not just me being an idiot!

 

Unfortunately both locos were bought secondhand. Having looked at the 08 again it's an earlier model with just two wires for the motor and one isn't long enough to reach over to the other motor connection from the pickup so I suspect the 66 to be the culprit. I don't currently have access to another loco for comparison so I'll have to investigate a bit more. 

But you're just guessing as to which is wrong! Why not do the test previously suggested & know for sure, before you start altering wiring?

[Midnight-Freight]

Oh dear this is starting to confuse me now. So I just have a basic Hornby R8250 controller with directional switch but how is the direction defined? My layout is end to end so obviously if I were to control the layout from the other side the locos would be moving in the opposite direction to the switch. Is it clockwise and anti-clockwise?

[newbryford]

Oh dear this is starting to confuse me now. So I just have a basic Hornby R8250 controller with directional switch but how is the direction defined? My layout is end to end so obviously if I were to control the layout from the other side the locos would be moving in the opposite direction to the switch. Is it clockwise and anti-clockwise?

 

As you say, it's likely that the 66 is the incorrect one.

 

If the lights work in the correct direction with the motor, then swap over the L and R bogie wires. (As mentioned above, the bogies may have been removed at some point and then incorrectly connected afterwards)

If the motor and lights do not match, then swap the motor wires.

 

Cheers,

Mick

[Midnight-Freight]

As you say, it's likely that the 66 is the incorrect one.

 

If the lights work in the correct direction with the motor, then swap over the L and R bogie wires. (As mentioned above, the bogies may have been removed at some point and then incorrectly connected afterwards)

If the motor and lights do not match, then swap the motor wires.

 

Cheers,

Mick

I think so, the 08 only has two soldered connections which don't look like they have been tampered with. The 66 is much easier to mess about with.

 

Ok so on the 66 the lights operate correctly with direction of travel. Also using the arrow on the pcb as being forward the pickups are connected to the correct connections on the pcb.

Assuming the controller direction selecter refers to forwards (right) and reverse (left), not just left and right then the 66 is behaving correctly in relation to the arrow on the pcb.

 

I think as others have said another 1 or 2 locos need to be tested to see which one is the odd one out. Perhaps I could justify the purchase of another couple of 66's purely for this purpose...

[Midnight-Freight]

OK so I've done every test I can including the 9v battery test and every thing points towards the 08 being the problem.

On a side note I really need to upgrade my controller. The motors on both locos were almost silent using the 9v battery compared to the horrible buzzing the Hornby toy controller produces.

[DCB]

OK so I've done every test I can including the 9v battery test and every thing points towards the 08 being the problem.

On a side note I really need to upgrade my controller. The motors on both locos were almost silent using the 9v battery compared to the horrible buzzing the Hornby toy controller produces.

You will need something like a Morley to get smooth quiet running.  Most people put up with the frantic buzzing in order to get better slow running.

[Finsbury]

That sounds like your supply is raw. Smoothed dc.

[kevinlms]

Oh dear this is starting to confuse me now. So I just have a basic Hornby R8250 controller with directional switch but how is the direction defined? My layout is end to end so obviously if I were to control the layout from the other side the locos would be moving in the opposite direction to the switch. Is it clockwise and anti-clockwise?

If you change to the other side, just reverse the two output wires. If you do this on a regular basis, you can wire a switch under the baseboard to do that. You obviously only need to do it once each session.

 

Here is a step by step process to wire it. 

 

http://www.instructables.com/id/HOW-TO%3A-Wire-a-DPDT-rocker-switch-for-reversing-po/

 

The crossing of the wires, is the secret. Note the bottom diagram is all you really need. Make sure the switch does not have a centre off position. How do I know this?  ​ 

[Midnight-Freight]

You will need something like a Morley to get smooth quiet running.  Most people put up with the frantic buzzing in order to get better slow running.

 

The Hornby controller was only a temporary measure to get things working. I will be going dcc and have just ordered a Bachmann ez command (at a bargain price) as another temporary measure to test dcc running before eventually deciding on a final dcc unit.

[Midnight-Freight]

If you change to the other side, just reverse the two output wires. If you do this on a regular basis, you can wire a switch under the baseboard to do that. You obviously only need to do it once each session.

 

Here is a step by step process to wire it. 

 

http://www.instructables.com/id/HOW-TO%3A-Wire-a-DPDT-rocker-switch-for-reversing-po/

 

The crossing of the wires, is the secret. Note the bottom diagram is all you really need. Make sure the switch does not have a centre off position. How do I know this?  ​ 

 

 

Thanks for the info. It's unlikely I will ever control the layout from the other side but useful if it becomes an option in the future.

[34theletterbetweenB&D]

... I will be going dcc and have just ordered a Bachmann ez command (at a bargain price) as another temporary measure to test dcc running before eventually deciding on a final dcc unit.

 So, no need to do any rewiring. Direction can be set via CV29. Just one of many good features built into DCC.

[Midnight-Freight]

 So, no need to do any rewiring. Direction can be set via CV29. Just one of many good features built into DCC.

 

It was at the back of my mind that it could probably be done, just didn't like the thought that I was starting with something which might not be in it's original state.

[RAF96]

CV29 reverses what is already there so if direction of travel does not match directional lighting then a motor rewire is the only real correction.

 

Edit- unless your decoder supports function mapping when you can reallocate the directional lighting logic independant of CV29 motor fettling.

Rob

Edited June 19, 2018 by RAFHAAA96

[Midnight-Freight]

Following on from my plans to go dcc I was reading up on hard wiring a non-dcc ready Bachmann 08 and the guides I have seen describe removing the pcb in the nose end. I don't know if mine is an older model than the ones mentioned but there is no pcb, just two wires connecting pickups on either side to the motor. It runs fine i'm just curious if this could be a sign of tampering?

[Clive Mortimore]

I use to have a problem with locos having a wrong polarity. One was my MTK class 47 so that was easy to remember which way to have the direction switch when I was running that. The other was an 04 or 03 with a kit or scratchbuilt chassis. Now when that went the wrong way I would remember and forget next time it was out of its box. It would have been quite simple to swap the wires over. Four layouts later the class 47 now goes the same way as the others, but could someone tell me which 204hp shunter is the one that goes the wrong way without me having to test them all?

 

 

Edit, on layout number two all the locos went the wrong way when first built. so I swapped the wires at the controller end over and if by magic they all went the right way , except that shunter.

Edited June 19, 2018 by Clive Mortimore