Motor polarity

[Mallard60022]

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?

Doubt it buddy. Just an older model. I think I remember seeing some really good stuff on hardwiring on the internet; just search Hardwiring (and add model locomotives otherw ise some 'interesting posts will appear  ' . However, many Baccy loco's had/have a split chassis and they are (as far as I can remember) an arse to DCC. I await being shot down because this is incorrect and if it is, my apologies.

DCC is fun as it gives the owner such surprises and interesting oppoetunities. However, I thought it would help me because I was/am hopeless at lectrikery. Nope!

Phil

[NHY 581]

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.

 

 

Blimey Clive. I had exactly the same issue. Loco going backwards. I too swapped the wires over and lo and behold it went the right way. All my layouts are two wire DC. Very simple. I thought about DCC but bottled it as it seemed too complicated.

 

 

 

Rob.

[newbryford]

 

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.

 

You wouldn't have that problem with DCC - just sayin'

 

Cheers,

Mick

[Clive Mortimore]

You wouldn't have that problem with DCC - just sayin'

 

Cheers,

Mick

Hi Mick

 

Dc is just two wire, if they are the wrong way round, just swap them over. I can cope with that as for programing CV29 I am clueless (no I don't need advice).

[Stubby47]

You wouldn't have that problem with DCC - just sayin'

 

 

... but you will probably have plenty more...

[NHY 581]

... but you will probably have plenty more...

No you wouldn't DCC is a lot simpler........only two wires......mmm

Edited June 20, 2018 by NHY 581

[newbryford]

Hi Mick

 

 I am clueless

 

The joys of selective editing...…………..

 

 

 

Cheers,

Mick

[The Stationmaster]

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.

 

If the 204 behaves oddly why not give it an odd running number and give the others even running numbers.  Problem solved.

[NHY 581]

The joys of titi..…………..

 

 

 

Cheers,

Mick

[Clive Mortimore]

If the 204 behaves oddly why not give it an odd running number and give the others even running numbers.  Problem solved.

Hi Mike

 

That sounds a good idea, but also sounds more work than swapping two wires over when I find which one it is. As small shunters don't fit in the big scheme of the present layout it might be a very long time.

[Mallard60022]

If my loco's go the wrong way they get shot.

A.N. Archist

[Stubby47]

If my loco's go the wrong way they get shot.

A.N. Archist

 

If your locos don't go at all, the frogs get shot...

[NHY 581]

'Everyone move or the frog gets it....."

[cpman46]

'Everyone move or the frog gets it....."

 

 

If your locos don't go at all, the frogs get shot...

Hey, come on guys - lay off the frogs, they don't deserve it!!

[kevinlms]

I use Hammant & Morgan twin track controllers both bought second hand and still working many years after they were made.

 

I usually determine polarity by putting a tender loco on the track and with 2 different coloured wires attached to the controller, I then put the controller to Normal ( forwards ) and touch the wires to the rails.

 

If the loco goes forwards I will then try a 2nd & sometimes a 3rd loco to make sure its correct.

 

If this is correct, the wires are then soldered to the rails in that configuration, however if the loco goes backwards I just switch the wires around.

 

Now, in scenario 1, if the 1st loco goes forwards then 1 I have bought goes backwards, I open it up switch the wiring around at the motor itself.

 

On a Bachmann class 66 this can be very fiddly and time consuming because you have to practically dismantle the loco just to switch the wires around so I would definitely agree with anyone who says drop the bogies out and switch the wires over on the pickups.

 

This will be a lot less fiddly and takes much less time to do. A few minutes with a soldering iron and a quick test before putting the body back on is all it takes.

The easiest way to check the polarity is with a multimeter. With positive on the right hand rail the loco should going forward. A multimeter cannot lie for this purpose.

[AndyID]

The easiest way to check the polarity is with a multimeter. With positive on the right hand rail the loco should going forward. A multimeter cannot lie for this purpose.

 

and if a multimeter is too expensive (or too complicated) a couple of LEDs and a resistor should work.

[Clive Mortimore]

and if a multimeter is too expensive (or too complicated) a couple of LEDs and a resistor should work.

Or a 12 volt rated Dc motor as fitted in a model railway locomotive, if  it goes the same was as the indicator, switch, or the direction you turn the knob on the controller then it is right.

 

Unless you are in the position of the chap in the first post, which one of the two engines is wired the right way? The use of a third loco should help, if this goes the same way as one of the other two and matches the controller then  you will know which one is wrong. If it goes the same way as the one that does not match the controller then the controller wires are wrong so need swapping and the loco going its own way not that of the two is also wrong.

[Mallard60022]

H and M Controllers are XLNT, however I am led to understand that some modern motors do not 'like' the output. I was also warned by an electrician that the lead, and other stuff inside May have perished/deteriorated over the years and despite the case looking tidy and clean the trickery parts could be dodgy.

[Clive Mortimore]

H and M Controllers are XLNT, however I am led to understand that some modern motors do not 'like' the output. I was also warned by an electrician that the lead, and other stuff inside May have perished/deteriorated over the years and despite the case looking tidy and clean the trickery parts could be dodgy.

I agree with Phil, would anyone buy a secondhand 30 to 40 year old lamp, electric fire, fridge etc and expect the electrical side of things to be as new? So why do we as railway modellers expect the same from a controller?

[Ray H]

One thing a lot of (new and not so new) modellers seem to be confused by is the trend for controllers to be marked "Forward" & "Reverse" such that when you turn the knob and/or flick the switch to "Forward" they expect the loco to move forward even if that means it (for example) moving to the left when turning the knob clockwise.

 

Locos normally comply with forward & return settings on DCC controlled layouts but movements on DC powered layouts have historically (?) tended to follow the mantra of "Turn the knob (and set the switch) to the right and the loco moves to the right". What can be even more confusing with handheld controllers is that the exact converse is true if said handheld unit is "upside down".

 

BTW, how many new/relatively new modellers know how to establish which is the forward direction on a model diesel/electric loco? And this more senior modeller doesn't know how to determine which is the (equivalent of the) "No. 1 end" of a multiple unit. Fortunately I have nothing longer than 2 cars and treat the end with the Guard's brake as the "No. 1" end and thus the front of the train when it is being driven forward. 

[kevinlms]

Or a 12 volt rated Dc motor as fitted in a model railway locomotive, if  it goes the same was as the indicator, switch, or the direction you turn the knob on the controller then it is right.

 

Unless you are in the position of the chap in the first post, which one of the two engines is wired the right way? The use of a third loco should help, if this goes the same way as one of the other two and matches the controller then  you will know which one is wrong. If it goes the same way as the one that does not match the controller then the controller wires are wrong so need swapping and the loco going its own way not that of the two is also wrong.

I would disagree with the logic, that with 3 locos, if one goes the opposite direction to the other 2, then the single one is wrong. It maybe the case, but it is no guarantee, especially if any are 2nd hand.

 

If you do the 9 volt battery test, you'll get the correct answer, if you put the positive terminal on the right hand rail, it should go forward.

The actual test process, is far quicker than me typing this!

[Clive Mortimore]

I would disagree with the logic, that with 3 locos, if one goes the opposite direction to the other 2, then the single one is wrong. It maybe the case, but it is no guarantee, especially if any are 2nd hand.

 

If you do the 9 volt battery test, you'll get the correct answer, if you put the positive terminal on the right hand rail, it should go forward.

The actual test process, is far quicker than me typing this!

I was trying to make life simple for Midnight Freight but everyone else seems to want to make things complicated. Yes I had thought about the thrid loco being "wrong" but the chances should be very slim of this as most RTR is wired "correctly" when manufactured. 

 

I am still at a loss as to why a Bachmann 08 goes the opposite way to a class 66. The photo of the 66 does not show a problem with the wiring.

[newbryford]

I was trying to make life simple for Midnight Freight but everyone else seems to want to make things complicated. Yes I had thought about the thrid loco being "wrong" but the chances should be very slim of this as most RTR is wired "correctly" when manufactured. 

 

I am still at a loss as to why a Bachmann 08 goes the opposite way to a class 66. The photo of the 66 does not show a problem with the wiring.

 

Agreed about the 2 out of 3 chance of those being correct.

 

Back to the 66 - If the bogies have been removed from the loco at any time (particularly the mod that was needed on some of the early batch to help the bogie rotate correctly) it's quite easy to re clip the pickup leads back incorrectly - but still look OK.

 

In fact the earliest 66s had black and red wires from each bogie that were connected in the same orientation (red at the right if the bogie was leading), if you put black to black and red to red they shorted out!

 

Cheers,

Mick

[Ian Morgan]

In the 'good old days' of open frame motors and live chassis (Tri-ang) you could just dismantle the motor and turn the magnet round to make it change direction.

[kevinlms]

I was trying to make life simple for Midnight Freight but everyone else seems to want to make things complicated. Yes I had thought about the thrid loco being "wrong" but the chances should be very slim of this as most RTR is wired "correctly" when manufactured. 

 

I am still at a loss as to why a Bachmann 08 goes the opposite way to a class 66. The photo of the 66 does not show a problem with the wiring.

Please explain what is so complicated about a battery test? I fail to see the difficulty of something that takes 30 seconds and avoids guessing. Probably you are right that almost all RTR would conform - but if your wrong, you will end up with 3 locos wired backwards...