Series v parallel wiring? Question for F-Unitmad

[Willy]

A question for F-Unitmad if I may.

 

I believe that you have rewired your Atlas locos in series instead of in parallel as they are when delivered (I think it is that way round!). Now I understand the concept of series and parallel wiring but I wonder if you would tell me which coloured wires I have to move and how it is reconnected up again. Please bear in mind I am getting on a bit and I am not as dexterous as I once was!

 

I know it is a cheeky ask but I would be very grateful of the help.

 

Thanks

 

Willy.

[Willy]

I assume this is a twin-motored loco? Wiring in series may sound beneficial, but in fact it's a double-edged sword. Putting motors in series immediately cuts the current consumption by at least 50%, but you run the risk of burning out both motors. Under (heavy) load, there's a realistic chance the rear motor (bogie) will stall, while the other will spin its wheels as it has (too) little weight on it. This causes a high current (due to the stalled motor) and the full voltage, and current over the spinning motor. This could cause a thermal load that could destroy either, or both. The safer option is to have/keep the motors parallel instead. It still has the full power over the spinning motor, but not the heavy current, so the thermal load is lower, probably keeping it within spec.

 

 

Thank you and yes, they are twin motor locos. (Atlas RS-1, GP7 & GP35)

 

That sounds serious and it is certainly worth bearing in mind. However I know that some people have rewired these locos and I would be keen to learn of their experience.

 

Willy

[F-UnitMad]

Just seen your question, Willy, & I'll get back to you later.

Dutch Master has a point, but not really an issue for shunty-planks or shorter trains at slow speeds.

[Willy]

Just seen your question, Willy, & I'll get back to you later.

Dutch Master has a point, but not really an issue for shunty-planks or shorter trains at slow speeds.

 

 

 

No rush.

[mikjd]

Willy,

 

     We have discussed this before and added pictures here http://www.rmweb.co.uk/community/index.php?/topic/96531-midland-ohio-in-o/page-6

 

If you read forward from this page you should pick up some useful information. If fitting a decoder some people remove the Atlas board altogether, although I have left them in situ so far.    

There are other threads where this comes up as well. One point to watch as mentioned in the link above is that not all Atlas locos are wired the same way, which if you know beforehand helps no end.

[Willy]

Willy,

 

     We have discussed this before and added pictures here http://www.rmweb.co.uk/community/index.php?/topic/96531-midland-ohio-in-o/page-6

 

If you read forward from this page you should pick up some useful information. If fitting a decoder some people remove the Atlas board altogether, although I have left them in situ so far.    

There are other threads where this comes up as well. One point to watch as mentioned in the link above is that not all Atlas locos are wired the same way, which if you know beforehand helps no end.

 

 

Thank you Mick.

 

My locos are already fitted with decoders, 2 factory fitted with QSI and one retro fitted so I am not sure what it is, but I will read your post.

[F-UnitMad]

Atlas wiring is "usually" red & black for pick-ups, & blue & yellow for each feed on the motors.

To wire the motors in series you need to connect the '+' of one to the '-' of the other, so usually a yellow wire to a blue one.

If you get it wrong either:- the motors won't turn at all, or they might turn the same way. Remember the trucks face away from each other, so for the loco to move correctly, they should rotate in opposite directions!! Looks wierd somehow but that's what happens!!

The thing to really take care with is the pick-ups, as I think they are wired the same for each truck, but of course the trucks 'oppose' each other, so IIRC the red from one truck joins to the black of the other, & vice-versa.

 

With the DCC boards, hopefully the motor terminals are marked + & - ;just disconnect, say, the 'M+' at one end, & the 'M-' at the other (which with luck will be one blue wire & 1 yellow!!) & link those two wires together, with another length of wire if needed.

[Willy]

Atlas wiring is "usually" red & black for pick-ups, & blue & yellow for each feed on the motors.

To wire the motors in series you need to connect the '+' of one to the '-' of the other, so usually a yellow wire to a blue one.

If you get it wrong either:- the motors won't turn at all, or they might turn the same way. Remember the trucks face away from each other, so for the loco to move correctly, they should rotate in opposite directions!! Looks wierd somehow but that's what happens!!

The thing to really take care with is the pick-ups, as I think they are wired the same for each truck, but of course the trucks 'oppose' each other, so IIRC the red from one truck joins to the black of the other, & vice-versa.

 

With the DCC boards, hopefully the motor terminals are marked + & - ;just disconnect, say, the 'M+' at one end, & the 'M-' at the other (which with luck will be one blue wire & 1 yellow!!) & link those two wires together, with another length of wire if needed.

 

 

Thank you, I think I have got that!!!!   It will be next week before I have the time but I will give it a try and see what happens. As you say, with the shanty plank, there won’t be much danger of overloading the motors.

 

Willy