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Help with First Function Conversion


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The loco I have is a Lima OBB 2043 Class.

 

This is what the motor looks like:

post-29706-0-16541300-1520419896_thumb.jpg

 

I've converted 10 locos in the past, but all have been from the same manufacturer so I have some basic knowledge but this one is a little more complicated as it has lights on each end.

 

Each light operates in the direction of travel only.  Not that bothered there's no red lights as the loco will usually always be pulling something.

 

I have a Lenz decoder, either a Silver or Gold Direct.

 

On the photo, the wires from each of the lights go from the bulb to the black box where it gets power from the pickups.  The wire then travels to the PCB.  I'm sure it then does the same going back, possibly missing out the pickup.

 

The blue wire goes to the motor on one side.  There's a black wire that buries underneath the motor, which after a little maths and the powers of assumption, goes to the other side of the motor.

 

The pick up wires go to the PCB.

 

So my question is, how do I incorporate a light on each end to the decoder?

Edited by Sir TophamHatt
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The basic circuit looks something like this

 

post-28417-0-59307100-1520426017.jpg

 

CAUTION

 

​The metal frame that the lights are mounted in may be connected to one pick-up( I suspect that the frame is being used as a return for both lights )

 

If the metal frame is connected to one of the pick-ups then connecting the blue wire(from the decoder) to the frame will damage the decoder

 

If the metal frame is connected to one of the pick-ups then the blue (+) from the decoder is not required, the return for the lights goes to the rail that the frame is connected to.( the lights get 1/2 wave DC & wont be quite as bright)

 

I you want to use the decoder common (blue wire) then the lights must be insulated from the frame

 

It might be worth replacing the bulbs with LED's

 

I found it very difficult to trace the wires in the photo

 

Don't know if it is practical to use most of the existing wiring & circuit board

 

More photos showing the circuit board(close up) & the wiring untangled to make it easier to trace

 

John 

 

 

 

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Thanks for the replies.

 

The Lenz Decoder is just bare wires.

 

I need to investigate further but I think there is a wire connecting the bulb area to a pick up.

So if I don't connect the blue wire on the decoder to anything, I'll still have lights - but not as bright?

Or I can disconnect the connection to the pickup and use the blue wire?

 

Sounds silly but can anyone give me an example of an LED bulb I should be looking at?

 

Cheers

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Here's an updated photo with the wires a little more un-bundled:

 

post-29706-0-44576900-1521212116_thumb.jpg

 

Wire 1a - One side of the front bulb.

Wire 1b - One side of the rear bulb.

 

Wire 2a - Other side of bulb to left pickup.

Wire 2b - Left pickup to board.

Wire 2c - Board to left pickup.

Wire 2d - Left pickup to read bulb.

 

Wire 3a - Right pickup to board.

Wire 3b - Right pickup to board.

 

Wire 4 - To motor left.

 

Wire 5 - To motor right. (It actually disappears under the motor but the wiring makes sense.)

 

When running on DC, the bulbs get brighter the more I crank up the power.

 

If the frame isn't connected to the pickups and I don't use the blue return wire, will the lights just not work?

If I replace the bulbs with LEDs, I could make sure they're isolated from the frame, then use the blue wires I guess?

Wire 2a - Other side of bulb to left pickup.

Wire 2b - left pickup to board.

Wire 2c - board to left pickup.

Wire 2d - Left pickup to read bulb

Edited by Sir TophamHatt
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Blob 1 - One side of the front bulb.                 


Blob 2 - Front/Right pickup.                                         Are you sure it’s not the right motor


Blob 3 - Left motor.


Blob 4/5/6 - all connections underneath (long springs)  ?


Blob 7 - One side of the rear bulb


Blob 8 - Right motor AND rear/right pickup.                 Are you sure it’s not just the front & rear/right pickup


Blob 9 - Rear/Left pickup AND Front/Left pickups


 


The other side of the bulbs are going to each pickup.


 


When running on DC, the bulbs get brighter the more I crank up the power.  Are the lights directional?


 


If the frame isn't connected to the pickups and I don't use the blue return wire, will the lights just not work?              Yes


If I replace the bulbs with LEDs, I could make sure they're isolated from the frame, then use the blue wires I guess?            Yes. It looks to me like the body of the bulb which is the left pickups is touching the frame


 


If you would like to reuse the circuit board  a look at the underside of the board would be helpful


 


My guess it that the (long springs) you refer to are inductors


These inductors & the capacitor (brown disc) can be removed for DCC (they are for RFI suppression)


If the lights are directional then there should also be diodes on the circuit board.


 


Led looking something like this 3mm led


​Search the internet for a 3mm warm white LED


​White LEDs can have a blue tint to them & are not very suitable for older prototypes


Don't forget that the LED needs a resistor in series with it otherwise they burn bright but only for a few milliseconds (Don't ask me how I know)


 


post-28417-0-11301800-1520895492.png


 


My preferred Decoder for a conversion like yours would be an NCE DASR


Other DCC brands make similar format decoders


 


The image shows a US outline Kato model fitted with an NCE, DASR



 


post-28417-0-58537700-1520895413_thumb.jpg


 


More food for thought


​John

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More photos showing the circuit board(close up) & the wiring untangled to make it easier to trace

 

John 

 

I think a view of the lower side of the circuit board may be of more use.

 

There is a capacitor (looks like a typical suppression device) just visible mounted on the underside of the board.

I wonder if there are two diodes that will control the directional lights as well?

 

Cheers,

Mick

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The saga continues.

 

Firstly, thanks for helping me understand this :)

 

Secondly... here we go:

post-29706-0-38755400-1521211938_thumb.jpg

You're right, there are two resistors.  These are in series (?) connecting each of the bulbs (wire 1a and b below).  So it's wired like: B - w1a - R - R - w1b - B

 

 

I've labelled the wires now:

post-29706-0-25360400-1521212062_thumb.jpg

 

Wire 1a - One side of the front bulb.

Wire 1b - One side of the rear bulb.

 

Wire 2a - Other side of bulb to left pickup.

Wire 2b - Left pickup to board.

Wire 2c - Board to left pickup.

Wire 2d - Left pickup to read bulb.

 

Wire 3a - Right pickup to board.

Wire 3b - Right pickup to board.

 

Wire 4 - To motor left.

 

Wire 5 - To motor right. (It actually disappears under the motor but the wiring makes sense.)

 

What sort of resistor would I need and how would I wire this in to each bulb?  Or should/could I just use the resistors that are there?
I guess some of these would be okay - although a little worried about the white being too 'cool'.

Edited by Sir TophamHatt
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The saga continues.

 

Firstly, thanks for helping me understand this :)

 

Secondly... here we go:

attachicon.gifIMG_20180316_142343.jpg

You're right, there are two resistors.  These are in series (?) connecting each of the bulbs (wire 1a and b below).  So it's wired like: B - w1a - R - R - w1b - B

 

 

I've labelled the wires now:

attachicon.gifpost-29706-0-77106800-1520866421.jpg

 

Wire 1a - One side of the front bulb.

Wire 1b - One side of the rear bulb.

 

Wire 2a - Other side of bulb to left pickup.

Wire 2b - Left pickup to board.

Wire 2c - Board to left pickup.

Wire 2d - Left pickup to read bulb.

 

Wire 3a - Right pickup to board.

Wire 3b - Right pickup to board.

 

Wire 4 - To motor left.

 

Wire 5 - To motor right. (It actually disappears under the motor but the wiring makes sense.)

 

What sort of resistor would I need and how would I wire this in to each bulb?  Or should/could I just use the resistors that are there?

I guess some of these would be okay - although a little worried about the white being too 'cool'.

 

The small black/bronze items are diodes as suspected.

 

Just throw the board away.

 

Pickups to red/black on the decoder.

Motor from orange/grey on the decoder

Lights at one end white/blue

Lights at the other end yellow/blue

 

F0 will control the lights in direction mode

 

If the lights and motor are in opposite directions, you have a few options.

Swap the white and yellow.

Swap the orange and grey

Set CV29 for reverse direction.

 

Cheers,

Mick

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I have marked the components on the underside of the board


 


post-28417-0-37326900-1521262439_thumb.png


 


You can toss the board as Newbryford says


If you would like to reuse the board as a connection point


First strip all components from the underside of the board


 


post-28417-0-70755300-1521262862.png


 


& connect as shown


 


post-28417-0-42271600-1521262476.png


 


If you are going to retain the existing bulbs then connect as per the top half of the pic


The bulbs should be insulated from the frame, if the body of the bulb(the blue wire) is connected to or touching the frame then if any other wire touches the frame then you risk damaging the decoder or causing a short that could damage your DCC system


 


If you decide to go for LEDs then see the bottom of the pic


 


Looking here you might find suitable LEDs


 


The LEDs here are pre-wired for 12V , the red wires from the leds would go the blue decoder wire & the black LED lead goes to the white or yellow (front or rear) wires from the decoder


 


John

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Hi,

 

Do check that the body is not live to the track, just run a volt meter with a buzzer on to the frame and put one probe on frame and other probe to each side of the wheels. If it buzzes do not connect the blue common to the frame. If it is live frame most likely it gets this pick direct from the wheels, or it might use pickups.

 

Andy

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  • 1 month later...

post-28417-0-44869900-1526446966_thumb.jpg

 

If you use the blue wire from the decoder you must remove the wires from the bogie to the body of the bulb at both ends

( these wires are 2a & 2d & only need to be disconnected at the bogie end of the wire. These two ends then can be connected to the blue decoder wire)

 

The blue wire would be connected to the body of both bulbs

 

The centre pins of the bulbs go to the decoder White & Yellow Function wires.

 

Have another read of post 10

 

John

 

 

 

 

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I would simply get a 5mm LED and replace the bulb completely - if you want to be clever you can use a bi-colour (common anode) and have white at the front and red at the back. By using an LED you make the job much simpler.

 

5mm single colour LED - https://www.ebay.co.uk/itm/10-50-100pcs-3mm-5mm-Round-top-white-red-yellow-green-blue-Mix-LED-light-beads/121157725356?var=420162941909&hash=item1c35902cac:g:ZAwAAOSwTapV4AZ9

 

5mm bicolour LED - https://www.ebay.co.uk/itm/S682-10-pcs-Duo-leds-5mm-Bi-Color-White-Red-3-Pin-Light-Changing-Locomotives/253497592302?epid=1277479184&hash=item3b05a249ee:g:CSsAAOSw1DtXDlZv

 

others are available :)

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