Converting old Lima diesels

[Vecchio]

I started already some description in another thread, but I think I create my own as I have 3 diesels to convert and I do not want to kill somebody else's thread. So here we go. Who are the candidates?

 

37506 Railfreight British Steel Skinningrove

59005 Yeoman Kenneth J Painter

73126 NSE Kent & East Sussex Railway

 

I start with conversion number 2, and will come back to number one later.  

This is the victim, found it recently at the Milton Keynes model railway show, was used but in my opinion on display as it looks like it has never run.

 

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And what goes in?

I use a Zimo MX600, first I will just do  a basic wiring, later also the lights. On the left side you see the capacitors, there is a lot of room, so I use 6 x 3300uF. This is probably a bit of an overkill, the engine runs approximately 4 seconds when you take the locomotive off the track.

 

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All six capacitors are wired in parallel, behind the blue shrink tube is the charging resistor.

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Here the charging resistor and the bypass diode. They are necessary to limit the charging current, otherwise your controller may detect a short circuit as the charging current can be rather high. I looked for a maximum charging current of 300mA at 20V - so I use a 68 Ohm resistor.

 

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I changed the motor control according to Zimos advice for (Fleischmann) pancake motors: CV 9=89 and CV56=91. I think the engine runs a bit smoother with this settings.

 

I am happy with the running characteristics, you may think this is not a Lima engine when you see it.

Edited March 3, 2017 by Vecchio

[Vecchio]

Now we need to understand how to get the power to the lights (leds). Again not a problem as there is a lot of space. I decided to make a small PCB with a connector.

So -what is the connector to use?  I go for a IC socket. They are cheap and I have several at home.

 

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I cut a piece off so I have 5 pins.

 

Now the cables need to be soldered in.

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Now the connector is ready.

 

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[Vecchio]

Now we have a plug - were do we plug it into? Also we need to add resistors to limit the current for the LEDs. A way avoiding messy cables is to fix all on a small piece of PCB.

I found a very thin piece in my electronics parts- so here we go. Using normal leaded parts they will be mounted on the top while the "wiring", means the side with the copper cladding, is on the opposite site. As this little PCB will be glued to the inside of the roof of the loco I will make it the other way round. Resistors and copper clad are on the same side.

 

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A short time in the etching solution

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And here we have the result. Not very nice, was a little bit to long in the solution, so the acid started to attack the copper under the mask. But it is still good enough to be used. 

 

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​The first one was for SMD resistors - I made quickly a second one for normal leaded resistors. It came out a bit better, but also here we can see traces of over-etching. No problem for what we need it.

 

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Time to put the parts in. First the SMD version

 

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And now the slightly bigger one with normal resistors.

 

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Edited March 5, 2017 by Vecchio

[davetheroad]

Interesting stuff as I am thinking about adding lights to a Lima loco. A very tidy and neat circuit board for the resistors. How many ohms are they?

[bescotbeast]

Very impressive and ingenious work.

[Vecchio]

Interesting stuff as I am thinking about adding lights to a Lima loco. A very tidy and neat circuit board for the resistors. How many ohms are they?

 

1000 Ohm are the standard resistors, the SMD ones are 2000 Ohm. There is almost no noticeable difference in brightness. For the headboard lights on the 37 I will probably need to change the resistor to a higher vale as they should not be too bright.

After some dog walking it is time to go back into the workshop....

[Vecchio]

Now the LEDs need to be prepared. I mark the anode with black marker pen so I can clearly identify it also after I cut the leads shorter.

 

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I glue the LEDs into the loco using 2-component epoxy resin. Important to have a bottle of methylated spirit within reach as this is the solvent for epoxy resin - but only as long as it hasn't set. So if there are any glue stains you can wipe them easily away. I prefer epoxy for this reason against superglue.

 

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The photo has no mercy. It shows clearly that I slipped with the drill for the red light...

 

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After the glue has set it is time for wiring.

 

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I use one of the helping hands - adapted with a wooden peg - to hold the piece in a convenient position

 

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As a wire I use fine enamelled wire. This doesn't use a lot of space and follows the shape I want.

 

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Now the second side with the little PCB. The PCB has been glued to the roof using a self adhesive rubber pad.

 

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Here you can see the connector plugged in - I think this method allows working with a minimal "wire mess".

 

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The first trial showed that the white LED is much too strong.

 

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This photo shows the red warning light and the 2 headcode lights. In the meantime I reduced the light intensity by dimming the light down, I used CV60=30. It is still strong enough.

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Finally 2 small videos showing the lights but also the performance which is exceptional if we consider that his loco has a Lima pancake motor. Click on one of the following 2 photos to activate the video.

 

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For those who are interested - I also set a shunting mode on function key 4, by CV124 = 23

All Configuration Variables are related to Zimo decoders, and may be different on other decoder brands.

 

The first loco is done, and I can say it works very well, better than expected. And as usual - I had fun during the making...

Edited March 5, 2017 by Vecchio

[Kelly]

Have you stuck with all the original pancakes for these? I seem to only have about a 1/5 rate of decent running with my lima diesels (only the 73 and 50 seem to run ok, the rest either naff all or stuttery as hell).

[Vecchio]

This was a bad runner before the DCC conversion as well - even after. Just the stay alive made it.

[Kelly]

For Bo-Bo locos a High Level bogie is an option. Sadly not many options other than Hornby spares for Co-Cos.

[Vecchio]

From March to August - but finally I finished also the class 59. 

 

Find here a photo showing the wiring for the lights

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I used enamelled wire, doesn't take a lot of space and stays where you put it. 

 

For the lenses I used the same technology I used on other locos, I turn them on the lathe. I found a new material: the led itself.

I used cheap 5mm leds and turned the head down to 1.4 for the red and 1.8mm for the headlights. Works nice and has a nice clear lens on the end. Of course a bit fiddly as the whole thing is very small.

 

This shows the wiring on the end of the motorised side.

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Now a test run. Why is the light on without track? well the capacitors are large enough to let the lights on for 20 seconds...

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Job done, and as usual I had some fun in the making.

Edited August 14, 2017 by Vecchio

[sb67]

Lovely bit of modelling there, thanks for the step by step photos.

Steve.