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Story

For a true Lego Train fan, 12V is the best system in terms of functionality. Remote-controlled points, signals and lights, classical sets offering excellent display value, but also a good degree of playability. The #7750 Steam Engine was not very popular back in the days (early 1980s) but has become a classical today, with copies selling EURO 150-200 easily. Highlights of this set are the black windows, the large train-wheels and the red 12V train engine. 
This engine, which is also featured in set 7727 en 7730 is a classic on its own. It is used in many Lego-replica's of, especially, German "DB" steam-engines. Working engines sell at over EUR 80 individually.

However, how good the 12V system may seem, everyone agrees that trains do not always run optimally, and that at large distances from the power source the signal tends to get kind of weak. Not to mention the low degree of realism in the tracks.

9V overcomes this problem largely: excellent conductivity of the tracks, smoothly operated trains, better looking tracks and the fact that 9V train motors and tracks are easily to come by makes that this system is more affordable.

Downside of the 9V system is that is doesn't have all the functionalities of the 12V system; no remote-controlled special effects, and great uniformity in special parts: no large train wheels, and no red 9V train motor.

12V trains can be made to run on 9V tracks, all needed is a 9V train engine to be put under the engine. However, as no red copies of this motor exist, this is not as easy with the #7750. Sure, a black one can be put under the tender, but it would not do justice to the excellent red-with-black design of the steam engine. 

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#7750 on 9V: how?

So: how to get my #7750 to run on 9V tracks? Of course I could put the 9V motor under one of the carriages. But this would mean that the train could never be run without this carriage, which is not realistic. Putting a black motor under the tender would esthetically be unacceptable to me. 

Basically, one option remained: creating my own red 9V train engine! Perhaps not the most obvious solution, and maybe not a commonly accepted option (Lego-purists tend to oppose every sort of painting of Lego). Of course I agree with them into a certain extend, but in this case I felt that the cause justified the act ;-)

So I did a little research on internet on how to paint Lego bricks, searched for the right products, did some try-outs on some older black bricks and eventually created my own red 9V train motor!

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The actual coloring

First of all: I did not PAINT the engine.
 
Painting Lego means that you put a thin "film" of paint on the Lego. Advantage of this would be that almost every spray-paint is suitable, and that these paints are widely available against competitive rates. The most important downside is that this type of painting doesn't last; the paint flakes over time, and can be chipped off easily. In Lego, where building with bricks is quite an essential part ;-), this is not an option.

So instead, I decided to dye the bricks. For this, I used a dye containing acetone. Acetone dissolve a thin upper layer of the Lego-plastic, allowing the dye to fuse with the plastic. This "dissolving" of the dye then creates a durable, lasting new color, which cannot be chipped off. As such, the dyed bricks can the be incorporated in constructions without being subject to wear and tear of their new color.

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Results

Take a look at the photos (if you haven't already done that). The dyed motor is a little darker red than the original one. However, this is hardly noticeable when being build under the tender. It runs excellently, just like a normal black one would; the metal wheels and internal components are not affected by the dye. All in all, I'm happy with the result: my #7750 can now run on both 12V and 9V tracks. It's just a matter of switching the motors. Esthetically, it looks excellent in my opinion.

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I want one too!

I can imagine ;-) If you're interested in obtaining a red 9V train motor, please contact me by mail: (pietergrotenhuisATgmail.com; replace the AT by @)

Best regards,
Pieter