Introduction
Heljan made two series of Di3, one for Bergen Modelljernbane and a few years later for NMJ. Both series are long sold out. The Heljan Di3 is a very nice model and is a great starting point for creating a 'long' Di3. The real Di3 was made in two lenghts. The standard 18900mm and a shorter version (18600mm) for the Norwegian Di3. The original NOHAB 2246 (later Di3.602) and the original for the Finish market destined Di3b and 622/623 are the long version. The current NMJ Di3 model is the best Di3 model on the market and it is really a little shorter in length.
This length difference is why the Heljan second series (made for NMJ) are only the long models.
The Di3b models (641-643) were frequent visitors in Dombås and therefore should be represented in my collection. Roco has great models of the 641 and 643 but these are presentations of the model in the 1960's (in green) and actually outside of my modelling area. The 642 was part of the Heljan/NMJ second series and represents the 1990's (with the new front glass installed). I also have a BMJ Spesialmodel of the 643, also in the 1990's version.
I had a spare Heljan model (second hand eBay) and decided to make this the Di3.641 in the new red colors (ny design) but representing the later 1980's (1987-1990). This model would also get the full DCC treatment with Loksound 5 install. To address the current pickup issues that are typical for heljan (see Heljan wheels), I decided to install a powerpack and see whether this would address these issues.
The original front windows, which represent the 1990's (with the hardend glass) need to be removed and replaced with standard windows and the typicall norwegian gitter (steel bars in front of the windows). I used another donor model for this. After this change both cabs (1 & 2) look identical.
A few years ago I found out that airbrush thinner was an easy way to remove the old Heljan numbers. Applying a small amount with a Q-tip (cotton swab) and a little bit of rubbing and the old number dissapears without a trace.
The Heljan PCB board has a NEM652 8 pin connector. This makes the install of a DCC decoder very easy. I soldered a ESU powerpack directly to the decoder (per ESU instructions) and 'buried' the powerpack in the dieseltank. This requires the temporary removal of the PCB board and lifting the motor to lead the wires to the tank area. An iPhone 4 speaker is used and that has been a great success in the past.
The second picture shows the complete install. The iPhone 4 speaker and the Loksound 5 decoder can be placed next to each other and put tight with kapton tape.
The final result on the layout, a NSB Di3.641 representing the late 1980's.