Heljan O gauge class 25 - dcc sound - nearing completion

This week I managed to sit down and tackle the install of the class 25 ESU Loksound XL decoder into the class 25. This locomotive has been sat in the paint boxes since last summer, but over the last couple of months I have made a concerted effort to move this model towards completion. One of the big stumbling blocks was the fitting of the DCC sound chip - in OO gauge this is the most simple of tasks - take off the backing plate and put the new chip in - solder up a speaker and you are good to go. In O gauge this was a slightly more daunting task.

The factory finished bodyshell - note the end glazing is out - but the side glazing has been left in. I could not get the side glazing out without damaging the body shell.

The class 25 from Heljan has come in for loads of criticism on internet forums - mainly to do with a perceived error in the cab end.  When I got my version (about 6 years ago now) I was worried that the model was inaccurate (O gauge locomotives are not cheap!) - however, since taking it all apart I think it is a cracking model.  A bit of detailing on the body and the model really comes to life.  So progress so far has been to spray and then varnish the body shell - this weathering was applied on top of the BR blue factory finish, using streaks of faded blue, before building up the weathering coats. I found the glazing a nightmare to get out, so I ended up leaving some of it in place - however before I finished varnishing I removed the masking from the glazing - to blend the model together. This was a big mistake, as the glazing reacted with the thinners in the varnish and clouded over - I have tried to correct this with a little acrylic varnish, which has been partially successful - I guess it is all learning! The glazing now looks OK - although the original glue used by Heljan for the glazing is noticeable on the factory finished model (see above). Likewise, the underframe had the bogies removed and was weathered separately to the bogies before reassembly.

Weathered body shell - note the streaks of faded BR blue - it is all finished with a satin varnish. Also note the clouded windows after reacting with the thinners in the varnish - this has now been partially cured.

The finished underframe, prior to the DCC chip install.

With the body only now needing the final reassembly (a job for later this week/next week) I managed to fit the DCC sound chip yesterday. Not knowing what I was doing meant that it was quite a long job. In the end through it all works - I wired in the track feeds and the motor connections first. After this I added the headlights to the front light / rear light terminals, whilst putting the tail lights on the Aux1 and Aux2.  All the lights on the Heljan locomotive work through a common positive and these were all wired through U+, via a 10KOhm resistor. It took some time to get it done - whilst watching some You Tube tutorials (thank god for Hither Green!) - as I had to work out quite what I was doing alongside testing it as I went. Of course the biggest concern was getting it wrong the blowing the chip up - luckily this did not happen!! 

Wired up DCC chip - with the common positive U+ resistor feed yet to be placed in its terminal. The track feeds and motor are to the left of the chip, whilst the lights and Aux functions are on the right.

So jobs for this week are to reassemble the body shell by adding in the glazing, put the roof fan back (it is now non motorised), put on the headcodes (Railtec) and then finally reattach to the chassis. The underframe needs the DCC chip secured alongside making a small plasticard cradle for the speaker, which will then be glued to the chassis block. Fingers crossed that it should not take too long to achieve this and then hopefully I will have finished my first O gauge locomotive.  Lots of lessons learnt about how to handle O gauge locomotives whilst weathering them, removing glazing, masking, installing the DCC chip after removing the PCB board - so hopefully this will stand me in good stead fr future projects.

And it all works (somehow!!!!!!)