07/02/2021.

A10 VTU, profile view

A10tu VTU 75 LS Models.

Electric jumper housing correction

This correction only concerns the first VTUs released by LS Models in 2009. This defect has been corrected on the 2019 version.

The housing receiving the electrical heating jumpers does not spread high enough. It should cover two thirds of the white band (well, rather light grey).

Comparison of jumper housings

We can see that, in reality, the jumper’s location rises to the level of the middle or even the top of the lamp holder. But on the model, if we did the same, the area painted in light grey would become too narrow, which would be very - and too much - visible. So I prefer to stop underneath.

Compared to the current upper edge, the new one has to be 3 mm higher. The milling depth is 2 × 2 mm. As the internal angle is rounded, a ø 1.5 milling bit should be suitable.

Machining of jumper housings

I make a machining assembly for series production. It’s a simple trihedron made from recycled parts: a 20 mm thick wooden base, a 10 mm thick plywood wall, and a 4 mm MDF stop.

Machining assembly of the housings

Aesthetics is not the main concern…

The body, wrapped in a non-woven cloth, is held in place with clamps via another 4 mm MDF board.

Milling of the body

Milling of the body

The machining assembly does not allow the exact same settings each time, but it is within 1 or 2 tenths of a millimetre. It is therefore necessary to redo the origin for each body.

There’s a problem: while some buffers are easy to remove, others are very well glued and cannot be extracted. And, as luck would have it, the best glued ones are crooked! I broke one when I tried to straighten it. If it is impossible to remove the buffer, you have to start by milling vertically over the buffer, taking care not to touch it.

Note that milling exposes the plastic, which is fortunately white. It pierces the body, in a place that will be masked by the jumper head. You could mask this hole with putty, but I did not do it.

Holes for jumpers

The jumper fixing holes must also be relocated. The same assembly is used, placing the body on a side. The holes are made by limiting the drilling depth to approx. 1 mm; drilling diameter: 0.6.

Drilling for jumper support

Repainting

The machined set is painted in Humbrol Acrylic White No. 34, not ideal as it is not off-white. It would be possible to add a drop of grey. Then the bottom is painted again in grey No. 31 rather close to Corail grey.

Making the jumpers

The original jumpers break like glass. What’s more, they are too thin. So I levelled off all the jumpers and drilled a ø 0.3 hole into the head. The hardest part is to hold the jumper head in the vice.

Drilling the jumper head

Click on the photo for a closer view.

The insertion of a mini wrapping wire is shown in this video. See the video.

The jumper is mounted and glued before shaping. For shaping, I start by bending it on a round screwdriver blade placed at the footstep level, then I bend it after half a turn. After arrangement, the wire is shortened and then glued into the junction box under the buffer beam. This was previously put in place using a cocktail pick planted in the cable entry. Holding it with tweezers or pliers is very risky: the part slips and escapes. And good luck to find it again…

Mounted jumper. Normally, the heads should be the colour of the body, here white, which I should have done before mounting them.

Mounted jumper

Painting is done.

Mounted jumper

Click on the photo for a closer view.