Thursday, 20 September 2012

Sinclair Spectrum 128k +2 MINI

Sinclair Spectrum 128k +2 Mini!
The above image is a mock-up of what a sawed-off Sinclair Spectrum 128k +2 might look like. Read below to see how it turned out to be reality! The idea for this picture came from Marq, who suggested removing the ugly and unnecessary tape device in a rather brutal manner.

The original
The initial idea was that the cut would be aligned with the left edge of the cassette slot opening, giving a very straight line from which to begin. The whole operation ought to be simple, as the tape recorder is not really very integrated to the other stuff inside the casing. The motherboard is entirely contained at the left side.

128+2 insides: With the cut, the heat sink would have to be re-arranged and the casing would lose one support.
Still, the cut suggested in the first image may not be quite as straightforward. There are some parts beside the tape recorder that extend beyond the cutting line. This could be covered by having some kind of addition to the right side, perhaps something that resembles the original 128k Spectrum. Another option might be to use a couple of centimeters of the +2 casing itself! But this would probably leave a visible seam.

Preparing for the cut


Removing the cassette recorder proved to be simple. Also, the computer appears to work just as well without the tape recorder, which comes as no big surprise. In this process the power LED has come off, and I think someone else will have to figure out how to rewire it.


The now revealed plastic protrusions and screw holders can hinder the cut, so some re-thinking is in order at this stage. On the plus side the heat sink (A strange L-shaped contraption) may indeed be possible to turn around to the front side. However, it is unlikely to fit without at least some changes.

Cutting


About that re-thinking... Nah, I just decided to go with the original line. I first used a sharp paper knife to cut as deep as possible along the side of the tape recorder opening. Using a ruler, I also made careful lines using the opening as a guideline. When it came to actually cutting the plastic, the paper knife turned out to be surprisingly poor, so for the rest of the project I only used it for initiating points for sawing.

Some care needs to be taken when sawing the front. I used a straightedge and the paper knife before sawing.

I used a "Japanese" style back saw, meant for wood cutting. I probably ruined the blade but it had seen its best days anyway. This saw took to the plastic surprisingly well, and I felt encouraged to just push violently through the screw holders and other protrusions. However as I progressed I realised the casing would loose most of its support at the same time, and the part remaining to the right side of the keyboard became quite fragile. So I did away with the protrusions with some more care, trying to saw them sideways from below when possible.

The tape recorder part could be made into a unique, stand alone, Spectrum-themed tape unit. But who cares?

It might have been a wiser move to saw first the bottom half, leaving the more visible parts for later stage. Then I could have used the "gained experience" for the more important parts. But this way, I can use the existing cut for lining up the bottom half of the casing. Had the bottom been cut first, the resulting alignment might have been unsuitable. 

But really, I just could not resist getting first at the meat of the matter!

And now, what at first was just a mock-up, is rapidly becoming a reality...
The resulting edge is surprisingly straight given it is hand sawn and my sawing skills are a bit rusty. The success is mostly thanks to the existing tape recorder opening edge. The face certainly needs sanding, but perhaps not as much as I had feared.

Cutting the bottom half posed no problems, but making the end part from the remaining plastic and solving the heat sink placement is a bit tricky.

Closing the case


I have bent the heat sink from the L-shape to a formless blob. It does not quite go into a neat U-shape, at least without sawing the piece. I'm hoping to avoid that work phase, yet it may come to that.

Yet another decision to make...
The seam looks worrying at the moment, and at this stage I am tempted to cap off the end with a flat plastic plane cut from the former case bottom. This would diminish the effect of the seam and make the computer look very neat (from front and above) and much like the original mock-up image. However this would buy very little room for the heatsink and would maybe not look so nice from the side.

Adding the pictured end piece gives some more length to the computer, a bit like the original 128k Spectrum. The bent heat sink would fit easily. This direction means that there will be nearly endless sanding of the two parts and still the seam will probably be somewhat visible.

So, which ever route will be chosen, there will be work. But then again so far everything has gone quite smoothly.

(Continued to Part Two)

7 comments:

  1. +2 with that mod would be very convenient size-wise and definitely unique. I thought of using a piece of the right end, too, even though the seam would be hard to hide. I have a semi-working useless +2 around, in case we want to take this project forward...

    ReplyDelete
  2. Additionally, the heat sink could go in the front, since there are those ventilation holes in place already. The right end could be sealed with a thin slice of the cut out piece

    -Marq

    ReplyDelete
  3. Following this with great interest...

    ReplyDelete
  4. Maybe the heatsink doesn't need to relocated? It could fit in just by bending it into U-shape.

    ReplyDelete
  5. Elegant and simple solutions would be welcome. Perhaps moving it around too much should be avoided.

    ReplyDelete
  6. Get a RECOM regulator and replace the 7805, then you can do away with the heatsink completely

    ReplyDelete