Acorn BBC A3000 - Case restoration

I was recently asked to help out with the repair and restoration of an A3000 and as part of the project, I documented all of the problems and solutions that were found with the machine as I went along. If you read on, you'll find lots on information covering all of the techniques and tools used to clean and repair common issues with the A3000's case.

The A3000 case

The Acorn BBC A3000 case design signalled a return to the "one box" design ethos that Acorn used for the Atom, BBC Micro and BBC Master series of machines. The case design resembles that of the Commodore Amiga A500 and the Atari ST which were contemporary designs.

The A3000's case design had some unique features, using only three screws and a set of clips to hold the two halves of the case together. The screw fittings consisted of two small screws at the rear of the case and one large screw located on the underside of the case in the centre. 

Case screw locations on the Acorn BBC A3000

All of the photo's detailing the restoration of the A3000 on this page are from one computer with the exception of the fixing screw montage photo above which have been taken to illustrate their locations when writing this guide.

Checking internally

When buying a second hand Acorn Computer, it's quite common to come across a computer that was originally owned and operated by a school. In these cases, it's quite common to find all manner of foreign objects inside the computer with the most common two items being staples and glitter. To ensure that any foreign objects do not cause permanent damage to the machine, it's imperative that it is thoroughly checked before it is powered on as transportation of the machine can dislodge foreign items that were previously safely stuck somewhere within the machine.

The A3000 sporting an unwanted staple inside its case

The photo below shows the staple after extraction. If the staple had been wedged between pins on the motherboard it could have caused untold damage when the machine was powered on. Luckily, the A3000's speakers provided a way of capturing the staple and keeping it safely away from the motherboard.

A detail shot of the staple after extraction with some needle nose pliers

Cleaning the case

The A3000's case has large expanses of ventilation grille's and these can gather dirt over a long period of time. Successfully cleaning them requires that the A3000 is stripped down and the case soaked in warm water and then gently cleaned with a suitable soft bristle brush and mild detergent to remove the ground in dirt.

The A3000 ventilation grilles are a dirt trap

Once soaked and cleaned the grille and rest of the case looks a lot better as shown in the photo below.

The A3000 ventilation grille after a deep clean

Masking off labels

This is a purely optional point but I like to keep as much of the original case as possible when restoring a machine. This includes the quality control labels that were applied during the manufacturing process. To avoid them being damaged during the washing process, I mask them off using a waterproof tape and a credit card shaped piece of plastic to protect the delicate labels.

The lower half of the A3000 case with labels

Using an old credit card, cover the labels and then stick the card down to the case with a water proof tape suitable for the cleaning process. Remember to do this for the machines serial number if still present on the outside part of the case too.

Masking the labels using a credit card sized piece of plastic and some waterproof tape

Reducing scratches on smooth surfaces

The case of the A3000 is predominantly textured with a fine texture to give a matte finish to the look of the case. There are however a couple of areas where the case is perfectly smooth. These smooth areas show up even the smallest of scratches so it's desirable to remove as many of them as possible. Using a metal cleaning product such as Brasso Metal Polish Wading (previously called Duraglit in the UK), you can polish out many of the minor scuffs and scratches restoring a smooth, reflective surface to the case where needed.

Smooth surfaces can have the number of small scratches reduced

When polishing the smooth areas, use small circular movements to polish out the scratches with the wadding and then use a dry fine cloth to clean off any metal polish left by the wadding in the same way to reveal the newly restored surface.

Repairing the case

Once the cleaning has been completed, then your attention can be turned to repairing the case if needed. There are a couple of common faults that occur with the A3000's case which can be repaired relatively easily.

The first common fault is usually one or more missing case clips that hold the top and bottom parts of the case together along the front leading edge. These clips often break off when people are too rough attempting to open up the A3000's case.

The second fault that occurs with the case involves the support posts that are part of the lower half of the injection moulded design. Quite often these posts can break off due to external shock or incorrect fitting or removal of the keyboard.

Repairing the case clips

Case clips once broken usually go missing as the part that breaks is on the outside of the case. This means that an alternate means of securing the top half of the case to the lower half is required. The photos below show an original clip and how the clip can break from the case.

An original A3000 case clip

The photo below shows how the clip breaks off from the rest of the case leaving an obvious space. Once the clip has broken in this way, the front of the A3000's case no longer fits together tightly and the case appears to "flap" about or lift entirely at the front depending on the number of damaged clips.

A detail shot of the case with the clip broken off

To replace a broken clip, I use some old white DVD cases that I have spare which provide a reasonable way of creating an L shaped clip device which can then be affixed to the original case to re-create the original clip.

Using an old DVD case, cut out the plastic to achieve an L shaped clip like this

A detail shot of the reverse of the new L shaped clip

Using Araldite or similar epoxy resin adhesive, attach the newly fashioned clip to the case as pictured below. Allow the epoxy resin to cure for 24 hours to ensure a good solid fix for the case. 

Using epoxy resin, attach the new clip to the case and allow to cure

Repairing the support posts

The support posts if broken can usually be found rattling around inside the A3000's case. Quite often, the posts find their way underneath the motherboard and get wedged in so it's worth taking out the motherboard to check if they're in there.

The base of the missing post on the lower half of the case

The posts are used to support the keyboard and keep it aligned correctly so they're quite important to the structure of the A3000 ensuring a good solid "feel" to the keyboard.

The broken A3000 keyboard support post

Where the broken posts are still available having simply snapped off, it's an easy task to repair the post using some "Liquid Poly" or "Plastic Weld" to fix the post back into place. After cleaning the area thoroughly, using some "Liquid Poly" to re-affix the post allowing the plastic to cure for 24 hours before re-assembly.

The keyboard support post re-affixed to the case

The finished article

Once re-assembled, the A3000 is ready for action again and should provide years of service and pleasure to its owner.

The A3000 restoration completed and fully tested

Whilst stripped down, the battery in this A3000 was replaced and the floppy disc drive was cleaned and serviced.

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