November, 2015 | bootsiescomputers.com

Month: November 2015

GB-A1000 motherboard build

28th November 2015 by bootsie·0 Comments

I loved the style of the Amiga 1000 – the desktop case with the keyboard “garage” underneath where it can slide away out of sight. However it’s running pretty old tech now – even by Amiga standards. They only have 512k RAM as standard and no expansion slots other than the same edge connector an A500 has – but upside down, just to make it even more difficult to fit expansions. So, when I came across the GB-A1000 motherboard (designed by Georg Braun, hence the name) I immediately decided to try and source one.

The GB-A1000 is a motherboard using the orginal Amiga chipset but with 8MB RAM, a Flicker-Fixer, an IDE controller for Hard Disks and a 68030 processor (plus a 68882 FPU) to take the Amiga 1000 well into A3000/A4000 territory.

I came across an unbuilt kit on Amibay and set about tracking down all the various components required to build a working board. It was the largest project I’d ever taken on with lots of surface-mount soldering required – quite a challenge. These are some pictures from the motherboard build process. I started this in 2013 and just about finished by the end of 2015!

Motherboard received – wow, that’s quite large..

I built up these Video Hybrid kits first to get me used to the SMT soldering before working on the mainboard

Start by soldering all of the small surface-mount components first

and then.. well nothing for 2 years according to my image archive. I built the board up quite slowly, had a few issues sourcing parts here and there, just worked in small chunks and then left it alone for a while. Apparently I didn’t take any pictures either – until..

Tada! Ready for the first power-up.

Will it work first time? ..

Of course it will! Just a quick power-up at this point to make sure it all appears to work before mounting the board inside the A1000 case. I also programmed a newer Workbench 3.1 and the IDE ROM and added a lithium battery (along with a small diode to prevent charging). The 2.5″ IDE connector for the onboard hard disk was particularly tricky to find – eventually I had to hack down another 2.5″ connector to make it fit the board properly. Looks ok though.

I’m using that with a 32GB Compact Flash card via an IDE converter.

When I mounted the board into the Amiga case it wouldn’t sit quite flush. When I looked closely I could see why – the motherboard D-plugs had pronged mounting pins which went through the board but these were hitting the posts in the case.

I had to cut these off in order to get it to mount flush against the case standoffs and then I could use the self-tapping screws through the top of the D-plug to secure the plug – and the board – to the case.

So, trial fit of the motherboard into my A1000 case:

Everything seems to fit ok, let’s carry on fitting the PSU

and then the rear panel

The complete system up and running.

Right now it’s booting Workbench 3.1 from a CF card and I’m in the process of loading up WHDLoad and a chunk of old games.

Amiga 1000 case respray

16th November 2015 by bootsie·5 Comments

As part of refurbishing some Amiga 1000s I’d picked up, I wanted to clean up the cases which had yellowed over the years. I’d tried retr0bright on the cases and whilst this worked in a few instances, in others I either got a bleached effect or I just couldn’t get all of the staining off. Plus some parts of the cases were scratched, which retr0brite doesn’t help with anyway.

I’d been looking for something to respray the plastic with. Conventional plastic spray paint seemed to be too messy and too thick – you needed special primer and then a plastic top coat. Cases I’d seen sprayed had lost their texture and looked obviously resprayed. I found some Vinyl spray paint which purported to do exactly what I wanted – change the colour of plastics without needing a primer and because the coats were very thin it didn’t affect the texture. However, when I tried some of these paints I just didn’t get a particularly good result – I found even with very thin coats that the paint never seemed to really dry properly and would just get wiped off with IPA or other cleaners.

I kept searching and eventually stumbled onto Kolorbond. This was paint specifically designed for plastics – specifically uPVC window frames – but also including ABS which is what the Amiga cases were made of. I contacted the manufacturer and asked if they would colour-match against a piece of the Amiga case (the memory slot cover). They said they would, and supplied me with a 1L tin of Matt-finish Kolorbond, along with WindowPrep which is used to clean the plastic before spraying.

I stripped the Amiga cases down then started to spray them, first with dust coat of Kolorbond and then two “proper” coats which was enough to cover all the discolouration and the light sanding marks from where I’d cleaned up the scratches with wet & dry. These are the pictures I took along the way.

Keyboard before:

RAM Cover and Front Panel before (notice the original colour behind the RAM cover)

Top cover and rear panel before (again, notice the colour staining – very bad on the rear panel)

One coat applied, getting better

and the completed parts

I have to admin to being a little apprehensive about spraying these A1000 cases and possibly ruining them, but actually I’m really pleased with the results. The only problem I had is that there was some “Commodore” text on the front panel which I had to spray over, but I think I prefer the look without this anyway. The colour match is almost perfect and the original texture of the plastic has been kept. The paint doesn’t chip or peel off and also doesn’t wipe away with IPA. They just look like new again.

Now on to building them back up into working machines again.