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December 2001



> Issue 14







Tip of the day


A Bird's Nest


Snap Happy


The SCSIDRV programming interface


Sprite Editor


Atari UK


E-Jag Day 2k1


Put some Charm in your Chaos


Anodyne Competition results





PhotoTip 3.10


AtarIRC and AtarICQ





A Bird's Nest

Falcon recasing by Lyndon Amsdon


When the Falcon was released it looked pretty much like an ST from 1985, surely this was not a good strategy by Atari, or did it think this would make it instantly recognisable? Who knows, but what I do know is that the old case is far too limiting for such a powerful machine. The Falcon was sold with very slow 2.5" drives and very little space for expansion, this was all powered off a PSU that was crammed into the case which causes quite a lot of heat to build up.

These are just some of the better reasons to put your precious Falcon in a tower case with that fast 3.5" IDE drive that had to be pulled out of your PC because Windows XP wouldn't fit on it. You'll get a lot better cooling, which, combined with a better PSU will help make the machine more stable. The CT60 (a super 68060 booster) also requires the ATX style power supply that is common in all modern tower cases because it needs 3.3V which the Falcon PSU doesn't supply.

The main thing you need for this project is patience and preparation. Start off by stripping the computer right down to the motherboard, removing any internal drives and the PSU. Next, get a piece of card the same size as the motherboard and place the motherboard on top of it. Draw around it with a pen and mark out roughly the places for the ports and any headers on the board (like the IDE). Also familiarise yourself with the board and check for loose wires on any hardware upgrades while you're at it. Give it a gentle dust down as well as the Atari ST style cases tend to collect dust.

Take the piece of card and pop into your local computer shop to see it it'll fit in a PC full tower. The tower case needs to be at least 50cm high. You may get some funny looks so just say your motherboard is larger than normal because it's so good!

The ST and Falcon motherboards are a lot longer than PC ones so there is some metal work involved. The majority of full tower cases are split in two sections, one at the top for the drives and the lower section for the motherboard and cards. There is a metal strut separating these two sections and a piece of this has to be cut so the board can get in.


Diagram of case

Tower case with side off. Notice the two struts that run from front to back, seperating the two sections.


When you feel the case is fine then buy it and when you get home remove everything off it including PSU, drive carriers and if you can, the front panel. Try fitting your card template in and see what needs to be cut. Be extremely careful when you do cut as the metal is very sharp and in my second tower job I covered the sharp edges with insulating tape as I sliced the top of my knuckle off on the STE tower, ouch.

Tools I used were a junior hacksaw (with a sharp new blade, it does help!) and a Dremel fitted with a circular cutting wheel attachment. My Dremel was too weak to actually cut the tough steel so I used it to score and then I used some pliers to bend it back and forth until it snapped off. File the rough edges smooth and make sure you clean out any metal fragments, you don't want these anywhere near your sensitive motherboard.


Case with card template

This shows the piece of card in place. As you can see the case was stripped right back and sharp edges covered with insulating tape.


Now you'll have to move the tower's PSU as the chances are it will hit the motherboard when it is in place. I mounted it at the top of the case. The power supply had some screws on the top to keep its enclosure together. I removed these and bought some slightly longer ones so I could drill holes in the top of the tower case and screw through holding the power supply up there.


Motherboard inside case

The PSU had to be moved to make way for the large Falcon board.


When you're happy try fitting the card template in place and see if any adjustments are needed. When it fits fine bring in the Falcon motherboard and see if this fits. Leave the metal shielding on the back of the motherboard but remove the top shielding for easy access to the components. Position the motherboard remembering that you'll probably have to sacrifice a couple of 5.25" drive bays. Remember the connectors at the bottom (cartridge, MIDI...) so leave space if you need to use them. On my Falcon I didn't want to use these so I managed to get the gap from the bottom of the case to the bottom of the motherboard down to only a few centimetres. You can get right-angled plugs to fit the MIDI ports from Maplin so you don't have to leave a huge gap, but if you use the cartridge port for dongles and other add-ons then you may need up to 10cm. Take into consideration where the back ports will be lined up against the tower's back panel, leave roughly 5cm here as well.

Now use marker pen to stencil the motherboard's mounting holes onto the tower case, where you'll drill holes. Please remove the board before you start drilling these! Use 6-10mm board spacers then use some small bolts (about 12-15mm long) to hold the motherboard in place, remembering to use fibre washers on the motherboard side. Don't tighten them all the way up as there is still a fair way to go. You'll need to remove the board again to work on the electronics.

You'll need to make or find leads to attach the ports to the back of the tower case. I recommend Maplin and Farnell. Maplin even stock those rather odd 13-pin and 14-pin DIN sockets!

Go to Maplin Electronics

13-pin DIN plug from Maplin Electronics

You'll also need to extend the floppy ribbon cable. The motherboard doesn't have a header that simply unplugs, so you have to undo the latches either side of this and carefully pull the ribbon cable out. Now use a PC floppy cable and snip off the connector that connects to the PC motherboard. Place the end of the ribbon cable over the Falcon motherboard's connector so the red stripe is towards the back of the motherboard and each wire is in its groove. Use the end of a match stick (not the ignitable end) to push down the individual wires one by one. After you think the wires are down, place the connector's top on and press quite firmly. If it doesn't latch on then you'll need to press the wires down a bit more with the matchstick.

If you have a Falcon you will probably want to use a decent, fast 3.5" drive so you can buy an adaptor. These are generic so a good computer shop may have one, although they are not that common. Wizztronics sell them but you should be able to find other sources of them. I believe they are also used on Amigas.

If you are attempting this on a normal Falcon without a CT60 then you will need a new power switch. You'll need to change the power switch from the momentary type supplied to a latching one. If you look through electronics catalogues you'll probably find something very similar to the one in your case but of a latching type. Use the wires off the old switch and solder them to the new switch. Keep the old switch if you're intending on using a CT60 as you'll need to fit that momentary switch back in place.

All the front panel switches and LEDs have small plugs to fit headers mounted on the board. I used a single row header to mate with these plugs so they could be disconnected easily without having to unsolder. At the moment the CT60 is still in development but it will come with an ATX power supply connector so it'll be a "plug-and-play" affair. The CT60 will also support the PSU's full features like automatic shutdown. However, with a normal Falcon, work has to be done to accept this newer PSU.

Find the grey wire coming out of the PSU (may be labelled as PS-ON on the PSU's enclosure) and a black ground wire to connect to the power switch header. Polarity isn't a concern. This will now turn the PSU on. Check by plugging in the PSU and connecting an old hard drive or fan up to the power connector. It'll be a good idea not to cut off the ATX connector if you intend to use a CT60.

The power LED is quite simple and requires taking one of the 5V wires (red) and putting a 100 ohm resistor in series with the LED and then taking this to ground. LEDs only work one way around but it won't destroy it having it around the wrong way so play around before finalising the soldering.


PSU connection schematic

This is how to connect up the new PSU to the Falcon connector. Please check the voltages in case your PSU doesn't follow the standard for these power supplies.


To use the reset switch on the front of the tower case you need to get the reset header and connect the two reset wires across the capacitor near the 3.6720MHz oscillator. It's a large axial type. Polarity of the reset wires is also not a concern.


Reset switch schematic

These points on the Falcon hook up to the tower's reset switch.


This is a freeware schematic I used to construct my multi-scan adaptor. When the Falcon is connected to a multi-scan monitor that is capable of a horizontal sync. down to 15KHz the switch can be used to select VGA or RGB mode. Warning: trying to run in RGB mode on an old VGA monitor may cause permanent damage to it if it is not designed to work at 15KHz. This switch can be switched in the middle of a session without having to do a reset, which is particularly useful. The change takes place when a program is run that checks the type of monitor attached like most demos and games do. Use shielded wires to stop ghosting and any other forms of noise and distortion on the screen.


RGB/VGA switch

A freeware adaptor for selecting between RGB and VGA for multi-scan displays.
Click to enlarge]


SCSI is quite difficult if you wish to have an internal bus as well as external. I used an internal style 50-pin Micro D, IDC connector to connect to the Falcon's SCSI 2 port. This is crimp-on which uses very fine ribbon cable with a pitch of 0.025 inch, the same as SCSI 3. You then need to solder on internal SCSI cable. I used 50-way with 5 headers. This went
around the front for the drive bays then back to the back panel where I soldered it onto a SCSI Micro D port, just like the one on the back of the Falcon. This was simply a case of wiring pin 1:1, 2:2 and so on up to 50:50. You may wish to use other plugs inside your Falcon as newer drives commonly come with SCSI 3 connector. Look at Connect World ( for pin-outs for all the SCSI connectors. Just match up the names when wiring up. The pin numbers for the connectors should be given on the conenctor itself, you may need a magnifying glass on those Micro D connectors! Avoid SCSI differential drives (LVD: Low Voltage Differential) altogether for the Falcon.

The keyboard was the original keyboard but I extended the lead and placed a mini DIN 8-way plug on the back of the tower. I used a spare ST case and carefully cut off the back to make it smaller. The Falcon's keyboard was put in there as it had Keyclicks which isn't too bad a feel compared to the spongey ST. I would recommend hooking up a Mega ST keyboard though as these have a better feel and it took a lot of time to cut up the case. There are free schematics on how to do this, or you can buy an adaptor for a PC keyboard and mouse called Qwertyx from Mario Becroft.


Re-cased keyboard

My Falcon keyboard sitting in half an ST case.


The light for the hard drive on the front of the tower case can be connected straight up to the keyboard connector. I recommend soldering two wires to the underside of the board where the connector pins come through. This light will function just like the one found on the keyboard.


IDE LED schematic

Hooking up the tower's hard disk activity LED to the Falcon.


To finish it off I replaced the stock LEDs in the case with super-bright blue LEDs. I then made a custom Atari Fuji logo badge to fit the 25mm square on the front of the case. I got a logo and resized it in Imagecopy then printed it out and laminated it for durability. I also built a special temperature display that controls the fans inside the case and fitted it into a spare drive bay. I've got to use all those drive bays for something, right?! I also added an external pixel clock by following Jo Even Skarstein's instructions.

Lastly I made a LAN port to serial port convertor because I had nothing that used the LAN port. I can now leave my modem connected to the Falcon and also have a null modem cable connection to my PC for file transfer.

LAN-to-RS232 schematic


Tower almost finished

At this stage it was almost completed, just finishing the temperature display.


Custom Atari badge

Ahh, as you can see the fans are doing their job.


Back panel

Here are the ports lined up on the back panel. The PSU's connectors were extended to a panel made of 1mm thick steel bolted in where the PSU would normally sit.


Tower complete

The finished product.


Overall it is a modification worth doing if you wish to have more space and a decent PSU that can cope with lots of hardware extensions. Just can't wait to slot in the CT60!

Useful contacts

MyAtari magazine - Feature #3, December 2001

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