Converting and Retro-Fitting an mATX to an Amiga PSU

Zetr0

Ya' Like it Retr0?
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Hello there my fellow AmiBayers,

I am please to present this little project I had undertaken for my friend Kinnie.

With Kin Hells recent Amiga Specification really pushing the old 60watt Power Pack I promised a present that would solve his problem, so here is the -

mATX (micro ATX) to Amiga Power Supply

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This unit provides a nice stable 150watt, but more so it provides 20 amps on the +5v rail, very important for Amiga usage.

So how was it done?

well... if you want to know more you best carry on reading.
 
The Micro ATX Power supply


To begin with we need a Micro ATX PSU of around 150 watts - with this we must make sure that it provides atleast a good 15 amps on the +5volt line/rail.

Once we have our mATX PSU (I got mine from eBay for £0.99p) we can get to work

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1. Testing the unit

This is very important, to begin we must test that this unit output good clean power under-load. so I use my trusty ATX tester

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Okay she passed all but the -5v test, this PSU does not provide -5... wich is no matter as the Amiga model this is destined for doesn't need it

so we discharge the unit and begin


Dissembling the mATX unit

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So off comes the ATX bracket,

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And we unscrew the primary housing of the unit -

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As we can see theres a bit of a clean-up job to do!

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Okay, to be fair its a lot of a clean-up job... clearly the previous occupants have a wolly mammoth that was shedding a lot.

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Now removing the Fan from the secondary housing plate

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We then unscrew the PCB from the chassis

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Yeah... got a clean-up job to do...

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And heres the PCB, free of the filthy housing..

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Stripping down the mATX PSU


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Theres a lot of wire, that we really dont need in this build... infact... out of the 30+ wires connected we only need 8.

To make the job easier we apply some flux-paste to the area to de-solder.

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Its best to note that you will need atleast 380c to re-work most PSU PCB's

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Dont worry about the brown dirty area thats just old flux NOT a burn in the PCB.

We continue on, stripping out the non-needed wire looms from the PCB

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Once removed we snip both the -12(blue) and PSON (green), this is because these points (among many) are not designated on the board, so its best just having them there for reference later.

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After that is complete I re-construct the Power Socket Molex, Note that I have placed some Capacitors from both the Live and Nutral terminals to the Earth.

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At this point I take the opportunity to lengthen the wire from the motherboard to the socket

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Its also best at this juncture to clean as you go. Flux is nasty NASTY stuff if left uncleaned.

Moving on to add some wires here -

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The red +5v, the Yellow +12v, the Black Ground and the Blue -12v are the onyl things we need to setup for the Amiga side of things,

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Once all the wire is connected, its time for the PCB to get a good clean, courtesy of Mr. Electric Toothbrush and his friend, Mr Car Screen Wash =)

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Mmmmm Foamy =D

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Normaly I Dab-Dry and then I leave it to air dry, of course if you have Hot-Air then go-for it... but you MUST make sure that you dry the PCB and Wires completely

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Now to tidy things up we use Heat-Shrink tubing

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This gives a safe and proffessional finish

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Reconstructing the mATX PCB


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Now that we have the right wires we need to attache them to the correct lines for the Amiga Connector Cable.

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Using this Pinout from Ian Steadmans site

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you can buzz out on a multi-meter which is recomended as not all Amiga PSU's use the same colour wiring.

for General Reference you can use this,

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but again its wiser to buzz-out the correct configuration


So to finalize the connections with heat-shrink tubing

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The Amiga (A500/A600 and A1200) PSU


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The Amiga Power Supply is a little weedy at the best of times and after a good 20 year service, its way beyond servicable for the most part.

The moment you put in the upgrades, to ramp up the power, its only inevitable the long standing friend will eventually stop giving reliable power. This will cause errors / crashes and even sound distortions.

A 60 watt unit... at over 20 years old, its seen much better days
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Unfortunately you cannot just pop-into the shops and buy a new Amiga PSU, infact if you asked you would probably get the response "Omega whu?!"

What we need is a cheap-reliable power supply that can give us the juice our expanded Amiga's needs, but housed in a familar chassis that we know and love.


Disassembling the Amiga Power Supply


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For the most part Dissasembling the Amiga Power supply is easy, by unscrewing each screw in the four corners we can open up the PSU

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From here we can easly open the unit and inspect it.

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This particualr unit is from an old Amiga A600


Once you remove the PCB from the housing its interesting to note or marvel at just how simple the PSU actually is,

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So, onto the disassembly - all we need from this PCB is the ON/OFF switch and the Amiga Connector Cable

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Once we have taken what we want we can either discard the broken PCB or, keep it as a reminder of a friend from a long-gone-era

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Customizing the Amiga PSU housing
to accomodate an mATX PSU

Before we can retro-fit an matx power supply for our Amiga, we must first modify the ABS plastic enclousure of the Amiga Power Supply.

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To begin with the is a small *rib* of plastic that needs to be removed other the mATX PCB wont sit properly.

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Since the ABS is old and brittle this thickness of plastic is no match for plyers and will!!
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See -
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There now the mATX looks all nice and comfy

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Now, unlike the Amiga PSU, the mATX PSU does require active cooling, alas the Amiga PSU housing isn't really designed for that purpose so we need to be pro-active and make it happen

Using a simple alignment from the 80mm Fan Plate, marking out the area for the fan.

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No point re-inveting a square me thinks-

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Lucky for me I have one of these wee beasties, (£25 from Aldi at the time)

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Anyway we need a Pilot hole first before we get to the next level -

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Holey Amiga housing batman!!!

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so what the Pilot hole for eh? well my friend its for one of these

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dont they look MEAN! now all I do is find one with the right circumference

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Bingo!


Now that was light work (beats using a dremel!!!)

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Just a for more small holes for screws

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Here we attach the fan by screw-fixing an old protector plate from the inside

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Now in this particular build the fan is ontop, this could ealy be inside the housing a thiner (slim line) version of the fan was used

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Heres a finishing touch so NO ONE losses thier fingers

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Retro Fitting the mATX into a modified Amiga PSU Chassis

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Before we can put this project to be we need to reconstruct the Amiga PSU chassis a little to get everything nice and tight -

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For the most part this is quite a simple case of where do you want it and two minutes with a Dremel

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In the above pic I decided to pretty much keep it standard, with the power out the back and the Amiga 5 pin Cable leading from the front. You will also notice that I decided to put the "Volt In" selector on the side...

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Yes this puppy will work anywhere where theres either 110 or 220volt system (its important lol)


Heres a shot to prove I am only human,

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thats a cut twice and measure once fail that one... (sorry charlie)


Anyway - once everything is in the way you want it, its time to BOND the PCB to the chassis - my method is 3 fold,

Standoffs with Kelepto pads, (these can hold 5KG each once stuck)

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And High Bond Hotglue

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and eh viola!

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dont beleve me its rigid -

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So time to plug-in the fan

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And put the two halfs together (in holey matromony!)

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The Final shots of the PSU running
(a modestly expanded Amiga A1200)



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So what would I do differently now?

well I would probably not of made the 5mm mistake on alignmment for the rear power socket and I would also hunted for a slim-line 80mm fan to fit internally.

Thinking about it now, I would also look at introducing an Air-release vent to reduce air pressure inside the housing.

but I better Give Kin Hell somthing to do... or he might be upset with me lol =D
 
Nice one Zetr0. (y)
I knew you were busy beavering away, but I think you've excelled yourself.

Defnitely worth a Serious Sticky me-thinks. ;)

Kin
 
Zetro, that is fan-bloody-tastic mate! You skills are awesome dude, I wish I could do a job that looks as professional as that one! Well done :)

@ Kin

Thats one neat PSU you have there now mate :)
 
nice guide

nice guide

Enjoyed this guide, and learned alot from it... txs..

Would not wan't that fan on top :huh: But you are sure it is a proper psu..:)
 
I did the very same to one of mine weak A500 PSU.

I was lucky enough to find a 230W mATX with a very thin fan. So on mine the fan is internal.

I've put the voltage selector at the bottom and used the original power switch, cord and Amiga power cable.:)

Also used the Dremmel on the underside and top vents to allow a bit more more air to circulate.

Oh, BTW: I made this thread sticky!
 
Haha, amazing, guess how I spent last night? That's right, converting an mATX PSU :) I opted to keep the original power cable, hardwired it to 230 V (I won't be traveling with my A1200 anyway), and left one drive power cable hanging out (you never know). Amazingly the mounting holes for the mATX PCB lined up perfectly with the Amiga case, so fitting it was easy. Still to do is mounting the small secondary PCB, and mounting a fan.
 

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Z, one thing I didn't get was that the mATX needs a toggle switch and the Amiga power brick has a button, a "statefull switch".

How was that solved?
 
Excelent !!! :)

@arnljot : http://pinouts.ru/Power/atxpower_pinout.shtml
taking a look on the ATX connector you can connect pin 14 (usually either green or purple) with 0V (just one of the black ones)
and the PSU will be on. the PSU usually has a direct ON/OFF from the 115/230V which is the one you want to use to switch on/off the psu.

Puttin the ON/OFF between the PSU and Amiga is doable, but not recommended, eg if you switch off your Amiga, there'll still be power consumption in the PSU itself.
 
Hmm I think my first post disappeared. or perhaps it has to go through the moderator first ?

@Zetr0 - Great guide, thanks :) makes it much better than having an ATX psu scratching the table (I'll no doubt follow your inspiration one of these days)
Perhaps to drill some holes for the air to get out ?
both for the movement, but also to prevent higher pressure inside, high pressured air becomes warmer, though I doubt that the temp will rise that much.

@arnjlot in post #4 picture 4 you'll actually see the switch connecting pin 14 to 15 (or was it 13?) pin 14 when connected to 0V turns on the PSU.

This is a way to do it, though not recommended in the essence that the PSU still consumes power when switched off.

I'd recomend a break on the phase from the 115/230V instead.

___/ ____ AC Voltage

_________ Null


then just connect pin 14 to 0V permanently, eg pin 15 (or actually, where the pins whould have been before removing the exessive wires).
 
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