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Flush PowerMac Mod

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Small(ish) update

Welding is pretty much a no go - because the aluminium is so thin and has so many close holes, welding may warp the whole back piece

So, I'm going down the trodden path of epoxy and spray paint! Trip to the engineering shop wasn't a waste though - came home a jigsaw, orbital sander and dremel 300 heavier

I ended up drilling out the spot welds possibly to reuse the PCI bracket - looks reasonably intact!
A whole afternoon later and here's the result of 20+ cutting discs:

Note - I've not epoxied anything yet, I got lucky and the panel sits in place without any help
 

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Another update:

Tried to use some old meccano, but it turns out there was some kind of laquer so the epoxy sheared as soon as I started drilling back through :(

Cut up an aluminium table leg and used strips of that instead. Got through 25 holes before the drill just stopped, turns out after 8 years the carbon brushes have worn out - new ones are on the way but the projects now on hold ... again!
 
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Most likely the last update for a while now - can't take 2 PowerMacs to uni sadly!

All the epoxy is sanded, the PCI bracket is back in place, and it's ready to paint.

9824862395_27bf488a35_b.jpg

9824872086_2f8ab37056_h.jpg

9824839294_1432cba894_b.jpg
 
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Well, a bit of an update - I drilled quite a few holes in the panel after filling with epoxy (sadly the 5 minute stuff) and err, the results weren't brilliant (epoxy sheared on the seam and disintegrated where I'd filled in previous holes in the panel)

YY5KHpa.jpg



I'm not sure whether it's the fact that I was leaving so little of the epoxy or that it was the quick set variety, but it isn't promising

Anyway, I'll try and work something out - if anyone has any input I'd appreciate it!
 
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So, (almost) a year on, and the project is out storage. I now have proper JB-Weld!

Refilled the borked holes with JB Weld, then redrilled most of the old holes and some new ones ... I'm pretty sure the drill bit is dull now!

IMG_20150709_221917309.jpg


Some holes will need filling and redrilling again, but I'm pretty happy so far

You can see the holes that need redrilling here:

IMG_20150709_221902519.jpg


If I was doing this project again, I'd just buy a LaserHive kit and be done with it. As I said in the initial post, the PowerMac was mint before I started chopping away.

Oh well, we'll see how it all turns out!
 
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A quick post about the G5 fans.

So most don't bother with the original fans because they're perceived to be too loud.

'sheriff' created a pinout for the fans back in 2012 that I've attached here.

PIN 1) - Power / Speed Control. Similar to the Mac Pro fan, the driving current is taken from this pin. RPM is determined via the voltage. 3.3V gives c.1000rpm. Input: 0-12V
PIN 2) - Tacho / Feedback. This will be left floating
PIN 3) - Ground
PIN 4) - 12V

The next stage will be working out how to marry this up with an Arduino.
Learning my way around an Arduino should be interesting. I've ordered a 32U4 to get started with: http://www.ebay.co.uk/itm/Arduino-P...518?pt=LH_DefaultDomain_3&hash=item25a99742e6

The fans can pull 0.75A at full load from the speed control pin ...

----

Currently I have no clue how to wire the Arduino to the fans since the ground can't be modulated the same way you usually would.

Transistor from 12V to PWR (PIN1)?

----
 

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Hi Flush,

I dug up the old post from "sheriff" too.
I also considered using a proper PWM controller using a raspberry pi. The problem I had with that was only one PWM channel on the pi. so would need to obtain a controller for more channels.

Never used an Arduino does it have many PWM channels?

I settled on rewiring using those pin-out and a standard pc controller.

So I am not using a true PWM signal just a variable voltage, but, as long as the fans have that 12v for logic. Then it behaves in same way as if controlled by PWM.

The limitations of my fan controller mean that i can only go from 4.5 to 12v. Never tried running them as low as 3.3v.
I like the original fans. They are not too loud imho.

Also good luck with the rest of your mod.
I like your approach. looks like a lot of work and drilling involved, but, should be worth it when complete.
 
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Never used an Arduino does it have many PWM channels?

Depends which Arduino you buy - I'm using a 32U4 'Pro Micro' which isn't a genuine Arduino board because it's cheap, and MacTester/Esterhend have written a lot of code for it I should be able to reuse(!)

The Pro Micro & Leonardo (genuine arduino) have "20 digital input/output pins (of which 7 can be used as PWM outputs and 12 as analog inputs)"

Also good luck with the rest of your mod.
I like your approach. looks like a lot of work and drilling involved, but, should be worth it when complete.

Thanks! Hopefully it will ... Just worried about the paint colour at the minute

------

As for the fans, I believe I will have to use a high side DC-DC circuit like so:

1784Fig08f.gif


Taken from: http://www.maximintegrated.com/en/app-notes/index.mvp/id/1784

Now to find values for the various components
 
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