Bondi power supply load concerns.

6 replies [Last post]
Offline
Joined: Oct 21 2004
Posts: 8

Hi! First - I love applefritter and have lurked on the site for a couple of years now. Thanks applefritter!

Second - I'm currently modding an upgraded Bondi into a large bright yellow steel cube case. (Pictures once it's complete.)

Everything is working ok but I'm a little concerned about loading down the power supply too much. Let me start from the beginning.

A year or so ago somebody gave me a Bondi 233 iMac that had the dead flyback issue common to those models. I decided not to fix it but to run it in another case and make it my first mod project.

So I had the guys at work punch me what is in effect a 1ft by 1ft steel cube that is powder-coated (think of this as a bonded paint if you don't know what it is) bright yellow in color. It took them a long time to get to my project so in the meantime I used the machine.

Along the way I upgraded the ram and the processor to a Sonnet Harmoni G3/600 with firewire. Recently I added a Hitachi laptop DVD-ROM in place of the 24x CD-ROM and a Pioneer Superdrive to the system off the same channel as the hard drive. (The only side-effect to adding the DVD-ROM is that I can't boot off of it.)

With all these parts you can see my sudden concern about the load on the power supply - especially since iMacs were not really meant to be all that expandable in the first place.

I'm concerned that all this will overload the system - especially when I start hanging firewire drives off the Harmoni port.

Should I be concerned? I actually have a second power supply from an old firewire case that I could add to the mix but even though it's small it will add to the internal heat and space problems in this case. (Admittedly not many once a good central fan is put in but still.)

Anybody have any thoughts on the subject?

YellowCube

__________________

YellowCube

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
martakz's picture
Offline
Joined: Dec 20 2003
Posts: 634
Personally I would junk the s

Personally I would junk the stock psu...its huge and install a 350W + atx pc powersupply. All the juice you need.

Monitor the powerlines,are you seeing a power drop? Use a multimeter with frequency measurment...is the frequency changing? Is it getting hot?

Personally, if I did not use the pc powersupply, I would just keep using the PSU. If its kept cool, it should be ok. Ive seen overdriven PSUs work fine for years when extra fans were added.

__________________

Now using x86 machines. Bye bye iMac266 (Strawberry), G3 1400 and the G3 IIsi.

Offline
Joined: Oct 21 2004
Posts: 8
Re: Personally I would junkt he stock psu...

Personally I would junk the stock psu…its huge and install a 350W + atx pc powersupply. All the juice you need.

I'd like to keep as much of the iMac infrastructure as possible here just for my own personal reasons. (Mixing PC and Mac parts should only be done on a peripheral level IMHO otherwise it taints the Mac. Wink

And actually the stock power supply seems to fit the case design much better than a PC one.

Monitor the powerlines,are you seeing a power drop? Use a multimeter with frequency measurment…is the frequency changing? Is it getting hot?

I haven't put a meter on it - still trying to dig up the Bondi service manual on the web somewhere but Apple keeps stamping them out. Sad

It gets a little warm but nothing I'd call "hot". But then I haven't reall put my hand on it or IR-temped it either. Where would I measure the frequency at?

Personally, if I did not use the pc powersupply, I would just keep using the PSU. If its kept cool, it should be ok. Ive seen overdriven PSUs work fine for years when extra fans were added.

True but after a decade and a half of I/T work I don't trust many manufacturers to build quality stuff. Though oddly it's the reason I use Macs and Sun boxes as my personal machines.

I think I'm going to take your advice here and see if the power supply shows any signs of sickness. Maybe I just need to attach bunch of stuff and extract a DVD chapter to an external firewire drive while burning a DVD. That workout would cover all the bases and unless it kills it all it would cost me would be probably a DVD-R coast if the burn underran.

YellowCube

__________________

YellowCube

martakz's picture
Offline
Joined: Dec 20 2003
Posts: 634
Well, I removed the ATX psu c

Well, I removed the ATX psu circuit board from the PSU case and it was alot smaller than the iMac powersupply. You could try the same.

I do not advice you touch the iMac powersupply. It gave me a shock even after I turned it off.

You dont really need to measure the frequency...measuring voltage should be sufficient. Look at the waveform on an osciliscope, is it flutuating? Or is nice an linear?

__________________

Now using x86 machines. Bye bye iMac266 (Strawberry), G3 1400 and the G3 IIsi.

Offline
Joined: Oct 21 2004
Posts: 8
I'll look at it this week - thanks!

I'm in Solidworks training (ugh Windows CAD) this week so I won't have much time to play.

I suppose I have to look up all the conversion techniques for adapting an ATX power supply to work with the iMac board. *sigh* More Googling. Wink

__________________

YellowCube

martakz's picture
Offline
Joined: Dec 20 2003
Posts: 634
Luckily its really really eas

Luckily its really really easy. The only tricky part is making the soft power work...but with a few transistors and resitors thats not hard either.

__________________

Now using x86 machines. Bye bye iMac266 (Strawberry), G3 1400 and the G3 IIsi.

Offline
Joined: Dec 20 2003
Posts: 279
The stock PSU is junk. Its st

The stock PSU is junk. Its stressed enough as it is with just the basic machine. Ditch it and get a ATX PSU.

__________________

G4 in a G5 Case: http://www.mlode.com/~stuka/g45/
iMac in FlexATX Case: http://www.mlode.com/~stuka/imac-atx/