iMac SMPS

pinkmouse · 26th November 2006, 05:16 PM

Ok guys, I need your help.

My iMac's CRT monitor died today, so I'm going to recase it as per the many mods out there on the web. That bit's no problem. However,all the mods I can find use an ATX power supply, and I'm a cheapskate and want to recycle as much of this as possible.

So, the iMac logic card uses a downconverter, pic below, to convert 24AC to the various DC levels required. However, I assume that this is already switched from mains voltage, so that 24V will be running at a much higher frequency than mains 50Hz. So, my question. Is it possible to reuse the big traffo from the main PSU and create a simple switching front end to drive it at the higher frequency required?

Thanks in advance.

Eva · 26th November 2006, 07:32 PM

It looks like a flyback so it may work with DC input too. Can you provide more detailed pictures including the bottom side of the PCB?

pinkmouse · 26th November 2006, 07:48 PM

Thanks Eva.

I'll post some more pics in a bit, but I just had to put my camera on charge. I suspect it needs AC though as the input goes directly to the legs of the big transformer on the right.

stokessd · 26th November 2006, 08:05 PM

You've got a prehistoric iMac, back in the dark days of OS9. I've got some service manuals, which generation is it? The manuals won't go as deep as you want, but may be helpful.

Have you considered a refurbished mini? You can run OS X and windows, and it's all in a small tidy package already. Hard to beat if you consider the cost of your time.

Sheldon

pinkmouse · 26th November 2006, 09:23 PM

Quote:

Originally posted by stokessd
I've got some service manuals, which generation is it?

It's the first version of the slot loading DV, I found a pdf of the service manual online, but as you say, it doesn't really go into enough detail, "Take this board out and order a replacement from us "doesn't really cut it.

Quote:

... Hard to beat if you consider the cost of your time...

I'm "between jobs" at the moment, so time is plentiful, but cash is short.

stokessd · 26th November 2006, 09:54 PM

Not that I'm trying to get you to not rebuild your computer, but have you checked on ebay? The CRT imac units are always selling for like $40. I thinking it would be hard to repackage and get a working CRT for the same price.

Sheldon

jleaman · 26th November 2006, 10:28 PM

I don't want to offer something that might not happen. But I CAN bet that if you ask planet10 for one youll get one for xmas

He has so many of them. My therory never hurts to ask, the worst some one will say is no D:

pinkmouse · 26th November 2006, 11:01 PM

Quote:

Originally posted by stokessd
The CRT imac units are always selling for like $40. I thinking it would be hard to repackage and get a working CRT for the same price.

Sheldon

In the UK, they go for around £60-£100!

Anyway, pic of the underside by the input/output connector:

pinkmouse · 26th November 2006, 11:03 PM

And the main rest, I've indicated where the traffo is with a sharpie, and I've also marked the two AC tracks:

pinkmouse · 26th November 2006, 11:04 PM

Close up of the input traffo:

26th November 2006, 07:32 PM	#2
Eva diyAudio Member Join Date: Oct 2003 Location: Near the sea	It looks like a flyback so it may work with DC input too. Can you provide more detailed pictures including the bottom side of the PCB? __________________ I use to feel like the small child in The Emperor's New Clothes tale

26th November 2006, 07:48 PM	#3
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Thanks Eva. I'll post some more pics in a bit, but I just had to put my camera on charge. I suspect it needs AC though as the input goes directly to the legs of the big transformer on the right. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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26th November 2006, 08:05 PM	#4
stokessd diyAudio Member Join Date: Nov 2002 Location: Fort Wayne, IN	You've got a prehistoric iMac, back in the dark days of OS9. I've got some service manuals, which generation is it? The manuals won't go as deep as you want, but may be helpful. Have you considered a refurbished mini? You can run OS X and windows, and it's all in a small tidy package already. Hard to beat if you consider the cost of your time. Sheldon

26th November 2006, 09:54 PM	#6
stokessd diyAudio Member Join Date: Nov 2002 Location: Fort Wayne, IN	Not that I'm trying to get you to not rebuild your computer, but have you checked on ebay? The CRT imac units are always selling for like $40. I thinking it would be hard to repackage and get a working CRT for the same price. Sheldon

26th November 2006, 10:28 PM	#7
jleaman diyAudio Member Join Date: Apr 2002 Location: Nanaimo	I don't want to offer something that might not happen. But I CAN bet that if you ask planet10 for one youll get one for xmas He has so many of them. My therory never hurts to ask, the worst some one will say is no D:

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