Thursday, May 31, 2012

The 17" iMac G4 Native PSU

Introduction

While I have not hooked the native PSU up to a mod and there is one wire that I do not understand the purpose of, I have checked all the collages of a working PSU.  I now know that is it similar in principal to the 20" PSU.  As this is all based off of my work with the 20", more information is available in that post:

The 20" iMac G4 Native PSU

17" iMac G4 PSU

vs ATX PSU



ATXPSU
The Native PSU is an always on, 12V only power supply.  Always on meaning that unlike standard ATX PSUs, the moment the AC cable is plugged into an outlet, there is DC power in the pins.  To get an ATX PSU to work without a motherboard, a pin in the motherboard connector needs to be grounded (known as "jumping" the PSU).

12V only means that unlike standard PSUs, only 12VDC and Grounds are supplied to the motherboard.   ATX PSUs transform the 120VAC in the wall to 12V DC and also downconvert the 12V to 5V and 3.3V.  These 3 different DC voltages are supplied to the motherboard in multiple rails via a 20 or 24pin connector.  Because the PSU supplies the iMac's motherboard with only 12V rails, the downconversion to 5V and 3.3V happen on the motherboard itself.

ATX PSUs also tend to supply peripherals directly, Molex, SATA power, 8pin PCIe etc emanate directly from the PSU itself.  As noted, ATX PSUs are not "always on", they have to be "jumped" either manually or by the motherboard.  As a result, the peripherals will not be given power until the motherboard is switched on, despite the fact that the power is supplied directly from the PSU to the peripherals.  Because the iMac's PSU only has 12V, the one molex line with 2 molex connectors (for the cd and hdd) emerge from the motherboard.  Although the molex wires share the same 16pin connector, it comes from the motherboard and does not interact with the PSU at all.  As the peripherals are supplied by the motherboard they will be off when the mobo is off despite the "always on" PSU.

The Connector

"Clip Side"
"Non-Clip" Side - All Grounds
The connector is 8x2 for a total of 16pins, one slot is empty for a total of 15 wires.  Of those 15, 4 (Yellow, Red, Black x 2) go from the main connector to the molex connectors.  Because we will not use of the original mobo, these wires connect to nothing and have nothing to do with the PSU at all.  That leaves 11 Power supply wires.  The blue wire seems to have no detectable voltage and grounding it does not seem to have any effect.  In the 20", the blue wire acted as the ground component (with a white wire supplying +5V DC to the PSU - the white wire is not found on the 17" - the pin is left empty) of a switch to turn on 24V DC supply to the LCDs backlight.

In the 17" the 24V Green line is replaced by an extra yellow +12V DC.  While I do believe this (similar to the 24V required by the 20" backlights) does go to the blue wire of the inverter to supply the power to the backlights, the "switch" to turn the backlights on works differently.  Here the extra 12V DC line is on as soon as you plug in the power cable.  This is the same as the other 12V lines.  No voltage needs to be applied to the PSU in order to get all the lines working.

So, I am not exactly sure the purpose of the blue wire.  Since, I don't have a working 17" mobo to even voltage test it.  I do have a theory, I believe it acts as a ground for a similar switch mechanism as seen in the 20", however, this switch (which also uses 5V) happens in the inverter itself, not the PSU.  I'll talk more abut this later.  For our purposes its really of no consequence.  What we are left with is 10 PSU cables, 5 Yellows and 5 Blacks.  This means there are 5 12V DC rails supplied to the motherboard, as soon as the iMac is plugged in.

The Pinout:

17" iMac G4 PSU Pinout
Please note this is an alteration of an image from my 20" pinout - hence the crude "photoshop"

Again I break it down into four zones:
1. Yellow Zone: Pins 1 - 4 and 9 - 12: 4 rails of 12V DC and grounds
2, Blue Zone - Pin 13 - The blue wire is the only pin (will not be used here)
3. Red Zone - Pins 6, 7, 14, and 15 - The molex connector comes out from here.  You will want to save the actual wires and connectors for use in this mod, but these pins are of no consequence.
4. Green Zone - Pin 8 and 16 - This likely is the 12V rail which the motherboard routes to the inverter, but since its automatically on and we aren't using the original mobo , its just another 12V DC rail with ground to us.

Getting a 5V Line:

The 2 plug connector connects to the AC port on the back of the iMac G4 which contains the C5 receptacle (The 3 pronged plug with 3 circles that resembles Mickey Mouse).  This plugs into the AC on the wall and there is +12V DC in our yellow wires.  In total there are 5 rails (Pairs of Yellows and Black Ground wires).  However, this mod calls for a molex adapter to be used as a PSU.  The molex adapter has a Yellow +12V DC rail and a Red +5V DC rail.

My switch theory (Optional Reading):

The 17" Inverter Pinout
For those of you that are familiar with the 20" PSU you may be aware that I mentioned in my post that a 5V line is not necessary to get the LCD working.  This is because the one place on the 20" that required 5V was "the switch".  This switch worked by the motherboard downconverting 12V to 5V then feeding it back to the PSU via the White/Blue wires.  The 5V turned on an upconverter (or possibly a transformer) that produced the 24V line.  +24V now flowed in the Green wire of the PSU, this went through the connector and got directly routed through the motherboard to the Blue/Red (+24V)  and Green/Black (as Ground) wires of the inverter cable.  When 24V reached the inverter the backlights turned on. On the 20", I used the 5V that came from the DVI cable.  As this is just a switch I was not worried about overtaxing the low current available in this line.  

For the 17" PSU, there is no switch involving the PSU.  The Yellow wire at the end (in the Green Wire's Place from the 20") is on as soon as it is plugged in.  However, I believe there is a similar switch mechanism, but it is in the inverter, not the PSU.  The 20" has 6 backlights, the 17" has 2 backlights, so I understand the need for (2) 24V lines and (2) Grounds.  In the 17" inverter cable there is (1) Ground and (1) Power Wire +12V via the Blue Wire.  Initially I thought that 5V was also somehow required to power the inverter, however after some experimentation, I realized the 5V required for the Red inverter cable acts as a switch and not as a true "power source".  Because of this, the Red Inverter cable can be connected to the DVI +5VDC power source.  Obviously this is similar to what I just described as the switch mechanism in the 20" iMac G4.
The 20" Inverter Pinout - Revised

Comparing the 2 inverter pinouts shows similarities.  The Orange (Dimmer) and Purple (Possible role in Sleep?) are left unconnected.  The 6 backlights in the 20" need two power rails, so both Blue and Red wires supply + current with Green and Black as their respective Grounds.  The 17" has 2 backlights and needs only one power rail, the Blue wire as + current with Black as its Ground.

In addition there is a Yellow in the 20" and a Green in the 17" that need very low current via Resistor connected to 5V.  This wire appears to be involved in wake from sleep.

All wires are accounted to except for the RED wire in the 17" inverter cable.  This wire uses 5V produced by the motherboard from downconversion of the PSU's 12V and uses it to "turn on" the inverter, acting as a switch.  This is exactly what the White Wire (which is missing from the 17" PSU) of the PSU does for the 20". Except it acts at a different location.  This also makes me think the remaining Blue Wire may somehow be a ground wire that the motherboard uses for this mechanism.  But, as we ground our 5V DVI Current via the DVI, it is not used.

Need for 5V and Preparing the PSU:

Although the inverter could probably all be handled by the DVI input (could likely get away connecting the Green inverter wire as well.  There is one more thing which requires 5V, the LCD itself.  The Gray cable of the LCD contains 3 wires which power the LCD screen.  In the 20", 12V is needed, but in the 17" 5V or 3.3V is needed.  As this is not just a switch, but actually powering something, I would not use the DVI source as you will likely overtax it.  This may actually damage your source, computer, video card etc.  So 5V must be created from the PSU.

At this point, I would recommend cutting off the motherboard connector to free all the PSU's wires.   Right above where the wires enter the connector cut them free.  This gets rid of the molex connector (you do not need the cut these 4 as they are not attached to the PSU itself).  You should be left with 5 Yellows, 5 Blacks, and 1 Blue (which will not be used) coming out of the PSU.

Option 1 - A computer in the base:

This is for how that are using some type of small form factor board i.e. Nano, Pico, or ECX.  Many of these boards are powered by a P4 connector.  This is a 4 pinned connector (2x2) that uses 2 - 12V and 2 - Grounds.  As there are plenty of 12V rails available from the PSU, simply take your motherboard power connector and attach the 12V DC lines to the Yellow wires from the PSU and the Grounds to the Black PSU wires.  In the picture of my KEEX-6100 below, the P4 connector can be seen in the front right corner of the motherboard.  This connector attaches to a 12V rail from the native PSU.
KEEX 6100 with P4 connector to Native PSU
The reason this will work is that this board (as well as several other small form factor boards) works just like the original iMac G4 motherboard in that it requires only 12V in to work and it itself has downconverters on it.  The KEEX-6100 actually has a mini-Molex/SATA power out port, which can be seen in the back, just left of the fan.  This gives a couple molex out, including 5V.  So you have a 5V line from here.  Just note that I would still recommend taking the 12V backlight power from a Yellow 12V rail from the PSU itself, but the LCD power and ground can connect to the Red 5V and Black-Ground line here.  The Green from the inverter can also go here or the DVI 5V as noted.


Option 2 - Use a second PSU - a PICO PSU connected to the native PSU

A PICO PSU with rocker switch
Almost all PICO PSUs use 12V DC input (some have wide ranges in DC input).  Power it by hooking a 12V line from the native PSU to the DC power in (the white and black wires pictured that hook up to the connector for an external power brick).  As the native PSU gives you 12V DC already, you do not need a power brick.  You must "jump" the PICO PSU in some fashion, depending on what your intended iMac G4 mod is.  The Jump mechanism can be "always on" with a simple wire or "on/off" with a rocker switch (as pictured) to control power out from the PSU.

If you are using a motherboard in the base that requires an ATX Power connector, this is without a doubt the way to go.  You can plug this into the motherboard connector, without having to wire all sorts of adapters and converters, at a negligible loss of space.  Of course if its connected to an ATX mobo, the motherboard will jump it for you.  

If you are using this for an external monitor with peripherals (ex. dvd drive), you can use the requirement to "jump" this psu to your advantage.  You can put a rocker switch here that will allow you to turn off everything its connected to.  Remember the native PSU will be on as soon as you plug it in, by jumping this psu without a switch, it will also be on.  Thus, drives will be spinning, leds will be glowing etc whenever it is plugged in.  With a switch here you can turn the whole unit LCD and peripherals completely off.  Just remember, no matter what wattage PSU you get, these are not additive, they are connected in serial, so you are still limited by the overall wattage of the native PSU.  Also, you have to make sure that the wattage is adequate for anything you have connected "downstream" of PICO PSU including the LCD power (though the backlights can be connected to either the native or PICO PSU).

The PICO PSU is probably the most flexible option as they are available with P4 connectors. molex connectors. SATA power connectors etc.  If you are not using an ATX motherboard, you could even use the power from the pins intended for the motherboard.  However its expensive and not needed if you use Option #1.  And if you aren't using peripherals requiring 5V - you can likely use the cheaper option #3.

Option 3 - Use a 12V to 5V DC-DC Downconverter

15W 12V to 5V DC downconverter
These can usually be found for around $5.  Connect one 12V and Ground in and you get 1 5V and Ground out.  Combine this 5V rail with a different 12V from the native PSU.  With a 12V and 5V rail, we now have our "molex wires" that acts as our power source.

All these are acceptable, as is using a different PSU altogether, it simply depends on your goals and needs.  As always - thanks for reading!!

43 comments:

  1. You probably gonna have a look at the 3,5" Commel LS-378 Board.

    This features a 9 to 24VDC wide range input and intenal DVI header. No more soldering a DVI plug.

    Another option could be the iBase IB905F.

    Both are Sandy Bridge Mobile boards

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  2. Thanks - they both look like great ECX boards. Its nice to see that there are options with this form factor. It seems that pico and nano itx have gone largely to low power fusion or atom.

    Both boards are impressive. The Commel in particular has 2 mini PCIe slots. However, be careful with the onboard DVI header. This doesn't necessarily help. This is likely there because there is not room for a DVI connector on the back of the board. Its not like the iMac G4s motherboard connector will simply plug into this 26 pin connector. You would have to plug the individual wires into the pins on the board, but its not possible to tell the pin size. The best case scenario, the pins fit perfectly and then you do not need to bother with the "DVI Connector" that I use in my mods. Worst case scenario the pins do not fit then you use the DVI cable they include and the DVI Connector as normal. The wide range of voltages accepted in are potentially helpful if you want to use 24V input for the 20" mod, but for most mods 12V DC in will work fine. Don't get me wrong, the board looks great, I just wouldn't overpay for these two features.

    Keep in mind, with the "DVI connector" you don't have to solder the DVI cable. You simply push the pins in. Here's hoping Ivy Bridge Chipsets are on the horizon! Thanks again

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    1. I´ll order the Commel for my mod.
      I´m concerned about fitting the board at the position of the former 3,5" HDD when using the original PSU. In case of using the Commel board it should fit, because i do not need any of the plugs on the side. I haven´t measured the space in the iMac housing yet, but i believe there´s not much of it.

      This board is not cheap (280€, should be around 300$ because products are often nearly 1:1 priced in USD and Euro). But you won´t get Sandy-Bridge 3,5" embedded boards any cheaper in germany.

      Btw: Why waiting for Ivy? USB3?

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    2. This mod uses onboard/on chip graphics. The hd 4000 of ivy bridge is supposed to represent a substantial leap forward from the hd 3000 of sandy bridge

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    3. I looked it up. You're right, the difference in graphics performance is significant. Pray for a bios update. Would save a lot of money

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    4. Unfortunately the qm67 that all these boards are based on will not be ivy bridge compatible. I have no idea when or even if an ecx ivy bridge board will be released . Given that several companies have sandy bridge boards, I would be surprised if an ecx ivy bridge was not in the horizon. Graphics are by far the weakest component of this mod and having an HD 4000 would def be an improvement. There is neither space, power, or a true pcie (non-mini) slot for an external card.

      I'm not saying not to buy the board, it all depends upon your goals and obviously finances. For instance, if you wanted to game and didn't care about hackintoshing, I would probably recommend an amd fusion board, like the one inside the new zotac Xbox, for its ati onboard graphics. But, all things being equal and if you are not in a rush, you may want to hear if an ivy bridge is on the horizon, given that the first wave is coming out over the next few weeks.

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    5. check this:

      http://www.hwtools.net/Adapter/PE4L%20V2.1.html

      PE4L-PM060A

      The best graphics card with Pcie 1x I found is the ATI HD5450. Should blast a HD4000, right?

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    6. Better:

      PE4H-PM3N ver2.4

      PCIe 4x to mPCIe (obvoiusly limited to PCIe 1x Speed)

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    7. That's certainly an interesting adapter, but I'm very wary of the words "allows you to TEST your graphics card" and "not for home use". I am the proud owner of a x1 HD 5450 and trust me that it doesn't blast anything. In tests the x16 HD5450 tended to fare worse than the HD3000 on a sandy bridge i5 2500K. Anandtech.com did a comparison. I can assure you that at x1 through this adapter it will be even worse. And this is the HD3000, not even the ivy bridge HD4000.

      I'm sure you could even add a pciex16 to x1 adapter and use a more powerful card, but I wouldn't recommend it. First off, I'm not sure any graphics card with its connectors will fit. If they do, you are severely minimizing the space and adding another element that generates heat into the metal no ventilation faraday cage. Secondly, power will be a problem. The largest pico psu's are 160 watts and the 20" PSU is 180 watts or so. As 40+ watts goes to the screen and you need some leeway so your system doesn't shut down when you plug an iPhone in, you should target a 100 or so watt system. Some graphics cards can consume 3 times that alone. Having an external atx powersource is an idea, but at that point, I would recommend keeping the entire computer external as a Mac mini isn't much bigger than an atx PSU.

      It's my opinion that any marginal upgrade to the onboard graphics you may find that will fit, be low heat, low power, and work via mPCIe would be marginal at best and come at a high cost to the other components of the system. To be honest the HD3000 is more than adequate and the hd4000 is supposed to be quite a leap as you noted. They are capable of something the iMac isn't - HD. Neither the 1650X1080 of the 20" or the 1440x900 of the 17" support 1080 true HD. So I wouldn't go to crazy regarding graphics. But, if a gaming machine is your goal, I wouldn't recommend an all-in-one. Good Luck

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  3. Hi, I'm the guy who is trying to mod an iMac G4 17" with a mac mini.
    I have disassembled my 17" and noticed that my PSU has a white wire that is missing in yours.
    I'll ignore it and follow your guide, see if it works.
    The photos are below:
    http://dl.dropbox.com/u/7008950/web%20photo/P1050913.JPG
    http://dl.dropbox.com/u/7008950/web%20photo/P1050912.JPG

    Tim

    P.S. I have taken some macro photos of the plugs which you might find useful, please do use them here if you wish :)
    http://dl.dropbox.com/u/7008950/web%20photo/P1050907.JPG
    http://dl.dropbox.com/u/7008950/web%20photo/P1050908.JPG
    http://dl.dropbox.com/u/7008950/web%20photo/P1050911.JPG

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    1. Very interesting. Thanks for letting me know, this seems to resemble the 20". Do you know which 17" this came from? Variation between models is frustratingly common. There are two possibilities: the white/blue wires are part of some mechanism that we are bypassing and therefore irrelevant like my 17" or the are part of an on switch for that 12v yellow wire at the end. What I would do is plug in the PSU and use a voltmeter to test if the lone yellow on the end is live. Either way, as you already have plenty of 12v rails, even if it wasn't live, it wouldn't be required.

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    2. I have just checked the PSU, the lone yellow is live with 12v, seems fairly consistent with yours except the blue/white pair.

      I bought this working unit off an auction site, I have checked that this is a 17" 1GHz model by measuring the diagonal of display and the system profile says it is running a 1GHz CPU. However, when I use the serial number from the drive door with this site: http://www.powerbookmedic.com/identify-mac-serial.php, it says my iMac G4 is a 15" model. Also, the LCD cable from my mac have a Blue-Green-Orange-Red combination which resembles a 800MHz neck. I have already disassembled the machine so it's not possible to put it back together. Any other methods that can identify my machine? It seems like my machine is not original.
      https://dl.dropbox.com/u/7008950/web%20photo/P1050916.JPG

      Tim

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    3. Just checked off the metal bottom plate, the bottom plate says the mac is a 1GHz model with 256MB ram and 80G HDD.

      Tim

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    4. Cool. Variation has been frustrating, especially when you factor run that many of these machines have been serviced with replacement parts, and apple has never been forthcoming about exactly what's inside their machines. Its one of the reasons why making a simple step by step tutorial is difficult. When I started getting contacted by people with multiple failures, I thought they were likely not doing something right. It wasn't until someone showed me pics that I realized there was a second type of neck for the 17".

      It does seem like your machine is somewhat of a Frankenstein. Its OK though, with that color combo I would follow the 800mhz guide. In terms of the psu, it looks like the white and blue are essentially bypassed, whatever they do. So you have a bunch of 12v rails. I don't know much about the Mac mini (are you talking about plastic or aluminum version). Obviously the new one has its own psu, the old one has a power brick. Good luck.

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    5. I was trying to connect my inverter cables and the backlight is not on. I'm sure the inverter is working properly as I have a working display before disassembling it, unless I have done something just now which damages it.
      I have used my multimeter to check the voltages and they are all correct. Can you please help me check if the connections are right? The color of alligator wires are consistent with your guide i.e. green,red - 5V, yellow - 12V
      https://dl.dropbox.com/u/7008950/web%20photo/P1050917.JPG

      I'm just gonna work on my DVI connector first and hopefully it is just due to a stupid mistake which can be reversed.

      Tim

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    6. After trying few more times, the backlight is on.
      However, when I try the whole thing after connecting the LCD cables, the alligator wire providing 5V to the Grey LCD cable becomes red hot and almost burn itself. My best guess would be something is short. Any experiences in this?

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    7. Yes, something is short. Are you sure you are using the right neck. Are you sure you have not swapped blue and purple?

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    8. After guessing my LCD might be gone after shorting it, I tried to follow the 1GHz neck method by treating the "orange" as brown and it finally worked! I have to say the orange and brown looks extremely similar to me. I even compared it to the thin orange wire from the gray LCD wire and they looks the same! Luckily the LCD panel appears to be working even after the first failed attempt.

      https://dl.dropbox.com/u/7008950/web%20photo/P1050920.JPG

      Now I only have the crosstalk issues to deal with, as there are many blue and red pixels on screen.

      Also, I would like to know how you protect the pins? Do you have plastic casings that locks the whole thing up or you just leave it as it after using hot glue to strengthen the connections?

      Once again, thanks so much for your guide and prompt reply. I could not make this far without your help and contributions.

      Tim

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    9. https://dl.dropbox.com/u/7008950/web%20photo/P1050922.JPG
      https://dl.dropbox.com/u/7008950/web%20photo/P1050921.JPG

      here are two more pictures showing the situation, some pixels flicker while some do not.

      Tim

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    10. Hi Tim,

      did you manage to repair the red/green dots?

      i have them too... and i am 100% sure its not the DVI but more a power problem :(

      https://www.icloud.com/photostream/fr-fr/#A4G4TcsmGS5OiK;4386FD1A-30B2-4D8E-A6E5-9105110CBB57
      https://www.icloud.com/photostream/fr-fr/#A4G4TcsmGS5OiK;BE1DFA31-41C4-493F-A455-64490848B1C7

      thanks!

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  4. I came on this thread since I have a G4 17" 800Mhz with a blown PSU and am looking at fabricating a replacement PSU to match the pinouts.

    Have you considered that the blue wire you haven't diagnosed might be -12volts, to be used with a +12v to generate 24volts potential for the LCD backlight? Since my PSU is fused at the VAC connection, I can't test anything yet. With a working PSU, you could put a voltmeter between the blue and a yellow to see how they compare.

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    Replies
    1. There is no voltage at blue either vs ground or +12V in either + or - direction. The 17" needs on,y 12V for the backlight, the 20" requires the 24V line, but that PSU I have already figured out

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    2. Thanks - I mentioned it because I have come across that -vdc technique in some vintage PSUs - eg the DEC VT100 serial terminal. Your work on this PSU is very helpful to my effort to revive my G4 17:

      [former Anonymous]
      Rick

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    3. No problem and you're very welcome. And thanks for the idea, I appreciate any suggestions and help

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  5. Hey, got a problem. So I got all of the parts to do a 17in 1.25ghz conversion to an external monitor using the native PSU (I have a backup external PSU if the native one fails). The problem I just noticed is that your pinout says that pin 9 has a yellow wire. Mine is empty, and I know this isn't a mistake because when I bought the computer it was fully functional (I tested it myself) and when I gutted it, I did nothing to the wiring (I was very carful to not mess anything up). How can I remedy this issue? Also, the image is backwards and that had me really freaking confused for like five minutes straight. Mind flipping it horizontally?

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    1. Its certainly possible, there is considerable variation in these PSUs. You don't need to do anything. All the yellows supply 12V and the blacks are grounds. They are essentially the same wire originating from the same source. Since you are using one yellow/black pair as a 12V source and down converting one to 5V - you only need two. It doesn't matter if you have one less, plus if you need more 12V rails just split them.

      Not sure why you think the image is backwards? It is a real photograph looking at the connector, with the clip on the bottom. The numbers are added over the images of the ports. If you are confused by the right to left numbering this wasn't done randomly. The numbers correspond to the actual pin numbers of the connector. The reason they appear backwards is because PSU pins (as is standard on most computer connections) are named by the way they orient on the female receptacle. This would be the part on the motherboard. So, if you were to plug the PSU in pin 1 goes to port 1 and thus would be the mirror image. You'll notice this is the same for all PSU numbering as well as the DVI numbering scheme in this very mod. So the number 1 refers to that pin no matter what orientation you hold it.

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    2. Well when put next to mine it is backwards. No matter, I guess it's just another variation. I have a few more questions. 1) Can you recommand a good soldering iron? 2) Where do I wire up the power switch? (Is it possible to use the plastic button (not the actual BUTTON, but the plastic circle you see from the outside) from the origonal computer? Mine is still connected and as tactile and pushable as ever) 3) Can you recommend a good USB DVD drive that I could put inside this? I have seen plenty on NewEgg, but they all seem too tall to fit and I'm curious what your thought is.

      Thanks,

      CJ

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    3. There are plenty of good soldering irons. If you plan on having it around for a while, I'd recommend a soldering station by Weller. I use the WLC100 by Weller and a 0.03" tip for most small electronics work. Again, this is just what I use and I like it because its durable and I was going through irons pretty fast. If you just need something to use for a few solder points, you don't need something this expensive.
      The power switch depends on what you intend to do with this mod. Remember, the PSU is "always on", it will supply 12V as soon as the cord is plugged in. If you use a motherboard, the motherboard supplies the on/off to the LCD and backlights. So, the power switch is a momentary switch connected to the motherboard. The plastic button connects to a "plunger" inside. If you see my post "finishing touches and ports" in may, 2011. You'll see that I simply mounted a momentary switch behind the plunger so the existing button would depress the internal momentary switch. You could also but off the original mobos button and solder new wires to it.

      Without a motherboard it's a little complex, because a switch should be a toggle switch at the AC power or PSU to LCD level. Toggle switches are typically on/off switches, not push buttons which are usually momentary switches. You'll have to see if a push button toggle switch which can fit in that area exists. I am not sure.

      For the DVD you can't use an external DVD without disassembling it. Use an internal DVD with a Sata to USB and power converter.


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  6. I cut the wires from the motherboard connector and these are what remain

    http://i.imur.com/Qc0Sr.jpg

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    1. sry, that link appears to be broken. Here's a mirror.

      http://db.tt/MUgYpw8m

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  7. I'm somewhat afraid that you wont believe me so I took a picture of where all the wires come out of the PSU just to show I only have 4 yellow ones.

    http://db.tt/vXS6I9LJ

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    1. Seriously, I believe you, its OK. But, it doesn't matter use a different yellow wire

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  8. Hi, I tried to use the native PSU with the pico PSU. In theory it should work but in practical in my case it didn't. The backlight are not activated and the screen stay dark but display a very dark picture. So finally I use only the picoPSU with its power adapter. it's a pity but at least it works

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    Replies
    1. Sorry to hear that, not sure why the native PSU failed for you

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  9. I have tried to follow your blog as best as possible, but I have run into an issue . I have all the cords connected, buy I get no picture when I test the monitor I get vertical lines and the back lights turn on very slowly. Do you know what could cause this? I I'm sorry to ask for help as you offer these guides for free, but any assistance would be of tremendous value to me.

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    Replies
    1. I would love to help, but its difficult to say. Something is either not connected properly or damaged on a hardware level. Are you sure you used the right neck? The right resistors? Is your psu adequate?

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  10. G4 native PSU in iMac is all about graphics and it is very important to configure it manually from the authentic and trusted service providers. From electric supply to G4 your tutorial is very easy to understand as well as for silicon chips with the help of BGA rework station is awesome.
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  11. Majority of people don't have any platform to get help and information about different issues of their play stations. The students who are in the field of technical education may require to prepare assignments and research paper writing making it easy to research on any topic and finally prepare the detailed reports.

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  12. Thanks for this great information.

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  13. Hello there - if the iMac G4 I'm modding has a perfectly working computer in it, would you foresee any issue with getting power from a disconnected optical drive molex? Essentially, I want the iMac to still function as a headless unit on the network for whatever function I desire while still being able to be connected the miniVGA port to a monitor should the need arise. I would love it if the monitor continued to be powered by the original PSU so when the monitor was on, the Mac was on. Any insight?

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  14. Thanks for the sharing of such information we will pass it on to our readers.
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    ReplyDelete