The benefits of this screen and power supply retrofit are multi-fold. Here are a few:
Gutting out that dusty ol' CRT creates a lot of extra space inside the G3 case. The CRT and its related components literally take up the solid majority of interior space. Reclaiming this interior space provides quite a bit of room for installing a beefier ATX power supply of your choice for powering additional formerly impossible hardware mods. What could the truly creative modder possibly add with all this reclamed real estate? Probably the best reason for performing this mod is just how many new possibilities for other internal mods this opens up. Here's a few mod projects I thought of in about 5 minutes time brainstorming:
There are a few problems that have prevent others from doing this very thing. I will address these problems with practical solutions:
D-sub15 Connector: iMac video cable
pin# name description color pin# color
1 RED red signal black 17 large pink (2 of 6)
2 GREEN green signal black&wht 15 large light green (4 of 6)
3 BLUE blue signal brown 13 large light blue (6 of 6)
4 no connection
5 GND ground red 3 pink (2 of 14)
6 RED_RTN red signal return red w/ wht 18 large black (1 of 6)
7 GREEN_RTN green sig return pink 16 large black (3 of 6)
8 BLUE_RTN blue sig return orange 14 large black (5 of 6)
9 no connection
10 GND ground green 3 pink (2 of 14)
11 no connection
12 SDA sync data blue 1 yellow (3 of 14)
13 HSYNC horizontal sync purple 9 black w/ white (6 of 14)
14 VSYNC vertical sync grey 11 white (4 of 14)
15 SCL sync clock white 2 black (1 of 14)
Here is the completed hacked end connected as shown:
Here's the wiring connection chart for the adaptor cable:
ATX pins: signal: iMac connector pins:
3,5,7,13,15,16,17 Ground --> 3,5,8,10,11,13,22
1,2,11 +3.3V -> 1,12,14,16,184,6,19,20 +5V --> 4,6,2410 +12V --> 2,20,23
8,12,18 NO CONNECTION 7,9,15,17,19,21
9 +5VSB solder to jumper on main board closest to 5V battery
14 Power good solder to a ground pin on ATX side (3, 5, 7 etc)
WIRE HARNESS CONNECTOR PIN SOLDERING TIP: DO NOT SKIP SOLDER REINFORCING CRIMPED PIN CONNECTIONS. Trust me, this is necessary to do. I've seen many technicians out in the field regret that they didn't take those extra couple minutes to prevent hundreds or thousands of dollars of costly field service by soldering crimped pins every opportunity they had. A crimp is simply a mechanical connection binding a connector pin to the end of a wire, but to insure solid electrical connection over time, whereas mechanical connections loosen over time or oxidation or dirt can prevent good electrical contact, you must systematically solder all such connector pins to the wire to ensure a good durable electrical bond between them. After crimping, dab flux on top of the electrical connection crimp on the wire to clean oxidation and dirt off the wire and the pin. Quickly flow fine solder through the crimp and into the wire strands, and then rapidly cool the pin and wire off (to prevent melting) by dunking the pin into a small glass of water. Be sure not to overheat the pin or you will melt the second crimp that crimps around the wire insulation. You don't wanna do that because that crimp is primarily responsible for physically holding the wire in the pin. It acts as a strain relief for the other crimp (and its associated solder joint.) For the true perfectionist, you can effectively clean the remaining rosin solder and flux residues left over off the pin, wire, and insulation with a couple quick swipes of acetone (which evaporates leaving no residue) using a lint-free swab. It doesn't get any cleaner or more sure than that. Yeah, sure you could simply crimp them and stuff them in that white thingy, but in this case, the higher level of technical perfection is worth it in the long run.. You will likely experience far fewer or no problems at all in the future with connectorized wire harness connections degrading over time or coming loose under constant strain or mechanical vibration loosening. Paying this much attention to each micro operation also will help train yourself to be more methodical in your approaches to electronics assembly and repair practices in general, and that's a good thing from a quality perspective. If you stop to think about each thing you do, you are more likely to notice small problems which lead to larger ones later and stomp them before they get a chance.
WIRE HARNESS CONNECTOR PIN SEATING VISUAL INSPECTION TIP: When inserting pins into the back of each connector, your should feel it lock or "click" into place. Visually from the other side of the connector, you can see usually two little metal "wings" pop out on the other side which locks the pin in place from backing out when pushed on. Be sure to inspect each one visually to make sure both wings popped out. One wingers tend to break over time with any amount of constant vibration or tension and subsequently become intermittent as they slowly back out of the connector over time. If only one pops out, keep pushing on the wire until the other one pops out too. If it's being difficult, wiggle it while you push. For really stubborn ones, pull on the pin gently (don't squish it!) with a pair of needle-nose plyers wiggling it slightly from side to side to encourage the little bugger to pop out. Occasionally there is the freak pin that is defective with only one locking wing, or some small solder got onto the wing and held it in, or defective wing metal was fatigued already and broke off in the connector. For those problems, pin removal with the proper extraction tool (so not to ruin the plastic connector) and pin replacement is usually necessary.
WIRE HARNESS CONNECTOR PIN SEATING PHYSICAL INSPECTION TIP: Thoroughly double checking the integrity of each wire's physical connection to the connector is easy. This simultaneously tests the pin's crimp, the solder job, and the completeness of the pin insertion in the connector to make sure it is fully seated and locked in place. Hold the connector in one hand and use the other hand to moderately tug (pull a little more forcefully than "gental" but do not use "rip" level force) on each wire a couple times after insertion to make sure they don't back out under pressure. If you pull the wire and it comes out leaving a pin sitting by itself in the connector, chances are you overheated the pin during soldering which melts/weakens the wire, or you didn't solder at all and the crimp was too forceful which damaged the wire or too loose (in which case you will know which way it was by checking for the presence or absense of a stub of wire in the lonely pin. Logically, if you crimped it too hard, wires will break off in the pin, but if you didn't crimp it hard enough, the entire wire and all or most of its strands will simply "slip" or pull out of the pin leaving just the pin behind. Nothing will kill your harddrive or fry your main board faster than a power or ground connection which becomes loose and flakey/intermittent in its connection. It's a quick check that could stave off a big headache later.
WIRE ROUTING TIP 1: Try to keep wiring harnesses for digital data, analog video signals, wireless network antenna feeds, DC supply, and particularly AC power routed neatly, attached or zip-tied to keep them in place and as physically separated as much as possible both for electronic safety and to minimize possible interference between separate subsystems which can cause random data errors and video display distortion.
WIRE ROUTING TIP 2: For visual neatness that does not endanger overstressing the wire strands and making them fragile, make sure that all right-angle type turns made in wire routing are rounded (loosely bent) turns, not perfectly squared-corner overtight turns. Picture a square with rounded corners. That's how to do your 90 degree turns.
Pictures of the completed unit, in convertible mode.. Ah.. how svelt!
WARNING: PERFORMING THE CRT-REMOVAL AND REPLACEMENT MODIFICATIONS LISTED HERE-IN TO YOUR iMAC ARE POTENTIALLY HAZARDOUS TO YOUR HEALTH IF NOT CONDUCTED PROPERLY. THERE IS A POTENTIAL FOR HIGH VOLTAGE TO BE STANDING ACROSS THE iMAC CATHODE RAY TUBE (AS IT IS VERY MUCH A LARGE CAPACITOR IN A WAY) AND EVEN THOUGH IT IS DESIGNED TO BLEED OFF THIS STANDING VOLTAGE WHEN POWERED DOWN, YOU MUST NOT TRUST THAT THIS SELF-DISCHARGE DESIGN ASPECT ALWAYS WORKS. IT IS THEREFORE A CRITICAL SAFETY RULE TO ALWAYS MANUALLY DISCHARGE THE CRT WITH PROPER SAFE METHODS BEFORE WORKING ON OR AROUND THE CRT IN ANY CAPACITY. PLEASE READ THROUGH THIS ENTIRE MOD AND HEED ALL SAFETY WARNINGS BEFORE DOING ANY OF IT AND MIND THE WARNINGS WHILE PERFORMING THIS MOD OR DO NOT ATTEMPT TO DO THIS MOD AT ALL. THE AUTHOR OF THIS DOCUMENT CAN NOT BE HELD LIABLE FOR ANY PROPERTY DAMAGE, PERSONAL INJURY OR LOSS OF LIFE IN CONNECTION TO IMPROPERLY PERFORMED ELECTRONIC ALTERATIONS MADE IN CONNECTION WITH THIS DOCUMENT INCLUDING BUT NOT LIMITED TO FAILURE TO PROPERLY FULLY DISCHARGE ANY STANDING VOLTAGES SITTING ON THE iMAC CATHODE RAY TUBE, FAILURE TO UNPLUG AN EXPOSED POWER SUPPLY BEFORE ATTEMPTING MODIFICATIONS OR REPAIRS TO IT, AND OPERATING ELECTRONIC EQUIPMENT WITH OPEN AND EXPOSED HIGH VOLTAGE SOURCES PRESENT. THE AUTHOR IS ALSO NOT RESPONSIBLE FOR FAILURE TO READ OR COMPREHEND ANY AND ALL DIRECTIONS AND WARNINGS BEFORE PERFORMING STEPS LISTED BELOW.
YOUR IMAC'S CONTINUED OPERATION WILL BE JEOPARDIZED IF YOU DO NOT CAREFULLY PERFORM THE INSTRUCTIONS EXACTLY AS WRITTEN WITH COMPETENT MECHANICAL SKILLS. YOUR SKILL LEVEL OF SOLDERING, WIRE STRIPPING, PIN CRIMPING, EXPOXY APPLICATION AND WIRE-HARNESS HEAT SHRINKING SHOULD ALL BE EXCELLENT IN ORDER TO DO THIS MOD AND HAVE ANY CONFIDENCE THAT IT PERFORM PROPERLY AND RELIABLY. KNOW BEFORE PERFORMING THIS MOD THAT IT WORKS SOUNDLY WHEN PROPERLY EXECUTED WITH GOOD QUALITY COMPONENTS, BUT ANYONE PERFORMING ELECTRONICS MODIFICATIONS OR REPAIRS SHOULD KNOW THAT LITERALLY ANYTHING CAN GO WRONG WHEN IT COMES TO REAL TIME TESTING NEWLY CREATED ELECTRONIC MODIFICATIONS. EVEN THE BEST ELECTRONIC TECHNICIANS OCCASIONALLY MAKE A MISTAKE. FOR THE SAFETY OF YOURSELF AND YOUR EQUIPMENT PLEASE AVOID EXCESSIVE DISTRACTIONS WHEN PERFORMING DELICATE OPERATIONS LIKE SOLDERING AND CHECK OFF EACH AND ALL OF THE STEPS PERFORMED IN THIS MOD ON A PRINTED HARD-COPY OF THIS MOD GUIDE SO YOU DON'T LOSE YOUR PLACE IF INTERRUPTED OR LEAVE ANYTHING OUT TO BITE YOU LATER.
YOU WILL BE REQUIRED TO PERFORM MODERATE LEVELS OF ELECTRONIC TROUBLE-SHOOTING AND REPAIRS IN ORDER TO FIX YOUR NOLONGER FUNCTIONING iMAC IF YOU BRAKE SOMETHING, LEAVE OUT A STEP SOMEWHERE, STATIC ZAP SOMETHING, MIX UP COMPONENTS, MISWIRE A CONNECTOR, SPILL EPOXY ON SOMETHING YOU SHOULDN'T HAVE, FORGET TO REINSTALL ANY ONE PIECE, OR ANY OTHER KIND OF COMPONENT FAILURE OR TECHNICAL PERFORMANCE ERROR IN EXECUTING THE MOD. LOTS OF ODD PROBLEMS COULD POTENTIALLY HAPPEN SUCH AS A COLD SOLDER JOINT IN CONJUNCTION WITH MIS-CRIMPING A PIN ON TOP OF A WIRE INSULATOR OR A NEW COMPONENT FAILURE OR OTHER PROBLEMS UNFORSEEN BY THE AUTHOR OF THIS DOCUMENT. THIS MOD IS PARTICULARLY BAD TO MAKE MISTAKES IN EXECUTING AND COULD LEAD VERY EASILY TO UNFORSEEN PROPERTY DESTRUCTION BECAUSE THIS MOD DEALS WITH MAKING ALTERATIONS AND SUBSTITUTIONS FOR YOUR COMPUTER'S MAIN POWER SUPPLY. ONE MISTAKE OR OVERSIGHT ON A POWER SUPPLY CONNECTION COULD FRY EVERYTHING IN YOUR COMPUTER INSTANTLY NOT TO MENTION THE EXTREME POSSIBILITIES OF CATCHING FIRE OR EXPLODING AND SUBSEQUENTLY BURNING YOUR HOUSE DOWN! BE WARNED THAT SOME MISTAKE-DRIVEN DAMAGE MIGHT NOT EVEN OCCURE INSTANTLY, DEPENDING ON WHICH POWER SUPPLY LINES ARE INCORRECTLY MISWIRED TO WHAT. IF POWER LINES ARE OVERSUPPLIED BY THE WRONG VOLTAGE LEVEL, THEY COULD BURN OUT, SLOWLY OVERHEAT, SMOLDER, ARC, SMOKE, AND/OR BURN OUT OVER A NUMBER OF SECONDS, MINUTES, OR EVEN HOURS. YOU ARE ADVISED TO BE READY TO TURN YOUR COMPUTER OFF IMMEDIATELY IF SOMETHING APPEARS TO BE WRONG WITH THE COMPLETED MOD IN ORDER TO CORRECT ANY MISTAKES MADE BEFORE MORE SEVERE OR PERMANENT DAMAGE OCCURS. YOU ARE ADMONISHED TO TEST EVERYTHING OUT IN STAGES BOTH BY VISUALLY INSPECTING EACH STEP AT COMPLETION BEFORE MOVING ON TO THE NEXT AND BY ELECTRONICALLY TESTING EACH COMPLETELY SUB ASSEMBLY WITH AN OHM OR VOLT METER AS APPROPRIATE AND TO RECHECK EVERYTHING VISUALLY AGAINST THE INSTRUCTIONS AND WIRING DIAGRAMS ONCE AGAIN BEFORE FINALLY HOOKING IT ALL UP TO AC AND THROWING THE POWER SWITCH!
THE AUTHOR OF THIS DOCUMENT ASSERTS THAT YOU MUST HAVE GOOD TECHNICAL SKILLS IN TERMS OF ELECTRONIC ASSEMBLY, TROUBLESHOOTING, AND MANUAL DEXTERITY OR YOU MAY NOT BE QUALIFIED TO PERFORM THIS MOD. IF AFTER YOU READ THROUGH THIS ENTIRE MOD GUIDE YOU AREN'T COMPLETELY CONFIDENT THAT YOU ARE QUALIFIED TO PERFORM THIS MOD, THEN YOU SHOULD NOT DESTROY YOUR iMAC BY ATTEMPTING IT ANYWAYS. YOU ARE HEREBY WARNED THAT I KNOW THAT YOU KNOW NOW THAT DOING THIS MOD IS COMPLETELY AT YOUR OWN RISK. THE AUTHOR OF THIS MOD THEREFORE CAN NOT BE HELD RESPONSIBLE FOR ANY INCIDENTAL, RANDOM, INTENTIONAL, SEQUENTIAL AND/OR COINCIDENTAL DAMAGE, DATA LOSS OR REPAIRS NECESSITATED IN CONNECTION TO ANY INCORRECT EXECUTION OF STEPS IN THIS MOD, INCORRECT PART SUBSTITUTION OR ANY KIND OF POST-MOD FAILURE BE IT A RANDOM COMPONENT FAILURE OR YOUR FAILURE TO PERFORM STEPS PROPERLY IN THE ORDER AS LISTED WITH SKILL.
All that necessary legal whining err--warning crap now out of the way, and disclaimers disclosed, yaddah yaddah yaddah, if you're competent, confident, thoughtful, and methodical, this mod should work great for ya!
