I am reporting how I fixed the Mac screen connector recently. The short answer is that pins 1 and 31 are grounds, and and the frame of the connector on the board (the two anchors) should be connected to two square pads, one on each side. Here's the long story.
Last year, when trying to replace the DVD drive on the Mac, the display pulled and damaged the display connector on the computer. The computer works (displays) only when the cable is at a certain fixed angle. It has worked for months that way. I finally tried to fix it recently, as summer is coming and the temperature would be too high with the present make-shift (where the display was supported and leaning off the back of the computer at an angle, so the fans had to work hard to remove the heat). The camera on the computer was also unusable because of the big gap between the lens and the aperture on the display.
Apple's design was at fault to use such flimsy connectors when the display MUST be removed to do any work on the computer like replacing a drive. The web is full of people losing the monitor display due to these problems. Fortunately, the connector in this case was not damaged too much. I had always suspected it was a loose connection or disconnected ground.
The computer with screen was laid down with the base at the bottom, and the glass cover was lifted using the suction cup a corner at a time (using a wedge to support lifted corners). Don't ever remove the glass cover when the computer is vertical! (That was the mistake I, and I suspect, many others made.)
The display connector at the computer side is at an angle to the board rather than parallel to it (at least in my case); possibly when the display was removed last time, the connector on the display side pulled the connector from the board, disconnecting the two anchors which should be connected to ground---two small square terminals on the board, one on each side of the connector. That they were ripped by a simple pull suggests that the solder joints were cold joints (that is, not enough temperature when soldered---perhaps Apple or the factory wants to save a few penny of electricity). The ground terminals (anchors) on the connector were disconnected to the main board, and one of the two pins (these are pins 1 and 32, ground), the one on the right near the metal bracket, pin 32, seemed broken from the board also---the connecting piece of metal (pins 1 and 32 are not gold plated; the other 30 pins are). The ground of the connector on the left was soldered back to the metal square on the board using a small piece from a paper clip to bridge the gap so as not to bend it and disturb the connector (which had been working for probably 8 months or more). The right side square on the board had the metallic part actually ripped and what remained on the board did not take any solder even after flux was used. The terminal on the connector was soldered, again using a small piece from the paper clip, to the metal frame. Pin 32 was reconnected to the point on the board by using a soldering tip with a very small diameter. The tip was held steady using a long nose plier during soldering. The entire connector is then supported by a short piece of rubber sheath of telephone wire, and a shorter paper clip piece was inserted to strength it. It was then glued to the back of the connector and wedged between it and the board. The connector cannot move back towards the board (when the male connector from the display is inserted---it is quite awkward to do because there is only a very small angle to insert my hand---any force to make the insertion can damage the connector on the board. To prevent the connector from bending away from the board, a rubber band was used to hold it to the rubber sheath.
The display was put back with all 4 connectors reconnected. These are the display connector, a two pin temperature sensor wire ending in a jumper like tiny piece of plastic, a power supply wire for the display---this being the best constructed of the four connectors, and lastly, a very delicate ribbon connector with 4 embedded wires ending in very thin piece of plastic and 4 gold contacts on it. Powering the computer up, the display came on, but there was a momentary 1 inch at the bottom showing bars. This did not recur. Unexpectedly, the Mac Fan Control program went haywire: it did not display correctly. Moreover, half of the sensors were not detected and some of the temperatures were not in their normal range. The temperature reported at the CPU went to 290 degree Fahrenheit! I thought the sensors were cooked.
Other than that, the computer and display worked. Trying different settings of the Macs Fan Control, none fixed the problems. Using another fan program gave temperature of -120 degrees for one of two readings, I forgot which. Uninstalled and reinstalling Macs Fan made no difference. I almost wanted to upgrade the computer to Yosemite (10.10.3, free) to see if things might changed, but was again dissuaded by very poor reviews. I wondered it I should upgrade to merely Lion (10.7) for $20.
Since I didn't believe I could have damaged the sensors, and the display was fixed, the only cause for the fans problems would have to be the other cables. Well it turned out that the sensors were influenced by both the LCD temperature sensor and the 4 pin ribbon cable. The temperature sensor cable has a pair of wires twisted together so they get very close at the point where the stripped portions enter the jumper like connector. I separated the wires right before they enter the plastic plug; this fixed the LCD temperature problem (before, it went as high as 190 degrees Fahrenheit. when normal is about 80) . Firefox for example turned on the screen saver after a very short time because, I guess, the LCD was "too hot" according to the possibly shorted temperature sensor for the LCD.
The flimsy end of the ribbon cable was to be inserted to a receptor at the upper left, by force. They look like a "insert once" cable. Two of the gold contacts, in the form of rectangular gold leaves, had been detached from the plastic holder, making them look like creased flakes. Very carefully, they were glued back using superglue before reinserting. A long nose plier was used to do the insertion, since the hand (or finger) is too large for the opening between the computer and the display, which is about only two inches wide at the top. By carefully fixing the 4 pin wire gold terminals, the missing and erratic sensors turned normal again. This took a couple of tries to get the female receptor to "bite" the contacts without breaking them or unattaching them again.
After testing, I found the Macs Fan Control 1.2.1 program is alright. And the temperatures are where they should be, and the fans were quiet at speeds only slightly above the minimums.
To finally finish the repair, 8 screws have to be used to secure the display to the computer. I used to do this with the computer in a vertical position and gravity makes it difficult to align the holes. So I laid the computer flat or nearly so (due to the stand) and then the weight won't be a problem and aligning the holes was easy. Still the magnets make it more difficult than it should be by grabbing the screws when you are not paying attention!
Hope your repair is not as adventurous as mine.
1 