iMac won't turn on

[williambr]

I have this problem on my iMac, when I press the power button it makes the noise of the dvd drive and does not turn on, only the logic board led 1 is on, to turn it on, I have to plug in the power supply connector of the motherboard leaving the bottom part fitted and the top part a little disengaged and press the Power button until the noise of the DVD drive is emitted, so I give a light touch on the connector so that the top part fits a little, this way the leds 1, 2 3 and 4 light up, and the iMac turns on and works normally, only when turning off it is necessary to do this procedure again, what could this be, could someone help me?

 

[zarmanto]

This is just a guess... but I think you may have some solder joints under that power connector on the motherboard which have broken loose. You're not just partially disengaging the top part of that connector; you're also putting pressure on the connector, enabling those solder joints to remain securely engaged long enough to get past post. After you release that pressure, the loosely touching broken solder joints are really only permitting a trickle of power ... not quite enough to post, as you've observed, but perhaps just barely enough to operate under most normal loads. Honestly, you're on borrowed time right now, because those loose joints could be causing stress on other components whenever the computer is running.

If you're handy with a small tip soldering iron, it might be possible to fix it yourself. If it's an older computer with which you're just experimenting, have at it. But if you can't afford to have that computer abruptly give up its last puff of magic blue smoke, I'd suggest it may be time to take it to a professional.

 

[williambr]

This is just a guess... but I think you may have some solder joints under that power connector on the motherboard which have broken loose. You're not just partially disengaging the top part of that connector; you're also putting pressure on the connector, enabling those solder joints to remain securely engaged long enough to get past post. After you release that pressure, the loosely touching broken solder joints are really only permitting a trickle of power ... not quite enough to post, as you've observed, but perhaps just barely enough to operate under most normal loads. Honestly, you're on borrowed time right now, because those loose joints could be causing stress on other components whenever the computer is running.

If you're handy with a small tip soldering iron, it might be possible to fix it yourself. If it's an older computer with which you're just experimenting, have at it. But if you can't afford to have that computer abruptly give up its last puff of magic blue smoke, I'd suggest it may be time to take it to a professional.

I just checked the connector and all the pins are soldered on the board, even so I resoldered the pins again and the problem still persists

 

[williambr]

This is just a guess... but I think you may have some solder joints under that power connector on the motherboard which have broken loose. You're not just partially disengaging the top part of that connector; you're also putting pressure on the connector, enabling those solder joints to remain securely engaged long enough to get past post. After you release that pressure, the loosely touching broken solder joints are really only permitting a trickle of power ... not quite enough to post, as you've observed, but perhaps just barely enough to operate under most normal loads. Honestly, you're on borrowed time right now, because those loose joints could be causing stress on other components whenever the computer is running.

If you're handy with a small tip soldering iron, it might be possible to fix it yourself. If it's an older computer with which you're just experimenting, have at it. But if you can't afford to have that computer abruptly give up its last puff of magic blue smoke, I'd suggest it may be time to take it to a professional.

the connector is ok, I kept the connector in the same position that makes the iMac turn on, then I turned off the iMac and tried to turn it on again and it did not turn on, that is, whenever it is turned off it is necessary to remove the power connector from the board and do the procedure described above

 

[zarmanto]

Huh.

Have you considered removing the faulty connector from the equation? First run would be desoldering it from the board and detaching the cable from the other end of the connector, and then attaching wires jumpering from the board to the cable. Make sure your jumper wires are as close to the gauge of the original wiring as possible without going smaller, of course. If that works, a replacement connector would be a reasonable second run. If it doesn't... well, in that case you probably just broke it even further -- but I'm guessing you're okay with that risk if you've already tried resoldering the connector.

It probably goes without saying that you need to be very careful about mapping the wires to the board correctly, or this could turn into yet another opportunity to release the blue smoke... so keep one hand hovering over the off switch of your power strip, and make sure your fire extinguisher is close at hand, just in case.