Model A1225 / Mid 2007 and Early 2008 / 2.4, 2.8, or 3.06 GHz Core 2 Duo processor

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Display hat Streifen und Mac startet nicht - Screen has stripes

Mein iMac 24" A1225 2,8 GHz Core 2 duo produziert Streifen im Bild, startet aber nicht durch.

Startsound kommt, alle 4 StatusLED leuchten ständig, aber sobald das Display den weißen Hintergrund zeigt, liegen bunte senkrechte Streifen darüber. Manchmal wechseln sie die Farbe oder haben anderes Muster. Man sieht immer im Hintergrund den Apfel und den drehenden Kringel, aber er fährt nicht hoch.

Manchmal, nach etwa 20 - 30 sec flackert das ganze Bild in großen orangenen waagerechten breiten Streifen mit weiß oder schwarz.

Grafikkarte defekt? oder Inverter defekt? oder LCD-Display defekt?

Wo bekomme ich sinnvolles Ersatzteil oder die Reparatur?

Gruß Bernd

English - Screen has stripes and Mac will not start

''My iMac 24 "A1225 2.8GHz Core 2 duo produces banding in the image, but does not start through.

Startup sound comes every 4 status LED lights constantly, but when the display shows the white background, colorful vertical stripes lie about it. Sometimes they change color or have different pattern. You always see in the background the apple and the rotating curl, but it does not boot.

Sometimes, after about 20 - 30 sec flickers the whole picture in big orange horizontal stripes with wide white or black.

Graphics card broken? defective or inverter? or LCD screen broken?

Where can I get meaningful parts or repair?

Greetings Bernd''

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Bernd, have you tried to connect an external monitor to the mini-2. DVI port. Does the external display exhibit the same problems?

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Hi

yes, today I tested with an adapter MiniDVI to VGA, but the external monitor doesn't say anything. Perhaps it is cause the system does not boot? On the internal display there are still the stripes.

Do you have a graphiccard, may be an old one, to test with?

Many thanks

Bernd

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It sounds like you may have a power supply problem.

Do you have access to the recovery CD/DVD that came with the system? Or, do you have an external FireWire/USB (self-powered) HD or SSD which you can use to start your system? That way you should be able to see if the HD is reacting badly because it can't get enough power. If it boots up it may freeze up so don't let that alarm you.

Do you have a UPS or a serge protector for your system?

German: Es klingt wie Sie ein Problem mit der Stromversorgung haben können.

Sie haben Zugriff auf die Recovery CD / DVD, die mit dem System geliefert wurde? Oder haben Sie eine externe FireWire / USB (self-powered) HD oder SSD, die Sie verwenden, um Ihr System starten können? Auf diese Weise sollte es möglich sein zu sehen, ob die HD schlecht reagiert wird, weil es nicht genug bekommen können Macht. Wenn es bootet es einfrieren kann bis so lassen Sie sich nicht, dass Sie Alarm.

Haben Sie eine USV oder ein serge Schutz für Ihr System?

Update

Sorry for the bad news here ;-{

You'll need decide if this system is worth putting the effort in to bring it back to life. Getting a new (or used) graphics board should still be possible. You'll need to look on eBay/Goggle to find one.

To repair this you'll need to follow this IFIXIT guide to take the logo board out: iMac Intel 24" EMC 2111 Logic Board Replacement Go to Step 47 of this guide to get the board off iMac Intel 21.5" EMC 2428 GPU Card Replacement it is similar to yours.

iMac Intel 24" EMC 2111 Logic Board Image

Guide

iMac Intel 24" EMC 2111 Logic Board Replacement

Difficulty: Difficult2 - 4 hours

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Hello

I also have another HD with complete installation, that has been installed, before I get the problems. After changing to the first HD, the problem is the same. I don't think that the hd could be the problem. I could use the former internal HD outside with external power to test weather the system would start with it. I'll test it.

Do you think, that one of the voltages is not good?

I can't imagine that.

The stripes are visible directly on the screen. They don't appear a few seconds later on the screen.

I think the problem is more in the graphics card or display ...

Thanks for answer.

Greetings Bernd

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The power supply offers multiple power feeds. In this case I suspect one of the feeds is not working correctly. Yes, the Graphics board is driving the display and is being effected here. A bad capacitor in the power supply is a possibility, which is why the problem appears then goes away. The reason I wanted you to use an external drive was to isolate out the power draw it needs to see if your system is able to startup fully.

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Hi Dan

I now find the time to do the tests.

I have an internal 3,5“ HD that has been working in the mac before. With this system (10.8.2) I’m able to start for example my macbook pro.

But connected to the iMac the problems with the strips are the same.

I start the mac and directly on the white screen there are the colored vertical stripes. By holding „Alt“ I can choose the external HD (visible behind the stripes) and start with it. But the OS doesn’t start completely. For a minute or two you see the circle circling and then it stops and freezes. I have also windows via boot camp on the HD. By starting this you get dark screen and after 1 minute you hear the start sound of windows 7, but the display shows nothing.

What else can i check? Or do you still think, one of the power feeds is not correct.

I have a multimeter and a stroboskop. Is there a way to check the voltages?

Greetings Bernd

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I think you got confused here. I didn't have any worries about your HD. I suspect your power supply or the display has an issue. To figure out which I wanted you to use an external HD to boot up you're system. But, it needs to use it's own power source so you remove the power draw of the HD off your system. Hopefully, this then allows your system to fully load.

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Ah, ok. So I will test as followed:

I open my mac an unplug the power supply from internal HD.

Then I start the system with the external HD with its own power supply.

I tell you tomorrow the result.

I must say, you have very much patience in helping me. And excuse my English, it's not very good.

Many thanks

Bernd

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