Intel iMac

[twbranch]

Ok so I did a search and see that maybe one post is close to my problem. So here is my problem:

My iMac is 2006 24" (not sure the model exactly-2111?). It doesn't start. The LEDs show that the power supply is getting power and further checks point to the logic board. My question is, do you guys think it may be the caps on the logic board? Or do you have any other suggestions? I know most of you don't use Macs but maybe you know more than I do.

Thanks!

[JuniperSprouts]

Re: Intel iMac

You will want to determine the exact model of your unit.

You used to use it? It just did not turn on one day? Which LEDs light up? What "further checks" have you done? Have you disassembled it?

I have repaired 3-4 Intel iMacs. The power supply is more likely to fail than the mobo, in my experience.

[twbranch]

Re: Intel iMac

Its the EMC 2111 model A1200. I turned it on and the power light lit up and stayed on. The first two leds are lit. Thats why I am not sure it is the power supply. I have opened it up and couldn't find any obvious problems. I asked guys at ifixit.com and they are never sure about anything. I have yet to test the power supply based on the fact according to the LEDs it is supplying power. I plan to disassemble it again this weekend to do more t/s. I packed it up to send to get repaired until I found out the repair could be 700 bux. Any Ideas to help me along a bit? Thanks.

[twbranch]

Re: Intel iMac

Ok got the mobo out. The caps are ruby and chemicon. The chemi is kzj type. Heard somewhere they are suspect. What do yall think?

[twbranch]

Re: Intel iMac

Update again! Hope somebody knows something. I found L7222 burned. Not sure if its a victim or the cause but I have no schematic to get PN and it is SMD so too small to get info off of.

Anybody know of a schematic for these logic boards? Mine is an Intel 2.16mhz.

[Toasty]

Re: Intel iMac

Ok got the mobo out. The caps are ruby and chemicon. The chemi is kzj type. Heard somewhere they are suspect. What do yall think?

KZJ (and KZG) are notorious heat failure caps. Replace them.

What series are the Ruby's?

Photos?

T

[twbranch]

Re: Intel iMac

I cant get a good shot of the caps. I am goin to try to replace burned inductor and the suspect caps. I will update afterwards. However i unsure of the inductor pn.

Thanks

[Toasty]

Re: Intel iMac

No schematics. Proprietary.

Without photos, can't direct or see the inductor. Best wishes!

T

[twbranch]

Re: Intel iMac

I will have to get the pics this weekend as I am working out of town. Thanks toasty.

Do you think you can help with a picture? Hope so!

[Toasty]

Re: Intel iMac

The caps I'm not concerned with. I want to see the inductor that blew. That's usually not a good sign.

We don't see these later model ones like we did the G5's. That's why the pics will help.

[twbranch]

Re: Intel iMac

Ok. I will get a good pic of the inductor this weekend. I hate I can't do the pic tonight but I am not in town until friday. Thanks.

[twbranch]

Re: Intel iMac



Here is the pic! Hope someone can help!

[Toasty]

Re: Intel iMac

Since it and it's neighbor both seem to be across the same path, perhaps the neighbor (unburned) is open, and everything got fed through the burned one. Only way to be sure is to measure across them with an ohmmeter and see if they are conducting or open. You may end up taking both off the board as other components could fool you into thinking they are good.

Sorry, I don't have enough information to work with here. Replacements are anywhere from $99 (used) to $199 (stupid) out on the web.

Some searching produces:

http://www.applecomponents.com/items...ket/0000001392

and

http://natramelec.com/iMac24/whiteimac24.htm

I'd look at it for you, but I'm uncertain I could help.

T

[twbranch]

Re: Intel iMac

Thanks toasty. The one next to it is conducting. I have been looking for a new one but just cant seem to justify 200 bux yet.

[Toasty]

Re: Intel iMac

How do you know it's the one conducting? How did you test it?

Buy a used one for 1/2 the money.

[twbranch]

Re: Intel iMac

A little reverse engineering goes a long way. I traced the pins to where they came from on the board. That is standard procedure in my business it just takes a while to do sometimes. I have yet to find a used board except on ePay and they seem to be scarce because everybody seems willing to pay way too much for them.

Thanks Toasty.

[Toasty]

Re: Intel iMac

No, I think you are missing the point.

If other devices are across these, you cant read them accurately without removing each and testing them. The burnt one -may- still be conducting and the good one may be broken internally.

For $109, National Ram gives a 1 year warranty. Certainly better than $199.

T

[twbranch]

Re: Intel iMac

I know that. That is why I did some reverse engineering. National Ram repair power supplies. This is a motherboard.

Thanks. You did help!

[Toasty]

Re: Intel iMac

My bad. Disregard.

-edit-

Let me retract that a bit.

Damage to mobo = not good. Underlying problems in multilayer boards are impossible to repair. Nor, do you know where or what some of the vias connect to -inside- the board.

Reason for damage -may- be the power supply. As JuniperSprouts pointed out, it's a more common failure.

But as noted, KZJ's are failure-prone without any visible signs. Especially in high-heat situations.

Yes, it could be a failure on the mobo as well.
Two inductors side by side passing power to a circuit on equal terms, and only 1 fails? Very odd. That's why checking both off board is what I recommended. I would check around the board and see if there are any other inductor pairs like these.

T

[twbranch]

Re: Intel iMac

Well after further examination I found a washer loose in the case and screw missing from where it was supposed to be. Hm? The iMac has never been open before until a couple weekends ago. So I am screwed. My assessment is that the washer or screw (wherever it is...haven't found it) shorted something out and burned the inductor. No other damage found and it seems I may need to find a replacement. It sucks that a 20 cent part will cause that much damage but all caps check good and power supply checks good.

I appreciate the help!