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 Post subject: Funny pop
PostPosted: Mon Dec 05, 2016 3:02 pm 
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Last night while running handbrake, I heard/saw a pop and some smoke, my iMac went dead.
It was rather comical at the time, but I did an autopsy today on my 24" iMac (A1200 model )
And it seems like the power supply blew a cap, I'm hoping that nothing else was cooked when
the ps cap blew.
There's quite a few power supplies on eBay to choose from, used and "new".
The Oem blown ps is a 614-0387, there are some listings that say the 614-0402
is compatible.
The question is, does anyone's know what the ps revision numbers are for my iMac ?


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 Post subject: Re: Funny pop
PostPosted: Mon Dec 05, 2016 6:30 pm 
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Apple service parts have two different part numbers. Exchange parts, where the service provider is expected to return the old part to Apple when it's replaced, are a seven digit number prefaced with "661-". Most expensive/durable/repairable parts are 661 parts. Non-exchange parts are generally 922- parts, but also sometimes 076- parts. Knowing the 661- or 922- part number for the part you need will reliably identify it. In your case, you probably need a 661-4183. These numbers aren't stamped on the parts and only parts available to Apple service providers get these numbers, so for some parts you need some alternative identifier like the internal part number (next paragraph). Sometimes Apple releases replacement parts with different specifications but which are backwards compatible with old parts, and these get a new part number, so there can be multiple 661 or 922 part number for a given module and any of them will work with the device they're listed for.

There are also internal part numbers stamped on the parts themselves. These number can vary between otherwise seemingly identical compatible parts. They may represent different physical layouts, components, or be assigned to parts from different suppliers. I don't really know. I do know they can vary a lot, so they're challenging to use as a reference. When I worked for an Apple Authorized Service Provider we paid no regard to them and they were never referenced in Apple's repair documentation. When a 661 or 922 part number exists, I'd try to use that number since it broadly defines a compatible part in a specific application.

A few 661 parts are permanently burned in to my brain, like 661-0474 (auto-inject 1.44MB floppy drive) because we replaced so many of them. Apple may, however, eventually reuse old part numbers so be careful if you've got a museum piece you're trying to repair.

Since I've been out of the business for quite a while Apple may have since changed their part numbering scheme, but I haven't heard anything definitive.

Bottom line, you probably need a 661-4183 since the internal part number stamped on the part can vary widely.

- Anonymous


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 Post subject: Re: Funny pop
PostPosted: Wed Dec 07, 2016 3:22 pm 
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Thanks anon, for the thorough explanation, the psu part seems inexpensive enough to
look for and try a 661-4183 numbered part.

What's interesting to me is the prevalence of bad capacitors, mind you, this iMac is 10 years old
and I'm not sure when the exploding / defective cap issue started. I lucked out on eBay with
a whole working 24" A1200 model iMac with the intention of using it as donor parts.
Examining the logic board in the donor iMac there were quite a few bulging caps.
Guess an order to mouser is due.


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 Post subject: Re: Funny pop
PostPosted: Wed Dec 07, 2016 4:35 pm 
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I think common problems with capacitors started around 2002-2003 and continued to roughly 2007. That's definitely around the time when these machines were being manufactured. I'm kind of surprised it didn't die earlier.

- Anonymous


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 Post subject: Re: Funny pop
PostPosted: Wed Dec 07, 2016 5:31 pm 
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I'm surprised that both the donor and the recipient iMacs didn't die long ago myself.
Since I'm going to recap the logic boards I'm in a quandry over which type of capacitor to
use, the original caps were Rubycon caps, MCZ series which had been discontinued in 2010.
Do I need to get specific type ( low ESR, long life, etc. ) or will a general purpose cap do just as well ?


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 Post subject: Re: Funny pop
PostPosted: Wed Dec 07, 2016 8:37 pm 
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You don't need to match the manufacturer, but you should attempt to mirror the type (uF, voltage, etc.) and general packaging dimensions, although in the latter case if you can make it fit without shorting out anything it'll be fine (within reason). If I remember right the voltage is a maximum rating, so something higher should be fine, but the uF rating should be the same. Er. Maybe higher is fine too. Sorry, I'm tired and hopefully someone else will chime in...

I've never specifically replaced caps in an iMac PSU before, since its in a cramped space with inadequate cooling there may be additional specifications to help it cope with the heat.


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 Post subject: Re: Funny pop
PostPosted: Thu Dec 08, 2016 8:41 am 
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Monkeyboy, I'm not going to recap the PSU, since I have no idea what other compnent is damaged from the
cap failure, what I'm going to do is recap the logic boards, since there are bulging caps in there.
It became confusing when reading about all the non Mac PC cap replacements, low ESR and ripple current etc.
A bit over my head at this time.


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 Post subject: Re: Funny pop
PostPosted: Thu Dec 08, 2016 10:29 am 
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There are kits. I didn't see you model number.

http://www.ifixmaccomputers.com/capacitor-repair-kit


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 Post subject: Re: Funny pop
PostPosted: Thu Dec 08, 2016 3:20 pm 
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Sorry, I thought you were doing the PSU. This is actually the third or fourth thread I'm responding to about capacitor replacement across a few sites, they must have jumbled together. Or maybe I need a nap. Definitely a nap.

As a rule of thumb when investigating replacement components I try to find data sheets on the original component and then see what same spec components are available. Places like digikey sometimes (though not always) have datasheets available for discontinued parts for a while after they've been discontinued. After that point you're stuck to the whim of the internets.

That kit looks to be a big timesaver on hunting down compatible parts.


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 Post subject: Re: Funny pop
PostPosted: Thu Dec 08, 2016 5:06 pm 
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Thanks for the link rccharles, they don't have a capacitor kit for
my iMac which is a late 2006 intel.
I've ordered caps from Mouser and Digikey, I took a stab in the dark without cross
checking the cap specs, only the diameter and height
I'm hoping that they'll work fine.
If not I'll be parting out the iMacs :)


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 Post subject: Re: Funny pop
PostPosted: Thu Dec 08, 2016 5:26 pm 
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Voltage and uF should match, otherwise you could end up popping all the new caps (if they're too low).

Also, look at this stuff. It's the devil's handiwork, I tell you.
https://www.youtube.com/watch?v=H0m_d52m1DU


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 Post subject: Re: Funny pop
PostPosted: Thu Dec 08, 2016 7:42 pm 
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Maybe of some help here
http://www.badcaps.net/forum/index.php


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 Post subject: Re: Funny pop
PostPosted: Fri Dec 09, 2016 12:13 pm 
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MonkeyBoy wrote:
Voltage and uF should match, otherwise you could end up popping all the new caps (if they're too low).

Also, look at this stuff. It's the devil's handiwork, I tell you.
https://www.youtube.com/watch?v=H0m_d52m1DU


I actually should have said that I matched the physical size as close as i could
and the capacitance and voltage as well as temperature.


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 Post subject: Re: Funny pop
PostPosted: Fri Dec 09, 2016 2:54 pm 
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Ahhhh, good. Unless you have trouble getting the old caps out you should be fine. I've heard of guys reflowing traces inside a board while trying to melt lead-free solder enough to free a part. The stuff's just nasty.


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 Post subject: Re: Funny pop
PostPosted: Fri Dec 09, 2016 4:53 pm 
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They are a pain to remove because the board is so damned thick, but if you have a good soldering iron and good flux it will be tedious but should work out.

- Anonymous


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 Post subject: Re: Funny pop
PostPosted: Thu Dec 15, 2016 7:00 pm 
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I did the recapping, but rather than do them all I just recapped the swollen ones.
That solder is s.o.b. to melt ! I started at 600F on my Hakko iron which works
great with the solder I use normally but had to crank it up to 800F,
and the solder still barely goes fluid.

The iMac passes the power up, but has now started to exhibit video issues.
I started another thread on the "solder ball theory" why the video cards fail.


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