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Old 06-14-2020, 12:36 PM   #1
MAVA
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Default Another dead Apple A1418 21.5" i5 computer

Good day Gentelmen,

Hope everyone is staying safe these days...

Got a dead A1418 with NO service LED's turning on, yet I guess it is a popular thing with this generation of iMacs.

Searched the entire forum here for anything on a dead iMac with no service ON.. LED(s) with a supply that puts-out 12v at the power connector. I guess mine is the exception with a unique problem.

I was expecting to see multiple voltages like a PC power supply from that six-wire output, but all it's just "+12v DC"( 3 wires for ground and 3 wires for +12.1v ). All the other voltages needed the main digital board regulates them down.

Wondering if really the "Power Good" connector really has anything to do as it really seems I should have the one-LED lit-up with the 12.1 volts at the main output terminals, or did the "power good" electronics on the power supply went out, and it just cannot communicate with the digital board.

The power supply is a Delta Electronics ADP-185 BFT CCA. Some numbers on the supply are +12.1v @15.4A TDC-168

I wish I had a pin-out of the power-good connector, or maybe inject some voltage, orrr short something to jump-start it to see the diagnostic LED(s) come-on.

I removed the main board and removed the coin battery, and shorted the terminals of the digital board at the coin battery, and my coin battery is measuring 2.99 v

Should I just gamble it and buy another power supply when I have 12.1v at the main terminals?

Some other info on this A1418 iMac it went dark on a stormy day in Puerto Rico.

Any suggestions/tips...

Thanks,

Martin
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Old 06-17-2020, 04:50 PM   #2
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Default Re: Another dead Apple A1418 21.5" i5 computer

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Originally Posted by MAVA View Post
Some other info on this A1418 iMac it went dark on a stormy day in Puerto Rico.
That's an important piece of information.

It could be that a power-surge has damaged the PSU.

But it could also be a power-surge has damage something else, typically through a long cable for a peripheral device. In that regard, was the iMac connected wirelessly to the Internet, or through an Ethernet cable? The latter can cause damage to the motherboard if a very long Ethernet cable is used.

Of course, it could also have been a random failure on the motherboard too.

On that note, do you know the GPU model of your iMac?
I'm not well-verse in iMacs at all, but I do know some of them did have issues with AMD/ATI GPUs.

Last but not least, some pictures of your board and PSU might help.

Quote:
Originally Posted by MAVA View Post
Should I just gamble it and buy another power supply when I have 12.1v at the main terminals?
If the price of a replacement PSU is reasonable to you (vs. spending time to trying to troubleshoot something else), then go for it. I'm not sure what that PSU should output, so I can't tell you if 12.1V on its output is good or not. Hopefully someone with more Macs knowledge will chime in here to answer that.
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Old 06-18-2020, 04:36 AM   #3
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Default Re: Another dead Apple A1418 21.5" i5 computer

meh, send it to the rossman group
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Old 06-19-2020, 08:40 AM   #4
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Default Re: Another dead Apple A1418 21.5" i5 computer

LOL, Rossmann is too busy being led around by his dragon lady to work on anything he has to go make videos with her buying crappy half million dollars in New York to put on youtube. 3rd re-post with less offensive language is that good enough for the gestapo on bad caps? or does it still offend someone?
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Old 06-19-2020, 09:42 AM   #5
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Default Re: Another dead Apple A1418 21.5" i5 computer

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Originally Posted by BigTroll View Post
LOL, Rossmann is too busy being led around by his dragon lady to work on anything he has to go make videos with her buying crappy half million dollars in New York to put on youtube. 3rd re-post with less offensive language is that good enough for the gestapo on bad caps? or does it still offend someone?
Jawohl, Mein fuhrer!
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Old 06-19-2020, 10:54 AM   #6
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Default Re: Another dead Apple A1418 21.5" i5 computer

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Jawohl, Mein fuhrer!
Such a lack of professionalism from the staff here...
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Old 06-19-2020, 11:09 AM   #7
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Default Re: Another dead Apple A1418 21.5" i5 computer

Staff get paid, volunteers don`t.I`m quite happy doing what i do. Can we get this thread back on track, it is a tech forum afterall .
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Old 06-19-2020, 11:24 AM   #8
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Default Re: Another dead Apple A1418 21.5" i5 computer

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Staff get paid, volunteers don`t.I`m quite happy doing what i do. Can we get this thread back on track, it is a tech forum afterall .
Agreed, but all I am asking for is a fair shake, my original post probably worded a bit dirty for this thread, but it just disappeared and I didn't know why I thought maybe it was a software error so re-posted a similarly worded post. At about that time per hansson finally told me the reason why it was removed which I appreciate. I posted a 3rd time with the language removed, then you came in giving your 2 cents which is fine, but if you did your job right and let me know in the first place I wouldn't have posted it again. People are fed up being shadow banned and posts being removed on other platforms without knowing reason, being transparent goes along ways toward building trust.
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Old 06-19-2020, 01:11 PM   #9
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Default Re: Another dead Apple A1418 21.5" i5 computer

Quote:
Originally Posted by momaka View Post
That's an important piece of information.

It could be that a power-surge has damaged the PSU.

But it could also be a power-surge has damage something else, typically through a long cable for a peripheral device. In that regard, was the iMac connected wirelessly to the Internet, or through an Ethernet cable? The latter can cause damage to the motherboard if a very long Ethernet cable is used.

Of course, it could also have been a random failure on the motherboard too.

On that note, do you know the GPU model of your iMac?
I'm not well-verse in iMacs at all, but I do know some of them did have issues with AMD/ATI GPUs.

Last but not least, some pictures of your board and PSU might help.


If the price of a replacement PSU is reasonable to you (vs. spending time to trying to troubleshoot something else), then go for it. I'm not sure what that PSU should output, so I can't tell you if 12.1V on its output is good or not. Hopefully someone with more Macs knowledge will chime in here to answer that.
Thank you for your post...

I will pull that info out of the GPU if it matters... The power supply was cheap, so I took the gamble and bough another one, and NO LEDs AGAIN
I did poke around and removed the heat sink and found the thermal paste almost dried up, and Puerto Rico is hot and humid, and some of the screws had a ting of rust on them

I'm no genius at board level with Mac's, but I did have have one get hot to kill the hard drive(data-wise), so I put new thermal paste-American Made stuff... as the paste was powder from a 13 year old iMac 24"

I separated the boards from the housing, and I will be thermally looking for a short, or a fuse of some kind on the board

But the replacement power supply was a NO-GO even with 12v at the terminals, so it is another demon....

Quote:
Originally Posted by Uranium-235 View Post
meh, send it to the rossman group
Thank you, but most of us here on BADCAPS are asking for punishment, and trying to fix it A-LA-Cheap, Yet I have looked at a few videos, but nothing exact, but saw one with a shorted FET on the board, but it still had ONE-LED, but I got NONE... LEDs, so hoping for that fuse.......

No LEDs with replacement power supply, and I have 12.1v with replacement supply too...

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Old 06-19-2020, 01:23 PM   #10
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Default Re: Another dead Apple A1418 21.5" i5 computer

MAVA Iam sorry I didn't mean to crap on your thread, My 2010 iMac had black screen but it was a dead GPU and I replaced it but I bet the 2012 wont be so simple. Also louis doesn't seem to focus on Mac mini's or iMac's as they aren't profitable for his business so finding information or repair videos seems to be a bit more limited.
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Old 06-19-2020, 03:03 PM   #11
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Default Re: Another dead Apple A1418 21.5" i5 computer

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Originally Posted by BigTroll View Post
MAVA Iam sorry I didn't mean to crap on your thread, My 2010 iMac had black screen but it was a dead GPU and I replaced it but I bet the 2012 wont be so simple. Also louis doesn't seem to focus on Mac mini's or iMac's as they aren't profitable for his business so finding information or repair videos seems to be a bit more limited.
It is all cool

The web is loaded with many "fixes". I do not normally fix these PCBs, but I'd like to get it going if I spend a little time, but like everything else we can always buy or replace our selves out of problem in this world. I know I can find the PCB's for around 100usd, yet it may a fuse(wishful thinking) or trace because I have NOTHING in terms of LEDs

I'm idling, so I got time to spare.

Martin
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