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Modelo A1312 / Mediados de 2011 / Procesador Core i5 de 2.7 & 3.1 GHz o Core i7 de 3.4 GHz

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iMac keeps randomly restarting

My iMac keeps restarting every time I turn it on. Sometimes it doesn't get to the desktop before restarting and other times it restarts while using it.

I have already replaced the power supply with the same result. I also have tried unplugging both the HDD and the SSD and it still was restarting. I have tried switching out the RAM from another iMac and it still restarts.

When it restarts, it randomly shuts off and then boots again, sometimes over and over.

I have already taken it to an authorized Apple tech, and they told me they could never get it to reboot... the closet Apple Store is over 3 hours away so I am trying to troubleshoot this myself.

Any ideas on what I can try next? Thanks for your help!

Contestado! View the answer Yo también tengo este problema

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I think you started down the right path as being a power issue. Given the fact the Apple tech couldn't get it to fail when he had it I suspect your issue is within your homes power not your system.

First you'll need to get a cheap AC Outlet Tester to check your outlet to see if the the outlet is correctly wired. You could also have a grounding issue if you don't have a three prong outlet. This is were you will need to call in your local electrician to fix the outlet. Even still you do need to make sure the outlets wiring is correct (don't cheat here, you need all three wires). Following the wiring back to your fuse/breaker panel make sure you have a 20Amp circuit for 120volts and ideally you should have a dedicated line for your computer and your peripheral gear. Make sure the buildings Ground circuit is in good shape. Often a grounding rod stuck into the ground or strapped to the metal water line feeding the building. Over time the wire and/or the connection point corrode (green stuff) and need to be cleaned. The rod can also have degraded and may need to be replaced or positioned in a better location to be effective. Many people put electricians grease on the exposed surfaces of the connections after wiring it up to help prevent corrosion.

So we went as far as the fuse/breaker panel and we still have problems. You may need to get a UPS to stabilize the power as your power provider maybe having problems giving you reliable power. Many of the better units have power meters which can show you how good/bad your power is.

You could ask your utility provider to test your power:

Have them put a power monitor in your house for a good week or so. They may need to service your homes power feed or replace a transformer that feeds your neighborhood.

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Thanks for the help. I originally thought the same thing, that something was wrong with the outlet. I plugged the iMac into my UPS and it still has the same problems. My other iMac is plugged into the same UPS and it doesn't reboot randomly. I tried plugging it into a different outlet not on the UPS and it was still rebooting. I'll pick up an AC outlet tester though and see if the outlets are bad.

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You could try swapping the AC power cords between your systems to see if the cord is bad (less likely though)

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Okay, I have tested the outlet and all seems well on that end. I also tried using the power cord from the other imac and it still restarts randomly. Any other ideas I can try? I might try and take it to the Apple Store next time I'm in Chicago at the end of November, but I really don't want to spend more than $300 trying to get it fixed. I'm worried it could be the logic board which I've read costs ~$600 to replace.

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What happens when you take the system to work (or someone else home that is not too near you) and use the power outlet there? does it react the same way?

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Took the iMac to work and it still had the same problems. Work is about 30 miles away so on a totally different power grid. Also checked the outlets home and everything seemed fine.

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When the iMac starts-up, the graphics card supposedly uses the Intel processor does the initial work. Once you arrive at the stage when you see your user accounts, the graphics processing has been delegated to the on-board dedicated graphics card at this point.

This is also why the you can use older iMacs pre-2014in target display mode by hitting the F-2 key.

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I'm dealing with same issue now but I don't understand what you're trying to say hear please.

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I have the same problem with a refurbed model I bought from BestBuy.ca with 4 years of Bestbuy warranty... The computer clicks and shuts off as if the cord got unplugged, then reboots. Sometimes happens during the boot process, other times during regular usage (though seems to be frequently triggered by GPU usage... but not consistent).

Same results with Lion, Mavericks and Yosemite. Pretty sure it's hardware.

BestBuy Geeksquad replaced the logic board, and it still crashes. I, like you, have tried different cord, different outlet, with and without UPS, all with the same random results. Other 2008 iMac in same UPS is solid. I have to assume it's the power supply.

Going back to best buy tomorrow for them to send away again. Their no-lemon policy states that if they replace hardware 3 times, they'll give me a whole new equivalent or new current model as a replacement. I'm looking forward to my brand new 27" iMac soon!!

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Having same problems but it's really weird since sometimes it starts like if it was new and sometimes it keeps restarting when I turn it on.... But then after several times it restarts by itself I can use it like normal... Second day with this problem and let's until when my mood can take it... Closer Apple support is about 2 hours from here.....

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My iMac 27 Intel Core i7 OS X Yosemite 10.10.3 Prosessor 3.4 with 2 HD discs keeps restarting everytime I turn it on. Sometimes it doesn't get to the desktop before restarting, other times it restarts while I use it.

When it restarts, it randomly shuts off and then boots again, sometimes over and over. But it doesn't restart when using disk utility program. It just began after test & video card replacement at Apple store service ("Gatortech" in Gainsville, Fl.) The guy replaced video card and asked me to replace power inverter. I didn't get it why and what for, until I got home and turn on iMac. Have tried everything: diagnostic hardware, reinstall OS to the initial, uncheck "Automatic restart..." , recovery both HDs, Mount & Unmount HD, even reformat drives making partitions - the problem exist. Any meaningful advice would be appreciated. Thanks

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My 27" iMac. Model No. 814LL/A is crashing as well.

My iMac keeps crashing and restarting, gets grey screen with pink stripes.

Crash Report

My issues started occurring after some recent Apple updates to El Capitan, about two weeks ago.

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Crashes are mostly caused by software issues like misbehaving apps or drivers. I rare cases hardware could be the cause as well. Like a bad RAM module. Here's a good Apple T/N that goes into crashes: OS X: About kernel panics. Most of the time I try running the system in Safe Mode to see if it continues to crash. Here's a good Apple T/N on it: Use safe mode to isolate issues with your Mac.

While Apple did have a recall on some models that had a bad graphics card you should have seen some odd color or patterns on the screen when doing a clean boot (cold restart). Sadly Apple recall has ended so you'll need to get a new graphics card here.

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I'm having the same problem:

Crash Report

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Crashes are mostly caused by software issues like misbehaving apps or drivers. I rare cases hardware could be the cause as well. Like a bad RAM module. Here's a good Apple T/N that goes into crashes: OS X: About kernel panics. Most of the time I try running the system in Safe Mode to see if it continues to crash. Here's a good Apple T/N on it: Use safe mode to isolate issues with your Mac.

While Apple did have a recall on some models that had a bad graphics card you should have seen some odd color or patterns on the screen when doing a clean boot (cold restart). Sadly Apple recall has ended so you'll need to get a new graphics card here.

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Yes that is correct, when using my mid-2011 iMac in "Target Display Mode", it will freeze up, and then the iMac will eventually reboot after a minute, or two, an hour, a few hours, no set pattern. This occurs even when just using the older mid-2011 iMac in "Target Display" mode.

* The purple bars started appearing during the boot up a few months back in October 2016.

* Ran the full Apple hardware tests on the memory.

* The Apple Store ran their hardware tests, all checked out as well.

* The iMac has been completely reloaded with Mac OS, two times with a fresh install of Mac OS.

The full history of the mid-2011 iMac:

Previously, owned by a Mr. Richard Freely, the logic board and power cord had been replaced a few years ago, before I purchased the mid-2011 iMac from PowerMax located in Portland, Oregon as a previously owned iMac at a decent discount. I guess that was a mistake, should Judy purchased a new iMac, with full factory warranty.

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I have the same problem. The repair guy said that it could be the problem of logic board, so I changed a new one, but not the graphic card. When I took it home, it went well for couple of days. But then, the same problem reappeared. And I changed different electric outlet and different cord, not working. I am wondering will change the graphic card work? It's so frustrating.

Update (02/27/2017)

I think I got the problem solved.

Originally, I got the same restarting problem. So I sent it for repair, and the shop told me that it was the logic board problem. I thought since I have to change the logic board, I should upgrade it at the same time. So I changed the logic board, CPU, and SSD hard drive, but not graphic card. When it came back, it worked fine for a couple of days, but the same problem came back. Then I sent it back for test, and the shop told me it might be the hard drive problem, so they changed it and sent it back. Unfortunately, the same problem came back in a couple of days. I was desperate, and ready to buy a new iMac. Luckily, I found this post:

https://discussions.apple.com/thread/617...

In the end, I asked the shop changing the PSU unit. It's been a week, I never shut down the computer, and it never got one instant of that restarting problem.

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Same issue, response from authorized Apple tech:

"Machine worked fine for a couple of days then on restart, it showed the fault as described. Found that if the unit is cool, it will power on and boot. If it is then restarted, the fault shows. Swapped in a test power suppply. The fault remains. Issue likely to be the logic board and could be graphics card."

iMac now sold for parts and purchased new one.

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I ended up purchasing a new iMac to resolve my issue. However, the general consensus is that the technical issue is caused by the graphics card on this iMac model. A clue, is the observation of odd happenings, a gray screen with pink stripes on the screen during boot up of the problem 27 inch iMac.

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The problems have been documented over the past couple of years on Apple’s own Support Forums. Additionally, the iMacs must fall in the following serial number configurations:

The last four characters of the serial number must contain one of the following groups (for example, xxxxxxxxDHJQ):

DHJQ, DHJW, DL8Q, DNGH, DNJ9, or DMW8

DPM1, DPM2, DPNV, DNY0, DRVP, DY6F, F610

If the iMac falls within one of the above the serial number categories and is confirmed to have the graphics card issues, Apple will replace the AMD card free of charge up to three years from the computer’s purchase date. Additionally, if an affected iMac user had their graphics card already replaced at cost, the customer is said to be eligible for a refund.

https://9to5mac.com/2013/08/16/apple-ope...

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I have the same model and had this problem and narrowed it down to the video card.

Argued with the apple service guy and after replacing power inverter, problem remained. Finally failed the apple video card test and got a replacement free from Apple.

A year and a half later, and the problem has returned. Out of 1 year warranty of course. Sometimes I can run 3D benchmarks for hours with no problems, other days just reboots after starting login.

Removed the card and stable as anything. At this point a AmD 6970 is too expensive and how long will it last?

I'm going to put a slower 6770 in it this time. Sucks for high end games, but at least I can get a few more years out of what is otherwise a great system.

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I had the same problem with a Imac bought in 2017. Random restarts. After trying everything I knew, I took it to the Apple Store and they told me it was completely fine but when I brought it back, same issue. I tried to upgrade it to Mojave to see if that would clear whatever but it actually made it worse and would freeze and give me a black screen. After a downgrade I had an idea that it must have something to do with the graphics card possibly overheating( at times the fan would spin loudly during a freeze) Installed macs fan control and had it target the GPU diode and havent had a freeze since. I am an IT guy and this is a company computer but I really expected Apple’s people to know more than a random help desk dude.

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Seems like you solved it. The main issue is overheating. I had the same issue on my 2011 iMac as well.

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My solution was cleaning the cooling vents to allow the system to breath — core temps didn’t approach the auto-cutoff. I suspect the interior boards and bits need a good dusting, too — that’ll be the next step if the exterior cooling doesn’t resolve things completely. Design flaw — too pretty for its own good so it can’t breath worth a dang — fans included.

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I have the same computer as yours and the same issue for months. Last year I bought a new iMac to replace it (iMac Pro baseline) and since then I tried everything like you did to save the old one. I replaced the power supply as well. I detached original SSD and HD, once at time and both also, disconnected the motherboard, disconnected superdrive, tried to install a very old mac OS (Mavericks). I realize now it's been 5 years ago for you, but I only have read now. The strange thing is the computer is behaving like when there is a power loss, but after that is restarting itself and at login (when it works) doesn't say "Your computer shut down because a problem". When is on and powered for at least 30 minutes, that trouble doesn't happen anymore, and I tried the graphic test "Valley" for long time, with very intensive use of the GPU, so, GPU have to be ok. I'm giving up, though, don't know what to try anymore.

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Hi, try replacing the CMOS/SMC battery. If your mac is more than five years old it could cause funny issues like that. Also, if your iMac is overheating, go for TG Pro to help regulate fan speed and temperatures. Of course, go for a new thermal paste prior to doing that.

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https://support.apple.com/en-us/HT200553

This is Apple’s HOW-TO solve this problem.

I think it’s better to print out and do the testing according to Apple’s step-by-step plan.

==================================

If your Mac spontaneously restarts or displays a message that it restarted or shut down because of a problem

In rare cases, your Mac might spontaneously restart, become unresponsive, turn off, display a message that your computer restarted because of a problem, or display a message that you shut down your computer because of a problem.

About unexpected restarts

In rare cases, your Mac might encounter an unrecoverable issue affecting all open apps. When this happens, your Mac must be restarted. This is sometimes due to what is known as a "kernel panic" because an underlying part of the operating system (the "kernel") has determined there is an issue that requires a restart.

If your computer experiences a kernel panic, a message may appear for a few seconds explaining that the computer has been restarted: "Your computer restarted because of a problem. Press a key or wait a few seconds to continue starting up." After a moment, the computer continues starting up. 


Preventing unexpected restarts

In most cases, kernel panics are not caused by an issue with the Mac itself. They are usually caused by software that was installed, or a problem with connected hardware.

To help avoid kernel panics, install all available software updates until Software Update reports, "Your software is up to date." OS X updates help your Mac handle the kinds of issues that can cause kernel panics, such as malformed network packets, or third party software issues. For most kernel panics, updating your software is all you have to do.

After your computer restarts

Once your Mac restarts successfully, an alert message appears, "You shut down your computer because of a problem."


Click Open to re-open any apps that were active before you restarted. If you believe the issue may have been caused by one of the apps that you were using, click Cancel instead. If you don't click anything for 60 seconds, OS X automatically continues as if you had clicked Open.

Note: If your computer is unable to recover from the issue, it may restart repeatedly, and then shut down. If this happens, or if you see the "computer restarted because of a problem" message frequently, see the Additional Information section of this article for guidance.

Reporting the issue to Apple

Once you log in, OS X lets you know that, "Your computer was restarted because of a problem."


Click "Report…" if you want to see details related to the issue. You can also send these details to Apple. Sending these reports helps Apple to investigate the kinds of issues that cause panics to occur. Viewing the report may also provide additional clues as to what caused the issue. 


Note: If you find the term "machine check" in the "Problem Details and System Configuration" field of this report, it may indicate a hardware-related issue. See the Additional Information section of this article for guidance.

Click OK to send the report to Apple, or close the window to dismiss the report. If the issue doesn't happen again during the next few weeks, the issue is likely resolved.

Software known to cause kernel panics

OS X Mavericks helps you correct kernel panics related to software you may have installed. If the cause of the kernel panic is known, Mavericks offers to help you disable its related software:

  • If "More Info…" appears, click it to see more details about the issue, including possible workarounds or resolutions.
  • Selecting the option to "Ignore" does not alter the software that may be related to the issue.
  • "Move to Trash" moves software that is likely related to the issue to the Trash, but the Trash is not automatically emptied. When you select this option, an additional sheet appears:
  1. Click "Restart" to disable the software that may be responsible for the issue.
  2. When prompted, enter an administrator name and password.
  3. Click "Move to Trash".
  4. After restarting, the related software is in your Trash.

Click the Trash icon in the Dock to see which software was removed. 

Contact the developer of the software to see if an update or more information is available.

  1. Empty the Trash if you want to permanently remove the third party software.

Additional Information

Read the following information to learn more about diagnosing and troubleshooting a recurring kernel panic.

Troubleshooting a recurring kernel panic

Diagnosing a recurring kernel panic can be difficult. If you need help with this process, consider bringing your Mac to a Genius at an Apple Store or an Apple Authorized Service Provider for help.  If you plan to visit an Apple Retail store, you can make a reservation (available in some countries and regions only).

Tip: To help diagnose recurring kernel panics, record the date and time it occurs, and any information that appears with the kernel panic message.

  • Was the computer starting up, shutting down, or performing a particular task when the recurring kernel panic happened?
  • Is the kernel panic intermittent, or does it happen every time you do a certain thing? For example, were you playing a particular game, or printing at the time?
  • Does it occur only when a certain external device is connected, or a device is connected to a certain port?

Isolate hardware or software as the cause of the issue

To try to figure out if the issue is related to software or hardware, use the computer with a fresh installation of OS X on an external drive.

  1. Start the Mac from OS X Recovery. 

If a kernel panic still occurs when started from Recovery, there is likely a hardware issue. See the "Hardware troubleshooting" section below for additional information.

  1. Open Disk Utility and use "Repair Disk" on your Mac's internal hard drive (named Macintosh HD by default).


Important: If Disk Utility is unable to repair the internal drive, you should back up your important data immediately and if possible, reformat the drive. Consider bringing the Mac to a Genius at an Apple Store or an Apple Authorized Service Provider for further diagnosis. Be sure to ask that, if the drive needs reformatting or replacing, they contact you about escalating your case to a special data recovery service. If you plan to visit an Apple Retail store, you can make a reservation (available in some countries and regions only).

 

  1. Connect an external drive with at least 10 GB of free space. Note: Make sure the external drive does not cause kernel panics, and is the only device on its USB, FireWire, or Thunderbolt port. Connecting the external drive and its cables to another Mac can help make sure the drive does not cause kernel panics.
  2. Install OS X on the external drive.
  3. Start up from the external drive.
  4. Use Software Update to install all updates until it reports "Your software is up to date."
  5. Don't install additional software on the external drive, but instead use the Apple applications to surf the web, view QuickTime movies, email, print, scan, and/or other activities. Continue using your Mac for the amount of time it would usually take for the issue to occur.
  6. If a panic occurs, select the "Hardware troubleshooting" section below to further diagnose the issue.

If a panic does not occur, select the "Software troubleshooting" section below article to further diagnose the issue.

Hardware troubleshooting

Disconnect the external drive used in the above test to determine if the kernel panic is due to a hardware issue.

Check peripheral devices first

Go to the next section if you have no devices attached to your Mac.

  1. Turn off your Mac.
  2. Disconnect all peripheral devices. If you have a desktop Mac, make sure all you have connected is a display and Apple keyboard with Apple mouse or trackpad.
  3. Turn on your Mac.
  4. Use your Mac for the amount of time it would usually take for a kernel panic to occur.
  5. If a kernel panic does occur: Proceed the next section to check the internal RAM and third-party hardware.

If a kernel panic does not occur: Power down the Mac and connect one peripheral device at a time and test until a kernel panic occurs.

  • Note: A combination of peripherals may be the cause of a kernel panic. Disconnect one peripheral at a time to see if it causes a kernel panic by itself. If the kernel panic does not occur, continue to add peripherals until you find the other peripheral needed to cause the kernel panic.

Check internal RAM and third-party hardware

  1. Turn off your Mac.
  2. Reseat the Apple RAM, and remove third-party RAM and third-party internal hardware.  If you do not have the Apple RAM that came with the system, reseat the third-party RAM.
  3. Turn on your Mac.
  4. Use your Mac for the amount of time it would usually take for a kernel panic to occur.
  5. If the kernel panic does not occur: The third-party RAM or internal third-party hardware may need to be replaced.

If a kernel panic does occur:  Bring your Mac to an Apple Store, or an Apple Authorized Service Provider for service and support. Be sure to ask that, if the drive needs reformatting or replacing, they contact you about escalating your case to a special data recovery service. If you plan to visit an Apple Retail store, you can make a reservation (available in some countries and regions only).

Software troubleshooting

Disconnect the external drive used in the above test to determine the kernel panic is due to a software based issue.

  1. Start the Mac from OS X Recovery and reinstall OS X on your Mac.
  2. Start from the installation of OS X you just created.
  3. Use Software Update to install all updates until it reports "Your software is up to date."
  4. Download and install any third-party software updates before reinstalling third-party software, especially drivers and kernel extensions.

     Examples include:

  • Virtualization software
    • Drivers for add-on third party display cards
    • Anti-virus software
    • Networking software (especially software which enables third party network devices)
    • Add-on file system support software; for example, software that lets your write to NTFS formatted media.

If the issue continues, you will need to erase and install OS X as follows:

  1. Start the Mac from OS X Recovery.
  2. Complete a disk image backup via Disk Utility of the internal drive to an external drive with enough free space.
  3. Erase the internal drive using Disk Utility.
  4. Install OS X.
  5. Start from the internal drive.
  6. Use Software Update to install all updates until it reports "Your software is up to date."
  7. Re-install your third-party apps and copy your user data from the disk image backup you created in step 2. 

Note: Avoid copying data from the /Library and /System folders on your backup disk image.

Advanced information about kernel panics and panic logs

You can check kernel panic logs for more information. The kernel panic text is added to the log after you restart the computer, assuming that you did not reset PRAM (the kernel panic text is stored in PRAM until you restart). In Mac OS X v10.6 or later, the logs are located in in /Library/Logs/DiagnosticReports.

Information that may aid developers in the investigation of a software issue may be in the log. The information may also provide clues as to what may have caused the kernel panic.

Understanding and Debugging Kernel Panics – This technote addresses kernel panics: what they are, how to read panic logs and how to debug the code that caused the panic.

Kernel Core Dumps – This technote explains how you can enable remote kernel core dumps used to collect data about the kernel panic.

Note: If you are a software developer, booter settings and debug flags may cause different symptoms for kernel panics.

Information about products not manufactured by Apple, or independent websites not controlled or tested by Apple, is provided without recommendation or endorsement. Apple assumes no responsibility with regard to the selection, performance, or use of third-party websites or products. Apple makes no representations regarding third-party website accuracy or reliability. Risks are inherent in the use of the Internet. Contact the vendor for additional information. Other company and product names may be trademarks of their respective owners.

Published Date: January 14, 2018

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On the iMac (21.5-inch, Late 2009) I noticed that the built in wireless would go out after a few minutes of operation and thereafter would reboot. Having tried all other suggestions here and other sites and opening up iMac to clean and check boards I found that turning off the Apple wifi resolved the repetitive rebooting. I installed a wifi adapter card and solved this iMac’s problem.

Also found the Apple fan control very useful to keep temperatures down.

Hope this helps.

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