Blowing Fuses

[vjj]

Good morning, I am new on here so apologies if in the wrong thread. I have a 2015 iMac 27 non 5k which when in sleep mode blows the plug top fuse and now it has started doing this even in screensaver mode. Tried a new power lead plus different locations including another property so have eliminated every possible cause. I see on other forums this is an issue in some instances. Does anyone have any ideas, is it worth a repair attempt or do I buy new. The spec is high on this model so there is some reluctance but cost of repair I imagine could be quite high. Thanks for any help with this.

 

[chscag]

Welcome to our forums.

Not sure I understand what you're referring to by the "plug top fuse"? Okay.... I see you're from the UK. (You have AC cords that are protected by a fuse on both sides of the line.)

You probably should not operate the iMac until you can troubleshoot the source of the problem that's blowing the fuse. It may be the iMac internal power supply or something related to the AC main that feeds the iMac. In any event, you should get it repaired before you damage your iMac beyond economical repair.

You can always buy a new iMac but it certainly makes sense to find out how much it would cost to repair the 2015 model before you spend money for a new one.

 

[ferrarr]

Everywhere I look, all 2015 27" model year iMacs are 5k.

 

[vjj]

I purchased this in January 2015 but it is actually listed as a late 2013 model. 3.4ghz quad intel i5 16gb ram 1tb Sata 7200rpm. My issue is £160 to get it inspected and the risk that the screens don’t always come off without cracking. I am beginning to think it’s not worth the risk. It’s nothing on the mains side as it has been tried in different outlets and a different property and it still does the same. It’s a surge of some type that goes back from the iMac through the power lead (possible capacitor issue or power supply) and blows the plug fuse. If not in sleep or screensaver mode it stays on and works so there must be some type of spike causing this.

 

[chscag]

The 2013 27" iMac models were good machines. I gave one that I had to my son when I purchased a newer model.

It's very likely the internal power supply is acting up and causing the fuse to blow. Any good Mac repair shop should have no problem removing the display and changing out the power supply. Unfortunately, that will probably cost you much more than £160.

Apple has just announced a new 2020 iMac which will be the last model that contains an Intel processor. Any future iMac will be one that has Apple's own designed CPU within. Commonly referred to as Apple Silicon. I have no idea what a new iMac will cost there in the UK, but here in the US an entry level 27" model is $2000.00 and up.

 

[krs]

When you say: "I see on other forums this is an issue in some instances" do these threads mention/suggest what the problem actually is?

I assume you have used this iMac since Jan 2015 without any issues and this is something new that has come up?

If the problem is easily duplicated (which is what this sounds like), any shop should be able to monitor the AC mains with a scope to see why the fuse blows. What value fuse do you use? Is it a slo-blow or regular?
And exactly when does the fuse blow? When the iMac switches to sleep mode? or when it comes out of sleep mode, or randomly when in sleep mode?
Seems odd that you can use the iMac normally without an issue and for some reason there is a current surge in sleep mode that blows the fuse.

 

[vjj]

The 2013 27" iMac models were good machines. I gave one that I had to my son when I purchased a newer model.

It's very likely the internal power supply is acting up and causing the fuse to blow. Any good Mac repair shop should have no problem removing the display and changing out the power supply. Unfortunately, that will probably cost you much more than £160.

Apple has just announced a new 2020 iMac which will be the last model that contains an Intel processor. Any future iMac will be one that has Apple's own designed CPU within. Commonly referred to as Apple Silicon. I have no idea what a new iMac will cost there in the UK, but here in the US an entry level 27" model is $2000.00 and up.

I have looked at a new Mac but was tempted to wait it out to see if the silicon will come soon and if Adobe will get on board with the new processors immediately. It’s how long can I wait now Is the issue. I would be looking at the mid range otherwise with a memory upgrade which I would do myself.

 

[vjj]

When you say: "I see on other forums this is an issue in some instances" do these threads mention/suggest what the problem actually is?

I assume you have used this iMac since Jan 2015 without any issues and this is something new that has come up?

If the problem is easily duplicated (which is what this sounds like), any shop should be able to monitor the AC mains with a scope to see why the fuse blows. What value fuse do you use? Is it a slo-blow or regular?
And exactly when does the fuse blow? When the iMac switches to sleep mode? or when it comes out of sleep mode, or randomly when in sleep mode?
Seems odd that you can use the iMac normally without an issue and for some reason there is a current surge in sleep mode that blows the fuse.

Thanks for your response but I think truthfully I need to look at a new one. I suppose there comes a point where economics come into it in how much do I throw at a repair compared to buying a new one. As far as the fuse blowing it seems to be when it goes into sleep mode not when it comes out of sleep but in screensaver it happens randomly!!

 

[chscag]

Apple has hinted at sometime next year for a new iMac and maybe a new Mini with Apple's new CPU. We may see several portable models (MacBook Pro and perhaps a MacBook Air) with the new CPUs before the end of this year.

Adobe is a major player and has been developing software for Apple for many years and has been thru at least the last two architecture changes. I expect we will see Adobe, Microsoft, and many others who will be on board and ready when the new machines appear.

 

[TotalSolutions]

Hi vjj. Let’s talk real numbers here. I just checked my (UK) 2019 iMac 27”, and the fuse is rated at 10amp.

Are you by any chance using 3A or 5A as normal, for small appliances?
There was a spate of fake fuses. Are your 10A fuses you keep replacing from the same stock. Try a different brand, British?

You did not answer fully the question from krs.
I would like to learn more about this phenomenon.

Re capacitors in the PSU. There are suppression caps across the the full mains potential. Designed to be there and self heal. Really old caps will let out the magic smoke but that’s all. The unit will continue to work without issue and you may never know.

I am also new to the Mac, one year in now and still learning. Maybe the Mac is doing intensive housework in the background and taking more power than when you are browsing etc, then the underrated fuse slowly burns out.

Update The PSU will protect itself going into the workings of the Mac. The 10A fuse is there to provide protection for the mains lead only, nothing else. The fuse is to slow to provide any electrical safety of the PSU, only the connection cable to prevent overheating effects and ultimately a fire risk of a melt down.

Paul

 

[vjj]

I have used fuses from different sources all with the same outcome, both 10amp and 13amp. I have now made the commercial decision because of age and possible cost risk to invest in a new iMac. I actually had been considering downsizing because of where the 27” is placed which I have always struggled with and having tried a friend’s 21.5” found the size really easy to work with so not being able to wait for the new possibly 23” to arrive have just purchased a 21.5” with 1TB ssd drive and 32 gb of ram with Radeon Pro Vega graphics. Just a shame that a five year old iMac is probably commercially not worth the risk of a repair although I will keep it just in case.

 

[chscag]

Congratulations on your new purchase. I see you had the foresight to get a new 21.5" iMac that is fully loaded with enough memory and graphics. Good decision on your part as that particular machine is non upgradeable.

Don't give up on your 27" model. You may even be able to sell it and recoup some of the ££ you spent on the new machine.

 

[jasongoldworthy]

hi guys just my 2 pence here

vjj the screen removal isn't too hard for a competent person to do.

ive replaced my blade ssd in my iMac late 2013 27" and had no problems getting the screen back on without any damage.

now it does sound like the PSU is the problem but It shouldn't be sending spikes back to the fuse in the plug,

sourcing a PSU won't be an issue but fitting it may be if your not sure of doing it.

 

[vjj]

Thanks for the response. I have taken delivery now of a new iMac which I am thrilled with so maybe some time in the near future will think about a repair but would not attempt the PSU myself. It would be whether the repair costs are justified in relation to what I could sell it for but for now it sits with its face to the wall until I decide.

 

[techiesteve]

I'm curious to know after you removed the fuse from the 13A plug, did you check it for continuity or just replace it?

If just replacing it by disconnecting power you are resetting the SMC that may be temporarily be resolving your issue. If you haven't checked the fuses you removed for continuity try refitting one in the 13A plug and retesting. 27" iMac power supplies can also die intermittently and then power back on after powering off from the mains, leaving for a while and powering back on again. From my experience once the fuse blows due to a PSU fault it will immediately blow again if replaced and powered on. Either way, the fault is likely to be caused either by the PSU failing which is economical to have replaced, or the logic board with an SMC fault, uneconomical to replace.

Although your late 2013 iMac is classed as vintage and Apple themselves won't now service it, Apple Authorised Service Providers can still obtain spares until Apple's stock is depleted. Also a £160.00 inspection fee is more than most Apple Authorised Service Providers would charge. If an AASP has to order parts in to assist diagnosis they can return to Apple for full credit.

Enjoy your new iMac.

 

[vjj]

Hi
Yes I checked continuity and the fuses have blown however the new fuse would not blow when the iMac was powered up, only when in sleep or screensaver mode so that would indicate a logic board fault by what you say!! (if the screen was left on the fuse never blew) As for an AASP looking at it, not sure where you are based but none in the UK at present will look at it which I thought was disappointing yet they will repair iPhones, iPads and Macbooks etc. At this time I will sit on it and wait see what happens but in the meantime am impressed with the speed and performance of my new 21.5" which I love as it also sits better and I find easier to look at and use.

 

[jasongoldworthy]

sorry to jump on this so late again,

if it was the logic board it wouldn't take out the 13amp fuse

id say there is feedback from the PSU and its the reason its popping the fuse,

it could be dust related internally.

or even the PSU is bad and is the cheapest option to replace.

so if you do replace the PSU make sure the iMac has been off for a few hours but also press the power button a couple times also.

and then you should be fine to remove it from the innards of the iMac.

if you was closer id take a look for you

as I know these machines inside out,