Macbook pro PS gone phut.

My wife’s MacBook Pro power supply went phut yesterday. If had a look inside and a reasonably sized resistor has burnt out (about 4mm in diameter).
Is there any point in just replacing the resistor or has something else almost certainly blown as well (even if invisibly)? If so, what would be the next most likely candidate? Bridge rectifier?
Tim
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The problem can be with SMPSU's is that when they do go 'phut' they can take a few bits with them, so if you replace one bit, it goes phut again very quickly when powering back on.
A neighbour gave me his old / big Dell monitor because it was 'dead'. I opened it up and noticed quite a bit of damage (burned devices and tracks) on the SMPSU. Reading up on it it seemed people had spent quite a lot of time replacing ever increasing numbers of components because sometimes, getting all of the damaged bits replaced and the PSU working again ended up costing quite a bit.
Not wanting to waste such time and money (on something quite dangerous), I searched out and found a new PSU from China and just swapped out the most important capacitors for the recommended / quality branded ones and now I have a nice big monitor. ;-)
However, swapping out the actual PSU 'guts' might not be an option with your particular PSU but the good news is that being fairly expensive (Apple), if it is a known / common thing, someone out there should have fixed it (Youtube)?
Cheers, T i m
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Does the machine still run on the battery? If so then I'd suggest you might be better off getting a replacement psu.
Not knowing the circuit I could not comment further. I had a dell go down, reason? Damaged cable from the psu to the laptop, it could be seen where it had melted near the power plug on the computer itself, I imagine psus do not like a sudden short across their output and something will give. However you need to get yourself a meter and check a few things. If I could see, I'd probably first decide if its a switch mode or not. The give away is that it will have a tiny transformer, but if its analogue then it will have a big heavy one. If its a switch mode then, personally I'd not mess with it any more its knackered. However if its an analogue, which these days is unlikely, take out the bridge and see if there is ac volts on the transformer secondary, Put a battery across the bridge in either direction, and measure the volts on the other two legs, It should be the same polarity no matter which way around the battery is placed. If it is not then the bridge is dead. Then you need to figure out what the circuit itself after that does. Very old psus were simply a smoothing capacitor and that was it, but I suspect there is at the very least some kind of regulator in there.
From your description though my feeling is that its fried quite a lot of stuff. You need a manual. As though, I suspect a switch mode, mostly these are bin it jobs. Brian
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The best designed ones handle that fine.

They all are now.

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Nope, those don’t usually die by themselves.

Yes, almost certainly.

Very likely.

That wouldn’t normally see a power resistor fried because the rectifier usually fails open circuit. More likely the main ic controller that has failed in a way that has the switching transistor on all the time instead of being switched.
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Okay. I guess I’ll ditch plans to try and mend it. I’ll keep the magnetic power lead though as it’s in good nick and we’ve had one of these fail in the past.
Tim
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That doesn’t appear to be burnt out from the later photo.
Presumably you mean its open circuit,

But if its just open circuit, likely it would be worth trying.

I'd replace the resistor if its just open circuit.

Yeah, they lead a pretty hard life,
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On 07/10/2019 22:25, Tim+ wrote:

Bullshit.
Most failures on PN junction start as a loss of bakwards resistance due to reverse breakdown - especailly under voltage spike cinditions. Only if there is no fuse does what is now just a silicon resistor go open circuit. With the magic smoke coming out ]
More likely the main

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