Lately one of the MacPro computers at the studio has been shutting down for no reason. One minute you are working away happily and then boom! The computer would be off, as if someone had pulled the power chord out.
After much checking stuff, jiggling of cables, googling, switching ram in and out etc etc etc I came to the conclusion that something was wrong with the power supply circuit in the computer. Not a totally systematic and precise diagnosis but everything was pointing to it being the smoking gun.
A quick look on eBay and power supplies for the machine cost between $200 and $900. Not exactly the sort of money I want to spend on an 8 year old computer. Especially when you can pick up a second hand Mac Mini for the same amount of money that is more powerful (no PCIe slots though).
–This is the part of the post where I put in the standard warning about how working with electronics can be dangerous and don’t do it if you don’t know what you are doing – read more here—
I began to wonder if, after 8 years of operation and associated temperature fluctuations, the power supply was suffering from dry solder joints. I pulled the unit out (a bit of googling provided this tutorial) thinking I would tidy up the solder joints with my trusty soldering iron. But the power supply was (naturally) a whole lot more complicated than power supplies in other gear I own and have done simple repairs on. I shouldn’t have been surprised really, this is Apple after all. What really scuppered my plan was all the tiny surface mount components. Not the sort of thing I want to go poking around with only a hand held soldering iron, I just don’t have the skills for that sort of thing. I had to think of a plan B.
A few years back I had a USB tv tuner that was going a bit weird / USB connection problem. A bit of googling showed it was a common problem with these devices. The soldering of the circuit board was not great, the manufacturing was a little too ‘efficient’, and after a while they were all getting dry joints. The solution for these little devices was to bake them in the oven. The theory being that you heat up the circuit board enough to melt the solder and then let it reset again. I gave it a go and it worked – and still works to this day.
So, I began to wonder if it would work on my power supply. The 2 items are quite different; one a small USB device with a couple of little chips and components, the other , 2 much larger circuit boards with not only small surface mount components but large transformers, big filter caps, inductors and god knows what else – and a lot of cables that I couldn’t easily remove. Well, the computer already didn’t work and if I wrecked the power supply it still wouldn’t work. No real loss. Also, there are plenty of people out on the internet who are baking CPU boards from all sorts of devices with varying degrees of success which I, perhaps foolishly, took as an encouraging sign.
So into the oven it went at 200C for 10 minutes and then left to cool down for about half an hour before I touched it. I reassembled the computer, pugged it into my RCD and switched it on fully expecting to see the magic smoke come out.
To my surprise it booted up properly and worked perfectly.
Excellent, one fixed computer.
Now, back to work.
UPDATE: About 2 weeks later the power supply started playing up again. Fortunately I had copied all the data off it to be on the safe side. I suppose the old machine is trying to tell me that it would like to retire gracefully. So it has now, sadly, become a box of spare parts for my remaining MacPro.
If you make a mistake with mains power it can kill you. Large power caps can hold charge long after the power has been removed (largely the reason why I avoid instrument amplifiers), and there are plenty of other ways to hurt yourself badly if you do not take care.
If you choose to undertake work similar to what I have outlined here, that is entirely your responsibility. If you do not know what you are doing or even feel a bit out of your comfort zone, PLEASE DON’T CONTINUE. Pack up, find a tech that does know what they are doing and give it to them.
I am not trained in electronics, fault diagnosis or repairs. I am simply an enthusiastic tinkerer who has built up some basic knowledge over the years. Most importantly, I know where my boundaries are and when I should stop work and hand a repair job over to a real technician.
When working, I always check the power is off and unplugged at least twice and use an RCD when I do need to power something up. This healthy paranoia has kept me accident free for more than 20 years.
Please, be sensible, stay safe and live to a ripe old age.