Archive for the 'Technology' category
Spilled tea on my Macbook Pro
laurei | April 12, 2009 10:00 am
Just this morning I spilled tea on my laptop, I was mixing a song in logic and that was important so breaking protocol I pressed [command+s] to save my project, but after the few seconds it should have saved in I followed the usual process of holding down the power key til it turned off, turned the macbook upside down and took the battery out. Yuck, there was tea on the battery, it seemed to have come through the mouse button.
Laurita had the great idea of using the vacuum cleaner to suck out the tea, so that’s what i did
I just left the laptop, hoping it would be alright, didn’t really bother to open it up, and as I’ve got home tonight it seems alright, yay!
I’m officially a component level electronic technician
laurei | April 9, 2009 2:06 pmThree days, is what it took me, but I’m happy
Truth B2031 Studio Monitor - kinda nice, kinda hi tech, kinda scary.
So it all started when I was cleaning up the office/workshop the other day when I came across a pair of studio monitors (by monitor I mean high quality speakers with the amps built into them for monitoring audio). I had inherited these from the recording studio I used to work at, and by all accounts they were broken beyond economical repair. They don’t sell for much these days, but I remembering them sounding nice and clear and I wanted to either get them working or throw them out….Becuase I hate junk so I decided to get them working…
… little did I know that my tenacity would cost me three days.
IEC60320 c14 Female Adaptor
Blue Smoke
It was actually only one speaker that was broken, the other one tested fine I found out (though after a look inside it was a mess and almost dead) The first thing I did of course was to try and find a fuse in the amp – I always find when something really bad happens to a nice piece of equipment you still have hope that it will be all okay, and that you’ve just made a mistake in diagnosing the problem- is that part of the mourning process? So I checked the IEC 60320 c14 connector and no … no fuses. I opened up the monitor that wouldn’t fire up and lo and behold we had a component that was completely blown – my heart sunk – blue smoke had stained the inside of the case, and one of the components (a ceramic capacitor) had literally blown apart – I was in for a big one. I opened up the case of the monitor that was working and I couldn’t understand it because there were four blown capacitors. It was a bit weird, the working amp had 4 blown caps, and the broken amp only had one. I certainly didn’t get it
104m Ceramic Capacitor
A simple Solution?
The first thing I did was check out the markings 104m, I made a few inquiries and found out that 104m means that it’s a 100 nanofarad cap with a 20% this_or_that. That was fine with me, I thought so I went and brought 8 of them – there was a row of four in each amp. It turns out that this was a good choice because If I had have only brought replacement caps for the ones that were obviously damaged then I may not have fixed it.
This marks the first time I’ve ever gone to the shop to actually buy components for something electronic! So yes I replace the 4 broken caps in the monitor that worked, and that was that, then turned my attention to the monitor that wasn’t working…
I replaced the capacitor that was blown in the broken monitor, and another one – then thought it would be pretty cool if I tried to make it work… but NOTHING. That made me very sad.
Feeling stupid
What I did next was take my multimeter and measure the voltages across the 3 pins of the transformer and compared them to the working speaker, what I found was that the speaker that was working had higher voltages (in fact the voltage actually printed on the transformer). I thought it might be the transformer that was blown and that was scary because I can’t just wind my own, so I had to cut some wiring and test the transformer’s input power… And this was kinda weird, I still don’t quite understand this but there were 3 wires going into it from the C14, and that wasn’t including the earth (which was bolted to the chassis)… anyway the voltage for the input was wrong so I poked and pulled at the c14 and lo and behold, I’d found a fuse holder!!!! With a broken fuse!! Well right then and there I felt really stupid because I hadn’t been smart enough to find a fuse accessible by an everyday consumer – this fuse was well hidden in a little compartment of the c14. I looked across all of my appliances and found a fuse that was similar and replaced it… hooked up the speaker, turned the power on and bzzzt…. nothing, check fuse, and fuse is blown. On one hand I was sad that it wasn’t fixed yet, and on the other hand I was happy that It wasn’t just my stupidity that was holding me back from getting it working.
Stripped to the bone
I went and brought 2 packets of 6 1/4 amp fuses – the same amperage (or so I thought) as the original, because I knew that I had to have fuses for testing, unlike normal this was a high cost piece of equipment and I didn’t wand to completely fry it! I spent the next one and a half days trying to make this thing work, but it didn’t. I tested every component with a multi-meter, I tested them against the values I got on the working speaker but I coudln’t find one value that was off – everything was spot on. So I brought myself a gas-powered soldering iron and de-soldered every main component, including diodes, resisters, and capacitors, and tested them – still nothing. Time started adding up – and I tried everything I could, started un-soldering the transformer leads, power leads, tried to take apart the c14 connecter because I was sure that there was something inside it that was skewif – nothing. It didn’t really help that I don’t quite understand AC power the way I should, and by the end of it it looked doubtful if I could be bothered to actually put everything back together again.
Third Day Lucky
By the Third Day I was feeling pretty dumb, and that feeling felt justified, as I started tracing the AC input through the solder tracks, into the diode rectifier, and finding something weird, that there was hardly any resistance in one of the quadrants, and that one of the capacitors was shorting on the inside, a capacitor that I’d tested before – suddenly it dawned on me – the capacitor was a non-polar type, and the diodes were in-fact a rectifier, so the capacitors didn’t even need to be there, they just smoothe out the wave – thats why the other monitor worked with NO capacitors in-tact. I quickly pulled out the capacitor with my newly found de-soldering skills. And replaced it with a new 104m.
Feeling dumb – ouch.
I plugged it in again and tested it, but the last 1/4 amp fuse had now blown, the last of the twelve that I’d brought from the shop. I decided to go buy some more – but I’d just stumbled across something that made me feel quite silly. The .25 Amp fuses I was using were actually meant to be 2.5 Amps, I’d read it wrong, and I was out my a magnitude of 10.. Why, oh why is a decimal point so small, it’s the most important thing in a number, it should be a big black square!
Bang – again.
So I replace the fuse, feeling stupid about getting the value wrong, and also the fact that I should have known that if 2 capacitors were broken then it’s pretty likely that there would be another one broken. Plugged it in … green light comes on and I am ECSTATIC! Wait 5 seconds, then BANG, this time it was huge, my heart sank – this bang was pretty huge! Sparks, and smoke for a good 30 seconds.
Home Run
I open up the case again, hoping that it’s just something simple, and I am pleasantly relieved that the 4th and last capacitor in the amp had exploded and nothing else was even burnt, I simply replace this 104m, turn the power on and its been working ever since… if only I had have replaced all of the caps in the first place would have saved myself a few days work
… but what would I have learned?
I now consider myself an electronics technician on the component level:)
