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Mike Macgirvin

mike@macgirvin.com

No Nobel Prize today

Mike Macgirvin
  last edited: Tue, 20 Nov 2007 22:07:43 +1100  from Diary and Other Rantings
I woke up this morning with the solution to the Unified Field Theory. I'm quite serious. It was absurdly simple, not any more complicated than the infamous E=MC2. I thought about it during the drive in to work and it was going to be my first post of the day. Like hey guys (and gals) - here is the answer to one of the most challenging problems of the last century. I mean matter (that which has mass) and energy are intimately intertwined - to the point that they are just different perspectives of each other. To say that there are four kinds of energy which aren't at all related is absurd, because that means there would have to be four kinds of mass which likewise are totally unrelated.  

Then I arrived at work and found the main staff file+mail server was in a catatonic state. Spent the rest of the day rebuilding the operating system and restoring files from backup. By mid afternoon, my brain was total mush from manually editing hundreds of obscure configuration files which had to be syntactically perfect for everything to work correctly. The whole chain of matter and energy calculations completely dissolved.

Sigh, looks like I won't be getting the Nobel Prize today.
Juli@ sound card and Vista

Mike Macgirvin
  from Diary and Other Rantings
If you're looking for a decent mid-range sound card and don't want to spend a fortune, the ESI Juli@ is pretty respectable. I really like the fact that it's about the cheapest card that'll provide balanced line. You do this by flipping the card around. Unbalanced connectors on one side, balanced on the other. It's a pretty neat concept.

Anyway, if you're trying to install one of these suckers on Vista, forget the installation CD. You can just throw it in the trash if you want. Even though the latest driver is for XP/2005, just go to the website and grab the latest. The driver on the install disk is a piece of crap and you'll be wondering why you bought such a sucky card. Can't even get the basic speaker test sounds to come out without about 300% signal distortion, dropouts, odd harmonics, etc. In short, the sound you get is almost totally unrecognizable.

The website driver makes it actually work.

Oh, and to use with Sonar, don't use the WDM channel. Just go with ASIO.
Aussie Power (Digitech)

Mike Macgirvin
  last edited: Thu, 04 Oct 2007 12:32:45 +1000  from Diary and Other Rantings
This is yet another informational post to save somebody a lot of headaches. It's about trying to convert a Digitech guitar effects board to work on native (220-240V 50hz) power.

In this case the model is a Digitech RP-12, which isn't made anymore, however this applies to most of the large pedal boards that Digitech has made in the last ten years. The actual power supply is a separate component that likewise isn't made anymore. They do offer a replacement (the PSS3), with an adapter (PS4BC) to fit the non-standard DIN power socket on the pedal board. These run about $110 AUD. Yikes. It's really a $20 power supply, and there's plenty of profit selling them for $20. I refuse to pay over a hundred. It's a freaking hobby transformer, fercrysakes.

It turns out there are reasons they charge so much. Nothing else seems to work. The ratings as specified are 9VAC, 2.1A. Simple enough. I can do this - yes?

Not quite. The commercial 9VAC wall-warts usually stop at 1 amp. A couple of months ago I tried to get around this by purchasing an adequate transformer and building a box for it. After much effort, I finally plugged it in and tried it. HUM and BUZZ. Loud and nasty. Not something you want for studio recording. I scratched my head a while and went back to using the original (110V/60hz mains) unit through a step-down transformer. No hum. So clearly it's not the 50hz that's causing me grief. I brought the original supply into work and put it on an oscilloscope to see what was special about the Digitech branded supply. Couldn't find anything obvious, except that it was a cheap transformer with a lot of inductance artifacts and the waveform was skewed a bit - pointy instead of pure sinusoidal.

So I took one of my 9VAC 1A wall-warts (that I have several of to power other equipment) and tried it briefly - maybe there was something wrong with my wiring. The 1 amp unit likewise gave me nasty HUM and BUZZ. I didn't leave it plugged in long enough to cook it.

There's no ground and no shielding in the Digitech supply, but I even tried grounding and shielding the lines to reduce the hum - no luck. I tried phase reversing both the primary and secondary (one at a time) in case it was phase sensitive. Nope. There's something obviously different about the Digitech supply.

Hmmm. Back to the drawing board. OK, looks like I just have to use the original 110V supply through a step-down transformer. It's the only thing that makes it work. I gave up on the project and that got me by for the last month or two.

Then last weekend, I turned everything on and the pedal board was dead. Defunct. After some probing it looks like the Digitech transformer just decided it was time to die. Open primary. This gave me an excuse to open the hermetically sealed enclosure to find out what was magic about the Digitech unit.  

Absolutely nothing. It's got a transformer and a fuse. Period. (And the fuse was still good.) OK. So I pulled out my homebrew transformer again. It's only a transformer. What's wrong here? Why is my solution so darned noisy? Why is a generic 9VAC supply so noisy? How do I get rid of the noise?

I tried to order a new 110V supply from the states (to save $50), but nobody will sell me one (even with the huge profit they get). They are forbidden from sending new Digitech products overseas. Even if it's a just a wall-wart that I need to make my old pedal work.  

So getting desperate, I tried a 9VDC supply. The logic boards work and the display lights up, but there's no audio signal at all. So obviously the audio circuitry requires AC. That's weird and I can't imagine what the engineers were smoking when they made that decision, but it doesn't matter - that's just the way it is.  

So I started trying different voltage taps on my homebrew transformer box. I went down to 3V. Nothing worked anymore. Not enough voltage to drive the logic boards. 6V, logic boards work, but the noise is back. 8.5V, noise. 9V, noise. 9.5V, noise. But now it's getting dangerous. Too much voltage can cook something. However, I've got nothing to lose. Right now it's all just an expensive paper weight. The absolute worst that could happen is that I'd be forced to buy a new pedal board, which wouldn't be horrible but the good ones run about $1000 here. Yeah, a new PodXT Live would be ok, as would a GNX4. But maybe, just maybe - my old board just needs a little bit more umph than they claim it does.  

So anyway I cringed (as one normally does when doing something that could end up being a thousand dollar mistake) and tapped into 10.5V. Bingo. Everything works, no noise, no hum. I breathed a sigh of relief. I finally found the issue. They lied. It doesn't take 9VAC, 2.1A. It requires something above 9.5, and probably about 10V for everything to work properly.

So that's the bottom line. If you need a replacement Digitech power unit, ignore the 9V rating. It won't work worth a darn. Get 10.5V (to be sure, since I don't have a variac handy to figure out exactly where it starts working).
power outage

Mike Macgirvin
  from Diary and Other Rantings
Well at least our power outage today didn't compare with the fiasco that hit San Francisco yesterday. I feel blessed. We had a scheduled interruption for about four hours to finish up the job they were doing three weeks back.

One of the workers came by to check on the breaker, so we asked what it was they were doing to the lines. Turns out that when they put up the telephone pole across the street, they encroached on our neighbor's property by about 18 inches. It was a simple mistake. There's a big drainage ditch and common sense says to put up the telephone pole on the edge of the drainage ditch rather than in the middle. But he complained to the council, and they complained to the power company. So here they were, rewiring the entire block to move the pole over 18 inches into the center of the drainage ditch.

Part of me applauds this action. Government doing the right thing by its citizens is a noble virtue. But now they've stuck an electric pole that supplies a quarter of the town smack dab in the middle of a drainage ditch. I've seen this ditch when the monsoon rains hit. Sure hope the pole doesn't get swept away in the next big rain.
Yankee Power

Mike Macgirvin
  last edited: Tue, 24 Jul 2007 07:27:51 +1000  from Diary and Other Rantings
I'm starting to get the electricity under control. Have managed to pick up most of the wall-wart transformers I need. Incidentally, for the benefit of anybody that may have to follow these footsteps, forget about Tandy and Dick Smith as electronics suppliers. You'll go broke. There's a little place in Bowral called 'Leading Edge Electronics' that has much better transformers for about half the price. They've also got a better selection.

I also have pretty much given up the process of converting most of the wall-cord equipment. Some of it can be rewired, but it's a very painful and time consuming process. So instead, we've set aside one room of the house with 'Yankee Power'. I've got the familiar U.S. power strips and line cords everywhere; all feeding off of a 2kw transformer that I picked up at Fry's for $150 USD. If you attempt this, get that transformer (or three). The biggest they've got on this side of the pond is 1kw for about $300 AUD. Big difference. You'll still have to change the power cord because the Fry's transformer is set up with a UK plug, and you don't want to pump a couple kilowatts through a little plastic Aussie travel plug adapter (which you also want to pick up a few dozen of at Fry's for $1.50 USD each - you can't find 'em here at all because nobody here needs Aussie travel converters). The power strips I'm using are the super heavy duty metal Home Depot power strips with about ten plugs and a fifteen foot cord. They're about $50 USD each. I've got six or seven of 'em from my music shoppe days. The only problem is the built-in surge suppressor. If you turn on the 2kw transformer, it will send a surge and throw the house circuit breaker every time. I took some clippers and clipped out the surge suppression circuitry on a couple of these boxes as I got tired of walking outdoors in the cold to reset the breaker. I've converted over enough stuff that I probably won't need the other power strips, so I'll probably sell them for $100 AUD each (or whatever the market will bear) on ebay.com.au. Yankee power strips sell at a premium here, usually along with a transformer and some kind of home theater device that somebody tried to save money on by buying overseas - and then spent a fortune trying to get working on 220v50hz. And mine are the premium power strips, not the $4.95 USD economy strips that sell here for $50 AUD.

In the Yankee room is my recording equipment, but also such things as region 1 DVD's,  NTSC television stuff,  and any other foreign formatted thingies.  It's starting to feel like home, so I draped a couple of US flags in the windows. Well we still need blinds and they're the only pieces of cloth I could find that are near the correct size. We used the extra sheets for the other windows. I've also got about 600w of 60hz power available, but luckily most of my stuff runs off of the transformer and I haven't yet had to build a container for a few 12v batteries and charging equipment to supply the sine wave generator. We'll probably need it for Amanda's and Isabella's sewing machines - so there might be yet another Yankee room dedicated to sewing.

UPDATE: Looks like the sewing machines will also work just fine on 50hz. Yay! Thanks to Chinese manufacturing and global markets. Ten years ago this wouldn't have been the case. This means that so far we haven't found a single thing that absolutely needs 60hz to run.  Of course the big reason for that is because we sold all the stuff that we knew positively would be a problem...
Stuck Tape

Mike Macgirvin
  last edited: Tue, 24 Jul 2007 07:29:02 +1000  from Diary and Other Rantings
Have you ever encountered a 'stuck' video/audio/data tape - one of those where the tape gets swallowed inside the machine in question? I have. More times than I can count. Oh, and the nearest authorized repair facility is halfway around the world (or worse, gone out of business)? I have - more times than I can count.

So what do you do?

You open up the darn thing and figure out how to extract the tape cartridge, that's what you do. I've also done this - more times than I can count. Usually it involves:
  • disassembly of the drive mechanics, which resemble the inside of a Swiss (mechanical) watch - except the gears are plastic
  • destruction of the tape cartridge, to get the pieces out of the way so that the mechanics can be further disassembled
  • all of the above
Faced with this task yet again, I finally came up with a more clever way to accomplish the task. You see, the drive mechanics are operated by motors, which load and unload the cartridges. In order to operate the mechanism in the absence of motor power (which has obviously failed for some as yet unknown reason or you probably wouldn't be reading this), you usually need to take it completely apart. You can't just spin the plastic gears by hand, because they're all intertwingled and won't budge unless you physically remove the motor and then spin the first gear in the chain.

But what if you didn't need to take it completely apart? Taking Swiss watches apart and putting them back together again (without messing them up completely) is no fun. Trust me on this.

So how can we convince the motor to perform the unload task? There are two of them. One spreads the tape around the spinning head assembly. The other drives the actual tape swallower assembly. Both are usually simple DC motors. And therein lies the solution. We just need a little DC. Take a 9V battery and a few inches of speaker wire. Hold or tape the leads on one end of the speaker wire to the battery. Turn the power off on the device in question. We're going to bypass the built in power (and logic circuitry). That's what got us into this mess.

Now touch the other ends to the leads of the spreader motor. Didn't do anything? That's OK, you've got a 50/50 chance here. Swap the leads around the other way. Voila, the tape spreader starts the unload sequence. Keep them connected until the spreader has done its job and it hits the end - at which point it will stop. That's also why we use a 9V battery. It doesn't have enough torque to over spin the thing since the normal limit switches aren't able to limit us from damage. Don't hold the leads very long or you really could damage something.

Now move the leads over to the swallower motor and touch them there. Again, swap the leads if you get it backward the first time and nothing happens. Yippee! Here comes the tape! Right out the drive door and into your hand. Yay!

Can't figure out which motor is the spreader, and which is the swallower? That's OK too. Just start touching motor leads (briefly) and see what moves. You'll find them soon enough.  

Now you've probably still got to figure out why the tape was stuck, but in the meantime you've got your tape back - intact; and the mechanism is unloaded and still in one piece. Chances are pretty high that something about the tape itself or how it was loaded is what made it stuck and things will just start magically working again. If not, oh well. I don't have all the answers. But if you're ever crazy enough or desperate enough to need to do this, you're probably capable of figuring out what to do next.
International electricity - oh the joys

Mike Macgirvin
  last edited: Tue, 24 Jul 2007 07:29:49 +1000  from Diary and Other Rantings
Even though we sold off all of the power tools and kitchen appliances, we still brought a huge number of electric devices overseas. It's been real <sarcasm>fun</sarcasm> trying to make all this stuff work on 220/240V 50hz. Some things were easy. These are the manufacturers I now swear my allegiance to. Just plug in an Australian power cable and it works. My next favorites are the ones like the PC's - just flip the red switch on the back and plug in the Aussie cable.

I've got a whole bunch of 'wall-wart' transformers that need to be replaced. These are all still pretty easy - just plug in a new wall-wart and everything is fine. The only problem is the price. These guys are about $30 each here. I need (let's see...) about 30 of them. You do the math. Luckily I found a bunch of standard 9V supplies on clearance for $5 each and bought all they had (7 or 8). They were on clearance because they use a different style connector. So I have to get out the soldering iron (oops, looks like I need a new soldering iron because my old one is 110V) and change the connectors.

Now we're getting to the real <sarcasm>fun</sarcasm> stuff. The Marshall amplifier. In fact Marshall claims that you should be able to use this anywhere in the world. Well yes, but you have to open the case and rewire the power transformer. This isn't something most people are comfortable with. Luckily I am. Did this one last night.

Next are the weird wall-warts. Dual 18V AC, 9VAC@2.1A, etc. These are getting hard. This takes a trip to Dick Smith (the only local place to buy electronic parts), and try and match a transformer to the job. It's hit or miss at this stage. Some of the transformers need to come from overseas, which costs more than the items I'm trying to convert. So it ends up being cheaper to throw them away and buy new - like the soldering iron. And I've got a kid and a house full of pets. Can't just hang a naked transformer off the edge of the desk like I could have twenty years ago. It needs to go in a box with all the bare wires taped up. That's another 5 bucks or so and another couple of hours each. I've gotten clever in a couple of spots - my wireless router for instance requires 5V at a couple of amps. So I plugged it into an extra drive cable on my PC.

But now I'm getting down to the nitty gritty. I've got about 20 more items to rewire and another twenty more wall-warts to purchase. 4 or 5 items that can only be run on an isolation (240V <-> 120V step down) transformer, and 2 or 3 that can only be run via a pure sine wave inverter off a car battery because they really, really need a clean 60 hz sine wave and this is the only way to get it.

Still a couple of months before everything is up and running. But every day I get another one or two working.  And I know what I'm doing. Most people attempting this would just have to suck up and buy everything fresh.