smd pcb rfid on the Cricut (semi-fail)
Using the "industrial" sharpies, fine and ultrafine point, I made two attempts at an AVR RFID card with integrated PCB antenna, with mixed results.
I designed all but the antenna in Eagle and exported to EPS, then imported into Make-the-Cut. The spiral antenna I created using Inkscape spiral tool, then cut-and-paste into Make-the-cut, and just rotate and move so the traces connect.
I draw a rectangular bounding box around the circuit and put into a separate layer, which I print first onto a piece of paper taped on the cutting mat. This shows me exactly where to place the blank circuit board.
Next I tape the circuit board to the paper using masking tape at the very edges only. I snipped off one of the grey friction rollers so it doesn't roll back and forth over the design and ruin it while the ink is still wet.
I remove the Expression keyboard to make room for the pen, and wrap a long thin strip of duct tape around the pen close to the tip to make it big enough for the tool holder to grip. I "cut" (draw) from Make-the-Cut at Extreme speed, low pressure, and etch in the usual way.
The experiment was very successful in that I was able to get pretty reliable traces in two sizes, roughly 0.5 and 0.8 mm, plenty for a sporting shot at surface mount stuff.
Unfortunately, while a magnet-wire coil produces upwards of 10v peak-to-peak, I can't seem to get better than 850mV or so across the pcb coil leads, regardless of my choice of tuning capacitor, so for now running the Tiny85 is still out of the question.
The two antennas have about 25 and 45 turns respectively, but so far I've been totally unable to get them tuned to produce enough voltage to run the AVR.
I've been probing the tag coil across the capacitor leads while the tag is being stimulated at 125khz with my homemade reader.
The second antenna is pushing the resolution limits in the spiral because the "jaggies" from the machine reduce clearance between lines. I had to do a little cleanup work with a razor blade, separating adjacent lines that had shorted in a very few places.
Cricut Repair Info
Cricut Repair Info
One way to get yourself a cheap Cricut machine is to buy a busted one off eBay. Try searching for both "broken cricut" and "defective cricut". Often you can win one for as low as $0.99 plus shipping for a Personal or Create model, or somewhat more for an Expression.
Where to get one
The main dealer of these machines, "websbestdeals," must have some exclusive arrangement with PC, because they seem to have a pretty inexhaustible supply of broken machines to sell.
Have patience and don't get carried away with your bid, it seems there will always be more listed within a few days.
Read the seller's description carefully to see what is included. Usually (but not always), they only include the power supply, but sometimes it comes with everything, cutting mat, blade holder, power adapter, cartridge, overlay and even the manual and warranty card. Once in a while they'll sell two for one, but missing one or both power adapters.
Sometimes the seller's description will tell you exactly the issue, as in the case with a dragging blade. I'm not quite sure yet what it means when "the blade makes a lot of noise", but the broken limit-switch wires definitely cause a horrible noise on startup. Many times they simply say "it has no power," which so far often (but not always) indicates a power supply or broken trace problem.
Mine didn't come with a cartridge!
If you don't have a real cartridge, you can make yourself a "Fake George" to at least get a machine with the stock firmware to start up fully. More details here. Basically, you just need to (carefully!) make something that will short together pins 4, 6, and 10 (or 11, 15, and 17) on the cartridge port, to fool the machine into using its own built-in "George and Basic Shapes" cartridge.
Here are some close-up photos of what a real "George" looks like inside.
Removing the Side Covers
Don't rush to take the sides off the machine. Many times this won't be necessary, and it's hard to get the trim pieces off without doing at least cosmetic damage.
The way I do it is to use a thin bladed putty knife to get in between the trim and side cover (from the outside edge inwards), while pulling outwards with your other hand, to depress the little fingers that clip the trim piece on, one at a time. I've broken off quite a few of them with poor technique, but don't usually bother putting them back on anyways.
Once the trim piece is off you can get access to the 5 or 6 phillips-head screws holding the actual side cover on.
Accessing the Motherboard
Usually all the action happens in the bottom of the machine where the motherboard is located.
To access it, all you need is a long #1 phillips-head screwdriver. Roll the machine onto its back on a towel or something else soft, and remove the 8-or-so most obvious screws around the outside of the bottom cover. Then, tip the cover down and towards yourself like opening a panel. If you carefully tug a little on the wires leading up into the side covers you can get just enough slack to be able to rest it flat on the table while the machine is still on its back.
Problems and Solutions
Here are some of the things I have discovered so far while fixing a bunch of these machines:
Schematic
I don't have a schematic drawn up for these, but one of my Creates is an older model with only a 2-layer board. This makes the circuit far easier to figure out than the 3-layer boards that came later. The Expression board is nearly identical, so this should be of assistance for figuring out those issues as well.
Here are close-up photos of the full front and back side of the 2-layer Create board.
Broken Dials
It seems the dials are pretty easy to break if the machine falls onto its front side. The size dial is expendable if you use Make-the-Cut or other cutting software on your PC, but if you cut with cartridges or the pressure dial is broken you may not have much choice but to try and find a replacement dial.
Bad Power Supply
An Expression I got with a bad power supply would constantly turn on and off, like a turn signal on a car. On, off, on, off. Replacing the power brick with a known-good one from another machine solved the problem.
Broken Inner-layer PCB traces
So far, two Create machines have been suffering from broken traces in the middle layer of the circuit board. Fixing these can be challenging since you can't see the inner layer to know where it was supposed to connect to.
Fortunately, I have a working older revision of both Personal and Create motherboards that are only 2-layers, and there were virtually no changes to the parts connections or positions when PC switched to the 3-layer boards. This means you can visually trace the connections on the older board, and verify those connections on the newer (broken 3-layer) one.
I will be adding specifics here to help with this process for anyone who doesn't have the benefit of a 2-layer board for reference.
1) One machine's power button would light up when you turned it on, but nothing else would happen. This was isolated to two broken inner-layer traces leading from the 5V regulator to two nearby parts.
Edit 4/28/2013:
At long last, I took a photo of the repairs for the "broken inner-layer traces" issue.
First photo shows the front of the board. The broken traces connect one of the inductor leads (circled) to the 5v voltage regulator and to the large capacitor below it.
This next photo shows where the jumpers were placed. Your mileage may vary, but this got mine working.
2) Another Create model would power up and boot fully, but the display would be either blank or show only a single line of pixels. Swapping out the display for another known-good one did not have any effect. This turned out to be a broken +5V power supply line to the OLED display connector. (pin 2, counting from the end with the red stripe). I repaired this one by adding a jumper over to the +5V power supply line on the keyboard connector an inch away.
Disconnected Cables
One expression, when you pushed the power button, would light up, but instead of booting would just beep three times and halt. This turned out to be simply a disconnected keyboard cable. The fix was simply to plug the cable back in to the motherboard.
Broken Limit Switch wires
Two different machines had this problem - they would start up okay, but when the carriage would slide all the way to right, it would crash at the end and make a horrible grinding noise. This indicates a problem with the button located in the right-side hidey-hole or the wires leading to it.
Upon removing the right-side cover, I discovered in one case that the pair of wires from the limit switch had been severed by the sharp edge of the metal motor bracket inside. Repairing the wires solved the problem. In another case, one of the wires had simply fallen off the switch, and I was able to just plug it back in.
Broken Solenoid wire
One Create would operate normally, except the cutting blade would not go up and down at all. Removing the carriage cover revealed the problem to be a broken solder joint at the top of the cutter solenoid. Space is pretty tight, but I was able to solder a short length of wire between the broken lead and the stub on the solenoid to fix this problem.
Blade Dragging
This problem seems to be one of the most common, and the easiest to fix as well. The machine seems to operate normally, except that the blade drags in some places, cutting where it shouldn't, and hangs up in some places, not cutting where it should. Normally, the blade holder should move smoothly up and down. You should be able to push it down with no friction detected, and when released, it should move smoothly and freely back upwards.
In some cases, the lower of the two leaf springs in the cutter solenoid mechanism can get bent, causing a slight misalignment, which creates friction that causes the observed "dragging" behavior.
The fix for this is about the simplest of all: remove 3 screws covering the cutter carriage, and simply pinch with your fingers the upper and lower leaf springs together at the right hinge point. (Where the red circles are in the photo below). This should straighten the bent lower leaf spring and free up the movement.
Replacement Parts
The power brick is an 18v 2.5A switching power supply with a pretty standard cord end, so you could probably find something compatible, but you can get the real thing from PC itself for $9.99.
If you're looking for used parts, Here's one place you could try, or Here's another
I'm not 100% certain, but the US Cutter Refine carriage looks identical from the photo.
Unsolved Machines
I have several machines that I have not yet repaired.
One is a Personal model that will often fail to boot, and show only dark squares on the LCD screen. It was described this way to me before I got it, worked fine upon receipt, but then stopped working again soon after.
Another is an Expression that, when powered on, the power light comes on, but nothing else, and the 5V regulator starts to get very hot. Although replacing the regulator may be the solution, I want to be sure the problem wasn't caused by something else.
(two other Personals have not been checked out yet).