Monday, November 17, 2014

Crown XTi 1000 power amplifier repair

Over the weekend I dissembled and repaired a Crown XTi-1000 amplifier.  The problem was caused by bad connections on a bridge rectifier located in the power supply section.

This is a close up of the bad connections.  The leads needed to be cleaned and re-soldered.

This is the corner of the board where the problem is found.

This is what the amplifier looks like with the cover removed.  You need to remove the front, then all the screws on the back, then all of the screws holding the board in place.  There are four screws holding the heat-sinks in place that are under the foam.

Tuesday, November 11, 2014

Chevy Cobalt Replacing the front door speakers

One of the first things I do when I buy something used is to make a list of things to repair.  On the car it is something like this:
1. Prime
2. Paint
3. Undercoat
4. Door locks stick
5. Snow tires
6. Front Speakers
7. Do Spider Spikes fit?

So far 1, 2, and 5 are fixed.  When it comes to the front speakers Pioneer actually makes speakers that fit.  You can also buy an adapter that will allow you to use any 6.5 inch speaker if you want.  The wiring adapter is not needed.  Just tin the wires and they will fit tightly into the jack that was connected to the old speaker.

The new speakers come with clips that need to be installed first as seen in the picture below.

To install the speaker first remove or pry out the door cover near the speaker.  There are three screws behind plastic snap in covers that you will need to remove to take the inside door cover off.  Remove one screw and the old speaker comes out.  Connect the wires for the new speaker.  The wires can be taped in place with electrical tape.

Put one side of the new speaker in and then rotate it up and down to catch the two clips on the opposite side.  Tighten up the screws.  Use duct tape to fill the gaps above and below the new speaker to block road noise.

You are done!  It only takes ten minutes to do.  Turn on the radio and make sure that the new speakers work.

Now I can actually hear the turn signals, as the sound comes through the speakers.  Hopefully the warning that the headlights were left on will work too.

Thursday, November 6, 2014

My New(er) car - a 2007 Chevy Cobalt

After 20 years of driving vans, I have made a drastic change.  I drive 45 miles to work every day and the cost of gas for the van was running around $5000 a year.  So I have bought a car that should get me about twice the gas mileage and save me the cost of the car every two years.  These pictures were taken right after I touched up the paint.  There were some rust spots on the fender around the rear tires.

So far the Cobalt is getting me around 34 MPG according to the built in mileage calculator.  I hope to make some minor changes to get that up to 40 MPG.

Wednesday, October 15, 2014

Building my own 3D printer part 3 and the first video

My 3D printer had its first test run last night.  So far I need to replace the X axis stepper motor it has a bad connection inside of it somewhere as can be seen in this video on Youtube.

Here is a picture of the jumpers to convert the Ramps board to a printer 25 pin interface.  I only connected to the pins that I needed for X, Y, and Z for Step, Direction and Enable, they are blue, green and yellow.  The enables are all connected to ground.  Then I also needed to connect to ground and 5 Volts, they are yellow and red, the top two connections..

Here is another video of the DIY 3D printer this time it is running with and Arduino Mega.

Here is a picture of the Ramps wiring.  The heat bed is not wired up yet.
Here is the wiring with the heat bed wires in.  I spliced the ribbon cable into some 14 gauge stranded cable and covered the splice with heat shrink.

Here is the third video.  This was my first extrusion attempt.

Here is what I got from my first attempt at making something.  It was supposed to be a 8mm bearing support.

Tuesday, October 7, 2014

Building my own Mendel 90 3D printer part 2

My 3D printer is coming along quite nicely but slowly.  I have started doing the electrical wiring as can be seen in this picture.  Notice the custom made aluminum motor mounts and the use of standard "off-the-shelf" parts throughout.  My next book will give the details of construction it will be titled "Inexpensive 3D Printer Projects".

I purchased standard ends for the X-Axis ends but I have come up with plans as to how to make my own X Axis ends.  I really think even the X Axis ends can be made with standard parts and a piece of Plexiglas or aluminum to hold it together.  The only tricky part would be the "Nut bracket".  That could be made out of Plexiglas.  Just drill a 1/2 inch hole in it and then melt the 5/16" nut into the hole.

Here is a picture of my homemade X axis carriage.  I had to cut the 1/2 inch pipe supports to fit them in the space available (There is approx 2.05 inches between the rails).  The two holes at the back are for mounting the Extruder. The holes at the front already existed but they are for the belt clamps.  The center hole was just a little over 1.25 inches in diameter but it was not big enough to lower the hot end down through.  I had to disassemble it and reassemble it through the hole.  I need to cut off 1/2 inch at the front as it is not needed.  I changed the design and moved the holes out 1/8 an inch.  Then I countersunk them and used flat head 6-32 screws.  Now the print head sits flush.

It is almost done!  Just the 25 pin connector at the bottom right and the heatbed to wire up and it will be done.  Here is what it looks like at this point.

Tuesday, September 23, 2014

Building my own 3D printer based upon Prusa and Mendel90 designs

I have been trying to build my own 3D printer.  I am trying to use "off the shelf" parts as much as possible. I did end up buying X axis ends on eBay.  I designed and made my own stepper motor mounts.

Here is a picture of the frame as I first assembled it.  The blue tape is so I can write on it for my hole markings.

Right now I am stuck on the lead screws for the Z axis.  The holes for the nuts are .55 inches across and they are supposed to be for 8mm nuts.  But 8mm nuts are .51 inches and 5/16 nuts are .5 inches. Both nuts rotate freely in the hole as the hole is for a nut that is .55 inches across.  The nuts that are found on hollow electrical threaded pipe commonly used in table lamps fit perfectly.  One of these is seen on the right side below.  However that would be hard to adapt that to the 5mm stepper motor shafts!

Some of the other problems I have faced so far include:

The stepper motors came with gears on them.  I used a gear puller to remove the gears.  When I connected the motors up to the lead screws I discovered that their shafts were bent so much that the top of the lead screws rotated in about a one inch circle.  I had to get new stepper motors.  When I installed the new stepper motors I discovered that the problem was actually the 5mm to 8mm shaft coupler!  It was drilled so crooked that it causes the lead screw to rotate.

As I said above the holes for the nuts in the X axis ends are .55 inches across and both 8mm and 5/16 nuts spin freely in them.  I might have to make my own "nuts" out of aluminum using a 5/16 tap.   Wow was I really off on that one.  It turns out that the nut holes on the top are .55 inches but the nut holes on the bottom are .51 inches!  So I was just looking at the wrong nut holes.

When I assembled the Y axis carriage and slid it towards the back it returns back to the front on its own!  That is because the rod spacing varies by 1/8 of an inch causing the bearings to bind.  I enlarged the holes on the back side and adjusted it so the platform moves smoothly now.

The 8mm bearings are terrible.  They do not move smoothly and they loose some of their balls every time I remove them from the rods.  I might have to replace them with better ones from another vendor?

Some of the 8mm rods are from printers and scanners.  The one on the right side is a tiny bit bigger than 8mm.  I used emery cloth to take it down a little bit so that the bearings move smoothly.

I used 10mm rods (from scanners) and bearing for the Y axis.  They work so much better than the 8 mm bearings.  However their outside diameter does not fit either 1/2 or 3/4 pipe holders.

The spacing of the z axis guide rods varies by 1/8 of an inch from the top to bottom.  That is a tricky measurement since there are rod holders at the top and a home made motor mount at the bottom.  I will have to move the rod holders in about 1/16 of an inch on each side to fix the problem.

While testing the Y axis I realized that the gantry is at the wrong position.  When I move the Y carriage back the print head will not reach the front edge.  I had to unbolt the gantry and move it forward one inch to resolve the problem.  It was six inches from the back edge but it is now 7 inches from the back edge.

The Y axis bearing holders hits the stepper motor that is mounted under it.  That is because I mounted the stepper motor all the way to the right.  It needs to be moved at least an inch to the left. It also needs to be moved so that the wires to the Y platform can be run in the center, the drive belt is there currently.

I cannot put nuts on the Y axis hot plate screws.  The bearing holders are too close to the front and back edge of the Y platform so there is not enough room to put the nuts on the hot plate screws.  I will have to move the Y axis bearing holders 1/4 inch further from the front and back edges.

I tried to mount the Arduino Mega, but like all Arduino's the mounting holes are an afterthought.  I wanted to have screws come through the plastic, then a nut, an insulator then through the Arduino then a last nut.  However the nuts cannot be on that side.  I am trying to rework it to use the standoff's that are used for ports on a PC.