Month: October 2018

Memory testing on Asus M5A97

Hurricane Michael touched only lightly in Northeast Florida, which was a relief after what Irma did the previous year. However, we weren’t completely unscathed. and the lights did blip and the UPS kicked in, but not soon enough. Thereafter, my desktop machine’s energy-saving modes started acting up.

This is a machine that had been swapped with a production server when it acted up there (turns out the CPU was overheating and needed some thermal paste), but it had already been diagnosed with bad RAM once, so when lesser remedies failed, I kicked the box into memtest86+.

The results were appalling. There were 2 4GB sticks and one 8GB stick in the machine and I tested them alone and in combination. The 8G stick failed outright, and the 4 GB sticks would test fine, but only one at a time. Add 2, and the machine would fail. Anything more than 4GB total in the box would blow it.

This wasn’t simply a test fail – the entire box would reboot shortly after the test started, before the CPU even hit full operating temperature. I feared the worst and bought another motherboard and more RAM.

When that came in, I tested it. And got the exact same results. The new motherboard rebooted. And the new memory sticks were both 8GB, and they both caused reboots. Anything more than 4 GB would fail on either motherboard.

Such consistency leaves only one other failure point and that’s the venerable memtest86+ test program itself. Not something that you’d usually expect to fail so catastrophically, especially since the latest Fedora release was installed, but I’d tweaked the daylights out of the the BIOS (including manually setting RAM timings), and no luck. And, incidentally, memtest86+ was displaying the wrong RAM timings.

So I did some searching for alternatives and found 2. One will run on a live Linux OS, although of course, its ability to test RAM is limited by having to work around the RAM being used by the OS and apps. The other is memtest86, which is what memtest86+ was forked from and is now available in both free and paid models.

I tried memtester, which runs under Linux, and it did flunk part of my original 8G stick. Then I tried memtest86. Unlike memtest86+, it did not spontaneously reboot. In fact, all the RAM passed!

Since memtester did claim certain bits were bad, I need to do more research, but apparently despite having been updated are recently as this past July, memtest86+ apparently lacks decent support for UEFI, DDR4 and who knows what else, making it essentially useless even for as dated a board as the M5A97. And yes, I know it’s showing its age, but it meets all the necessary criteria for my needs.

Using the Millright CNC machine to make custom printed circuits

Synopsis

This is the anchor for what will probably be a whole series of notes on using the Millright CNC machine. This first posting give some overview info about CNCs.

Basic info about the Millright CNC

The Millright CNC is a Computer Numerical Control machine. It functions much like a 3D printer, except that instead of adding material, it uses a process of cutting away (milling) material. Even much of the architecture and control circuitry is the same as for a 3D printer.

The Millright M3 CNC machine is available as a (relatively) inexpensive kit. I took about 4 days to assemble it, since I didn’t want to rush anything and I didn’t (yet) know what did what, how, or where.

The CNC itself is merely the platform. To do useful work you also need the following:

  1. A cutting device motor in a suitable carrier that bolts to the vertical (Z) assembly. One of the recommended options for this is the DeWalt DWP-11 finish router, which is what I’m using
  2. A “bit” (mill end) that chucks into the cutting motor. These come in many types depending on what you want to cut and what shape you want the cut to be.
  3. A shop vacuum, if you don’t want to end up quickly up to your knees in shavings.
  4. A vortex separator. If you don’t want the shop vacuum’s filters to clog up in 5 minuter or less. I use one that clamps to the top of a generic hardware store paint bucket (5 gallon size).
  5. An easy way to cut power to the CNC and motor. A power distribution strip with an on/off switch will do. A big red panic button is optional.

Cautions

A CNC machine is a lot scarier than a 3D printer. Think of a table saw that not only wants to randomly shred both you and anything you’re working on, but a killer robot that can rapidly strike out in unexpected directions. Think carefully before you set it in motion and make sure you can stop it quickly!

Next up: designing a printed circuit board for CNC milling (coming soon!)