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Posts from — October 2014

Common Equipment Failures

Most of the time, industrial equipment is rock solid.  However over the years, I’ve noticed a tendency for certain products to have characteristic failures or problems.  Examples:

  • MEI PCI/DSP Motion Controllers and blown I/O.  The PCI/DSP is pretty expensive motion controller, and as befits its price, has opto-isolated I/O, but the general purpose I/O is not protected against over current, so anything over say 20 mA will kill the opto-isolator.  The result: blown I/O and, if you’re lucky, a $500 repair bill.  We learned pretty quickly to make sure we always had appropriate current limiting resistors.
  • AMC DX15 and DX60 CANOpen servo drives have the blinking red light.  The drive powers up, the red light starts blinking, and the drive stays mute: it will not communicate over the CAN bus (and there’s no alternate port to try).  I’ve done some troubleshooting, but haven’t made any progress.  Of all the DX15/DX60 drives I’ve bought from eBay, probably about 50% had this problem (yes, an unfair sample, since the good ones are less likely to get on to eBay.  AMC is a good company, but this record indicates that the DX has a design weakness).
  • Parker ACR9040 Motion Controllers seen to have an easily blown 24V power supply, based on eBay: I’ve seen a few advertised as “won’t power up”, and I bought one that was in “unknown condition” that won’t power up (its physical condition is fine).  I’ve spent a little time troubleshooting, but haven’t found the problem yet.  On the plus side, I’ve enjoyed taking it apart and looking at Parker’s design decisions.
  • I’ve also had bad luck with Elmo servo drives off eBay, with only 1 of 3 working.
  • I have a number of old servo drives with broken halls or broken encoders.  My guess is too much heat for the halls, and too much mechanical shock for the encoders (one even had broken glass).

Now it’s time for some screw-up stories that were totally operator error:

  • One day many years ago, as I came in the back door, I was greeted by blue fireball about 1 foot in diameter.  A tech was live troubleshooting a variable speed conveyor motor, and accidentally shorted out the motor driver, causing the fireball and the top of a driver chip to vaporize.
  • More recently, I was going to measure the current supplied by an AMC PS300 unregulated linear power supply, but had my probes setup wrong, so I shorted across the power supply.  Result: a welder!  The meter and power supply survived, but my meter probe tip melted.
  • I had a weird problem with a FP-Sigma PLC output partially failing.  The PLC’s light was coming on, but the relay driven by that output wasn’t.  The problem was that Common at the relay coil was about 2V different from the PLC’s Common, and over time that destroyed the PLC’s output.  On the other hand, I’ve shorted Panasonic PLC’s (easily if you accidentally swap the input and output cables) and they’ve always survived.

 

October 22, 2014   2 Comments

Updated Information On Electro-Craft E-Series Motors

I’ve updated my trac page on the Electro-Craft E-3618 with a scanned datasheet with information on the E-3618, E-3622, E-3626, E-3629, and E-3633, and the BDC MINI-Series servo amplifier.  Since I only own E-3618’s, I didn’t add a new page for the other motors.

By the way, the end of Electro-Craft catalog contains a nice little overview of servo motor theory and operation.

October 21, 2014   No Comments

Favorite Tools – Fall 2014

Pens And Pencils

I use pens and pencils quite a bit.  Partly it’s simply because I like using them; I also feel that they are better for notes and initial drafts (sketching out software or electrical ideas and such) – you can quickly draw anything anywhere without constraints.

Gel pens are my favorites for their smoothness and solid, vivid lines.  Overall, Uniball is my favorite brand (Signo DX, Signo 207, Jetstream, etc).  I really love the Pilot G2 Limited body; it’s comfortable, attractive, reasonably priced, and takes Uni Signo 207 refills with ease.  In general, I’m not a Pentel pen fan, but the 0.35mm Energel Needlepoint is really sweet.

I didn’t use pencils much until I bought the Uni Kuru Toga Roulette; it’s still my favorite pencil, but I’ve been having fun testing out the Pentel Orenz 0.2 mm pencil.

When I’m doing sketches that require color, I use my Staedtler triplus fineliner 10-color set.  The only issue is that I can’t erase it; however, I haven’t found an erasable colored pencil or colored mechanical pencil lead, so sometime I plan on testing out a set of Pilot’s erasable Color Pencil Like Frixion pens.  I do have mixed feelings about the Frixion pens; they’re great for an erasable pen, but aren’t as nice (smoothness, color, line quality, refill life) as a decent pen.

Smart Phone

I’m not a big phone geek; I loved my old Palm Centro with its keyboard and excellent PIM apps.  I’m feeling a lot better about Android since installing DejaOffice; it’s not perfect, but provides integrated PIM functionality (Tasks, Memos, Calender, etc), synchronization (including to Palm Desktop/Pimlical), and is cross-platform (Android, iOS, BlackBerry, Windows Phone, Win 8.1).

My phone is a Samsung Note 2.  I really like it: battery life is great, there’s a micro-SD card for affordable storage, on-screen keyboard is good, the display is nice, it’s fast enough, it’s barely hand-holdable, and it’s affordable used.  If I ever really use my phone for business, I’ll take a serious look at the Blackberry Passport, but it’s currently too pricey for just personal use.

I also have to put in a plug for my provider, Ting.  Their prices are competitive for my usage, and their service is the best I’ve experienced.

Tablet/Laptop

I’m currently using an Asus T100TA 2-in-1 tablet with keyboard.  It’s not perfect (keyboard is a little small, for example), but it’s a good fit for me now because:

  • It’s cheap (<$250 refurbished) so I’m not worried about losing it
  • Powerful enough (quad core Baytrail; the browser seems to handle complex web sites better than Android or BB Tablet OS)
  • Can run standard Windows software (like LibreOffice) and screen resolution is low enough the menus aren’t microscopic
  • USB 3.0 port on keyboard, micro-SD card on the tablet part
  • Great battery life (except sometimes it doesn’t go to sleep when I tell it to) and quick boot times

In summary, I find it’s a lot more productive than an Android tablet, and smaller and more convenient than a notebook.  Most of the time I use it with the keyboard, but I do take the keyboard off when I’m doing more tablet-y things (like exploring in Maps).  I’m surprised that I use the touchscreen a lot, even with the keyboard attached.  I think that’s because it’s so small.

Desktop

For getting work done, I still find there’s no substitute for a good ergonomic setup with a desktop: mechanical keyboard (Cherry Blues, Cherry Greens, or Buckling Springs depending on my mood), big 24″ 1920 x 1200 monitor, octa-core CPU, 16G RAM, and a fast Samsung SSD.

Keeping Everything In Sync

I believe in using what works for me, not keeping up with fads.  I’m still sorting out what works best for what tasks.  I’ve played some with Dropbox, and I have mixed feelings about it (including their security record), and don’t want to go all-Google.

So I’ve setup an Owncloud server for an affordable price ($15/year for 15G storage).  I’m still working out what I want to put on Owncloud in what formats, what I want to put on trac, and what works best on WordPress.

For example, LibreOffice Calc is much nicer for tabular content, but doesn’t share well; trac is probably next best.

Obviously, WordPress is best for public blog posts, but for public directories and content I update over time, I’ve shifted between using WordPress pages and trac pages; right now, I’m learning towards using trac most of the time.

Blog Notes

I’ve still been quite busy at work and home this month, but I promise to get some more posts up before end of the month.

Postscript 11/25/2014: I really like the Note 2’s form factor (biggest display that’s barely hold-able and slim), and can see why the Note family as created a new category.  I also just received my 12-color set of Frixion color pencil like pens; my initial impression are positive, and I plan on donating my Staedtler tri-plus set to a more artistic family member.

October 20, 2014   No Comments