tektronix_logo_designsparkA year or so ago, when the Tektronix MDO3000 series scope was released, I signed up to win one from Tektronix. At the time, I used my personal email and home phone number since it was a competition (why would I used my office phone)? Shortly after, the calls from Tektronix started asking me if I wanted to buy anything, was looking to buy anything, etc (sales/marketing calls). Most of the time, they’d just call early in the morning (8-9am), or somehow, right when my one year old was taking a nap. =/

They would also send an email follow up, though they wouldn’t leave a voicemail. After the second time it happened, I emailed them back and said “please don’t call my home phone, call my work phone xxx-xxx-xxxx”. No response. Then a mouth or so later, another call and email. Respond to email, no response. The third time, I finally got a response to the email saying they would have to talk to their supervisor about removing me from the list. A follow up resulted in nothing, but also no calls for at least a month. Then another call at 8am one day, and I lost my patience. I emailed their main PR/Marketing email address on the Tektronix website with something rather stern, and commenting that I grew up across the street from Tektronix, and many of my family members, as well as my wife’s father, worked there for years. For a couple weeks, I heard nothing, but then I heard from a Senior Communications Manager apologizing, and saying she would look into where the process failed, and had me removed from their lists. Also, she said she was going to mail me a gift as an apology. I provided my mailing address, and a couple weeks later, got an overnight notice from UPS that something was due for delivery. What did it have?

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Fluke 12 repair

Fluke 12Another meter repair everyone! Anyway, as usual, I purchased a Fluke 12 off eBay listed as the buttons not working, but the meter itself worked as long as you were measuring diodes, or VDC. After a quick search online, this appeared to be due to the elastomeric strip between the buttons PCB and the main PCB being dirty, or failing. I contacted the seller to make sure the case wasn’t broken (as this meter seems to be on Fluke’s “Repair by Replace” list, I didn’t want to fall into that trap again), and after he said it was all intact, I ordered the unit for $30 + $6 shipping.

The meter arrived, and indeed, the buttons didn’t work. Nice “click” when pushing, but no registration. I pulled the screews from the back of the unit, and the main PCB clips into the case in a rather awkward way (really Fluke?). After getting that out, there’s a plastic/metal shield that holds the LCD and button board in place, and a cutout for the two elastomer strips to pass through. I cleaned the main PCB real well hoping that would help, but sadly, it still doesn’t work. I grabbed my meter, and checked the strip it came with, and it registered in 5 mega-ohms. Well, that’s not right. Online I found some references to stealing the elastomer strips out of a Harbor Freight cheapo multimeter. As luck would have it, I had one of those I got for free a while back. Indeed, it has two strips between the board and the screen, and while the height of them is right, the thickness is off (they’re just over 1/2 as thick is the stock strip). So, I cut two to the right length, and measured their resistance: about 5-10 kilo-ohms. Much better. I doubled them up and managed to shove them into the space where the old strip was, and closed the unit up. Once the screws were in (and therefore pressure applied to the strips), it worked! Total repair time, less than 10 minutes. Cost, free!

Good luck repairing one of these. It’s a cute little meter, and works great. While it doesn’t measure current, it does have a LoZ mode, and pretty much every other measuring mode I could want. Also, the autoranging for ohms is amazingly fast.

I only wish Fluke made some test leads with straight banana jacks on them… it just seems awkward to have 90° banana plugs going into the unit, and have those angled off. Weird.

Update: I’ve since bought a Fluke C10 holster, and reenforced just how much I like this meter. I am a bit sad that the holster is the “old” style “rubber” of Fluke holsters (kind of slick, almost greasy feeling), rather than the newer grippy type. Ah well. Also, I now see why the 90 degree test leads. Using the holster “stand”, straight leads wouldn’t allow it to use the stand. Brilliant!

The story of the mis-wired XT60 connector and the DJI Phantom

Mis-wired XT60I was recently handed a malfunctioning DJI Phantom Quadcopter that anytime the owner tried to lift off, it would just flip backward and crash. So, I went about recalibrating, and figuring out how to actually fly a Quadcopter. Anyway, I figured it out1. Anyway, I flew the unit around for a bit, then when the battery got low, the unit landed and showed me it’s wonderful flashing red light.

So, I brought it in, and plugged in the dead battery. As “luck” would have it, though, the place the unit was ordered from sent a free extra battery (RC-2220C3S) made by some other company (WATSON). So, I figured I’d try that. I checked the unit with a multimeter based on lead coloring, and saw it was at 11.2V, which is fine. So, I plugged the battery into the Quad, and was immediately greeted with flames, and a huge amount of “blue” smoke. I quickly unplugged the battery to figure out what the heck went wrong. An XT60 connector is polarized, so there’s no way to plug in backward. But, if you’re eagle-eye’d, you’ll notice the picture for this post, and something I didn’t even think about prior to plugging in the battery. The pos/neg (red/black) are wired backward! So basically 11.1V and all but unlimited amps (Lithium Poly battery) went up the ground plane, and anything that didn’t have polarity protection was fried (or at least the first thing to short was fried).

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  1. The “front” of the Phantom is determined by which end you point “down” during the compass calibration. According to their rather lackluster drawings, the “front” is the battery door side []