Electronics Archives - Page 8 of 23

Fluke 322 (failed) Repair

2015/04/26 By staze

I recently, mistakenly, purchased a Fluke 322 off eBay for far more than I should have paid (paid about $35 for a broken one). I thought it would be an easy repair, but sadly, the issue was that the case was broken (guessing it got dropped from some height, or was partially crushed). The self-taping screws all screwed into the plastic casing front, and several of those threaded lugs were broken, so the case wasn’t being held together fully, which results in the contacts from the rotating switch not making contact enough to turn the multimeter on.

My first thought was to contact Fluke and ask about purchasing a replacement front case. Thankfully, they got back to me quickly and said this unit is on their “repair by replace” list. Meaning for $90, I could send it in, and they would send me the new model of this unit, which is also on the “repair by replace” list, and also means they have no parts available.

My second attempt was to use some JBWeld to repair the broken lugs. Sadly, this resulted in the lugs being the wrong height such that the board, even though it would screw in at that point, still didn’t provide enough pressure to the contacts to power on.

So, sadly, this one is a loss. I’ve kept the unit in the parts drawer incase I ever see one for cheap… or I manage to see someone interested in one for the main board, clamp, etc. down the road.

FNET

2015/04/15 By staze

Being a data nut, a relatively recent electronics enthusiast, and now a burgeoning “time nut”, there was a thread on the timenuts email list on monitoring the mains frequency (60Hz in North America, and 50Hz most other places), and how accurate it actually is. One of the responses pointed toward FNET, or a project run by the University of Tennessee. They provide a “box” that you plug into your network, mains (120V in my case), and a GPS antenna. It measures your mains frequency with what I assume is a zero cross detector, correlates that frequency with a highly accurate 1PPS signal that it’s GPS receiver generates, and then streams that data to the FNET servers (which can be viewed here).

Thinking that sounded pretty awesome, I contacted them, and asked if they wanted a box in Eugene (my intent being to install it on Campus in my office). They jumped at the chance, and sent me a box. A week or two later, I got it, and tried to set it up. Sadly, after a couple days of futzing, I realized to my dismay that Low-E windows block GPS signals. =( BUT! I have access to the “penthouse” where they have all our HVAC equipment, and has roof access. After some investigation, and some help of a friend, I was able to run the GPS cable through an empty 1″ conduit, outside, up the side of the penthouse, and onto it’s roof, which is solid steel, so the magnetic GPS puck sticks great. The unit itself I hung from some electrical conduit using some Velcro straps. Also slapping a label on the unit saying to contact me if there are any questions (since a box with flashing lights on it, could be confusing to a random Facilities employee).

GPS lock was great (I average about 10 satellites), and the cable was a perfect length (5 meters). I would suggest they switch to SMA connections for their GPS in the future, but meh. If you’re curious, take a look here. I’m unit #1033. It’s interesting to see how the mains frequency droops, or elevates during the time of day, and knowing whether that’s when people are just getting home, or leaving, etc. I would also highly suggest reading up on the US Power grid, and how the West and East are joined by the Texas interconnect.

Technician mode on WelchAllyn 678

2015/03/08 By staze

When my son was “on the way” we went looking to buy a thermometer since we knew we’d need one. Being a geek, I looked on eBay and found a hospital/clinic grade WelchAllyn SureTemp. It was an older model, but seemed to be in good shape, and I got it for pretty cheap (like $30). It came with the Oral/Aux probe, but didn’t come with the wall holder, which is a slight issue, as I’ll find.

The unit, by and large, works great. It was pretty grimy when I got it, but it cleaned up with some IPA and cotton swabs. The problem was, since I was using it for my baby (then toddler) son, I wanted to use the under-arm mode. It defaults to the Oral mode, and you have to hold the mode button for 2 seconds to switch it. This can be changed if you read the Service Manual by placing the unit in the wall holder, and holding the mode button down while removing the probe. I don’t have the wall holder. Damn. A bit more reading in the Service Manual showed there is a magnetic read switch on the PCB that’s being toggled when placed in the wall holder. So, I grabbed a largish magnet (circular) ((the type you see a hook attached to. Think I got it at Harbor Freight)), and placed it on the front of the unit while holding Mode, and removing the probe. Viola! It went into Service, and I was able to change the default to ALY (Auxiliary) mode by default. Yay! Good luck (if you have one of these, and this behavior annoys you).

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