EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Merlysys on December 10, 2013, 08:30:52 pm
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When troubleshooting a PCB like the one in the pic below, one or both hands will be used to hold the scope or meter or other test probes, making it difficult to adjust the test equipment. With modern PCBs being so densely packed its easy for the hand with the probe to slid off the target. I am specifically seeking probes that can stay in a place where there is no wire or component legs to grab on to.
I know most of your are such experts at this that such a tool is unnecessary , but for the rest of you...what tools are there that will hold our probes freeing our hands to do other tasks? Such a tool should push down with the probe so good contact is made with the PCB's trace/shoe. Perhaps there are spring loaded devices??
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If need be, then I'll solder a short length of wire in place and hook onto that.
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micro grabber?
(http://www.emeraldinsight.com/content_images/nacimages/6312A020.GIF)
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I suppose you could use a "third hand", or something like a panavise to hold a probe in place. I use third hands for soldering, but I've never used one for probing yet. I'll keep that trick in mind; it's a way to do what you suggest in the original post.
Often a ground connection has some place to grab on, so sometimes you may only need to hold the red probe by hand. As KJDS suggests, you can sometimes solder a short wire in place, and grab that with your probe.
But in the vast majority of cases, I place my meter on the bench (or if operating away from the bench, I hang it using one of those TPAK magnetic hangers), leaving both hands free. Two hands, two probes. If I need it, I'll turn on AutoHOLD, so I don't even need to look at the meter while I'm probing.
Regarding your final point about spring loaded devices: For small electronics, you can get nice spring loaded probes. The Fluke 910 and Pomona 6341 are basically clones of each other (I bought the Fluke version before I knew the Pomona ones existed). They are spring loaded, very sharp, and excellent for probing tiny surface mount components in tight quarters. If you stick them in a third hand or vise, you could use the spring loaded nature of the probes to maintain even pressure and contact.
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You can make a helping hand out of loc-line (example (http://www.instructables.com/id/Third-Hand-A-multi-use-helping-hand-for-electro/)).
Possible to use something other than an alligator clip on the ends, such as a hemostat or a plastic split ring (uses a screw to tighten onto a round object).
If you're after spring loaded probes and live in the US, take a look at Probemaster (http://www.probemaster.com/index.php?cPath=2_16) as well.
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That's what I'm using. On small pitch parts with unprotected pins a a piece of masking tape with a pre-poked hole positioned on top of the pin of interest will provide some security.
Similar positioners are available commercially; however, they cost about 20x and can't be used as a clamp.
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If need be, then I'll solder a short length of wire in place and hook onto that.
This tends to be my preferred method. Short piece of fine enamelled wire or similar, and hook the probe onto that. Found it far more reliable, especially if you are inside an enclosure and hand access isn't as good as it might be.