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| Wavetek / Fluke ? SF10 short finder -A very useful tool if you can find it |
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| Fraser:
A few years ago I was hunting for a decent continuity tester to assist in tracing component interconnects on PCB's whilst reverse engineering for repair work. I stumbled upon an unusual unit from Wavetek named the 'SF10 Short Finder Brush' I could only find it available in the USA but as it was on offer at US$19 the additional postage cost wasn't too much of an issue. What makes this unit unusual? Well take a look at the picture. It has the normal multimeter like test probes for point to point continuity testing, plus a stainless steel brush. With the brush the user can pick a point of interest on a PCB circuit with the cabled test probe and then 'scan' the PCB with the brush until continuity is found. The brush is then replaced with the probe, at the other end of the unit, to zero in on the continuity point. It is designed to provide a continuity indication beep no matter how fast the brush is moved across the PCB. It also uses semiconductor safe voltages and currents, unlike some continuity testers designed for electrical work. Details are here: http://www.tequipment.net/WavetekSF10.html http://uk.rs-online.com/web/p/continuity-checkers/3389851/ Is it any good ? Well I ordered a couple of the units from the USA and can confirm that it is very well made and VERY quick to respond to continuity. I used it in anger today to reverse engineer a multi layer PCB that had issues. I was able to quickly locate the main interconnects between the chips of interest and it was much faster than the point to point testing that I have done with my Fluke 87 III. Does it have any flaws? Well maybe....it cannot be used on PCBs that have been marinised or coated with varnish. But then that is true of any contact probe unless you pierce the insulation. You can also use the brush on the component side of the PCB if that is not coated. So why did I say 'if you can find it'....well for some reason Wavetek/Meterman have discontinued this useful tool and no equivalent appears to be available. You could probably make something similar if you can find a metal filament brush and a very fast responding electronics safe continuity tester. For US$19 it was a bargain though. If you do any PCB reverse engineering I recommend this continuity tester so if you spot one....consider adding it to your tool kit. A simple idea that works well. |
| toli:
Why not build on yourself? Now with 3D printers being so wide spread I'm sure you can find someone who can even print a nice case for it, and the circuit isn't complicated at all. Or even easier, just make a similar brush "probe" for your DMM (assuming your DMM is fast enough on the continuity range). I'm sure its possible to figure our a method to place both the brush and the normal sharp probe tip on opposite sides of the same silicon/plastic handle. I might even give that a try one of these weekend if I can find the time :) |
| Fraser:
A DIY solution id definitely possible. A chap on Instructables made a version of it with a multimeter connected to a foil finger cap but that isn't quite the same IMHO. A metal brush connected to a fast multimeter, as you suggest is a better plan. http://www.instructables.com/id/How-To-Quickly-Find-And-Trace-PCB-Tracks-1/ I don't actually need another as I have one, and a spare :) The clever bit is really the fast responding continuity tester. It is as fast, or faster than my Fluke III beeper circuit and provides fast audio feedback, indicating that you have just passed over the continuity point for which you are hunting. I will take a picture of the units internals for anyone wanting to build their own. The low test voltage and low current is crucial for such a unit. I have found a price for when the unit was available in the UK....GBP39 (~$60) so it wasn't exactly cheap but it is well designed and built. I just noticed an interesting label on the unit: "WAVETEK is a trademark of Wavetek Wandel Goltermann Inc. (WWG) and is used by Fluke under a transitional licwence agreement. Fluke is not affiliated with WWG" So Fluke were involved in this unit ? Could it be that it is actually a Fluke product with Wavetek labelling ? That would explain the excellent performance and quality of the product, and possibly its discontinuation ? Interesting :) I have amended the title of this post to reflect this possibility. |
| Fraser:
Internal pictures :) It contains a LP324 and two TL555C's ....nice and simple :-+ Easy to repair if I fry it ! http://www.ti.com/lit/ds/symlink/lp324.pdf http://www.ti.com/lit/ds/symlink/tlc555.pdf |
| peter.mitchell:
cable "ringers" are also incredibly useful, essentially, you connect a tone generator to one end, then a receiver "wand" is waved over the cables, and the one that makes the wand "ring" is the one the generator is connected to. Incredibly useful for wiring harnesses and large scale cabling. |
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