A692 black axial part?  what can VS1 designator stand for? - Page 1
Forum section: electronics / repair

author: coppercone2
author_rank: Super Contributor
timestamp: December 16, 2021, 02:47:22 am
content: Does anyone know what the component designation VS1 might stand for?There is a part, that looks like a small axial cap or resistor, called VS1. It is written A692 on the top.It is on the distribution PCB of a miller welder. I thought VS might stand for voltage suppressor. It is a two terminal device that reads 0 ohms and shows no sign of damage. I was wondering if maybe its not meant to be a dead short.I can't find anything on google on A692.. is it some kind of fuse? It is next to a big foil capacitor and 2 power resistors.Hmm.. I wonder if it can be a inductor........... but the other inductors are designated as L.Voltage shunt 1? If they needed a 0 ohm shunt.. why not use a wire instead of a mysterious large part?

author: bob91343
author_rank: Super Contributor
timestamp: December 16, 2021, 03:08:08 am
content: To answer your last question, the reason has to do with logistics. The mindless assembly of electronic circuit boards is unable to call out short pieces of wire to jump across PC traces. So a 'zero Ohm' resistor is called for.I don't know if this is one of those, but it could be.

author: coppercone2
author_rank: Super Contributor
timestamp: December 16, 2021, 03:22:36 am
content: But why would it be called VS instead of R?Voltage short? voltage shunt? that does not really make sense...Uh.. so.. if it is a short.. there is no reason I can't replace it with some copper wire right?I kind of want to smash the part open to see wtf is inside.Hmm... would any RF test show up a burned shorted diode? Like nonlinear junction mixing?I suppose it would make more sense to draw out the PCB at this point then to mess with a possibly fried diode.. but its near some big silasticed capacitors and I really don't want to desolder all that to measure the circuit.So... does anyone have a fried diode detector? Non linear junction detector would work maybe...Voltage spark? a shorted arc gap? Its fully black and does not have a band on it. I would call a shunt S1, SC1, etc... never bring voltage into it. What does it have to do with voltage anyway, the idea is that voltage is not effected. I am kind of wondering if its supposed to be a series diode.I think I can score it with a jewelers saw and then snap it open with a screw driver if it comes down to it. Something is making a diode on this PCB blow up and I want to know if this is it.This board uses RV for varistor. I assume it means resistive varistor.The only thing that VS makes sense for me is that if someone put a low value shunt in the circuit so you can measure current with a multimeter if you wanted to. But that seems awfully thoughtful for an American company, I expect that would never get past the bean counters.I hooked it up to kelvin, it measures <1 miliohm. and its not like a jumper out of some kind of necessity, its a simple PCB. There is no reason they could not have extended the trace.

author: coppercone2
author_rank: Super Contributor
timestamp: December 16, 2021, 04:06:32 am
content: http://www.farnell.com/datasheets/1814218.pdfthis document lists "VS" under test points. Maybe it is a test point.I don't think a diode would fry to sub miliohm resistance would it? Perhaps I can just measure it with a caliper and measure it with a better miliohm meter to see what the resistance is and if it matches to what I expect a copper wire of those dimensions to be. It seems they refer to it as "voltage stack".

author: bob91343
author_rank: Super Contributor
timestamp: December 16, 2021, 04:26:17 am
content: It could also be a piece of ferrite for noise control.

author: coppercone2
author_rank: Super Contributor
timestamp: December 16, 2021, 04:30:03 am
content: Hmm... you know... I just assumed it was plastic because it has conformal coat on it that gives it a sheen. I would have figured ferrite bead = FB1. If its ferrite it will be magnetic. It IS attracted to a magnet. I need to find a tiny magnetMaybe its a plastic coated ferrite bead thats coated with conformal coating to make it more confusing. I will investigate tomorrow