FIRST TIME IN MY LIFE: 34401A continuity test fried a board... - Page 1
Forum section: electronics / general

author: Zucca
author_rank: Unknown
timestamp: June 29, 2017, 07:09:35 am
content: I was just reverse eng. this one:it's a ixon core iq2 light board... with a Li Ion Battery soldered on it:with a nice OSRAM LEDNow... I was just dicking arond and waiting to hear some cont. BEEEP, then I touched the board G point and the LED turned on, more bright, more bright, more bright, burned plastic smell started and then BOOM LED was gone, lost. 1 sec. later I had a broken board on my table. Who knows if other parts died as well...Ok, next time I will take out the battery, even if it is a soldered one....Very sad, just wanted to share... may be there are people like me out there who are thinking with a continuity test nothing will happen...

author: TheSteve
author_rank: Unknown
timestamp: June 29, 2017, 07:13:18 am
content: I think you mean that leaving power connected while probing the board caused it to fry.

author: Zucca
author_rank: Unknown
timestamp: June 29, 2017, 07:21:37 am
content: yes, even if the board was turned off, if it is just "soft switched" off then it is dangerous don't do that.

author: Cyberdragon
author_rank: Super Contributor
timestamp: June 29, 2017, 02:54:32 pm
content: Quote from: zucca on June 29, 2017, 07:21:37 amI'm pretty sure in most meter manuals it says to remove all power sources from a circuit before doing any ohms test. You failed to do so, and thus destroyed stuff (you're lucky it wasn't the meter).

author: alm
author_rank: Super Contributor
timestamp: June 29, 2017, 03:01:22 pm
content: Or maybe the voltage from the continuity test was sufficient to turn a FET on, shorting the battery.But the root cause was probing with power applied to the DUT. So no, the 34401A did not fry the board, you did.

author: Zucca
author_rank: Unknown
timestamp: June 29, 2017, 04:03:21 pm
content: Yes I was too lazy, I should have desoldered the battery. You are right guys.Quote from: Cyberdragon on June 29, 2017, 02:54:32 pmA 34401A killed by a Single cell Li Ion battery? How?I mean surely you can melt the protection fuses in current measurements but to destroy this meter with a single battery it is a real challenge IMO.Quote from: alm on June 29, 2017, 03:01:22 pmI did touched a transitor which caused the full V Bat to go an the poor LED. Good callalm!

author: senso
author_rank: Frequent Contributor
timestamp: June 29, 2017, 04:59:56 pm
content: A LiPo can dump 20-30Amps or more, no fuse will save you in the mili-seconds that such would take..

author: Dave
author_rank: Super Contributor
timestamp: June 29, 2017, 05:28:43 pm
content: Quote from: senso on June 29, 2017, 04:59:56 pmIf your meter gets damaged by 30 measly amps, it's a piece of shit.They install high rupture capacity (HRC) fuses into good multimeters, it's to protect them from INSANELY large overloads, such as shorting a the mains. The fuses are designed to break currents of several kiloamperes, 30A is a walk in the park.

author: Yansi
author_rank: Super Contributor
timestamp: June 29, 2017, 05:32:01 pm
content: You really are NOT going to damage any decent multimeter with a 30A surge...

author: Electro Detective
author_rank: Super Contributor
timestamp: July 31, 2017, 12:18:08 am
content: Sad news mateI did a 'quick' continuity test on some live gear back in my dark newb days, and the device exploded with parts flying everywhereThe DUT was beyond economical repair with my skill set then, but the Radio Shack digital meter survived unharmed, and miraculously so did II had no clue how it happened then, but decided it was my first and LAST 'bad multimeter experience'and bought a couple of good multimeter books and learned the ropes properly,no Darwin Award for me just yet, thank you

author: Cyberdragon
author_rank: Super Contributor
timestamp: July 31, 2017, 01:50:20 pm
content: Quote from: evb149 on July 31, 2017, 12:27:51 amPfft...try doing that with mains! Been there, done that (a few times). Less of a smell and more of a loud pop followed by darkness and swearing.Luckily analog scopes survive that kind of crap.