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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2039894@logan.com>
Subject: Re: [FlyRotary] Re: EC2 question
Date: Sat, 12 May 2007 15:33:09 -0400
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I truly appreciate all the information/experience with Tant capacitors.  I 
think that may explain why I have had two boards "burn up".  In one case the 
Voltage Regulator was fried to a crisp and charred the surrounding PC 
board - so you know it got hot.  In another case, I smelled the "Smoke" 
before it came out and found the VR shearing hot to the touch.  I had never 
used Tant capacitors before and I plan on going back to ceramic.

Thanks again, guys

Ed
----- Original Message ----- 
From: "Ernest Christley" <echristley@nc.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Saturday, May 12, 2007 12:08 PM
Subject: [FlyRotary] Re: EC2 question


> Ed Anderson wrote:
>> Geeze, Jim.  Here I've been using tantalum capacitors in my circuit 
>> boards.  Are these failure modes spontaneous or are they triggered by 
>> something like over voltage, over temp, etc.  I guess I'm a bit surprised 
>> at the violence of their demise - I would think something like that would 
>> have curtailed their use in electronic circuits.
>>
>>
> I've had the same experience, Ed.
>
> In my case, I worked as a QA tester.  I stood at the end of an assembly 
> line, and tested the circuit boards on a bed-of-nails test set.  One 
> particular board used cheap tatalums, and when the vacuum sucked the board 
> and power went to the nails, a random cap would pop, blow fire a foot high 
> and stink to high heaven.  I was second shift, and management wouldn't 
> believe what I was telling them until they started testing the same boards 
> on first shift 8*)  THEN THEY BELIEVED, as they were shaking the poo out 
> of their underwear.
>
> The test engineer implemented a partial fix by ramping the voltage up much 
> slower.  The initial charge inrush was responsible for finding many of the 
> cheaper caps.  Or so he said.  It didn't cure the problem completely, but 
> it did alleviate it some.
>
> --
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