X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 50 [XX] Return-Path: Received: from ms-smtp-02.southeast.rr.com ([24.25.9.101] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 2042171 for flyrotary@lancaironline.net; Sun, 13 May 2007 12:10:24 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.101; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-103-061.carolina.res.rr.com [24.74.103.61]) by ms-smtp-02.southeast.rr.com (8.13.6/8.13.6) with SMTP id l4DG9iKV016507 for ; Sun, 13 May 2007 12:09:44 -0400 (EDT) Message-ID: <000e01c79579$565dfc90$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" Subject: Another board overheating Date: Sun, 13 May 2007 12:11:17 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000B_01C79557.CEF42A70" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3028 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_000B_01C79557.CEF42A70 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Well, I just had my third board start to overheat since I began using = Tant Caps in them. But, this time, I got better insight to what was apparently causing it. = There is no ON/OFF switch on the module - it is designed to be ON from = the time you turn your master switch on. This to ensure that when you = start your engine the module starts recording your fuel burn. Normally, I simply unplug the connector which removes the power from the = unit - with no problem. However, this time when I was using an uncovered connector with just two = power wires connected for a temporary test. When I pulled the = connector, the power and ground lead made momentary contact - this = apparently caused a surge (voltage/current) that caused a chip to blow. = I had my finger on the heat sink for the voltage regulator and = immediately felt it start to heat up - so disconnected the power before = things escalated. I do have a 30 V schottky diode on the positive lead = side to prevent reverse voltage from damaging the circuit - So not = certain what mechanism triggered the failure mode- but it did. I do recall reading in some of the studies on Tant capacitors and some = of you have mentioned that sudden surges in voltage can cause failures - = I believe I have verified that {:>). That reinforces my decision to = remove the Tant capacitors - Apparently they work well under expected = conditions but apparently do not have as much tolerance for unexpected = conditions. Just thought I would mention my experience.=20 Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.dmack.net/mazda/index.html ------=_NextPart_000_000B_01C79557.CEF42A70 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Well, I just had my third board start to = overheat since I=20 began using Tant Caps in them.
 
But, this time, I got better insight to what was = apparently causing it.  There is no ON/OFF switch on the module - = it is=20 designed to be ON from the time you turn your master switch on.  = This to=20 ensure that when you start your engine the module starts recording your = fuel=20 burn.
 
Normally, I simply unplug the connector which = removes the=20 power from the unit - with no problem.
 
However, this time when I was using an uncovered = connector=20 with just two power wires connected for a temporary test.  When I = pulled=20 the connector, the power and ground lead made momentary contact - this=20 apparently caused a surge (voltage/current) that caused a chip to = blow.  I=20 had my finger on the heat sink for the voltage regulator and immediately = felt it=20 start to heat up - so disconnected the power before things = escalated.  I do=20 have a 30 V schottky diode on the positive lead side to prevent reverse = voltage=20 from damaging the circuit - So not certain what mechanism triggered the = failure=20 mode- but it did.
 
I do recall reading in some of the studies on = Tant=20 capacitors and some of you have mentioned that sudden surges in voltage = can=20 cause failures - I believe I have verified that = {:>).  That=20 reinforces my decision to remove the Tant capacitors - Apparently they = work well=20 under expected conditions but apparently do not have as much tolerance = for=20 unexpected conditions.
 
Just thought I would mention my experience. =
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary = Powered
Matthews,=20 NC
eanderson@carolina.rr.comhttp:/= /members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda= /index.html
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