Re: [time-nuts] The Smell of Tantalum in the Morning
My experience is that the plastic ones tend to burn. The mil grade ones in HP I have never seen fail (As in flame) On Mon, Feb 8, 2010 at 8:05 PM, Glenn Little WB4UIV glennmaill...@bellsouth.net wrote: While in the US Navy, we had to do equipment inspections. One quarterly was to examine the capacitors in the power supply of one piece of equipment. We were to look for leakage (sulfuric acid) from CL65 type wet slug tantalum capacitors. Shortly after that CL65 type capacitors were disapproved for military use. I never saw one that leaked in that equipment, but, have seen a number of boards damaged from seal leakage on CL65 capacitors. Something to look out for. The CL65 capacitors probably have a pure silver case a sulfuric acid as an electrolyte. The seal is Teflon. We also had an interesting failure mode for ATC ceramic capacitors. This failure mode will only occur in a sealed environment (submarine. Just an observation. 73 Glenn WB4UIV At 09:46 AM 2/8/2010, you wrote: The history of tantalum failures is wide and varied, but there are some common characteristics: 1) The tantalum is in a power supply circuit and receives a rapid ramp from 0V to operating voltage. 2) The tantalum is spec'd close to its operating voltage, very close 5V on a 6.3V part, 12.5V on a 15V part... 3) The tantalum is dry slug, and is sealed with epoxy. 4) The instrument has been powered down for an extended period. HP equipment from the 1980's is pretty immune to the problem because they typically use hermetically sealed mil spec tantalum capacitors. Tektronix equipment from the 1980's is infested with tantalum problems because they used the cheap epoxy dipped parts. Tantalum failures are pretty rare in equipment that is run continuously. Tantalum has a self healing feature that corrects any small problems while in operating... Large problems result in detonation. Dipped tantalum capacitors of any age are prone to failure. The tendency can be mitigated largely by never allowing a tantalum capacitor to see voltage above 50% of its rating. And finally, powering a tantalum in reverse, will cause instant and irreparable damage. -Chuck Harris Tom Van Baak wrote: I powered up a 5071A to watch the end of Loran-C today and was greeted by the special smell that only a mother board could love. Does anyone know the history of tantalum capacitor failures in ten-year old [HP/Agilent] test equipment? This is not my first. Last one was more like July 4th. Thanks, /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] The Smell of Tantalum in the Morning
I powered up a 5071A to watch the end of Loran-C today and was greeted by the special smell that only a mother board could love. Does anyone know the history of tantalum capacitor failures in ten-year old [HP/Agilent] test equipment? This is not my first. Last one was more like July 4th. Thanks, /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] The Smell of Tantalum in the Morning
I have a Philips counter where a Tantalum regularly fails in the oven. They also failed commonly in transceiver finals in the 80's I powered up a 5071A to watch the end of Loran-C today and was greeted by the special smell that only a mother board could love. Does anyone know the history of tantalum capacitor failures in ten-year old [HP/Agilent] test equipment? This is not my first. Last one was more like July 4th. Thanks, /tvb -- Raj, VU2ZAP Bangalore, India. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] The Smell of Tantalum in the Morning
I fired up a TEK 485 scope over the weekend and was greeted by a similar event. Sure smelled like tantalum but turned out it was a sacrificial 10 ohm resistor taken out by a shorted tantalum. I don't have any equipment that is only 10 years old. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Van Baak Sent: Monday, February 08, 2010 4:15 AM To: Discussion of precise time and frequency measurement Subject: [time-nuts] The Smell of Tantalum in the Morning I powered up a 5071A to watch the end of Loran-C today and was greeted by the special smell that only a mother board could love. Does anyone know the history of tantalum capacitor failures in ten-year old [HP/Agilent] test equipment? This is not my first. Last one was more like July 4th. Thanks, /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] The Smell of Tantalum in the Morning
The history of tantalum failures is wide and varied, but there are some common characteristics: 1) The tantalum is in a power supply circuit and receives a rapid ramp from 0V to operating voltage. 2) The tantalum is spec'd close to its operating voltage, very close 5V on a 6.3V part, 12.5V on a 15V part... 3) The tantalum is dry slug, and is sealed with epoxy. 4) The instrument has been powered down for an extended period. HP equipment from the 1980's is pretty immune to the problem because they typically use hermetically sealed mil spec tantalum capacitors. Tektronix equipment from the 1980's is infested with tantalum problems because they used the cheap epoxy dipped parts. Tantalum failures are pretty rare in equipment that is run continuously. Tantalum has a self healing feature that corrects any small problems while in operating... Large problems result in detonation. Dipped tantalum capacitors of any age are prone to failure. The tendency can be mitigated largely by never allowing a tantalum capacitor to see voltage above 50% of its rating. And finally, powering a tantalum in reverse, will cause instant and irreparable damage. -Chuck Harris Tom Van Baak wrote: I powered up a 5071A to watch the end of Loran-C today and was greeted by the special smell that only a mother board could love. Does anyone know the history of tantalum capacitor failures in ten-year old [HP/Agilent] test equipment? This is not my first. Last one was more like July 4th. Thanks, /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] The Smell of Tantalum in the Morning
I've seen the butt weld (or crimp) of the wire in hermetic units fail due to corrosion in both HP and Tek gear. In all cases (about 6), the gear appeared to not have been protected too well from the elements, or was exposed to high humidity for a long time. The good news is that it fails open and is pretty obvious. Dave - Original Message - From: Chuck Harris cfhar...@erols.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, February 8, 2010 6:46:54 AM GMT -08:00 US/Canada Pacific Subject: Re: [time-nuts] The Smell of Tantalum in the Morning The history of tantalum failures is wide and varied, but there are some common characteristics: 1) The tantalum is in a power supply circuit and receives a rapid ramp from 0V to operating voltage. 2) The tantalum is spec'd close to its operating voltage, very close 5V on a 6.3V part, 12.5V on a 15V part... 3) The tantalum is dry slug, and is sealed with epoxy. 4) The instrument has been powered down for an extended period. HP equipment from the 1980's is pretty immune to the problem because they typically use hermetically sealed mil spec tantalum capacitors. Tektronix equipment from the 1980's is infested with tantalum problems because they used the cheap epoxy dipped parts. Tantalum failures are pretty rare in equipment that is run continuously. Tantalum has a self healing feature that corrects any small problems while in operating... Large problems result in detonation. Dipped tantalum capacitors of any age are prone to failure. The tendency can be mitigated largely by never allowing a tantalum capacitor to see voltage above 50% of its rating. And finally, powering a tantalum in reverse, will cause instant and irreparable damage. -Chuck Harris Tom Van Baak wrote: I powered up a 5071A to watch the end of Loran-C today and was greeted by the special smell that only a mother board could love. Does anyone know the history of tantalum capacitor failures in ten-year old [HP/Agilent] test equipment? This is not my first. Last one was more like July 4th. Thanks, /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
