---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 07/22/18: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:27 AM - Re: aeroflash strobe repair (Robert L. Nuckolls, III) 2. 11:49 AM - Re: aeroflash strobe repair (C&K) ________________________________ Message 1 _____________________________________ Time: 09:27:28 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: aeroflash strobe repair At 10:26 PM 7/21/2018, you wrote: > >I just had another aeroflash 151-0011 strobe power supply fail. >Interestingly it was the second one I've seen with an open 330K >resistor that was preventing triggering. >On 12 volts the unit would almost immediately charge up to 400 volts >and then shutdown until the voltage decayed. >On about 6 volts the unit would charge continuously to about 300 >volts and you could hear the trigger fire but the signal was not >getting to the white wire going to the flash tube. >Across the 330K resistor measured about 450K in circuit and it was >in fact open. It was the larger (1/2 watt) of the two 330K resistors >that failed. >Simple fix but of course the usual safety cautions of respecting >high voltage and capacitors applies. Mine self discharged quickly >but yours might not. Good find. Thanks for sharing. I am mystified by the failure of so high value of resistor. Was it observably discolored or mechanically compromised? 1/2w was perhaps marginal. 300v/300k is one mil which is 300 milliwatts. Was it a carbon comp? Bob . . . ________________________________ Message 2 _____________________________________ Time: 11:49:30 AM PST US Subject: Re: AeroElectric-List: aeroflash strobe repair From: C&K It looked like a modern metal film resistor to me. Mounted parallel with the circuit board with a light conformal coating. No evidence of it getting hot, discolored, or mechanically stressed. In fact there was no evidence of anything on the circuit board running hot. This unit was 12 years old and bolted to the main spar in the outboard wing bay. The other failed unit was about 8 years old at the time and has continued working OK since the repair. Both units were almost certainly from the same production run. Ken On 22/07/2018 12:26 PM, Robert L. Nuckolls, III wrote: > At 10:26 PM 7/21/2018, you wrote: >> >> I just had another aeroflash 151-0011 strobe power supply fail. >> Interestingly it was the second one I've seen with an open 330K >> resistor that was preventing triggering. >> On 12 volts the unit would almost immediately charge up to 400 volts >> and then shutdown until the voltage decayed. >> On about 6 volts the unit would charge continuously to about 300 >> volts and you could hear the trigger fire but the signal was not >> getting to the white wire going to the flash tube. >> Across the 330K resistor measured about 450K in circuit and it was in >> fact open. It was the larger (1/2 watt) of the two 330K resistors >> that failed. >> Simple fix but of course the usual safety cautions of respecting high >> voltage and capacitors applies. Mine self discharged quickly but >> yours might not. > > Good find. Thanks for sharing. I am mystified by > the failure of so high value of resistor. Was > it observably discolored or mechanically compromised? > 1/2w was perhaps marginal. 300v/300k is one mil which > is 300 milliwatts. Was it a carbon comp? > > > Bob . . . > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.