---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 09/25/16: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:47 AM - Re: Problems Soldering DB-25 Connectors (Robert L. Nuckolls, III) 2. 02:10 AM - Re: Problems Soldering DB-25 Connectors (Robert L. Nuckolls, III) 3. 06:20 AM - Re: Problems Soldering DB-25 Connectors (Art Zemon) 4. 06:28 AM - Re: Problems Soldering DB-25 Connectors (Art Zemon) 5. 12:03 PM - Re: Problems Soldering DB-25 Connectors (Robert L. Nuckolls, III) 6. 01:06 PM - Re: Problems Soldering DB-25 Connectors (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 01:47:05 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Problems Soldering DB-25 Connectors > > >[] > > >Reinforcing my confidence in these connections, they were very >quick. Since the wire set neatly and securely into the cups, total >time to strip the wire, set it into the cup, and apply solder was >well under 60 seconds. Previously, I had been fighting the wire and >fighting with clamps to get everything to stay in position so that I >could solder; it was taking me 5-10 minutes per pin with lots of do-overs. > >Hat tip again to all of you who helped me. Thank you! You're gaining on it! My only impression now is that I would strive for better wetting/flow in the finished joints. Your iron temp may to too low. It could be a solder issue too. You said 60/40 . . . normally that alloy is quite satisfactory. Used it the first few decades of my solder slinging career. But I've had some 63/37 of some brands that did not behave optimally. What brand of solder are you using? I'll send you some solder Monday. What kind of iron are you using? Bob . . . ________________________________ Message 2 _____________________________________ Time: 02:10:30 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Problems Soldering DB-25 Connectors At 05:44 PM 9/24/2016, you wrote: >On Sat, Sep 24, 2016 at 2:46 PM, Art Zemon ><art@zemon.name> wrote: >On Fri, Sep 23, 2016 at 9:29 AM, Efraim Otero ><efraim.otero@gmail.com> wrote: >Art: >Please send pictures so us newbies can compare=85 thanks for sharing!! > > >Efraim, > >Your wish is my command :-) > > >One more photo. I disassembled and reassembled >the first connector that I did (more than a week >ago). I am much happier with this iteration: > >[] > > >These wires are for the pitot tube heater. It >draws 12 amps so I am using three pins each for >power, plus one pin for the status lamp. These >three 20 AWG pigtails join to 12 AWG wire which runs the length of the wing. These joints look good. I would use 22AWG "ballast resistor" pigtails. Here you are actually using the wire as a resistor . . . the larger the better from the standpoint of sharing loads across an array of pins. Also, be aware that the legacy heated pitot tubes have a strong temperature coefficient. A typical pitot heater for a Beechejt is 1.5 ohms at 0C . . . a time when the tube is likely to be turned on. 28V/1.5 ohms is 18A start up current. When the heater gets to 100C (typical high altitude condition) it goes to 2.2 ohms for 12.7A running current. 14v probes behave similarly at about 2x the current. What kind of probe are we talking about? If you've lots of unused pins in this connector, it wouldn't hurt to use 5 or 6 pins per path and I'd certainly drop to 22AWG ballast wires. Another thing to consider for the solder-cup connector is the form of the female pins in the connector . . . not quite as robust and uniform their crimp style cousins . . . so extra pins if available wouldn't hurt a thing. The work we did at Beech was entirely with crimped pins. I'm not suggesting that your design goals cannot be met with this connector, just that I have no experience with the parallel pins in the commercial connectors so if there are unused pins in the connector, bringing them into harness with the three already in service is not a bad thing to consider. The extra wire is a 'sense' wire? What does it do for you? Bob . . . ________________________________ Message 3 _____________________________________ Time: 06:20:38 AM PST US From: Art Zemon Subject: Re: AeroElectric-List: Problems Soldering DB-25 Connectors On Sun, Sep 25, 2016 at 3:43 AM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > > > [image: []] > > > Reinforcing my confidence in these connections, they were very quick. > Since the wire set neatly and securely into the cups, total time to strip > the wire, set it into the cup, and apply solder was well under 60 seconds. > Previously, I had been fighting the wire and fighting with clamps to get > everything to stay in position so that I could solder; it was taking me > 5-10 minutes per pin with lots of do-overs. > > Hat tip again to all of you who helped me. Thank you! > > > You're gaining on it! My only impression now is that > I would strive for better wetting/flow in the > finished joints. Your iron temp may to too low. > > It could be a solder issue too. You said 60/40 . . . > normally that alloy is quite satisfactory. Used it > the first few decades of my solder slinging career. > But I've had some 63/37 of some brands that did > not behave optimally. What brand of solder are you > using? > > I'll send you some solder Monday. What kind of > iron are you using? > Bob, I am using a Weller WES51. I have been setting it at 650 when butt splicing wires and bumped up to 700 degrees for the DB-25 pins. I can certainly try something hotter. I was worried about damaging the connector. I have two tips for the iron, the one that came with it and an extra narrow tip that I also bought. I find that extra narrow tip easier to control when working on the DB-25 pins but it doesn't transfer heat as well. I am using Kester 60/40 solder. Cheers, -- Art Z. -- http://CheerfulCurmudgeon.com/ *"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel* ________________________________ Message 4 _____________________________________ Time: 06:28:41 AM PST US From: Art Zemon Subject: Re: AeroElectric-List: Problems Soldering DB-25 Connectors On Sun, Sep 25, 2016 at 4:07 AM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > At 05:44 PM 9/24/2016, you wrote: > > > On Sat, Sep 24, 2016 at 2:46 PM, Art Zemon wrote: > > On Fri, Sep 23, 2016 at 9:29 AM, Efraim Otero > wrote: > Art: > Please send pictures so us newbies can compare thanks for sharin g!! > > > Efraim, > > Your wish is my command :-) > > > One more photo. I disassembled and reassembled the first connector that I > did (more than a week ago). I am much happier with this iteration: > > [image: []] > > These wires are for the pitot tube heater. It draws 12 amps so I am using > three pins each for power, plus one pin for the status lamp. These three 20 > AWG pigtails join to 12 AWG wire which runs the length of the wing. > These joints look good. I would use 22AWG "ballast > resistor" pigtails. Here you are actually using > the wire as a resistor . . . the larger the better > from the standpoint of sharing loads across an > array of pins. Also, be aware that the legacy > heated pitot tubes have a strong temperature > coefficient. A typical pitot heater for a Beechejt > is 1.5 ohms at 0C . . . a time when the tube is > likely to be turned on. 28V/1.5 ohms is 18A start > up current. When the heater gets to 100C (typical > high altitude condition) it goes to 2.2 ohms > for 12.7A running current. 14v probes behave similarly > at about 2x the current. > > What kind of probe are we talking about? > > If you've lots of unused pins in this connector, > it wouldn't hurt to use 5 or 6 pins per path > and I'd certainly drop to 22AWG ballast wires. > Another thing to consider for the solder-cup > connector is the form of the female pins in > the connector . . . not quite as robust and > uniform their crimp style cousins . . . so > extra pins if available wouldn't hurt a thing. > > The work we did at Beech was entirely with > crimped pins. I'm not suggesting that your > design goals cannot be met with this connector, > just that I have no experience with the parallel > pins in the commercial connectors so if there > are unused pins in the connector, bringing > them into harness with the three already in > service is not a bad thing to consider. > > The extra wire is a 'sense' wire? What does > it do for you? > Bob, I'm glad that those connections look better. The other ones that you criticized were my first two. I'll go back and rework them. I am planning a Dynon heated pitot tube. Here is my wiring diagram, including the warning lamp: =8B pitot.pdf =8B Dynon says that that lamp will illuminate if the heater fails. I have plenty of spare pins in the connector. See my connector "diagram" =8B wing root connectors.pdf =8B Dynon says 11-12 A for the heater so I planned on 3 pins @ 5 A per pin. I'll have to buy some more 22 AWG wire if I am going to switch the ballast wires. Do you see any reason why I cannot buy 22 AWG wire locally (which won't be tefzel insulated) instead of mail ordering a small amount of tefzel wire? I can't think of any reason to prefer one insulation material over another for this application. Cheers, -- Art Z. -- http://CheerfulCurmudgeon.com/ *"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel* ________________________________ Message 5 _____________________________________ Time: 12:03:56 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Problems Soldering DB-25 Connectors > >Bob, > >I am using a Weller WES51. I have been setting >it at 650 when butt splicing wires and bumped up >to 700 degrees for the DB-25 pins. I can >certainly try something hotter. I was worried about damaging the connector.=C2 700 is fine >I have two tips for the iron, the one that came >with it and an extra narrow tip that I also >bought. I find that extra narrow tip easier to >control when working on the DB-25 pins but it doesn't transfer heat as well. > >I am using Kester 60/40 solder.=C2 Okay . . . you're 95% of the way there. All that's left is to refine your technique. Bob . . . ________________________________ Message 6 _____________________________________ Time: 01:06:23 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Problems Soldering DB-25 Connectors >I'll have to buy some more 22 AWG wire if I am going to switch the >ballast wires. Do you see any reason why I cannot buy 22 AWG wire >locally (which won't be tefzel insulated) instead of mail ordering a >small amount of tefzel wire? I can't think of any reason to prefer >one insulation material over another for this application. I've packaged up enough 22AWG tefzel for this task. You may have it Tues, Wed for sure. I'd not kept track of Dynon's product line. Looks like their pitot tube is electronically controlled using a technique I proposed to Beech upteen years ago you duty cycle switch power to the heater (except that the OFF current is regulated to some very low value and accurately known). You measure voltage across the heater during off-time and you can deduce the heater's present temperature. I did a bunch of studies on pitot tubes used on the Beechjet during an analysis of loss of airspeed events. Turns out that these things are really easy to regulate by this methodology. I'm guessing that Dynon has exploited the smart controller's software to include soft-start during warm-up. Hence, extra-robust wiring for inrush mitigation is not necessary. But better ballasting of the pins . . . and adding some to the mix is not a bad idea. 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