++++++++++++++++++++++++ Date: Fri, 14 Dec 2001 14:59:23 -0700 From: Gary L Surrency Subject: [Elecraft] PTTL still way too common Hi all, (begin PTTL rant) This is an alert to those of you who are starting out building your new kits. The intent is to prevent problems before they arise and require a lot of troubleshooting later. I am once again seeing way too many kits that have the dreaded PTTL! PTTL stands for Poorly Tinned Toroid Leads, and it is still the #1 cause of all kit failures I see here on the service bench. Poor soldering is a close second, with improper parts placement coming in third. Please DO NOT begin or continue to build your kit until you have mastered the correct way to strip and tin the leads of the toroids!!! If you fail to do this, you will be causing yourself (and probably me) a lot of problems and time correcting PTTL later. Also be sure to wind the cores in the correct direction to match up with the PCB layout, and count the turns correctly. Each time the wire goes through the core, it counts as ONE turn. The best way to prevent PTTL is to use a soldering iron that is at least 750 to 800 degrees F to tin the leads. Hold the tip of the iron against the side of the wire, and apply enough solder to the tip to form a "blob" of solder that will encircle the lead. Hold the iron against the wire as long as it takes (usually 3-5 seconds) for the enamel to begin to bubble. Then move the tip and blob of solder back and forth on the wire to COMPLETELY tin the wire for about 1/2" in length, and right up to the core. Add a little fresh solder or flux to make the wire bright and shiny. Some builders prefer to start at the end of the wire where the bare copper speeds the transfer of heat so the wire gets hot faster. Others like to start near the toroid core and then push the melted solder and oxides toward the end of the wire, instead of the other way around. Don't waste time burning the enamel with a match or lighter, or sanding or scraping the enamel off. This is way too time consuming and does not work as well as the "hot blob" method. If your iron does not get hot enough, then use a soldering gun or some other higher wattage iron to tin the toroid leads. I use a Hakko 936 ESD safe iron, and I just turn up its temp control to 800 degrees F for toroid tinning. Make use of some old larger diameter solder for doing toroid lead tinning, and save your highest quality solder for the PCBs. If I have a lot of toroids to do, I use a small soldering pot I purchased from Halted Specialties: http://www.halted.com/ DO NOT install a toroid with bare copper leads that are not tinned. I see some of these in the kits I service, and many of them have become oxidized and are poor connections. TIN the wire first, and right up to the core so you don't pull some wire into the pad of the PCB that did not get tinned. Pull on the wire away from the core before tinning it so it is straight and tight, and then tin the wire as close to the edge of the core as possible. Scrape off any old enamel or oxide residue with your fingernails, tweezers, or pliers. The cores are NOT conductive, so do not worry about shorting the tinned wire to the core. Install the completed toroid after first counting its turns AGAIN to be sure they are correct, pull the leads tightly, and then bend them over to hold the toroid in place for soldering. Use enough heat and only the amount of solder needed to fill the pad and surround the lead a little, but with no large ball or blob of solder above the pad. Most kits I see in service simply have too much solder used, and too little heat applied. Our PCBs are of the highest quality, and most components will withstand much more heat than you think they can without being damaged. Clip the leads closely or flush to the PCB, and do NOT leave long wires extending beyond the pads. If you are cutting into the solder when you flush-cut the leads, you are using too much solder. Some kits I see have enough solder to build 3 or 4 kits, and the extra solder just adds waste and flux to the PCB. Check Tom Hammonds soldering tutorial for more excellent construction tips. We want you to enjoy the kit building process and complete the kits with zero problems. Don't rush through it. See: http://www.elecraft.com/TechNotes/N0SS_SolderNotes/N0SS_SolderNotesV6.pdf When the toroid leads are prepared correctly, you should see NO red enamel on the solder side of the PCB, and there should be a little portion of the tinned wire on the toroid side of the PCB, just where it goes into the pad. If this is not the case - STOP- and do it over so you are SURE the leads are tinned and soldered well. If your vision is poor, then use a magnifier light or lens to inspect the toroid and PCB for reliable installation and soldering. DO NOT rely on just the heat of the soldering iron to strip, tin, and solder the enameled wire in one operation. IT WILL NOT WORK, and you may overheat the PCB by attempting to do it that way. The toroids are the one part of the rig where you can put some personal skill and quality into the kit construction. You will be proud to show the kit to your friends or club, instead of wasting hours of time troubleshooting it. Use as much time as it takes to do the job correctly. I do not want to see any more kits with PTTL, as you can probably tell..... :-) Make your toroids a thing of beauty, and you'll have no problems with them. Study the toroid photos on our web site and practice tinning a piece of enamel wire until it is easy to do. Try to make your soldering look as good as wave-soldered commercially built equipment. Take the time to learn and build up your soldering skills, and your kits will never fail from cold soldered or poorly made connections. One other thing that needs to be mentioned, is you should NEVER solder all of the pins of any IC or PCB connector until you first make SURE it is installed correctly. Solder one or two pins, then double-check the IC orientation (and type) against the manual. Be sure to understand the relationship of connector between the various PCBs. We have diagrams in the manuals to prevent these errors, but it requires that you look at them carefully. Don't automatically assume you know which way the ICs or connectors are installed. Don't work ahead without reading the manual, and don't work too long or too late at night when most of these errors occur. There's nothing more frustrating that soldering all 36 pins of a connector or a 16 pin IC into the PCB, and then discovering it was installed backwards or on the wrong side of the PCB. If you do this, contact us for the proper way to remove the IC or connector without damaging the PCB. The PCB is to be protected from damage AT ALL COSTS. The connector or IC is expendable - the PCB is NOT. We have seen these errors many times, and we know tricks and ways to correct such problems without causing more damage. Elecraft will send replacement parts out as soon as possible to get you back on the right track, so just e-mail or call and let us know what happened. Don't be too shy or embarrassed to admit such mistakes, or attempt to correct them on your own unless you are an expert with desoldering and have the right tools. Soder Wik has its place, but it is also no substitute for the correct tool or good desoldering skills. (end of PTTL rant) Now back to the usual list discussions.....Thanks. Gary Surrency AB7MY Please use support at elecraft.com for all support related issues, and NOT this Juno account. You can also call 831-662-8345 for sales and parts orders. ++++++++++++++++++++++++ From: gsurrency at juno.com Subject: [Elecraft] PTTL ALERT! K2 Builders: I am still seeing a *LOT* of Poorly Tinned Toroid Leads (PTTL, for short) in the K2's I repair. This, and poor soldering is still the main reason for >90% of the K2 problems I correct. Please make an effort to learn how to properly tin the toroid leads *before* you install the toroids. Use a hot soldering iron of at least 700 degrees F, and apply a large amount of solder to the tip. Hold the tip and molten solder against the enamel wire until the insulation begins to bubble. Then move the tip down the wire, adding fresh solder as necessary to remove the oxides and insulation, thus tinning the wire with a nice silver color. Be sure to tin the toroid leads as close as you can to the edge of the toroid, so when you pull the leads through the PCB during installation, you do not pull any un-tinned portion of the wire through the pads. There should be some tinned portion or wire *above* the pad on the opposite side from the bottom of the PCB, where the leads are soldered. If this is not the case, the wire will appear like an "island" in the center of the pad, and will not be a reliable connection. Ideally, the solder should flow up through the pads and form a nice "fillet" with the wire where it enters the pad from the toroid. Some time spent preparing the toroid leads carefully will prevent you from having later problems that may require your kit being sent in for repair. Use a tool to hold the toroid if necessary, so you do not burn your fingertips. A wooden clothespin works well for this. Someone suggested using the hollow end of a cheap soldering iron filled with solder as a "solder pot". That should work well in tinning the leads too. You'd need to secure the iron in a vise or fixture to prevent it from falling over and spilling out hot solder. Be careful if you try this idea. Make your toroids "pretty", and you will never have to remove one to rework it or send your kit in for service. Sandpaper, burning off the enamel with a match or lighter, or scraping the toroid leads are all too time consuming and ineffective. Learn how to tin the leads directly using the soldering iron tip, and you will agree it is the best and easiest way to do it. I also have noted very few people are pre-trimming the leads of the components that go on the bottom of the PCB's. This is detailed in the current revision C manual on page 11. It is quite easy to hold the component near one edge of the PCB to gauge how much lead to trim off. Then it is not necessary to attempt to clip the leads from the top side of the PCB, where there may be interference from nearby parts. Solder the bottom mounted leads from_the_bottom_side_of_the printed_circuit_board!!! It is not necessary, nor easy to solder from the top side of the PCB. You may risk damage to relays or other previously mounted components. A quick application of the soldering iron with a *minimal amount* of solder is all that is needed. Just be sure to use enough heat so the solder flows well into the connection, but not so much heat that the PCB or part is overheated. About 2-3 seconds is long enough if the iron is clean and around 700 degrees F. Resist the urge to "pile on more solder" if the connection does not look good. Remove any excess solder if necessary, and reapply the soldering iron using a minimal amount of solder and sufficient heat to flow the solder, wet the joint, and flush the flux out. If the problem is a PTTL, then remove the toroid and correct that problem before continuing. Thanks for reading. I hope you all succeed in building your kits with no problems. 73, Gary Surrency AB7MY Elecraft Technical Support ++++++++++++++++++++++ Date: Tue, 10 Jul 2001 17:35:28 -0700 From: Gary L Surrency Subject: Re: [Elecraft] K1 on order! Hi Brad, Other than the excellent points you made, the most important thing IMHO, is to solder as well as possible and tin those toroid leads! Try to make your PCBs look like commercially wave-soldered boards. To many people do not put the effort into soldering the kits they should. This is a very important process, so don't rush through building the kit. I see more kit failures due to poor soldering and PTTL than any other reason. It accounts for probably 90-95% of all problems with the kits. Tom Hammond N0SS has written an excellent soldering tutorial that everyone should read: http://www.elecraft.com/TechNotes/tech_notes.htm It seems from the kits I work on here, that many people use way too much solder and do not heat the connections long enough to flow the solder and remove the flux. This results in cold solder joints, and excessive flux on the PCBs. Use as little solder as required to just fill the connection flush or form a small fillet of solder around the lead. See N0SS's photos. Don't build for too long at one time, or stay up until the wee hours of the morning! :-) Good luck with your kit(s)!! Here's hoping you have zero problems!! 73, Gary Surrency AB7MY support at elecraft.com (Use this address for all official tech support questions, please). On Tue, 10 Jul 2001 15:09:11 -0500 "Brad Johnson" writes: > I just placed an order for a K1, KNB1, and KAT1. I have not assembled > a kit > since I was a kid in 1974...Heathkit DX60B (which fried the wire > harness on > first power up!) I want to assemble a K2, but am a little > intimidated by it > right now. Watching something I spent hours on go up in smoke was a > traumatic experience from which I still haven't completely > recovered. What > can I say...I have a long memory...still can't look at a bottle of > cherry > vodka without getting queasy (1977) . > > Be it resolved: > > I WILL carefully inventory the components > > I WILL read the instructions carefully before beginning > > I WILL NOT attempt to assemble the K1 in one sitting > > I WILL NOT consider toroids to be the devil's most heinous creation > > I WILL ask for help if I get confused > > I WILL NOT eat cheese dip over the work in progress > > Okay...I can do this....definitely maybe! > > 73, > > Brad > AA5CH ++++++++++++++++++++++++ Note: The following may look a lot like the first entry, BUT it does contain some new material........... Editor DWN ++++++++++++++++++++++++ Date: Wed, 5 Sep 2001 12:51:03 -0700 From: Gary L Surrency Subject: [Elecraft] PTTL alert! Hi Elecrafters, I'm seeing way too many kits lately in service with poorly tinned toroid leads, or PTTL. There's also been a lot of toroids with the incorrect number of turns wound on them. So it's time for this posting!! Learn to tin the toroid leads well *before* you solder them in place. A hot soldering iron of 750º to 800ºF is best, with a "blob" of solder on the tip. I use some old solder I have that is a larger gauge for tinning only, since it is best to use small gauge solder of 0.20 to 0.015" for the actual kit assembly. Apply the hot solder to the end of the wires of the toroid that you have trimmed to about 1/2", and then watch for the enamel insulation to heat and bubble. Then move the tip of the iron right up to the edge of the toroid's core, being sure to tin the wire as close as possible to the toroid. If you do not do this, or if the wire is not pulled taut before you begin the tinning process, you may pull an un-tinned portion of the wire into the PCB when you install the toroid. This will definitely prevent a good connection. Apply a little more solder to clean the insulation and oxides off of the wire, so it is bright and shiny. Moving the iron back and forth on the wire also helps the process. Another method, is to start close to the toroid, and hold the molten solder against the side of the wire for 2-4 seconds until the heat starts to strip the wire. Then use the blob of solder to push the loosened insulation and oxides to the end of the wire, where you can either clip it off, or use your finger or tool to scrap it away. This keeps the "crud" from the stripping process from ending up close to the core. This method - once learned - is a far more successful and faster way to tin the leads. It's much more effort to scrape, sand, burn, etc. the insulation off. I often see that is how it was done, but then the wire was NOT tinned before the toroid was installed! Please be sure to tin the toroid leads first before attempting to install them. Do not rely only on the process of soldering the toroid into the PCB to tin the bare copper wire. There's nothing more time consuming to do than to have to remove and tin toroid leads..... Or, to have to remove turns or rewind the cores if enough turns were not wound in the first place. Each time the wire passes through the core, it counts as ONE turn. Wind the cores so the leads come off correctly to match up with the PCB outline. Spend some time and care doing this part of the construction, so it won't have to be done again later. Give soldering the proper care and attention it deserves, and do not rush the assembly process. I frequently service kits that have too much solder and too little heat applied to the connections. This just results in an excessive build-up of solder, deposits extra flux on the PCBs, and is likely to cause solder bridges and cold solder joints. Use a minimum amount of solder to just complete the joint, and enough heating time to assure the connection is cleaned by the fluxing action and the solder flows well. Usually, 2-3 seconds per joint is about right. If you are cutting into solder when you clip off the lead, you are probably using too much solder. Look at a commercially wave-soldered PCB and try to make your work look like that. Please save yourself a lot of trouble (and service costs!) by learning to do this properly, so you won't have to send in your kit to me for problems. Thanks, and have fun building. Toroids are really not that hard to do! But they are the single largest cause of problems I see in servicing your kits. I'll post my top ten list of kit problems again, too. Gary Surrency AB7MY Elecraft Technical Support (please do not send support queries to this juno email account) Use: support at elecraft.com +++++++++++++++++++++++++