+++++++++++++++++++ Date: Fri, 15 Nov 2002 12:12:29 -0600 To: elecraft at mailman.qth.net From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Subject: [Elecraft] Notes on maintenance of DEsoldering guns Folks: I offer the following notes (from my personal experience) for those of us who have (or may have) desoldering guns. While my comments are specifically with regard to the Hakko desoldering gun, I suspect many, if not all, will equally applicable to most devices of this type. Of course, YMMV. 1. When you are finished using your desoldering gun (for the day, or for a while), run the cleaning tool (looks like a long, thin wire with a spring on one end) through the complete solder path to ensure that nothing is clogging the passage. Do this BEFORE you put the device away, or DAILY, whichever is applicable. . Not only can solder accumulate, but the most damage comes from burnt rosin which builds up inside the heating tube. Since this is already burned, it will no longer melt (to be readily sucked into the catch tube the next use) and thus it can quickly clog up the tube. If not REGULARLY cleaned out (every 30 or so joints cleaned, especially if there's a lot of residue on the joint) it can build up to the point that it is VERY difficult to clean out. I used my DremelTool to grind the end of this cleaning rod down to a screwdriver-like tip. This allows me to twist the rod, as I run it in, to more easily loosen accumulated residues. It works almost like a drill bit. 2. Be aware of the temperature setting of your desoldering gun. Sometimes, as they come from the manufacturer, the temperature may be set quite a bit higher than required. To the point of doing damage to PC boards if left on the joint too long. I normally set my heat range so that I can effectively clean out a plated-thru hole in about 2-3 seconds (max.). If my gun heats the joint too slowly, I turn it up a bit. Sometimes GROUNDED pads (because they can 'sink' heat away more quickly) may require either a bit more heat or a slightly longer dwell time on the joint before it is thoroughly melted. 3. When using a desoldering gun, once the tip is on the joint and the joint is molten, hold the tip flush against the board and 'circle' it around the tip of the component lead AS you press the trigger. What I mean by 'circle' is NOT to spin the gun, but to hold the gun in the same position, but move the tip just so that the component lead circles around the inside edge of the nozzle. This causes the component lead to be moved away from the sides of the plated-thru hole and exposes all of the hole to the vacuum. 4. Keep your solder catch tube clean. This is the device which holds all of the solder you've removed from the PC board. After a period of time, the solder (and the vaporized rosin) will build up to the point that it begins to effect the gun's ability to sustain a usable vacuum. Clean out the catch tube (and any filters, if applicable) each day's use, BEFORE you put it away. On Hakko guns, you can pop out the catch tube, pull out the aluminum pre-filter, and pop off all of the stuck-on solder. At the same time, take your finger (or a smooth-edged/dull) knife blade) and lightly scrape away any bits of solder which have adhered to the inside of the catch tube. Check the filter itself. If it appears to be badly clogged with the residue of vaporized rosin, clean or replace it. Hakko filters are made of what they call 'ceramic paper' which can (to some extent) be rejuvenated by a bath in alcohol (isopropyl or denatured, NOT drinking!). Allow the filter to DRY COMPLETELY before you reinstall it. Filters will probably not require any attention for at least several HUNDRED desoldered joints. But it never hurts to check anyway. 5. The pre-filter of the Hakko 808 desoldering gun resides inside the black (silicone, I think) filter holder. The pre-filter resembles a disk with four short, equally-placed, arms sticking out. I found it rather difficult to reinstall the filter holder into the catch tube once the per-filter had been installed INTO the filter holder. The 'fit' is close enough that pressing this assembly back in was difficult to the point of risking damage to the thin walls of the filter holder. I solved this problem by using a fine file to take about 2-3 light passes across end of each of the 'arms' of the pre-filter. This does not compromise the effectiveness of the pre-filter, yet it allows the pre-filter and the filter holder to be VERY easily reinstalled following cleaning of the catch tube. 6. Hakko provides (in it's 'kit' of desoldering gun parts) what looks to be a terribly long, thin screwdriver... well, it DOES have a screwdriver tip... This device is another cleaning rod, but specifically for use in the heating tube of the gun ONLY. It will not fit through the nozzle itself. Use this device every 50-100 desoldered joints be first removing the nozzle and then passing the rod thru the length of the heating tube. You may have to heat the gun up in order to use this device. But DO NOT leave the gun plugged in for a long time. It heats VERY quickly (20 seconds without the nozzle attached) and will retain this heat more than long enough to clean out the heater tube. 7. DO NOT, UNDER ANY CIRCUMSTANCES grab hold of EITHER of the cleaning rods right after they've been passed thru the heating tube... bad things (and bad words) will happen...! Been there, done that... won't do it again... until the next time I forget. 8. Note that Hakko offers several different nozzle sizes and styles, a couple of which I bought for "special occasions": A1007 - Similar to the 1.0mm (.039") diameter tip supplied with the gun, but with a 1.6mm (.062") diameter hole. this addresses many of the larger leads and lugs found in Elecraft kits. Though I did not purchase it, the model A1396 nozzle offers a 2.3mm (.09") I.D. orifice as well. A1394 - A very long and slender nozzle with a 1.0mm (0.04") inside diameter and a 2.1mm (0.083") outer diameter tip. This allows me to get to those components which are mounted from the BOTTOM of the PC board and which cannot be easily accessed with the 'fatter' (original equipment) nozzles. Gets down between adjacent components with ease. This top is not cheap, running about $13. 9. Hakko offers 'drill bits', and a pin vise holder for use when you REALLY have an immovable accumulation of junk in the nozzle or heating tube. There are different bits for each I.D. of nozzle. This having been said, these bits and pin vise are pretty 'pricey' if purchased from Hakko. But you can just as easily find the pin vise and the drill bits 'wire gauge' (also metric and inch dimension) diameters at both hobby and some of the better hardware stores for a LOT less cost. 10. Get to 'know' your desoldering tool. LISTEN to what it's saying as it works. Soon, you'll be able to hear whether it's working properly or not. The sound is different when it's clogged up or when the joint hasn't been thoroughly heated or cleared. Sometimes, if you can't readily clear a hole, ADD a little more solder to the joint and then try again. Often it's nothing more than a case of there not being enough solder available for the nozzle to heat and transfer that heat the the rest of the joint. Of course, if the problem hole is GROUNDED, you may require a bit more heat, or a slightly longer dwell time before you hit the button. That's all folks... I'm sure there are a number of things I've missed. Hopefully some of you who have more experience with this type of desoldering tool will now chime in and add to this list, for the benefit of all of us. 73, Tom Hammond N0SS +++++++++++++++