| Electronics > Repair |
| HP-8569 Spectrum Analyzer Repairs |
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| AF6LJ:
Finally it's time to start this project. A friend acquired not one but three HP-8569B, and one HP-8569A spectrum analyzers. One 8569B would not power up, that was an easy find a bad tantalum cap on the supply module's -15V rail. The power supply module was borrowed from one of the A model and all four analyzers appear at this point to have no electrical issues, however.......... All of them do have one or more of the rotary switches, damaged. The front panels were removed from the two that are most likely to be easily fixed. And a rear view... Oh and then there are these... The one on the left has been straightened and is ready for re installation. Since the freely available manuals online were garbage, to put it nicely, I want to Artek Manuals http://artekmanuals.com/ and picked up the three volume set for a very reasonable price (under $20.00USD) and received a wonderfully scanned manual set. These guys are great and the price is so reasonable.... Moving along to the immediate problem... The switch rotor is a piece of what feels like ether nylon or delrin plastic. They have hot stakes that secure the contact fingers to the rotor, pay close attention to the inner pair of hot stakes, they were never used in this switch rotor, the outer ones as can be seen are sheered off, no doubt from the decades of pressure on the hot stakes.... At this point laziness kicks in, and I am going to ask if anybody has ever repaired these switch rotors before and what did you use to attach the contact fingers? |
| SeanB:
Small PCB drill and a tiny nail, with the drill diameter being a little smaller than the nail diameter. The nail is a push fit into the hole, after cutting it to size, filing the head round and the shank to round, and to leave a small chamfer to the leading edge to allow easy entry into the hole. Leave some ridges on the rivet shank, round the diameter, so it is harder to pull out. You cannot use any glue or such, unless you know for sure it will not attack the plastic material, and if it is nylon in any case many do not work nicely with it. Some cyanacuralates might be compatible with nylon and delrin, but YMMV with it. Done many a repair with rivets, including making new pins recently for my glasses to replace a stripped screw, and to replace worn pins in my watch strap. Of course also helps having used so many solid rivets in repairing airframe parts, and getting to know how to form them in places where it was impossible to get to them with a power riveter, but a small ball peen hammer was a perfect fit, plus i made a few mandrels to get the head shaped. |
| AF6LJ:
I have some ideas, there are adhesives made for Delrin and Nylon. It feels like Delrin and MEK (yes I still have some) will not attack the plastic, which confirms that this is not one of the more reactive plastics. |
| SeanB:
If you are wanting MEK simply look for Linx solvent or a generic clone, which is MEK in a bottle. Used in continuous jet industrial printers, and a consumable there. Still the rivet idea will work better than heat stakes, simply because it is a lot more area to hold them. |
| AF6LJ:
--- Quote from: SeanB on March 21, 2017, 07:58:20 pm ---If you are wanting MEK simply look for Linx solvent or a generic clone, which is MEK in a bottle. Used in continuous jet industrial printers, and a consumable there. Still the rivet idea will work better than heat stakes, simply because it is a lot more area to hold them. --- End quote --- I have all the MEK I need. I am thinking I am going to end up using glue... I don't have a drill press and it's going to take a #60 or smaller drill. I have a lot of these to fix. |
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