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| Need help! Test bench equipment recommendations. $2k+ budget |
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| kcbrown:
--- Quote from: kcbrown on April 03, 2022, 07:17:57 am ---So this is very definitely an encoder issue, and very definitely not an issue with the solder joints or any of that. The fact that both of the original encoders show the same patterns on the scope means that this isn't a production defect in the encoders, but a design defect. I'll play with them and see if I can characterize them better. Maybe something will stand out as faulty once I post up the various waveform characteristics of them. --- End quote --- Well, I did exactly this, and it is indeed a bad encoder after all. I don't know how I missed this before. Here's the encoder output from the bad Siglent encoder: Here's the encoder output from the good Siglent encoder: And here's the output from the Bourns encoder: As you can see, the output from the bad encoder is horribly noisy. This is with the debounce circuitry as shown in the Bourns datasheet, which has the output pin connected to a 10 pF capacitor in series with a 10K resistor to ground (and also has the output pin connected through a 10K resistor to +5V, and common to ground, so you get an active low circuit as seen in the above screenshots). No wonder the scope didn't detect my inputs from it. No matter what, I'd have had to replace it. Just as well that I replaced both. You can also see how the inputs from the Bourns encoder are reversed in phase compared with the Siglent encoders. |
| tggzzz:
--- Quote from: kcbrown on April 04, 2022, 05:10:45 am ---Here's the encoder output from the bad Siglent encoder: Here's the encoder output from the good Siglent encoder: --- End quote --- I had a "noise" problem with a rotary encoder on a bench PSU. Thorough rinsing with IPA was sufficient to clean out whatever was causing the problem. |
| kcbrown:
--- Quote from: tggzzz on April 04, 2022, 08:30:10 am --- --- Quote from: kcbrown on April 04, 2022, 05:10:45 am ---Here's the encoder output from the bad Siglent encoder: Here's the encoder output from the good Siglent encoder: --- End quote --- I had a "noise" problem with a rotary encoder on a bench PSU. Thorough rinsing with IPA was sufficient to clean out whatever was causing the problem. --- End quote --- Oh, wow. That worked fantastically. If I ever need to replace these encoders again, I'll have ready-made replacements. :) EDIT: Well, it worked temporarily. But the noise issue came back after it sat overnight. So I dropped some DeOxit into it and we'll see how long that lasts. |
| kcbrown:
--- Quote from: kcbrown on April 04, 2022, 05:35:10 pm ---EDIT: Well, it worked temporarily. But the noise issue came back after it sat overnight. So I dropped some DeOxit into it and we'll see how long that lasts. --- End quote --- Nope, that also came back after it sat overnight. So I guess this encoder's basically done for any sort of production duty, at any rate. |
| kcbrown:
--- Quote from: tautech on April 01, 2022, 02:11:53 am --- --- Quote from: kcbrown on April 01, 2022, 01:26:07 am ---How strong is the adhesive in those? Remember that the goal is to make it possible to peel the sticker off of the scope by hand without damaging it, so as to make it relatively easy to remove the front plastic panel if that should prove necessary. --- End quote --- Pretty strong but it depends on the surface substrate how well they hold together. The large dispenser gun we stick light card nonglossy business cards to catalogues with a single 20mm strip of glue and they won't come off without one or the other tearing or delaminating. Years ago I used it to stick a 1/4" glass pull tab to a sliding glass panel and it stayed put and worked great whereas a previous one stuck down with epoxy stressed the glass and it broke. Flexy vinyl label to thermoplastic housing I would have no hesitation like for X+ however I do know you can get the sticker in question from Siglent NA as member mwyatt needed one for his X+ when it had an accident with liquids and he had to fully strip and wash it to recover it. --- End quote --- It turns out that I wound up solving the problem a bit differently than others might have. I noticed that there were other screws that attached the input board to the frame and which were behind the front plastic section that the label applies to. It turns out that this plastic section has a taper to it such that there's no distance between it and the input board at the bottom but there's some distance between it and the input board at the top, just enough for the heads of the screws at the top of the input board to fit behind. This fact caused me to look at how the front part of the housing was mounted to the frame, and to see whether the screws that sit behind the label are necessary for structural integrity. They're not, really. So I drilled out the holes in the front plastic section that those screws go through, such that their heads would be able to fit within the resulting widened holes, and then used those screws to attach the input board to the frame directly before attaching the front housing to the frame. I then used transfer tape on the back of the sticker, and carefully cut around the periphery of the sticker as well as the holes in the sticker, peeled the backing paper off, and then very carefully applied the label to the scope after it was fully assembled (after cleaning the area it was being applied to with IPA). The end result looks like I never took the thing apart. I'm very pleased with the result. The stuff is sticky enough that the label isn't going anywhere and with the alterations I made, I can disassemble the scope at will without having to worry about the sticker at all. If you ever decide to take your scope apart, I highly recommend re-assembling as described above so that you don't have to fool with the sticker ever again. |
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