#garfield Logs

Feb 03 2021

09:01 AM spline: I had an old p4 stinkpad from 2010 - friend gave for free. even ubu running on no fancy gfx, etc got laggy to run
09:08 AM spline: was my shop machine but also got covered in metal dust so I cycle'd it
09:14 AM rue_mohr: might have had a hardware problem, laggyness usually is
09:14 AM rue_mohr: intel is quick to cut their speed down if running too hot
09:14 AM rue_mohr: always was
09:23 AM aandrew: there's a woman near me who does massive machining. no idea where she works but the equipment is absolutely humongous. @4jawjan on twitter
09:24 AM rue_mohr: think I seen her before, ...
09:49 AM aandrew: apparently she likes taking coolant showers at work. :-)
12:08 PM aandrew: I'd forgotten how much fun it is to fidget with a good quality microswitch
12:08 PM aandrew: I've been playing with it on and off for the last few days
02:30 PM aandrew: ok here's a design challenge... rue, ready to be distracted?
02:32 PM aandrew: I have a bare 6 layer board (not mine) that has a good solid short somewhere in it between the power rails. I've verified that the EDA software netlist is right, I've verified that the gerbers look right (imported them into cam350 and gnerated a netlist, then walked the netlist to see if power/ground are seen as one net), verified the same with the gerbers for the panel
02:33 PM aandrew: I've put my biggest CC power supply on it, cranking 5A into the short to see if anything got warm. 30m in, nothing I can detect. mV probing around I found several locations in the 1.5-1.8mV range
02:33 PM aandrew: a quick back-of-napkin calculation says that this short is about 600uOhms, so it's GOOD and shorted
02:33 PM aandrew: my suspicion is that the board house is lying through their teeth that ALL boards in ALL panels (40 boards) passed 100% electrical testing
02:34 PM aandrew: my question, and the distraction is this: if I wanted to sink about 20-100A into this thing, how could I go about designing a quick and dirty circuit to regulate into a dead short using something like a car battery as a source?
02:34 PM aandrew: I don't want to blow it up, I just want the short(s) to get hot
02:34 PM aandrew: I suspect the entire board is going ot be warm
06:36 PM aandrew: I do have an autotransformer, but I don't think I can use that to current regulate very well. :-)
07:17 PM rue_mohr: you dont have to, just use the 5A you have, and find the point with the lowest voltage
07:17 PM rue_mohr: thats your short
07:17 PM rue_mohr: uV
07:29 PM aandrew: you're not understanding
07:30 PM aandrew: I'm finding multiple places
07:30 PM aandrew: I read about 3mV at the lowest point, but there are several "lowest points"
07:30 PM aandrew: I get anywhere from about 50mV down to 2.8-3
07:31 PM aandrew: I want to drive much more current in to see if I can find a few
07:31 PM rue_mohr: !?
07:31 PM rue_mohr: have a thermal camera?
07:32 PM aandrew: no
07:32 PM aandrew: just calibrated finger tip
07:32 PM rue_mohr: ok then
07:32 PM aandrew: with more current I also get more resolution to more finely pinpoint it
07:32 PM rue_mohr: put the board in the freezer till its good and cold
07:32 PM rue_mohr: take it out in a moist env, and let it frost over
07:32 PM aandrew: oh, that's a neat trick
07:32 PM rue_mohr: might need a 2nd trip in the freezer
07:32 PM aandrew: use the frost melting
07:33 PM rue_mohr: exactly
07:33 PM aandrew: I've found a number of shorts over the years, but this one (600uOhm) is pretty solid
07:33 PM rue_mohr: they said it was tested or it passed?
07:34 PM aandrew: the chinese fab claims all 20 panels (2 boards per panel) passed 100%
07:34 PM aandrew: which is already dubious, but it's possible that they simply discarded the panels with bad boards
07:35 PM aandrew: and I used Cam350 to take the eagle-generated gerbers and create a netlist from them, and also the panel gerbers and create another netlist, then walked the netlists one at a time to find GND/5V and they are separate as far as CAM350 is concerned, so the gerbers are good
07:35 PM aandrew: (that is really nice software by the way, highly recommend, uh, procuring it
07:37 PM aandrew: they want US$500 but for the once in 30y that i needed it it's not worth it, if I end up doing more of this I might buy it, but i might also just pay a board house to take a look instead
08:10 PM aandrew: rue_mohr: you're a telecomms kind of guy
08:11 PM aandrew: I have what I'm pretty sure is an attenuator on my cable line
08:11 PM aandrew: it's got a red stripe sticker and a "3" sticker and "ATP3-1006KV" stamped on the metal cylinder
08:13 PM aandrew: http://cdn2.hubspot.net/hubfs/2057289/Downloadable_docs/Spec_sheets/Traps/Line_Conditioning/Attenuators/ATP-spec-sheet.pdf pretty sure that's it
08:14 PM aandrew: guessing it's a 3dB "all band" attenuator
08:17 PM rue_mohr: propbably a band filter
08:17 PM rue_mohr: ugh pdf
08:17 PM rue_mohr: technology is being annoying
08:17 PM rue_mohr: why will broswers REFUSE to spawn adobe reader?
08:26 PM MoonyMoon: mime types homie
08:26 PM MoonyMoon: find a jacked up one liner for updating your mimetypes
08:27 PM rue_mohr: no
08:27 PM rue_mohr: not it at all
08:27 PM MoonyMoon: :|
08:27 PM rue_mohr: adobe WILL NOT start when triggered by the browser
08:27 PM rue_mohr: I'm not sure who did what
08:28 PM rue_mohr: if its on adobe or the browsers end
08:28 PM MoonyMoon: what are you? some kinda COMPUTER EXPERT!?
08:28 PM MoonyMoon: pshh
08:28 PM rue_mohr: "acroread" is actually a script
08:28 PM rue_mohr: I been meaning to short-cut it to see if that helps
08:28 PM MoonyMoon: ok Mr. Wizzard build mozilla from source and fix it
08:30 PM MoonyMoon: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwi0o5uGlc_uAhUOr54KHQahAwEQtwIwAXoECAQQAg&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3Dk_0U3DlLFSU&usg=AOvVaw0vibO_VX16NLerVoVh9IVZ
08:31 PM rue_mohr: I ran firefox via valgrind, it said something like "YOU CANT BE SERIOUS! TOO MANY ERRORS, FIX YOUR F******** CODE"
08:32 PM rue_mohr: it caught something like 12000 problems in the first 3 seconds
08:33 PM MoonyMoon: HA XD what the fuck! also what is valgrind?
08:34 PM rue_mohr: valgrind checks for things like memory leaks
08:34 PM MoonyMoon: oh geeeee
08:34 PM MoonyMoon: :P
08:51 PM rue_mohr: ok, I have some simple code to test
08:54 PM rue_mohr: hmm I'll do that reboot
08:54 PM rue_mohr: I hope this goes ok
09:02 PM Tom_L: rue_mohr lost in the abyss?
09:02 PM rue_bed2: still not working right
09:02 PM rue_bed2: the nfs isn't working
09:02 PM rue_bed2: I can navigate the dirs
09:03 PM rue_bed2: but reading any files gives me the right number of bytes, their just all 0x00 tho
09:06 PM rue_bed2: huh
09:12 PM aandrew: no, valgrind can be *very* noisy
09:12 PM aandrew: line, uselessly so
09:12 PM aandrew: like
09:24 PM MoonyMoon: hm :|
09:25 PM MoonyMoon: Have to go upstairs and play on my NOP slide
09:46 PM rue_ is now known as rue_mohr