- What is the shelf life of common adhesives? - 7 Updates
- Taper of Potentiometers - 4 Updates
- Suggestions How to Test No Spin Hard Drives? - 6 Updates
| N_Cook <diverse@tcp.co.uk>: Jan 26 09:01AM On 26/01/2018 01:27, Jeff Liebermann wrote: > Elmer's wood glue > Elmer's Craft Bond Rubber cement > Back to watching the glue dry... Thanks. Store superglue in sealed jamjars with a transparent sachet of activated silica gel or if in a sachet thensome loose crystals in the jar also ,no trouble after 5 years. Use gel with a colour indicator for dry/damp, not too obvious with plain white/off-white colour of damp/dry silica crystals |
| gregz <zekor@comcast.net>: Jan 26 09:03AM > shortly afterwards a parcel arrived with 12 tubes of the correct "neutral cure" type. > Unfortunately, most of the 12 tubes had gone rock hard they were so old. > .... Phil I never found acid cure do much of anything to copper. I put some on circuit board to test. Contrary to reading, i believe the stuff passes moisture and corrode metal underneath. Greg |
| gregz <zekor@comcast.net>: Jan 26 09:08AM > Elmer's wood glue > Elmer's Craft Bond Rubber cement > Back to watching the glue dry... Thanks. I often use GOOP as it's tuff, sticks well, slightly flexible. Also similar E6000. takes some days to fully dry. Stuff evaporates from tube if put on wrong. Greg |
| tabbypurr@gmail.com: Jan 26 03:27AM -0800 On Friday, 26 January 2018 01:27:23 UTC, Jeff Liebermann wrote: > Elmer's wood glue > Elmer's Craft Bond Rubber cement > Back to watching the glue dry... Thanks. I've got epoxy in plastic tubes bought somewhere around 15 years ago, it's still fine. The rest probably is nothing new... Cyanoacrylate never keeps well, but I've not tried anything special with it. Glues generally last best afer opening if capped off with ali foil, for containers that have no lid. Plastic film just doesn't do it. White pva lasts over a decade no problem, but some can moulder in the gallon container. Bitumen glue lasts well if the solvent doesn't disappear, it can always be redissolved with paraffin/kerosene. Never use diesel. NT |
| Terry Schwartz <tschw10117@aol.com>: Jan 26 05:32AM -0800 Jeff, you ARE the authority on most everything, so I probably should bow to your expertise. (But I won't) After all, you have been in the repair biz too long. Re-read Phils post -- he did not mention refrigeration "not working". He said the replacement tubes were "so old". Double unstated? What does that even mean? Obviously if it's unstated, even 1 day is potentially double that. YES I've had success refrigerating adhesives and silicones. Cold always slows chemical reactions, it's basic chemistry. I've had sealed tubes of caulk last 5 years in my garage fridge. Please be cautious about accusing me of "contriving" anything. I also refrigerate batteries, and I've got some Panasonic industrial C cells that are still at full cell voltage after more than 10 years. So you did find something regarding shelf life? Or not? Which is it? Unopened tubes of adhesive, if well manufactured and packaged, seem to last a long time. I've had silicones and cyanoacrylates last for many years. I have limited experience with epoxies, but one tube of plastic-specific epoxy has lasted at least two years -- even after being opened. I almost always seem to be able to find a manufacture date on the tube, either printed or on a crimp. Not so much on the tiny drugstore "superglue" packages. Reputable manufacturers commonly publish a short number for shelf life, (sometimes you have to actually ask for it) as you saw, 12 months, but in reality, that is a CYA number so that the consumer will 1) not be disappointed when his 2 year past date product goes bad, and 2) feel the need to buy another tube and when the stuff only *might* be bad. Helps revenue. I've found 3+ year old product on the shelves in the orange big box home stores. Caveat Emptor. Their warehouses do not have a FIFO system, and are not climate controlled. |
| tabbypurr@gmail.com: Jan 26 06:45AM -0800 On Friday, 26 January 2018 13:32:19 UTC, Terry Schwartz wrote: > I also refrigerate batteries, and I've got some Panasonic industrial C cells that are still at full cell voltage after more than 10 years. I've still got some unrefrigerated ZnC & alkaline cells almost twice that age, so yours should last a long time yet. What I notice is that while most keep, a minority go from full to zero at some point. It's as if some sort of fault occurs internally and they then drain out. NT |
| Harold Newton <harold@example.com>: Jan 26 03:00PM On Thu, 25 Jan 2018 17:27:13 -0800, Jeff Liebermann wrote: > So, in your experience, what are the approximate shelf lives of these > common adhesives? > RTV sealant REF: <https://groups.google.com/forum/#!topic/sci.electronics.repair/t5xXvDn_T-U> I have ten year old unopened Toyota FIPG (aka RTV) that I "hope" to use for a valve cover gasket. I "hope" it's still good. I do know that the tube of Home Depot gray-putty-like two-part "tootsie-roll" epoxy (with the cream in the middle) does NOT last more than about 5 years (ask me how I know). The epoxy still works, but once opened, and half used, the rest dries out easily (I didn't re-wrap it though). Likewise with "opened" cyanoacrylate ... I buy the *smallest* tubes I can find, because, to me, they're single-use only. They may last a few weeks once opened, maybe even a few months ... but not more than that. The bigger bottles get runny ... like water ... and never stick, in my experience. |
| Phil Allison <pallison49@gmail.com>: Jan 26 02:24AM -0800 jurb...@gmail.com wrote: ------------------------- > >"** Horrible idea - it shorts the signal at low settings and sends the > > output impedance high just when you want it low for noise/hum reasons. " > Isn't that how some guitar pickups are wired ? And don't ask me why. ** Only very rarely. That method has just *one* advantage where there are multiple PUs, each with its own volume pot. It forms a resistive mixer that allows signal to pass from any pickup to the output regardless of the other pot settings. The usual method requires no control be zeroed when PUs are switched in parallel or the instrument becomes silent. The wiring schemes used in most electric guitars are primitive, full of dodges and compromises - good examples of how NOT to do it. See wiring for early Gibson models. http://archive.gibson.com/Files/schematics/lespaul2.gif .... Phil |
| jurb6006@gmail.com: Jan 26 05:48AM -0800 >"Strangely, I have not come across a reverse linear pot anywhere. " Now I wonder what kind of taper is used in the pots in a graphic equalizer. Double reverse anti-log or some bizarre shit like that ? |
| Fox's Mercantile <jdangus@att.net>: Jan 26 08:33AM -0600 >> "Strangely, I have not come across a reverse linear pot anywhere." > Now I wonder what kind of taper is used in the pots in a graphic > equalizer. Double reverse anti-log or some bizarre shit like that ? For fuck's sake. Am I the only one here that got the joke? -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| tabbypurr@gmail.com: Jan 26 06:47AM -0800 On Friday, 26 January 2018 14:33:49 UTC, Fox's Mercantile wrote: > >> "Strangely, I have not come across a reverse linear pot anywhere." > > Now I wonder what kind of taper is used in the pots in a graphic > > equalizer. Double reverse anti-log or some bizarre shit like that ? I don't know, but would expect linear. > For fuck's sake. Am I the only one here that got the joke? someone hasn't been paying attention NT |
| Mike Coon <gravity@mjcoon.plus.com>: Jan 26 10:10AM In article <bd8b72ee-2cce-4d75-bf27-aa3d0f14a907@googlegroups.com>, tabbypurr@gmail.com says... > I sure am grateful that computing has improved. Funny that such a HDD was the latest & greatest thing at the time. My favourite when I worked for Univac was the FastRand (Remington Rand vs Random; geddit?). See https://en.wikipedia.org/wiki/UNIVAC_FASTRAND Pity no photo there - https://www.fourmilab.ch/documents/univac/fastrand.html They were amazing beasts; quote: "No UNIVAC programmer who ever encountered a FASTRAND is likely to forget it." Mike. |
| jack4747@gmail.com: Jan 26 02:20AM -0800 Il giorno venerdì 26 gennaio 2018 00:33:20 UTC+1, Jon Elson ha scritto: > platters that allows the heads to land on them without damage. (They may > have a dedicated landing area with no data written there.) > Jon No. https://en.wikipedia.org/wiki/Disk_read-and-write_head Paragraph "Description" When the HD is powered off, the heads are "parked" outside of the platters. Bye Jack |
| jack4747@gmail.com: Jan 26 02:21AM -0800 > Paragraph "Description" > When the HD is powered off, the heads are "parked" outside of the platters. > Bye Jack Here more pictures (and explanations): http://www.data-master.com/HeadCrash-explain-hard-disk-drive-fail_Q18.html Bye Jack |
| tabbypurr@gmail.com: Jan 26 03:30AM -0800 On Thursday, 25 January 2018 23:33:20 UTC, Jon Elson wrote: > platters that allows the heads to land on them without damage. (They may > have a dedicated landing area with no data written there.) > Jon I read about some laptop HDDs taking the head off-platter during the noughties to improve shock survival. NT |
| tabbypurr@gmail.com: Jan 26 03:33AM -0800 On Friday, 26 January 2018 10:10:36 UTC, Mike Coon wrote: > They were amazing beasts; quote: "No UNIVAC programmer who ever > encountered a FASTRAND is likely to forget it." > Mike. "There were reported cases of drum bearing failures that caused the machine to tear itself apart and send the heavy drum crashing through walls." NT |
| jurb6006@gmail.com: Jan 26 05:42AM -0800 On Wednesday, January 24, 2018 at 12:18:36 PM UTC-5, KenO wrote: > Then decided to try http://www.repairfaq.org and searched with how test "Hard drives" but only got "The Drexel mirror site of the Sci.Electronics.Repair FAQ is temporarily unavailable..." > Appreciate any suggestions > Ken Grab it by the end by the connectors and smack the SIDE of the drive in the direction to force rotation. You don't want to pull the heads off if they're only lightly stuck. Also, sometimes when the bearings are that tight they seize up. This used to happen to the drum motor on VCRs sometimes. But then before you smack anything try cold and heat of course. Heatwise it can stand up to maybe 140C or so. That would loosen up the grease and many ovens go that low. And sometimes, for reasons I haven't quite figured out completely, cold works. They can stand being in the freezer. Once it spins, copy everything worth a shit on it of course. You might only get one chance. |
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