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"Dave M" <dgminala@mediacombb.net>: Mar 29 10:07PM -0500 Yes, Jeff, I was addressing the question to you; sorry if I was ambiguous. Thanks for the info.   Dave M     Jeff Liebermann wrote:

"Michael A. Terrell" <mike.terrell@earthlink.net>: Apr 01 07:43PM -0400 krw wrote: > >antistatic bags with moisture adsorbing packets.   > Sure, baking humidity sensitive parts is common before pick-n-place. > It's a bit less common when hand (de)soldering, though. ;-)     We had a high failure rate on hand soldered FIR chips, before we started baking them. The bottom of the packaging was the thinnest, and it would bow out as it released steam during hand soldering. No one in EE or ME believed me, until I finally got them to try it for themselves.

"Michael A. Terrell" <mike.terrell@earthlink.net>: Apr 01 05:21PM -0400 krw wrote: > with end caps falling off. I haven't seen the issue for some time, > though perhaps it was a problem with the manufacturer. Our purchasing > group prefers Murata, so that's what I use (GRM series).     We pre baked some boards and other components before assembly and reflow. That eliminated cracked multilayer SMD capacitors, tombstoning of two lead components and losing end caps. That was in N Central Florida which has plenty of humidity problems. The so called HVAC 'engineers' were clueless about how to control the humidity, so we had to resort to baking. LSI SMD ICs were backed and heat sealed into antistatic bags with moisture adsorbing packets.

krw <krw@nowhere.com>: Apr 01 07:14PM -0400 On Fri, 01 Apr 2016 17:21:31 -0400, "Michael A. Terrell" >'engineers' were clueless about how to control the humidity, so we had >to resort to baking. LSI SMD ICs were backed and heat sealed into >antistatic bags with moisture adsorbing packets.   Sure, baking humidity sensitive parts is common before pick-n-place. It's a bit less common when hand (de)soldering, though. ;-)

Andre Majorel <cheney@halliburton.com>: Mar 31 10:40AM > Sorry for the delay but I missed the followups to my comment.   Not at all. That was very interesting. Thanks Jeff and everyone.   -- André Majorel http://www.teaser.fr/~amajorel/ J'ai des vrais problèmes, vous avez des faux problèmes.

Jeff Liebermann <jeffl@cruzio.com>: Mar 29 07:15PM -0700 On Mon, 28 Mar 2016 22:15:42 -0500, Jon Elson <elson@pico-systems.com> wrote:   What does this suppose to mean, do, or prove? Newsgroups: Choose,an,appropriate,group,to,redirect,replies... If you want to black hole replies, just redirect to /dev/null   Newsgroup changed to: sci.electronics.design,sci.electronics.repair     >I've heard these stories a number of times. And, yes, maybe some people use >insanely hot irons or in some other way cause this problem. And, some >really large caps are prone to this damage.   Yep. As James Arthur mentioned, it's not a problem with the physically small caps, which come to a uniform thermal equilibrium rather rapidly. It's only the big caps, with lots of plates, thin low voltage ceramic dielectric, and larger thermal mass, that were a problem for me.   >But, as I say, I have hand- >soldered over 25,000 0805 MLCC caps of modest value without seeing this >problem.   One exception will break any such rule. Dig out a larger and higher capacitance MLCC cap in a 1210 or larger package. Try soldering it with a single soldering iron. Unless you're very good, it won't take much to trash the cap.   <http://www.avx.com/products/ceramic-capacitors/high-voltage/high-voltage-mlc-chips/> "Chip sizes 1210 and larger should be reflow soldered only."   >I use a very good Weller temperature-controlled iron, and run it >at a modest temperature.   I use several ancient Weller WTCP TC201 and TC202 (because they were free) soldering stations. Most of my tips are 750F with a few at 850F.   >Much better to use an iron with really good >thermal conductivity at a lower temperature than one with poor conductivity >at a very high temperature.   I don't understand. All the tips are made of plated iron. There's little difference in thermal conductivity between tips, unless you want to throw in copper tips heated with a gas burner. What part of the soldering iron varies in thermal conductivity?     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

"Michael A. Terrell" <mike.terrell@earthlink.net>: Mar 31 04:20AM -0400 Jeff Liebermann wrote: > cool down slowly. I don't know if that was necessary, but it worked > every time. I'm told that two solding irons used as a tweezer also > works, but I haven't tried that yet.   How were the new caps stored? If it is where they can adsorb moisture, you can damage them with an iron that is too hot.

Jeff Liebermann <jeffl@cruzio.com>: Mar 31 08:34AM -0700 On Thu, 31 Mar 2016 04:20:59 -0400, "Michael A. Terrell" >> works, but I haven't tried that yet.   >How were the new caps stored? If it is where they can adsorb >moisture, you can damage them with an iron that is too hot.   Well, I must admit that I didn't take any special precautions. Methinks that the relative humidity in my office runs between 40% and 60% but is not monitored or recorded. Occasionally, it gets low enough to where static electricity becomes a problem, or high enough to where I'm rather uncomfortable, but those are rare. The caps a mix of cut tape and loose bags stored in Ziploc bags (mostly pink anti-static) and in paper coin envelopes. Nothing in hard plastic or metal drawers that might chip or crack them. Although I know that these caps make tolerable hydrometers (and microphones), I don't think they can absorb enough moisture from the air to where a steam explosion would be a problem.   I did some digging to see if humidity might be a problem in storage conditions. There were plenty of notes on how a cracked capacitor might allow water to enter the dielectric. Soft (solder) termination is the recommended fix. Some suggests pre-heating the capacitors before soldering to drive off any moisture. One demands that the caps be used within 12 months. I didn't see humidity as being a problem until AFTER the capacitors had cracked. It would take some time for the moisture to alter the capacitor characteristics. With my hand soldering technique, I managed to instantly produce shorted capacitors, which methinks was more likely due to uneven thermal expansion, than to moisture incursion.   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

krw <krw@nowhere.com>: Mar 31 08:10PM -0400 On Thu, 31 Mar 2016 04:20:59 -0400, "Michael A. Terrell" >> works, but I haven't tried that yet.   > How were the new caps stored? If it is where they can adsorb >moisture, you can damage them with an iron that is too hot.   I haven't had any problems with cracking but I used to have problems with end caps falling off. I haven't seen the issue for some time, though perhaps it was a problem with the manufacturer. Our purchasing group prefers Murata, so that's what I use (GRM series).

JW <none@dev.null>: Apr 01 11:21AM -0400 On Fri, 1 Apr 2016 04:13:00 -0700 (PDT) Phil Allison <pallison49@gmail.com> wrote in Message id:   >** A small scuba diving tank would do the job, you can get 3L ones.   > They hold air pressures up to 3000psi or about 200 atmospheres - so you get 600L of air.   > Only problem is recharging one.   Welding supply house should be able to do that. http://igoswelding.com/gases/3609608   This place lists UHP Air

"Gareth Magennis" <soundserviceleeds@outlook.com>: Apr 01 08:10PM +0100 "Phil Allison" wrote in message news:6446d7de-43d3-46e8-99c1-2a1634d8b4e3@googlegroups.com...   Gareth Magennis wrote:   > form, > and it might just mean I don't have to always cart a big heavy amp to my > local garage to use their mighty airline, as much fun as it is.   ** A small scuba diving tank would do the job, you can get 3L ones.   They hold air pressures up to 3000psi or about 200 atmospheres - so you get 600L of air.   Only problem is recharging one.     .... Phil                   Been Googling a bit, and it seems PCP Air Rifles commonly utilise Scuba tanks, and you can actually get hand pumps that will provide up to 250 bar. If you are young and fit enough.   http://www.airgunbuyer.com/Showproducts.asp?cat=Charging%20Eqpmt.&SubCat=pumps         Gareth.

Cydrome Leader <presence@MUNGEpanix.com>: Mar 31 08:58PM > In the earlier ones, I think the SRC (sine resonance choke) saved alot of flybacks from overload. The SRC was there to increase the efficiency of the HV rectifiers.   > Talk of these Sonys brings back a memory. I was working on a stock 26" console. (you know a toilet seart manufacturer made those cabinets, the only one could meet the specs, and like three guys could sit on top of one and you can still roll it across a thickly carpeted floor) I was pulling the control unit from the front and somehow caught the CRT board and broke the neck.   > I thought ih shit, there goes a couple hundred bucks, but that ain't how it is. Under warranty all you sent back was the neck of the CRT. They said to write it up as "unable to get good convergence". I almost had to laugh, with the neck broken like that, damn right I can't get good convergence. They even paid me to change it ! Well after all Sony paid them.   Hahaha.

David Lesher <wb8foz@panix.com>: Apr 01 02:30PM >n Electric could have built anything that sophisticated into this system in= > 1975 to detect anything like a kiss off, (I'm guessing) from the CO. Thank= >s, Lenny   An abandoned call...   When the far end abandons the call, that CO tells your local CO. It in turns drops [not reverses] the DC loop current for [ISTM] 450 ms. That was sufficient to drop the HOLD relay on a 1A2 KSU with 400D cards.   This caused grief later when Caller-ID arrived. On a 1AESS, it would announce such with a short DC glitch as it disabled incoming audio, poked in a BEEEEEP, and reconnected the audio. While the drop was far shorter, some cards would drop off hold. Newer 400G & 400H cards would not.     -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close.......................... Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433

Trevor Wilson <trevor@SPAMBLOCKrageaudio.com.au>: Mar 31 07:26AM +1100 > the closest thing to a super-conductor at any reasonable operating > temperature as exists in nature, much better than copper (or gold), > and so such fuses ought to be considered.   **Perhaps.   > (both stands included).   > But, a fuse on a $3,500 speaker?   > Wouldn't you?   **I am 62 years old. I've been listening a sound system since I built my first one at age 17. In my 20s, I purchased my first home and proceeded to assemble a sound system to please myself and my friends at various parties. It also drove my neighbours a little nuts. This is the amplifier I used to drive my KEF transimssion lines (rated at 50 Watts) at many, many drunken parties:   http://audio-database.com/MARANTZ/amp/model500-e.html   I still own the best, but no longer use it. I certainly don't operate my sound system at the kinds of levels I once did. I also use vastly more sophisticated amplification nowadays (soft clipping, soft current limiting, etc).   In my entire 45 years of listening, I only ever damaged one of the B139 drivers. The reason the driver failed was due to poor assembly at the KEF factory. So, no. I would not put a fuse on a speaker of MINE. I don't damage speakers. For all intents, I never have. For customers, the situation is different. For headbangers, I will certainly suggest the use of polyswitches or fuses, as the safety outweighs any potential downside. I would certainly not install a fuse or Polyswitch in any high end system, unless the client and I decided it was prudent. I did so with these speakers, after long consultation with a client however:   http://elac.ro/elac%20x-jet%203.jpg (exploded diagram of the mid/HF driver)   The HF element (equivalent to a Heil unit) had failed, after his children accessed his hi fi) was not repairable. A new driver had to be sourced at almost AUS$1,000.00.   So yes, I fitted Polyswitches to protect the drivers.     -- Trevor Wilson www.rageaudio.com.au   --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

Cydrome Leader <presence@MUNGEpanix.com>: Mar 31 04:48PM >> the DC lines, or the speaker lines, fuses introduce distortion and >> should not be used. This is electronics 101.   > Silver-link fuses using an eutectic formula add negligible resistance within their ratings. Nor are they cheap. As you well know, silver is the closest thing to a super-conductor at any reasonable operating temperature as exists in nature, much better than copper (or gold), and so such fuses ought to be considered.   powerline expulsion fuses use silver wire as the element. I was told nothing is as reliable during a factory tour.

"Mark Zacharias" <mark_zacharias@sbcglobal.net>: Mar 30 07:03AM -0500 Circa 1987   Harman Kardon HK-400XM:   Three-head cassette deck.   Intermittent failure to record on one channel. Playback fine.   Customer sent to HK twice for factory service.   Twice HK replaced the record / play head assembly. Problem persisted.   On the bench, at failure mode, discovered full peak-to-peak bias at the output of the affected channel, swamping out the audio.   Defective (intermittent coil) in bias trap. IIRC a small module.   That customer still looks me up 30 years later when he has a problem.   Couple years later, same problem on a Kenwood KX-1030. Open coil.   Over 30 years - never seen this since.     Mark Z.

"Michael A. Terrell" <mike.terrell@earthlink.net>: Mar 31 03:26AM -0400 N_Cook wrote: > Had another go at trying to find a user manual for a classic 2014, specs > yes, but no user manual to explain about that toggle switch, mute/boost > or normal/boost variants     Don't they have music stores in your country? They show you how to operate that type of equipment, over here.

Cursitor Doom <curd@notformail.com>: Apr 03 11:25PM Hi all,   Is there any reliable method for testing parts for authenticity? I just bought a bunch of LM317T variable voltage regs off Ebay (from a dealer with a solid rep, admittedly - but they could themselves have been fooled) and would like to know if they're genuine or not, as a quick search on the net showed there *are* fake LM317s around.   Would one be safe to assume that any fake part would not be capable of performing at the maximum levels claimed by genuine manufacturers in their datasheets? For example, the 317 is claimed to be good for 1.5A, but if mine burn up at say 1.3A, is that a clear indication that they're fake?   Your thoughts, gentlemen....

"jfeng@my-deja.com" <jfeng@my-deja.com>: Apr 03 05:50PM -0700 Are you willing to do something destructive? Remove the epoxy packaging and look at the chip. For a popular part like an LM317, you can probably find a picture of a genuine chip (maybe as they were made 40 years ago). Otherwise, you could compare it to a known good part.   Some manufacturers have active programs to find counterfeit parts and libraries of information ueful for identifying thenm (like the way the logos and the numbers got printed). You might contact them with pictures of the packaging and the silicon chip.   My buddy at Intel told me that one of the common problems is "NOS" Mil-spec versions of obsolete parts that were really repackaged pulls. They often seem OK, except that they have a higher wear-out failure rate (apparently, catastrophic infant mortality failures are relatively rare, as are the completely wrong chip which had been re-marked).   A priori, I would not automatically assume a failure at 1.3A instead of 1.5A was sufficient evidence, especially in a "new" design with no history of proper cooling, etc. You might have a case if it failed in a known and mature design.

Phil Allison <pallison49@gmail.com>: Apr 03 06:47PM -0700 Cursitor Doom wrote:     > Is there any reliable method for testing parts for authenticity?   ** Authenticity can only ever be proved by tracing the supply path of the device back to the actual manufacturer. Buying from authorised dealers is the only way to be able to do this.   If a device fails to meet specs for the part number, then it is probably "fake". There is no simple test.     > with a solid rep, admittedly - but they could themselves have been > fooled) and would like to know if they're genuine or not, as a quick > search on the net showed there *are* fake LM317s around.   ** When you buy parts from Ebay, you need to stop worrying about "authenticity" - cos most of them are not.   FYI: The terms "fake" and "counterfeit" refer to parts that are either rejects or relabelled from another much cheaper type that merely used the same package.       .... Phil

whit3rd <whit3rd@gmail.com>: Apr 03 07:23PM -0700 On Sunday, April 3, 2016 at 4:28:35 PM UTC-7, Cursitor Doom wrote:   > Is there any reliable method for testing parts for authenticity?   No.   High-reliability (aviation, medical, military) parts all have to have traceable sources, and that means paperwork as much as inspections. There have been a variety of counterfeits seen, from currency to rocket struts.   You can only buy an authentic Acme toe-hammer direct from Acme or through a currently-authorized Acme distributor. And, file all of the receipts (and be prepared to ask the distributor for HIS receipts). And invoices. And shipping labels. And purchase orders. Inspect repair/calibration facilities to be sure no one THERE is skimping on the paperwork, or performing procedures that aren't documented formally, or using metric hammer handles for the imperial hammer model.   There are formal procedures for authenticating Bitcoin, but not real physical parts.

frank <frank@invalid.net>: Apr 04 07:32AM > with a solid rep, admittedly - but they could themselves have been > fooled) and would like to know if they're genuine or not, as a quick > search on the net showed there *are* fake LM317s around.   in my experience with fake parts, they usually have nothing to share with the real one. Usually they bother to fake expensive parts (like out of production mosfets or BJT for example that cost many $$ a piece). I have fake mosfets that really are inexpensive switching high voltage parts, even the pinout is different, so it's easy to spot. BJT are usually much different dies, a quick curve tracer inspection shows them. I guess that nobody would really bother to fake an LM317, it's inexpensive and still in production, so why even think about that? The only gain would come from marking as LM317 some empty TO-220 parts, and that would be easy to spot :-)   > their datasheets? For example, the 317 is claimed to be good for 1.5A, > but if mine burn up at say 1.3A, is that a clear indication that they're > fake?   read the datasheet, most of the values are "typical".   Best regards Frank IZ8DWF

Cursitor Doom <curd@notformail.com>: Apr 04 09:50AM On Mon, 04 Apr 2016 07:32:13 +0000, frank wrote:   > I guess that nobody would really bother to fake an LM317, it's > inexpensive and still in production, so why even think about that?   You would think so, wouldn't you? But someone's done it: https://www.youtube.com/watch?v=vlw88Fq5SmA

Boris Mohar <borism_void_@sympatico.ca>: Apr 04 08:01AM -0400 On Sun, 3 Apr 2016 23:25:16 -0000 (UTC), Cursitor Doom <curd@notformail.com> wrote:   >Hi all,   >Is there any reliable method for testing parts for authenticity? I just On one chip Acetone took of all the markings in one swipe.   -- Boris   --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

frank <frank@invalid.net>: Apr 04 12:04PM >> inexpensive and still in production, so why even think about that?   > You would think so, wouldn't you? But someone's done it: > https://www.youtube.com/watch?v=vlw88Fq5SmA   that's what I said... empty case is the only way to gain from fake LM317. If it even does what's supposed to do, it's not likely to be a fake.   Frank IZ8DWF

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