sci.electronics.repair@googlegroups.com

Google Groups

"Ron D." <ron.dozier@gmail.com>: May 08 05:04PM -0700 I don't like the new DST schedule because it gets dark when it's time to do yard work during the weekday.

thekmanrocks@gmail.com: May 08 05:25PM -0700 Ron D wrote: " 8:04 PMRon D. I don't like the new DST schedule because it gets dark when it's time to do yard work during the weekday. "   ?   DST in United States runs from second Sunday in March to first Sunday in November. Clocks are +1 hour during that entire period. 'Noon' is at 1pm (by the clock) during that period.

bruce2bowser@gmail.com: May 08 10:16AM -0700 > Being ordinarily cheap, I nonetheless tend to buy quality tools (I hate to spend money, but I hate having to spend twice even more). I use a Raytek Raynger ST, and according to it's label, it was built in 2000. I can't believe I've owned this that long. It's a 12:1 and it does have some sort of rubberized grip, but it's still pliable with no sign of returning to it's original chemical state.   > I use this often and never had a problem with it. If it ever dies, I'll get another Raytek assuming it's still made somewhere other than China (this one is U.S. made).   > One thing a lot of people don't realize is that these work great, but won't work on reflective surfaces.   Really? So if you waved it along a wall, it wouldn't let you know when a sheet metal 2x4 was behind the wall or not? Or have you tried that?

etpm@whidbey.com: May 08 10:18AM -0700 >temperature than accurate because their emissivity is lower than the >unit is calibrated for.   >I can put mine up to my ear canal and read 96 °F. I had to figure out what y IR thermomometer would measure accurately by comparing measurements with an accurate thermometer that makes contact with the object or fluid being measured. I then amused myself for a little while measuring the temp of some aluminum surfaces. The reflected IR that you mentioned had me wondering for a bit because the temp indicated would change quite a bit depending on whether I was measuring the IR from the gas stove flame being reflected from the pot's surface into the IR sensor. Eric

bruce2bowser@gmail.com: May 08 10:24AM -0700 > Being ordinarily cheap, I nonetheless tend to buy quality tools (I hate to spend money, but I hate having to spend twice even more). I use a Raytek Raynger ST, and according to it's label, it was built in 2000. I can't believe I've owned this that long. It's a 12:1 and it does have some sort of rubberized grip, but it's still pliable with no sign of returning to it's original chemical state.   > I use this often and never had a problem with it. If it ever dies, I'll get another Raytek assuming it's still made somewhere other than China (this one is U.S. made).   > One thing a lot of people don't realize is that these work great, but won't work on reflective surfaces.   Really? So if you waved it along a wall, it wouldn't let you know when a sheet metal 2x4 was behind the wall or not? Or have you tried that?

MJC <gravity@mjcoon.plus.com>: May 08 10:42PM +0100 In article <oeq2tm$77p$1@dont-email.me>, gnuarm@gmail.com says...   > I've used it for any number of things including measuring the > temperature of the sky which can be so low the unit doesn't read a > number at all. Now that's cold!   Google "cosmic microwave background"...   Mike.

rickman <gnuarm@gmail.com>: May 08 06:17PM -0400 On 5/8/2017 5:42 PM, MJC wrote: >> temperature of the sky which can be so low the unit doesn't read a >> number at all. Now that's cold!   > Google "cosmic microwave background"...   Hard to measure that with a thermal sensor. Too much air in the way. But on a clear night you get an average of sorts of the various layers of atmosphere and outer space.   That's a funny name, "outer space". We seem to have found names for all the atmosphere layers, I wonder why we didn't find a more formal name for outer space.   --   Rick C

mike <ham789@netzero.net>: May 08 05:19PM -0700 >> I use this often and never had a problem with it. If it ever dies, I'll get another Raytek assuming it's still made somewhere other than China (this one is U.S. made).   >> One thing a lot of people don't realize is that these work great, but won't work on reflective surfaces.   > Really? So if you waved it along a wall, it wouldn't let you know when a sheet metal 2x4 was behind the wall or not? Or have you tried that?   This is a SEEK thermal picture of a quarter watt resistor dissipating a quarter watt. Background is 70F. Resistor is 113F according to the SEEK.   http://i.imgur.com/jmDIdQb.jpg   You can see the heat conducted thru the wires into the alligator clips. There's also a slight temperature rise all along the cable to the power supply due to the 1/4 amp thru the wire.   On a dense surface mount board, you can easily tell if a part is getting hotter than the surroundings.   It'll cost you $200, but if your time is worth anything, it will quickly pay for itself.   If I pass my 12:1 IR temperature probe across the resistor, the highest reading I can get is 71F if I stick it as close as possible to the resistor. You really need the area being sensed to fill the whole field of view of the sensor. Pretty much useless for today's electronics.   The built-in laser pointer is useless for close up work. Parallax causes you to point to the wrong place.   Emissivity is a big deal if you want accurate temperature measurements. Back in the '80's, I used IR imagery to find shorts in prototype circuit boards. Ran some current thru the shorted traces. If you limited the voltage to something below half a volt, you couldn't hurt anything on the board. Most shorts were to one of the ground planes. I could see the inner layers and where the short was.   But, for accurate temperature measurements on a running system, I had to normalize the emissivity. Somebody suggested that spraying the board with spray-on foot powder would work. It worked great. But they forgot to tell me that you can't get the stuff off. I didn't have any solvents that could remove it without harming some components on the board. That limited its usefulness to destructive testing. ;-)   With the seek, you can find the shorted cap on your laptop board by putting a little current thru the power trace and see where the heat stops. I had one laptop that was driving me nutz. Turned out there was a cap hidden under some other component that was bad. It was a .1uF cap. Those rarely short. I would never have found it without the thermal imager.   If you're doing very hot or cold measurements, pay attention to the specs on your thermal device. Many have range limited to less than you need. My SEEK can easily see the heating element on my soldering iron, but the temperature readout is wrong. My 800F Weller reads 656F on the heating element and -40F on the tip. Below about 480F, it reads the element correctly against the background at 70F.

whit3rd <whit3rd@gmail.com>: May 08 04:52PM -0700 On Wednesday, May 3, 2017 at 3:32:05 AM UTC-7, Phil Allison wrote: > > >> Fader-lube on controls and Pro-Gold on switches.   > But you have fallen, hook line and fucking sinker for one of the sleaziest product scams out.   > ANYTHING to do with "Caig" or "De-Oxit" is a 100% SCAM.   Not true. Caig L260np grease on a sliding connection got me good electrical contact (about 80 milliohms) for a difficulty with grounding safety on a product, once.   Their marketing looks like snake oil, but at least some of the products are useful. And, to the best of my knowledge, none of their competition is any better.

whit3rd <whit3rd@gmail.com>: May 08 04:56PM -0700 > In orgo labs we used acetone to be sure there was no water left on glassware.   > Acetone (spozably) evaporates completely.   There's better for that, though, because acetone is hygroscopic. It pulls in water from the air. If you can blow off droplets and bake dry afterward, alcohol is just as good, and less expensive.

whit3rd <whit3rd@gmail.com>: May 08 04:42PM -0700 > I have a Hameg HM-408 scope that uses extended shafts to go from the front panel to the switch / pots ...   > Five of these couplings have failed and so I'm looking for suitable replacement couplings that will connect to the 2mm shaft on the control knob and onto the 4mm shaft from the pots / switches.   Well, H. H. Smith used to make a line of couplings (and flexible shafts). I'm uncertain where to find them nowadays.   Most flexible couplings are intended for motor shafts, will be VERY expensive for your application. It's possible to buy speedometer cable by the foot, and anyone with a lathe can make epoxy-able ends for your choice of shafts. I've done that... only worthwhile for long runs, of course.   Do these couplings just need to have compliance for minor misalignment or shaft position offset? This kind is good for position offset <http://candycontrols.com/products/oldham-couplings/>   and the universal-joint and spring types only handle angle misalignment. Two of those with a stub shaft between is how they handle offset.

Trevor Wilson <trevor@SPAMBLOCKrageaudio.com.au>: May 09 07:39AM +1000 > locate the 5532A anywhere.   > Can you please explain what you mean and what I am supposed to do to > perform this test for DC offset and oscillation......   **Hang your multimeter and CRO off the audio output pins (1 & 7) and check for excessive DC or HF oscillation.   > Instruments) ones have the "P" suffix. I hope the "P" versions work as > replacements. I ordered 20 of them from ebay for about $4.50. Thats > surely cheap enough. They are TI brand.   **Should be fine.   > the device OFF and using the ohm scale on my VOM. > I dont have anything to test chips, and I dont even know if they make > such a thing, because every chip has a different pinout.     **I built a small test board just for OP amps. A +/- 15 Volt supply, two sockets and some RCA input and output sockets. A couple of resistors to set the gain at 2 and it's all good to go. One socket is for single OP amps (5534, LF351, TL071 etc) and one socket is for dual OP amps (5532, LF353, TL072 etc). That covers 99% of OP amps. Then there are single in-line ones, but they're pretty rare nowadays. So, no, they don't have different pinouts. They mostly have standard pinouts.     -- Trevor Wilson www.rageaudio.com.au

Jon Elson <jmelson@wustl.edu>: May 08 02:04PM -0500 John Robertson wrote:     > You were dialing the unit up in an effort to reform the electrolytic > capacitors, and if you didn't know that before now you do (look up the > term). The problem is, this may be catastrophically wrong with modern gear with swtiching power supplies. Old tube gear could very often be brought back to like like this. But, switching supplies are constant power devices, and if they start up at exceedingly low voltage, they will draw excessive current. So, one may have to reform capacitors out of circuit on such gear.   Jon

Jon Elson <jmelson@wustl.edu>: May 08 02:07PM -0500 Cursitor Doom wrote:   > electrostatics. So quite possibly it's a red herring and there may be > nothing amiss with the CRT supply circuitry at all. It may simply be > evidence of a previously-fixed failure elsewhere. Older gear with CRTs can have anazing amounts of black dust that has been attracted to the HV parts. It can come from local air pollution, just normal household dust, etc. not necessarily something that burned up. If you had a major component burn up, then the whole inside of the case would be black.   So, those black HV wires are not a sure sign of something burning.   Jon

Cursitor Doom <curd@notformail.com>: May 08 07:50PM On Mon, 08 May 2017 14:04:36 -0500, Jon Elson wrote:   > devices, and if they start up at exceedingly low voltage, they will draw > excessive current. So, one may have to reform capacitors out of circuit > on such gear.   Yes, but with a load other than the intended one (say some light bulbs).

Ralph Mowery <rmowery28146@earthlink.net>: May 08 04:33PM -0400 In article <g6udnWVlCZwnXY3EnZ2dnUU7-SudnZ2d@giganews.com>, jmelson@wustl.edu says... > they start up at exceedingly low voltage, they will draw excessive current. > So, one may have to reform capacitors out of circuit on such gear.   > Jon   It is often a bad idea to bring electronics up slow. Switching supplies do not like it. Some of the older tube equipment does not do well either unless most of the tubes are removed. You can run into what is called cathode stripping.   If the capacitors need the reforming, many times they will not last very long after. The equipment may seem to work ok, but it will often not be at its best.

John Robertson <spam@flippers.com>: May 08 02:25PM -0700 On 2017/05/08 1:33 PM, Ralph Mowery wrote:   > If the capacitors need the reforming, many times they will not last very > long after. The equipment may seem to work ok, but it will often not be > at its best.   Good points about equipment not liking slow power up. I will remember that in case the question comes up again.   We don't bother with reforming caps at our shop, we run an ESR test, if the cap passes, great, if it fails, we replace it. Not worth the call backs otherwise.   Thanks,   John

avagadro7@gmail.com: May 08 01:41PM -0700 Is wiring a Hella/Amazon switch to light power on to ground possible without using a relay ?

bruce2bowser@gmail.com: May 08 12:13PM -0700 > leave the unit, take the covers off, in the box for 2 weeks.   > then blow out the eggs with compressed air.   > your basic problem was leaving the unit exposed to possible insect infiltration.   Nice try at writing in complete sentences. Anyway, once you finished off that bucket of KFC and touched the laptop, that's probably what did it. Just like when a car mechanic touches your car wires after their lunch break ... the rats, mice and cats like your car when you get home.

avagadro7@gmail.com: May 08 01:37PM -0700 The 'pro level' insecticide housings may have solvent deposited insecticide then evaping gas

Foxs Mercantile <jdangus@att.net>: May 08 11:11AM -0500 On 5/8/2017 8:59 AM, J.B. Wood wrote: > I use Mozilla Thunderbird both as an e-mail client and > for usenet. Works fine for both IMHO.   I use Thunderbird as well, along with AIOE new server. Both are free. <https://www.mozilla.org/en-US/thunderbird/> <http://news.aioe.org/>   And yes, as mentioned, you have to periodically delete expired articles.     -- Jeff-1.0 wa6fwi http://www.foxsmercantile.com   --- This email has been checked for viruses by AVG. http://www.avg.com

Michael Black <et472@ncf.ca>: May 08 01:06PM -0400

John Robertson <spam@flippers.com>: May 08 10:16AM -0700 > Is there (and this is a serious question) any reason not to access the groups through Google? Maybe it's because I don't know what I'm missing, but the pages load immediately, new posts are updated almost as fast, it's free, and apparently my posts are getting through because Phil picks on me now and again!!   > What, if any, features or benefits will I gain by using a dedicated newsreader?   Mostly I use an alternate access to Usenet as I don't want to feed Google any more than I have to.   Also Thunderbird (and Giganews for access) works very well on my Mac.   Googegroups also redacts the senders email and that can be a problem if you want to ask or answer a question that you aren't interested in posting to the world.   It is fine that Google is archiving Usenet, however there have been many complaints over the years when compared to the previous archive - Dejanews.   John :-#)#

rickman <gnuarm@gmail.com>: May 08 03:06PM -0400 On 5/8/2017 12:26 PM, J.B. Wood wrote: > nntp news server no longer has the posts available they don't show up on > the client subscribed lists either. Other than using "mark as read" > I've never had to do any pruning. Sincerely,   I don't know what to tell you. I have found *numerous* bugs on more than one computer, all running a version of windows. One of the many bugs is that even though I've set it to download the full messages, it doesn't download them until I ask to read them and often doesn't retain them and has to download them repeatedly. That failure gives rise to   Error! newsgroup server responded:No such article number 3392   Perhaps the article has expired   Click here to remove all expired articles   These messages should have been downloaded and retained, but instead they are often lost.   T-bird on my system has serious problems with internal delays. I see nothing indicating the system is stressed, but T-bird hangs for seconds to as much as a minute or two. No other program does this, so it can't be a system issue.   --   Rick C

rickman <gnuarm@gmail.com>: May 08 03:22PM -0400 >> For the moment I'm slumming it with Google Groups.   >> Mark Z.   > Is there (and this is a serious question) any reason not to access the groups through Google? Maybe it's because I don't know what I'm missing, but the pages load immediately, new posts are updated almost as fast, it's free, and apparently my posts are getting through because Phil picks on me now and again!!   Phil will pick on you even if your posts never make it to the newsgroup. Phil's issues transcend the Internet.   --   Rick C

You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com.