Digest for sci.electronics.repair@googlegroups.com - 21 updates in 7 topics

Micky <misc07@bigfoot.com>: May 01 07:07PM +0300

WD-40 to clean electric contacts?
 
I'm on vacation and renting a room, and my landlady has a combination
CD/Radio/Cassette?, very compact, portable, works well except fo the
little on/off/CD slide switch.
 
The switch doesn't easily make contact, even when pushed to and past
the On position. So it's hard to get the radio on, and it turns off
by itself in about 30 minutes. Moving the switch back and forth 10
times to clean it hasn't worked yet.
 
Normally what I would do is spray contact cleaner or tuner cleaner in
the switch from above, where the plastic slider that goes over the
switch is, And normally that doesn't accomplish much.
 
Even taking such things apart and spraying the switch from underneath
has taken longer to work than for rheostats, for example, and here I
don't want to take it apart. She's only my landlady.
 
I don't know where in this non-English-speaking country to buy
contact cleaner and she might balk at the extra money, but she does
have something in an aerosol can that looks mighty like WD-40.
 
I have this vague recollection that WD-40 is good to clean electric
contacts?? Either that or it's bad for them. Should I try it.
 
BTW, I want to use the radio, so that's one big reason I want it
fixed. When it stopped playing while she was there, she said, "Oh,
yeah, maybe that's why I bought another one" (She speaks English.)
Sjouke Burry <burrynulnulfour@ppllaanneett.nnll>: May 01 06:39PM +0200

On 01.05.17 18:07, Micky wrote:
 
> BTW, I want to use the radio, so that's one big reason I want it
> fixed. When it stopped playing while she was there, she said, "Oh,
> yeah, maybe that's why I bought another one" (She speaks English.)
 
Trying it, will certainly not make things worse.
And cleaning/flooding the switch a day or two later with
something volatile,(alcohol,turpentine or such) will take
care of the wd40 residue(maybe).
I don't think it will make things worse.
"pfjw@aol.com" <pfjw@aol.com>: May 01 05:44AM -0700

First, you are writing of some sort of casual static discharge where the thumbdrive is in the current path. That would be unusual enough unless you slid across a wool carpet and then used the thumbdrive to ground yourself.
 
But, I expect you would need something on the order of a static generator to make enough current to actually do damage.
 
Try this: Purchase a very cheap thumbdrive, and try to wreck it via static. You should be reassured by the results.
 
Peter Wieck
Melrose Park, PA
N_Cook <diverse@tcp.co.uk>: May 01 05:35PM +0100


> Try this: Purchase a very cheap thumbdrive, and try to wreck it via static. You should be reassured by the results.
 
> Peter Wieck
> Melrose Park, PA
 
I assume an old SD card would make a reasonable stand-in. I'll dig out
an old ion-generator and have a go.
etpm@whidbey.com: Apr 30 10:06AM -0700


>Anyway, my laptop is infested. I have researched and found that when exposed to temperatures of 135 F for like 45 minutes it kills them and their eggs. The government and the companies who do this assure us that this is safe. It probably is if not running.
 
>I just checked the oven, the lowest it will go is 170 F. Is that safe for a non, running (at the time) computer ? Could it damage the screen if by nothing else but expansion and contraction ?
 
>We are about to bring in new matress and whatever, but anything happening to this laptop IS NOT AN OPTION.
I know bedbugs need to breathe. If you were to place your laptop in a
plastic bag with a chuck of dry ice, let the dry ice sublimate and
fill the bag with CO2, then seal it in for a week or so, maybe that
would kill 'em.
Eric
mike <ham789@netzero.net>: Apr 30 10:20AM -0700


> Anyway, my laptop is infested. I have researched and found that when exposed to temperatures of 135 F for like 45 minutes it kills them and their eggs. The government and the companies who do this assure us that this is safe. It probably is if not running.
 
> I just checked the oven, the lowest it will go is 170 F. Is that safe for a non, running (at the time) computer ? Could it damage the screen if by nothing else but expansion and contraction ?
 
> We are about to bring in new matress and whatever, but anything happening to this laptop IS NOT AN OPTION.
 
I'd not use a standard oven. The cycling extremes will melt stuff.
Start with an ACCURATE thermometer that you can read with the oven door
closed.
Preheat the oven to 150 F or so then turn it off.
Let it stabilize and let it drift down to your target temperature.
May have to do this more than once to get the heat evenly distributed.
Stick a 100W incandescent light bulb in the oven and watch the
temperature. If it rises, use a smaller bulb. If it drops, use a bigger
bulb.
Or maybe a big bulb on a light dimmer.
You want the heat from the bulb to match the heat loss of the oven.
 
Now, you have a well-controlled temperature that doesn't have wide
swings as it cycles. I'd still not leave it unattended.
Watch the thermometer. Stuff happens.
 
I've done the same thing with a cardboard box, but the lack of
insulation makes it less stable.
 
The weakest link in a laptop is the glue that holds the conductive
strip to the display glass. You don't want that temperature to
go any higher
than absolutely necessary.
ohger1s@gmail.com: Apr 30 10:59AM -0700

On Sunday, April 30, 2017 at 1:21:29 PM UTC-4, mike wrote:
> strip to the display glass. You don't want that temperature to
> go any higher
> than absolutely necessary.
 
 
 
 
 
^^^ Best answer^^^
 
A large cardboard box with an incandescent clamp light will make a nice oven (or preheater for warming up multilayer boards for tough desoldering). Adjustment of the flaps or poking holes will get you where you need to be temp-wise without destroying the computer.
Jon Elson <elson@pico-systems.com>: Apr 30 09:23PM -0500

> nothing else but expansion and contraction ?
 
> We are about to bring in new matress and whatever, but anything happening
> to this laptop IS NOT AN OPTION.
Have you ever left that laptop in a car on a hot day? Did it survive?
If so, then it probably experienced temperatures well over 120 F. I don't
know about the 135 F, though, that is getting pretty hot. I've heard rumors
that a car can get to 160 - 170 F in summer sun. I have doubts a laptop
would survive that.
 
Jon
stratus46@yahoo.com: May 01 01:30AM -0700

We use a commercial food dehydrator at work to bake old magnetic tapes that get sticky from moisture absorption. I've used it to dry out electronics that got washed. The dehydrator works in 5°F steps.
 
How hot does it get in your car on a sunny day? Leave it in there along with a thermometer to monitor the temp.
 

Chris Jones <lugnut808@spam.yahoo.com>: May 01 11:19PM +1000


> Anyway, my laptop is infested. I have researched and found that when exposed to temperatures of 135 F for like 45 minutes it kills them and their eggs. The government and the companies who do this assure us that this is safe. It probably is if not running.
 
> I just checked the oven, the lowest it will go is 170 F. Is that safe for a non, running (at the time) computer ? Could it damage the screen if by nothing else but expansion and contraction ?
 
> We are about to bring in new matress and whatever, but anything happening to this laptop IS NOT AN OPTION.
 
The battery won't like being hot.
Stephen Wolstenholme <steve@easynn.com>: May 01 02:33PM +0100

On Mon, 1 May 2017 23:19:26 +1000, Chris Jones
 
>> I just checked the oven, the lowest it will go is 170 F. Is that safe for a non, running (at the time) computer ? Could it damage the screen if by nothing else but expansion and contraction ?
 
>> We are about to bring in new matress and whatever, but anything happening to this laptop IS NOT AN OPTION.
 
>The battery won't like being hot.
 
The battery can be removed in most Laptops.
 
Steve
 
--
Neural Network Software for Windows http://www.npsnn.com
tabbypurr@gmail.com: May 01 07:13AM -0700

> We use a commercial food dehydrator at work to bake old magnetic tapes that get sticky from moisture absorption. I've used it to dry out electronics that got washed. The dehydrator works in 5°F steps.
 
> How hot does it get in your car on a sunny day? Leave it in there along with a thermometer to monitor the temp.
 
> G²
 
Extreme dryness might be another option. Seal it in a bag with a bowl of salt. That kills many bugs, not all, you'd need to check for bedbugs.
 
The laptop could be its own heater I expect, but I'd be nervous about getting it that hot. I wouldn't do it.
 
 
NT
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: May 01 12:17PM -0400

On 04/30/2017 09:09 AM, rickman wrote:
> temperature thing is supposed to be for real. It is a way to treat your
> entire apartment in fact as insecticides don't work very well. It seems
> to be hard to get the chemicals into the spaces where the bugs hide.
 
I had a squirrel living in a corner of my garage some years ago, and it
brought bed bugs that crawled up the pipe into a bedroom. They're
miserable, but we had no problems getting rid of them using Permethrin
spray in some quantity plus diatomaceous earth swept into the cracks in
the wood floor and under the moulding.
 
Since you can't afford to risk the computer, I'd probably just put it
on a Permethrin-treated tray and use it like that for a few months. A
bit of permethrin on the keyboard would probably also be a win. It's
pretty safe stuff, especially when it's had a chance to dry, and it
lasts a long time.
 
Cheers
 
Phil Hobbs
 
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
 
160 North State Road #203
Briarcliff Manor NY 10510
 
hobbs at electrooptical dot net
http://electrooptical.net
stratus46@yahoo.com: May 01 01:42AM -0700

On Saturday, April 29, 2017 at 12:28:50 PM UTC-7, Jeff Liebermann wrote:
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558
 
When I had an antenna with a rotator many years ago it was because I was about 40 miles out from 2 different cities about 140 degrees difference. For Milwaukee the antenna aimed ENE but for Madison it needed WNW. If I was attempting to record one city and forgot and changed to the other it would have ruined the recording. Of course those were the analog days. DTV is both better and worse.
 
My point was he might be able to use multiple antennas with diplexers and get one overall feed that could be treated like the cable company - all channels available all the time with no adjusting.
 

Jeff Liebermann <jeffl@cruzio.com>: May 01 08:45AM -0700

>and get one overall feed that could be treated like the cable company
> - all channels available all the time with no adjusting.
>G²
 
Nope. A few problems:
 
1. A diplexer splits the frequencies between VHF and UHF channels. If
one antenna is VHF and the other is UHF, it will work, but only if the
stations in one direction are all VHF and the other direction are UHF.
Methinks that's unlikely to happen.
 
2. If you replace the diplexer with a combiner/splitter, you
theoretically can get both VHF and UHF signals from both antennas at
the same time without switching. I think that's what you're
suggesting. However, that doesn't work because the same signals are
picked up by both antenna at the same time. If the signal are in
phase, then the signals combine and you get good reception. If
they're 180 degrees out of phase, you get cancellation and no signal.
However, that's an over-simplification. What really happens is that
the signal is 6 MHz wide and the phase cancellation varies with
frequency. Some of the 6 MHz wide frequency range gets added, but
other frequencies in this range get cancelled. The result is a very
rocky and erratic frequency response which makes an ugly mess of the
signal. Bad idea.
 
3. You can make it work with two antennas in two directions using a
coax switch. Only one antenna is connected at a time so there is no
interaction. You might need two coax cables from the mast to the TV
where the switch is located. Or, you can setup a remote antenna
switch. Or, you can setup a cross-over switch and two receivers,
where you can record on one receiver/antenna combination, while
viewing on the other.
 
--
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
tabbypurr@gmail.com: Apr 30 03:53PM -0700

> > > rather establish what I can before subbing it, as the construction of
> > > the whole thing is rather characterful.
 
> What, if anything, are the markings on the caps themselves?
 
the cap doesn't have a case, let alone markings.
 
> You ought to be able to screen a modern film cap to within a very few percent of the OEM values, go high on the voltage parameters, and go from there.
 
> Peter Wieck
> Melrose Park, PA
 
Of course I can replace it, and probably will need to, I just wanted to know if this thing might still be serviceable, if so I'll let it stay.
 
 
NT
"pfjw@aol.com" <pfjw@aol.com>: May 01 04:27AM -0700


> Of course I can replace it, and probably will need to, I just wanted to know if this thing might still be serviceable, if so I'll let it stay.
 
The short answer is No.
 
Peter Wieck
Melrose Park, PA
tabbypurr@gmail.com: Apr 30 04:25PM -0700


> Other than the fact that when a microwave oven starts to act out in this manner, the only safe 'next stop' is the knacker's yard.
 
> Peter Wieck
> Melrose Park, PA
 
It's many years since I saw a microwave capable of cooking with the door opened. Any such machine should be got rid of even if working ok, because one day it won't be. Since teh early 80s all machines (here at least) have had an interlock system that can't fail unsafely. Well almost, unfortunately. Always check the shorting resistor if there's any question at all of the interlock system's reliability.
 
 
NT
"Ian Field" <gangprobing.alien1@virginmedia.com>: Apr 30 06:14PM +0100

"philo" <philo@privacy.net> wrote in message
news:oe32cm$mms$3@dont-email.me...
 
>> Its virginmedia but the email address is an old ntlworld.com.
 
>> Thanks for any help.
 
> https://support.office.com/en-us/article/Set-up-email-in-the-2009-version-of-Windows-Live-Mail-8f596cb1-1e6a-4f0d-98d8-0cecf804dc65#__finding_my_server
 
Thanks.
 
I was desperate enough to ask in several places, so the answers will
probably keep coming in for a few days.
 
This crap never used to happen with XP.
"Mr. Man-wai Chang" <toylet.toylet@gmail.com>: May 01 02:02AM +0800

On 1/5/2017 1:14 AM, Ian Field wrote:
> I was desperate enough to ask in several places, so the answers will
> probably keep coming in for a few days.
 
> This crap never used to happen with XP.
 
It's a good chance to see whether the solution is consistent among
different sources. Something like the juror system in courts. ;)
 
--
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lsmartino <luismartino76@gmail.com>: Apr 30 11:16AM -0700

El domingo, 30 de abril de 2017, 13:14:15 (UTC-4), Ian Field escribió:
 
> I was desperate enough to ask in several places, so the answers will
> probably keep coming in for a few days.
 
> This crap never used to happen with XP.
 
Maybe you should check your hardware... HDD failing perhaps?
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