Digest for sci.electronics.repair@googlegroups.com - 16 updates in 4 topics

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jurb6006@gmail.com: Oct 31 08:50PM -0700

>> >bank, "
 
>> Which means jack shit a couple of miles away.
 
> Sigh. Why don't you sober up, and grow up? "
 
Me grow up ? I tell you that grounding something far away doesn't mean much, and you take that as a sign of immaturity or inebriation ?
 
Fuck you. Try responding. you got nothing here so you resort to dumb shit like a little kid. "Grow up and sober up". The fuck do you know about me ?
 
Who is calling whom names ?
 
Callingnames, and accusing of something you might think bad as if you are some sort of judge. I do not care if I am so fucking drunk I cannot walk, and that hasn't happened in decades, or so immature I still play with blocks. You got me beat in every fucking thing you ever called me.
 
YOU GROW UP.
junebug1701 <junebug1701@gmail.com>: Oct 31 10:24PM -0700


> WTF is wrong with you ? I am certainly not the fool here. That joke about the dog barking is a JOKE.
 
> Lemme splain it to you, telco wires are not grounded, they are a pair. IF, and this is a pretty good sized IF, one of them became grounded at all there would be a shitload of noise on the line, probably to the point of making it unusable.
 
> IT IS FICTION. And thanx for trying unsuccessfully to bust my balls. It makes me look good.
 
Are you calling me a liar? I WAS THERE, I SAW IT. This was 1979, rural Louisiana, South Central Bell. The customer's service was a PARTY LINE, with 2 parties sharing the same pair. When party 1 received a call, the ringing voltage was sent down the tip side of the line. The ringer in the phone was wired from the tip side to ground. When party 2 received a call, the ringing voltage was sent down the ring side of the line. His phone was wired as party 2, with the ringer connected to the ring side and ground. When the dog owner got a call, the ringing voltage went from his side of the line to ground, which was connected to a water pipe the dog was chained to. The soil was very dry, so the ground was not very good, probably a high resistance. The dog provided a better ground. And no, this is not a joke.
jurb6006@gmail.com: Nov 01 08:30AM -0700

> Are you calling me a liar? I WAS THERE, I SAW IT.
 
Wow.
 
I never intended to call you a liar at all, I meant to call you a joker. Really, I thought it was a joke or a not-quite-urban legend.
 
The story has certainly gotten around. What is even more surprising is that it was 1979 ! Was the thing installed in like the 1940s and never upgraded or anything ?
 
I guess I stand corrected. I never snopesed it or anything, just assumed it was a joke. Since I had read it on the internet I wasn't even skeptical, really, I simply believed it was a joke all these years.
 
I hope you don't mind if I snopes it just to make sure you're not pulling my leg... Not lying, but like sending the newbie in the shop to go get a...I forget what it was but it doesn't exist and the techs would always claim someone else has it... You know, a joke.
 
What's next, aliens tunnelling their way out of area 51 ?
N_Cook <diverse@tcp.co.uk>: Nov 01 02:29PM

Surprisingly strong "electrical" smell around the vent ports.
Blown TOP244YN , 20 ohms across rectified mains cap.
Considering crack to its encapsulation is just observable, on one side
only and then under x30. Distorted top to the sillypad (TM) , what may
be a puncture hole at the non-rounded, but then not sharp, rear upper edge.
Hang on a bit , although the tab holding bolt has an insulating washer,
the heatsink is isolated, anti-EMI ?. So if it did puncture , why
leading to failure?
Any known problems with these presumably fairly generic SMPS sub-units,
all else checks out (cold) ok. Mica will be going back in there.
"Gareth Magennis" <gareth.magennis@ntlworld.com>: Nov 01 02:53PM

"N_Cook" wrote in message news:m32qnj$qeb$1@dont-email.me...
 
Surprisingly strong "electrical" smell around the vent ports.
Blown TOP244YN , 20 ohms across rectified mains cap.
Considering crack to its encapsulation is just observable, on one side
only and then under x30. Distorted top to the sillypad (TM) , what may
be a puncture hole at the non-rounded, but then not sharp, rear upper edge.
Hang on a bit , although the tab holding bolt has an insulating washer,
the heatsink is isolated, anti-EMI ?. So if it did puncture , why
leading to failure?
Any known problems with these presumably fairly generic SMPS sub-units,
all else checks out (cold) ok. Mica will be going back in there.
 
 
 
 
 
I had a similar mixer in a while back, and it too had a blown TOP chip, but
not cracked like yours.
To save a bit of troubleshooting time I phoned Peavey UK service dept to see
if there were any knows issues regarding the PSU, and was there something
that might have broken the TOP chip, or was it just the TOP chip that broke.
I was told (a bit sheepishly) that they knew about these TOP chips blowing
up, and if I replaced it the mixer should be fine.
 
I did, and it was.
 
 
Cheers,
 
 
 
Gareth.
"Gareth Magennis" <gareth.magennis@ntlworld.com>: Nov 01 03:05PM

Are these "chinese versions" of TOP244YN or the real McKoy?
I bought mine from Farnell.
 
http://uk.farnell.com/power-integrations/top244yn/off-line-switcher-to-220-6-244/dp/9921265
 
 
 
Gareth.
N_Cook <diverse@tcp.co.uk>: Nov 01 03:17PM

On 01/11/2014 15:05, Gareth Magennis wrote:
 
> http://uk.farnell.com/power-integrations/top244yn/off-line-switcher-to-220-6-244/dp/9921265
 
> Gareth.
 
All I know is the back face is flat unlike the curved one I came across
in a blown Yamaha Stagepas recently, TOP249YN , one of two push-pull ,
pirate or just sloppy manufacture, maybe stress relieving of the metal
after guillotining/machining, developing over time.
 
Anyway this time.
The drummer knocked the mains lead. I wonder if there is an Achilles
heel with such 110/240V mains voltage auto-sensing SMPS drivers, if
there is a short duration interupt in power and then auto restart after
the 8 cycles noted in the datasheet of these TOP24*YN devices.
Did you get any insight in to what preceeded the failure of your unit?
"Gareth Magennis" <gareth.magennis@ntlworld.com>: Nov 01 03:21PM

"N_Cook" wrote in message news:m32qnj$qeb$1@dont-email.me...
 
Surprisingly strong "electrical" smell around the vent ports.
Blown TOP244YN , 20 ohms across rectified mains cap.
Considering crack to its encapsulation is just observable, on one side
only and then under x30. Distorted top to the sillypad (TM) , what may
be a puncture hole at the non-rounded, but then not sharp, rear upper edge.
Hang on a bit , although the tab holding bolt has an insulating washer,
the heatsink is isolated, anti-EMI ?. So if it did puncture , why
leading to failure?
Any known problems with these presumably fairly generic SMPS sub-units,
all else checks out (cold) ok. Mica will be going back in there.
 
 
 
 
 
 
Oops, I just remembered, my TOP chip wasn't "blown" as such, it was
overheating and shutting down.
I rang Peavey to try and quickly establish if they knew of anything that
might be overloading the chip, or was it just the chip.
 
 
 
Gareth.
"Michael A. Terrell" <mike.terrell@earthlink.net>: Oct 31 07:34PM -0400


> Less interruption? How so? When we were in high school (long before)
> there were no "bathroom passes". Classes were 50 minutes with 10
> minutes between. Young adults were expected to be potty trained.
 
By letting them get up and use it quickly without interrupting the
class to ask for the pass and the time it took to return it. Some people
have medical problems, and the need arises without much warning.
 
 
We had five minutes between classes. Then the principal retired. His
replacement cut it to three minutes between classes and turned off the
bells even though the clock system needed a lot of work. It turned into
a real mess when hundreds of kids were sent to the principal's office
for being tardy for each class. The teachers used whatever their watch
said, and no two were the same.
 
 
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
krw@attt.bizz: Oct 31 07:48PM -0400

On Fri, 31 Oct 2014 19:34:10 -0400, "Michael A. Terrell"
 
> By letting them get up and use it quickly without interrupting the
>class to ask for the pass and the time it took to return it. Some people
>have medical problems, and the need arises without much warning.
 
*Exceedingly* few high school students have such problems. There are
ways to deal with those few. IOW, a red herring.
 
>a real mess when hundreds of kids were sent to the principal's office
>for being tardy for each class. The teachers used whatever their watch
>said, and no two were the same.
 
Your principal and the entire faculty, in fact, were morons. Maybe
they were just ahead of their time. It also must have been a very
small high school.
"Michael A. Terrell" <mike.terrell@earthlink.net>: Oct 31 08:38PM -0400


> Your principal and the entire faculty, in fact, were morons. Maybe
> they were just ahead of their time. It also must have been a very
> small high school.
 
1400
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
J Burns <burns4@nowhere.com>: Nov 01 03:12AM -0400


>> When I was a kid, schools didn't have bathrooms. At home, my mother
>> made us bathe every week.
 
> OK, Abe. ;-)
 
Now I remember. Starting around 7th grade, my schools did have
bathrooms. No tubs, just communal showers. It was compulsory to bathe
together twice a week.
J Burns <burns4@nowhere.com>: Nov 01 03:29AM -0400

On 10/31/14, 7:34 PM, Michael A. Terrell wrote:
> a real mess when hundreds of kids were sent to the principal's office
> for being tardy for each class. The teachers used whatever their watch
> said, and no two were the same.
 
Our school had a Western Union clock system governed by a grandfather
clock in the office. Occasionally we'd see classroom clocks jump because
the principal was adjusting the grandfather clock.
 
I believed in punctuality, being neither late nor early. I'd generally
reach my desk 10 seconds before the bell. All we had at home was a 3"
electric clock on the stove. That couldn't be read precisely, so I
relied on my internal clock.
 
Sometimes on a Monday morning I'd be 10 seconds late instead of 10
seconds early. I couldn't reset my internal clock on the principal's
whim, so I'd be 10 seconds late every day. By Friday, teachers would be
complaining about my continuing presence in detention. The principal
would fix his clock and Monday the school would be back in sync with me.
 
He could have saved detention teachers a lot of unpleasantness if he'd
checked with me or the Naval Observatory before tampering with the
grandfather clock.
"Danny D." <dannydiamico@gmail.com>: Nov 01 12:15PM

krw wrote, on Fri, 31 Oct 2014 19:00:31 -0400:
 
> Less interruption? How so? When we were in high school (long before)
> there were no "bathroom passes". Classes were 50 minutes with 10
> minutes between. Young adults were expected to be potty trained.
 
San Jose high school classes are an hour and 45 minutes long, which is
double your class periods. On Mondays, they're very short. About an hour.
Stormin Mormon <cayoung61@hotmail.com>: Nov 01 08:59AM -0400

On 11/1/2014 8:15 AM, Danny D. wrote:
> hour and 45 minutes long, which is
> double your class periods. On Mondays,
> they're very short. About an hour.
 
That sounds like a lot too long to keep
students at a desk. Half hour to 45 mins
would make more sense. Need to get up and
walk around. I don't think this sounds
practical.
 
-
.
Christopher A. Young
Learn about Jesus
www.lds.org
.
Phil Allison <pallison49@gmail.com>: Oct 31 06:36PM -0700

David Platt wrote:
 
> Due to the way FM works, and due to the fact that the station is
> transmitting a stereo subcarrier (centered on 38 kHz, with its own
> sidebands going out as much as 15 kHz on either side),
 
 
** It's worth pointing out that there is only ONE carrier for an FM broadcast signal. At any instant in time, there is only one frequency to deal with and one signal voltage coming from the detector.
 
With FM stereo, the detector's output includes supersonic signals up to 50 KHz or so. The supersonic stuff provides the L-R difference signal.
 
 
> A lot of FM radios/receivers have fairly "broad" intermediate-
> frequency filters... e.g. one or two crystal filters with 220 kHz or
> even 250 kHz bandwidth.
 
** Crystal filters are a tad expensive for an FM radio - so designers make do with tuned transformers and Ceramic filters in the 10.7MHz amplifier stages.
 
Even a budget FM tuner will have at least one or two of each along with a tuned RF stage to provide good out of band and nearby signal rejection for normal use. FM DXing is NOT normal use.
 
 
 
> (200 kHz away), that signal's outer sidebands will end up getting
> through the filter, and will probably affect the stereo subcarrier and
> increase distortion or "break through" into audibility.
 
** There are never two, strong FM signals separated by 200KHz - authorities govern frequency allocations on the band so as to prevent this.
 
 
 
> If you're
> trying to tune in a weak, distant signal that's on an "adjacent"
> channel to a strong local (100 kHz away) the problem is even worse.
 
** Only mad FM DXers have that issue.
 

> often have a wide/narrow switch setting, with the narrow setting
> using different (or more) crystal filters with reduced bandwidth -
> 200, 180, 150, or even 110 kHz.
 
** Yep - mad FM DXers sometimes do that.
 
> station" (increasing its relative strength), or "aimed at an angle
> away from the undesired station" (to put the interfering station in
> a "null" in the antenna's reception pattern).
 
 
** Sure - an antenna rotator with a high gain Yagi on top is what every home needs. Pure bollocks.
 
The most common FM antenna is the TV antenna on the roof or maybe a dipole parked inside the roof cavity.
 
 
 
 
... Phil
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