sci.electronics.repair@googlegroups.com

Today's topics:

* remote control keypad conductivity repair - 3 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/8b03ab352dcfc1b2?hl=en
* Ethical question. - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/0951ee48819ee2bb?hl=en
* VAX AVC 1 Vacuum Cleaner - 3 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/37d26fc8499ec5c8?hl=en
* TVs compatible, from one continent to the next?? - 15 messages, 6 authors
http://groups.google.com/group/sci.electronics.repair/t/38d677af192b8653?hl=en
* OT: scope recommendations? - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/945010a432810e85?hl=en
* 12 volt automotive sealed beam lamps in series - 2 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/fbedfb20fe2856fd?hl=en

==============================================================================
TOPIC: remote control keypad conductivity repair
http://groups.google.com/group/sci.electronics.repair/t/8b03ab352dcfc1b2?hl=en
==============================================================================

== 1 of 3 ==
Date: Sun, Jan 9 2011 4:52 pm
From: "Steevo@my-deja.com"

On Sat, 8 Jan 2011 11:49:26 -0800 (PST), Thomas Williams
<twillia0@gmail.com> wrote:

>For remote controls that have been properly cleaned out and still
>don't work like new, I understand some conductive material needs to be
>coated onto the circuit board contacts on the inside of the pad
>buttons. Reviewing web discussions of this I wonder if a good approach
>may be to mix graphite in silicone glue and lightly coat the surface
>of the pad's underside. Anyone tried this or have a thought on it?
>Others have used electrically conductive paint (e.g., that purchased
>at auto supply stores to reconduct broken rear window defrost
>circuits) but that would not seem to be as flexible as silicone glue
>with conductive material mixed in it. I did read where someone mixed
>finely shredded copper (from pipe) with thinly diluted white glue and
>it worked well (but for how long?). It would seem that the latter
>approach would be better if silicone glue was used, as it is more
>flexible. What ye think?

There is conductive paint for just this purpose at electronics stores.
Ford Electronics in Fullerton, CA had some. I saw it there. I think
they ship.

FWIW I tried the aluminum foil glued on, I didn't have 100% success.
Since I wanted a 100% working remote control any less than 100% is
failure. I haven't tried the paint.

== 2 of 3 ==
Date: Sun, Jan 9 2011 5:30 pm
From: Jeff Liebermann

On Sun, 9 Jan 2011 12:36:16 -0800 (PST), "Ron D."
<ron.dozier@gmail.com> wrote:

>Commercial products exist. See www.mcmelectronics.com

Please note that the original question was about making his own
formulation.

<http://www.mcmelectronics.com/product/CAIG-LABORATORIES-K-CK44-G-/200-315>
I call your missing link and raise you 4 more:
<http://www.mgchemicals.com/products/8339.html>
<http://www.remotecontrolsinc.com/keypad_repair_kit.aspx>
<http://www.replacementremotes.com/Keypad-Repair-Kit/Buy-Keypad-Repair-Kit-Repair-your-Remote-TV-VCR-DVD-Remote.html>
<http://parts.digikey.com/1/parts/11927-rubber-keypad-repair-kit-cw2605.html>

--
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

== 3 of 3 ==
Date: Sun, Jan 9 2011 5:31 pm
From: "tm"

"Steevo@my-deja.com" <steevo@my-deja.com> wrote in message
news:ktlki6l34vkuk9s25lafln28o4i2n961om@4ax.com...
> On Sat, 8 Jan 2011 11:49:26 -0800 (PST), Thomas Williams
> <twillia0@gmail.com> wrote:
>
>>For remote controls that have been properly cleaned out and still
>>don't work like new, I understand some conductive material needs to be
>>coated onto the circuit board contacts on the inside of the pad
>>buttons. Reviewing web discussions of this I wonder if a good approach
>>may be to mix graphite in silicone glue and lightly coat the surface
>>of the pad's underside. Anyone tried this or have a thought on it?
>>Others have used electrically conductive paint (e.g., that purchased
>>at auto supply stores to reconduct broken rear window defrost
>>circuits) but that would not seem to be as flexible as silicone glue
>>with conductive material mixed in it. I did read where someone mixed
>>finely shredded copper (from pipe) with thinly diluted white glue and
>>it worked well (but for how long?). It would seem that the latter
>>approach would be better if silicone glue was used, as it is more
>>flexible. What ye think?
>
> There is conductive paint for just this purpose at electronics stores.
> Ford Electronics in Fullerton, CA had some. I saw it there. I think
> they ship.
>
> FWIW I tried the aluminum foil glued on, I didn't have 100% success.
> Since I wanted a 100% working remote control any less than 100% is
> failure. I haven't tried the paint.

How about Aqua-dag? I wonder if it is still available? Used to apply a
conductive coating inside and outside of CRT envelopes.

tm

==============================================================================
TOPIC: Ethical question.
http://groups.google.com/group/sci.electronics.repair/t/0951ee48819ee2bb?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Jan 9 2011 4:53 pm
From: PeterD

On Sun, 09 Jan 2011 13:36:10 -0700, The Peeler
<peelingthe@invalid,admin> wrote:

>On Sun, 09 Jan 2011 09:50:24 -0500, PeterD <peter2@hipson.net> wrote:
>
>>On Sun, 09 Jan 2011 08:41:08 -0700, The Peeler
>><peelingthe@invalid.admin> wrote:
>>
>>>On Thu, 06 Jan 2011 11:58:21 -0600, Jeffrey Angus
>>><jangus@suddenlink.net> wrote:
>>>
>>>>Customer brings in a lap top. "Won't boot"
>>>>...
>>>>
>>>>So, what to do?
>>>>
>>>>Jeff
>>>
>>>The customer may have bought the laptop used on eBay or elsewhere and
>>>may be totally unaware of its contents.
>>
>>That has nothting to do with the problem and what to do.
>
>It certainly does. He may have great difficulty proving his
>innocence.

The original post wasn't based on the 'owner' proving innocence or
not, only the ethical issues, and to a certain extent the legal issues
WRT the repair shop. We can save that issue for a later thread perhaps
(Say titled "My Friend Bought a Notebook on eBay and it Has Porn On
It")

==============================================================================
TOPIC: VAX AVC 1 Vacuum Cleaner
http://groups.google.com/group/sci.electronics.repair/t/37d26fc8499ec5c8?hl=en
==============================================================================

== 1 of 3 ==
Date: Sun, Jan 9 2011 5:42 pm
From: Protea

Hi

Can anyone help with instructions on opening the plastic motor housing
on the VAX AVC 1 vacuum cleaner. I have removed the 4 self tapping
screws joining the 2 halves, but the halves are still locked together.
I need to access the microswitch in the casing.

Have looked closely at diagram at
http://www.espares.co.uk/diagram/vacuum-cleaners/vax/avc1/p/1086/694/0/508710
but still can't work it out.

Thanks

== 2 of 3 ==
Date: Sun, Jan 9 2011 6:36 pm
From: D Yuniskis

On 1/9/2011 6:42 PM, Protea wrote:
> Hi
>
> Can anyone help with instructions on opening the plastic motor housing
> on the VAX AVC 1 vacuum cleaner. I have removed the 4 self tapping
> screws joining the 2 halves, but the halves are still locked together. I
> need to access the microswitch in the casing.
>
> Have looked closely at diagram at
> http://www.espares.co.uk/diagram/vacuum-cleaners/vax/avc1/p/1086/694/0/508710
> but still can't work it out.

Perhaps "Body Lock Bearing Ring"? (50) -- at each end of the case

== 3 of 3 ==
Date: Sun, Jan 9 2011 7:48 pm
From: Protea

On 10/01/2011 1:36 PM, D Yuniskis wrote:
> On 1/9/2011 6:42 PM, Protea wrote:
>> Hi
>>
>> Can anyone help with instructions on opening the plastic motor housing
>> on the VAX AVC 1 vacuum cleaner. I have removed the 4 self tapping
>> screws joining the 2 halves, but the halves are still locked together. I
>> need to access the microswitch in the casing.
>>
>> Have looked closely at diagram at
>> http://www.espares.co.uk/diagram/vacuum-cleaners/vax/avc1/p/1086/694/0/508710
>>
>> but still can't work it out.
>
> Perhaps "Body Lock Bearing Ring"? (50) -- at each end of the case

Yes, thanks very much D Yuniskis. That is helpful, and I should have
seen that myself.

However, I see now that the Body lock bearing rings (50) are covered by
the Brushroll upper housing (20), and the arm covers (23,24). It looks
like these have to come off first to get access to the Body lock bearing
rings. I will have to figure out how to get these apart.......

==============================================================================
TOPIC: TVs compatible, from one continent to the next??
http://groups.google.com/group/sci.electronics.repair/t/38d677af192b8653?hl=en
==============================================================================

== 1 of 15 ==
Date: Sun, Jan 9 2011 5:56 pm
From: Jeff Liebermann

On Sun, 9 Jan 2011 08:10:43 -0800, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

>I doubt that any American member of this group has adjusted the Hue control
>on their NTSC set for at least 30 years.

True. US receivers use the VIR (Vertical Interval Reference) on line
20 for chroma phase correction to automagically correct both static
and differential phase errors. I think this started in about 1980.

In a past life, when I was doing video, it meant "Now That Seems
Crazy", "Nobody Thinks Such Crap", or "Nail Through Some Coax".

--
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

== 2 of 15 ==
Date: Sun, Jan 9 2011 4:42 pm
From: "Zrupfter"

>"mm" <NOPSAMmm2005@bigfoot.com> wrote
> (I bought it by mistake, didn't notice the PAL, can't play it on my
> DVD player**, but can on the computer. **The DVD player in the other
> thread is broken.)
--
I bought a PAL DVD set from Australia (I'm in Canada),
and took a chance since many NTSC players are able to
play back PAL.
My LiteOn, Toshiba, and Apex DVD players are all able to
play it back, while my Samsung and Pioneer give 'error'
messages. You may find that some cheap import players
almost always play PAL *and* NTSC DVDs.

== 3 of 15 ==
Date: Sun, Jan 9 2011 8:20 pm
From: stratus46@yahoo.com

On Jan 9, 6:45 am, "Phil Allison" <phi...@tpg.com.au> wrote:
> "William Sommerwanker is a Cunt
>
>
>
> >>>> ** Everyone knows that NTSC stands for:
>
> >>>> "Never Twice the Same Color"
>
> >>> Though that might be the common opinion, it is, of course,
> >>> untrue. There is nothing inherently unstable or inaccurate
> >>> about NTSC.
>
> >> ** You have got to be the most ignorant wanker on the planet.
>
> > When was the last time you adjusted the Hue control on an NTSC receiver?
>
> ** Go fuck yourself  -  asshole.
>
> NTSC inherently suffers from sensitivity to phase shift in the sub carrier
> during transmission and reception that cause colour changes on the screen -
> particularly so when changing channel.
>
> PAL does not.
>
> Hence the famous acronym as quoted by me.
>
> Go fuck yourself.
>
> ....  Phil

Yes it does which is why VITS was developed in the '70s like Terrell
pointed out. Hue issues in the US were non-existent for the last 30+
years. Then we turned the whole analog mess off after running digital
for 10+ years

G²

== 4 of 15 ==
Date: Sun, Jan 9 2011 8:21 pm
From: stratus46@yahoo.com

On Jan 9, 8:18 am, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:
> > 1) NTSC I and Q color difference, PAL R-Y, B-Y
> > 2) Different primaries, especially green. PAL had a smaller color
> > gamut.
> > 3) Different color bandwidth for different colors. NTSC had 1.3
> > MHz for I and 0.5 MHz for Q. PAL was equal for R-Y and B-Y.
> > 4) Excellent interleaving of chroma-luminance frequency
> > components which was largely destroyed by the phase alteration.
>
> That isn't immediately clear to me. How badly would pahse alteration affect
> the frequency components of the subcarrier?
>
> You left out 3.5. The I and Q primaries' color and bandwidth are based on
> how the eye actually perceives color. NTSC not only transmits more color
> information, but uses the available bandwidth more effectively.
>
> > As a note, much of the advantage of points 2), 3) and 4) was lost
> > on early sets which just used 0.5 MHz bandwidth for decoding both
> > chroma components and bandwidth limiting the luminance signal to
> > minimize chroma-luma crosstalk.
>
> Actually, most early sets (at least RCA) had full-bandwidth color. RCA
> continued to offer such sets for two or three years. I suspect many current
> sets using digital processing are full-bandwidth, but there's no easy way to
> know which is which.
>
> > When integrated circuits became available, dual bandwidth chroma
> > decoders started appearing...
>
> Not that I'm aware of. Such sets require a second delay line, which runs up
> the cost.
>
> > as well as comb filters to separate the luminance and chroma
> > signals.
>
> Correct.
>
> > More accurate phosphors were also gradually used in
> > sets. The result was a major improvement in picture quality with
> > the original 1953 broadcast standards. No such receiver
> > improvement was possible with the PAL system.
>
> Oh? Why?

WHO CARES? Analog is thankfully gone.

G²

== 5 of 15 ==
Date: Sun, Jan 9 2011 8:27 pm
From: stratus46@yahoo.com

On Jan 9, 1:39 pm, Jim Yanik <jya...@abuse.gov> wrote:
> "Geoffrey S. Mendelson" <g...@mendelson.com> wrote innews:slrniiicdo.om2.gsm@cable.mendelson.com:
>
>
>
>
>
> > Michael A. Terrell wrote:
> >>   As stupid as always. VITS took care of that over 30 years ago.  
>
> > The real problem was not that the NTSC system did not have the
> > autocorrection that was in the original design and used in the PAL
> > system. The real problem was that there was a knob on the TV set that
> > could make everything change color.
>
> > Even with the early 1960's transmission errors, and differences
> > between the actual colors of various sources, if the color control was
> > set and left at 'about right", it always would have been a watchable
> > picture.
>
> > The problem was that almost no one had any clue of how to adjust it
> > properly, and most were set and left in a very wrong postion, while
> > others were being constantly misadjusted.
>
> > All of the TV magazines, science mags, etc had articles on how to
> > properly adjust your TV set, and I'm sure that for everyone who read
> > and followed them, there were 10 times the people who didn't.
>
> Which really didn't matter,as the program sources varied widely in color
> accuracy.
>
>
>
> > It was really bad in area where there were many TVs, such as a
> > department store. For some strange reason, the cheap TV's were never
> > adjusted properly and the expensive ones always were. :-)
>
> > Geoff.
>
> *VIRS* was the VITS signal meant for autocorrection,but it wasn't used much
> IIRC.
>
> VIRS = vertical interval reference signal
> VITS = vertical interval test signals.
>
> --
> Jim Yanik
> jyanik
> at
> localnet
> dot com

Thanks for that. In knew I was using the wrong term but I haven't
worked in a broadcast station since '85. The CBS affiliate in Madison
WI had the Tektronix VIRS corrector for the incoming network feed. One
of the engineers modified it to compensate for blacks below setup. The
only FCC citation the station got in 30 years was from the black level
on the CBS show 'The Price Is Right' when they spin the wheel.

G²

== 6 of 15 ==
Date: Sun, Jan 9 2011 8:52 pm
From: mm

On Mon, 10 Jan 2011 08:25:51 +1100, "Phil Allison" <phil_a@tpg.com.au>
wrote:

>
>"mm"
>>
>> The reason I care is the opposite of that. There are only two
>> DVDR-with-harddrives for sale in the US, and one is cheaper than the
>> one I have, which itself is inferior in design. The other may be
>> better or not. However there are other models for sale in Australia,
>> and probably other parts of the world. I want to buy one from
>> Australia and use it here.
>
>
>** In case you are still unaware - the DTV coding system used in the USA is
>quite different from that used in Europe and most places including
>Australia.

Do I trust the word of a jackass?

>Look it up on Wiki - you trolling, fucking PITA idiot.

Do I take advice from jackasses?

Kerplunk.

>
>.... Phil
>
>

== 7 of 15 ==
Date: Sun, Jan 9 2011 9:29 pm
From: "Geoffrey S. Mendelson"

Zrupfter wrote:
> I bought a PAL DVD set from Australia (I'm in Canada),
> and took a chance since many NTSC players are able to
> play back PAL.
> My LiteOn, Toshiba, and Apex DVD players are all able to
> play it back, while my Samsung and Pioneer give 'error'
> messages. You may find that some cheap import players
> almost always play PAL *and* NTSC DVDs.

What error message. I'll bet it was "incorrect disk", or something related
to region code, not because it was PAL.

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.

== 8 of 15 ==
Date: Sun, Jan 9 2011 10:10 pm
From: "Michael A. Terrell"

"Geoffrey S. Mendelson" wrote:
>
> Michael A. Terrell wrote:
> > As stupid as always. VITS took care of that over 30 years ago.
>
> The real problem was not that the NTSC system did not have the autocorrection
> that was in the original design and used in the PAL system. The real problem
> was that there was a knob on the TV set that could make everything change
> color.

The problem was that there were too many places in the system to
adjust the phase, and no way to match the phase of multiple sources
outside a single studio. The coaxial & microwave relays used by TV
networks needed amplifiers and correction circuits at regular
intervals. Every location required the careful adjustment of all
parameters so a usable signal was availible at the other end. I freind
of mine worked ATT longlines back then and told me what a PITA it was to
keep the system working properly. Not only was there a master E_W feed,
but most of it could be rerouted around an outage, even if the phasing
didn't match. that was the reason that ATT was able to quickly piece
together a nationwide feed to all network TV stations, no matter which
network on the day JFK was killed.

> Even with the early 1960's transmission errors, and differences between
> the actual colors of various sources, if the color control was set and
> left at 'about right", it always would have been a watchable picture.
>
> The problem was that almost no one had any clue of how to adjust it properly,
> and most were set and left in a very wrong postion, while others were
> being constantly misadjusted.
>
> All of the TV magazines, science mags, etc had articles on how to properly
> adjust your TV set, and I'm sure that for everyone who read and followed
> them, there were 10 times the people who didn't.
>
> It was really bad in area where there were many TVs, such as a department store.
> For some strange reason, the cheap TV's were never adjusted properly and the
> expensive ones always were. :-)

one of the problems with the cheap Tvs were that people would play
with the settings. Some people liked everyone to look like they were
wearing clown makeup. Or as one idiot put it when i told him not to
toch one of our TVs, "If I'm buying a color TV, I want all the color I
can get!" :(

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 9 of 15 ==
Date: Sun, Jan 9 2011 10:13 pm
From: "Michael A. Terrell"

William Sommerwerck wrote:
>
> >>> ** Everyone knows that NTSC stands for:
> >>> "Never Twice the Same Color"
>
> >> Though that might be the common opinion, it is, of course,
> >> untrue. There is nothing inherently unstable or inaccurate
> >> about NTSC.
>
> > ** You have got to be the most ignorant wanker on the planet.
>
> When was the last time you adjusted the Hue control on an NTSC receiver?
> That's not a rhetorical question.

William, Phil is a mentally ill Aussie who rarely takes his
medicine. Just ignore him.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 10 of 15 ==
Date: Sun, Jan 9 2011 10:15 pm
From: "Michael A. Terrell"

Meat Plow wrote:
>
> On Sun, 09 Jan 2011 14:21:01 +1100, Phil Allison wrote:
>
> > "Geoffrey S. Mendelson"
> >
> >
> >> NTSC stands for National Television Standrds Comittee, PAL for Phase
> >> Alternating
> >> Line, and SECAM is a French acronym for what could be loosely
> >> translated as
> >> system of transmitting color TV.
> >
> >
> > ** Everyone knows that NTSC stands for:
> >
> > " Never Twice the Same Color"
> >
> > and SECAM =
> >
> > " Something Essentially Contrary to the American Method "
> >
> >
> >
> > .... Phil
>
> And PHIL = PLEASE HELP I'M LOST!!

Pathetic Halfwit Infecting Lambs.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 11 of 15 ==
Date: Sun, Jan 9 2011 10:16 pm
From: "Michael A. Terrell"

"Dave Plowman (News)" wrote:
>
> In article <slrniii88s.ml5.gsm@cable.mendelson.com>,
> Geoffrey S. Mendelson <gsm@mendelson.com> wrote:
> > Those rates were chosen because the studio lights were arc lights and
> > flashed on and off at the power line rate, so the TV cameras had to be
> > syncronized to them or you would get moving black stripes across the
> > screen.
>
> Don't arc lights work on DC?
>
> But I don't think that's correct. For it to work, TV would have to be
> mains locked. It was in the very early days, but later was pulse generator
> locked with no direct reference to mains other than being nominally the
> same frequency. Mains lock was really just to make receiver design simpler.
>
> The only type of light I've seen which gives problems flicker wise on a TV
> camera is fluorescent. Before high frequency ballasts became available,
> the work round was to use them in groups of three - from different phases.

Early TVs often had a faint hum bar in the vertical. By being locked
to the line frequency, it was fixed to one location, and most people
never saw it.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 12 of 15 ==
Date: Sun, Jan 9 2011 10:19 pm
From: "Michael A. Terrell"

"Dave Plowman (News)" wrote:
>
> In article <slrniijjom.4r1.gsm@cable.mendelson.com>,
> Geoffrey S. Mendelson <gsm@mendelson.com> wrote:
> > Dave Plowman (News) wrote:
> > > Think you're well into hindsight. When the UK PAL system was finalised
> > > (1960?), computers were some esoteric device in a lab. But in any case
> > > a major priority of any colour TV system then was that it can be
> > > easily receivable on a monochrome only set - and not make that set
> > > more expensive to produce.
>
> > That's almost irrelevant. When the UK went to digital TV broadcasts (was
> > that around 2000 with Sky's digital terrestrial service?)
>
> No. Sky doesn't broadcast terrestrial signals in the UK. Satellite and
> cable only.
>
> Terrestrial digital started in '98 with a consortium including the BBC and
> ITV.
>
> > there was no no need to continue to support PAL. After all much of their
> > material was NTSC anyway.
>
> So you think they should have gone to NTSC? Why would the Uk replace a
> better newer system with an older inferior one?
>
> Digital was in addition to the UHF PAL service - with it carrying all the
> same channels and more.
>
> > They were encoding the signals in one place,
> > so there was no restriction on what equipment was used except cost, and
> > on the set end they could of used anything they wanted.
>
> > I expect they chose PAL because it was the existing standard, and they
> > could buy subassemblies cheaply.
>
> PAL has nothing to do with any digital transmission. Some of the
> originating sources may still have been PAL at some point though.
> STBs had a PAL output for use with sets with no line input.
>
> > However ATSC was compeltely different. It was supposed to be a new
> > standard, not a re-hashing of an old one. There was no need to keep NTSC
> > compability as long as it could be created in set top boxes.
>
> That applies to any STB. What goes in is irrelevant provided it will
> interface with the domestic TV.
>
> > Note that there were and still are two other incompatble digital TV
> > standards in use in the US. The cable companies use one of their own,
> > and the DBS companies use a different one. Since there are two
> > competing DBS companies, each using their own incompatible encryption,
> > you could say there are four incompatible ones.
>
> So the US is in a bit of a mess? ;-)

Why? Dish or Direct supply all the equipment and install it, just
like the various CATV companies.

> > They all use some sort of MPEG TS transmission, but the streams can not
> > be read with the other company's devices.
>
> That's business politics for you.

So, you think someone should be able to us one company's equipment to
steal service from another?

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 13 of 15 ==
Date: Sun, Jan 9 2011 10:23 pm
From: "Michael A. Terrell"

David wrote:
>
> "William Sommerwerck" wrote in message
> news:igc6v0$308$1@news.eternal-september.org...
>
> > A DC synchronization aka "sync" pluse was included to
> > keep everything together so if signal got scrambled, the TV
> > would bring it back together quickly.
>
> Actually, the sync pulses keep the horizontal and vertical
> scanning in the
> receiver at the same frequency and phase as the transmitted
> signal.
>
> > Those rates were chosen because the studio lights were arc
> > lights and flashed on and off at the power line rate, so the TV
> > cameras had to be syncronized to them or you would get moving
> > black stripes across the screen.
>
> This might have been a consideration, but the principal concern
> was "hum
> bars" in the receiver. Modern power supplies are sufficiently
> well-filtered
> that this isn't a concern.
>
> > The RCA system for compatible color TV (compatible with black
> > and white), used 1/4 of the color information based on the fact
> > that your eye only sees about that much.
>
> Actually, it's more like 1/3.
>
> > The color information was encoded on a phase modulated 3.57MHz
> > subcarrier, which at the time was beyond the picture
> > information, but
> > still within the transmitted signal.
>
> Actually, it was within the picture (luminance) information. NTSC
> has always
> had a potential video bandwidth of 4.2 MHz.
>
> > The original RCA system, alternated the phase of the carrier
> > every line,
> > so that it would fix itself if there was a transmssion or
> > syncrhonization
> > problem. To save money, the National Television Standards
> > Commitee
> > (NTSC) which chose the standard, dropped the alternating phase.
>
> Actually, it was dropped because it didn't seem possible at the
> time to
> design a reasonably priced receiver that would take full
> advantage of this
> feature (in particular, the elimnation of the Hue control). Also,
> the US
> distribution system didn't have problems with non-linear phase,
> so PAL had
> little practical advantage.
>
> Also, the original proposal used red and blue color-difference
> signals,
> rather than the more-efficient I and Q. The original NTSC
> proposal was
> virtually identical to PAL. (If you don't believe this, I have a
> copy of
> "Electronics" magazine that confirms it.)
>
> > The French used a different color encoding system called SECAM,
> > which was also based on the RCA system (1/4 color, 4.43mHz
> > color
> > carrier) but designed to be totally incompatible so that you
> > could not
> > watch French TV in England and vice versa.
>
> SECAM stands for "sequential avec memoire".
>
> SECAM was actually adopted because the French were idiots. They
> wanted a
> system that was relatively easy to record on videotape.
> Unfortunately, it
> made the receiver more-complex and expensive. A classic example
> of lousy
> engineering.
>
> Actually there are more differences between PAL and NTSC color
> encoding than the alternation of the phase:
>
> 1) NTSC I and Q color difference, PAL R-Y, B-Y
> 2) Different primaries, especially green. PAL had a smaller color
> gamut.
> 3) Different color bandwidth for different colors. NTSC had 1.3
> MHz for I and 0.5 MHz for Q. PAL was equal for R-Y and B-Y.
> 4) Excellent interleaving of chroma-luminance frequency
> components which was largely destroyed by the phase alteration.
>
> As a note, much of the advantage of points 2), 3) and 4) was lost
> on early sets which just used 0.5 MHz bandwidth for decoding both
> chroma components and bandwidth limiting the luminance signal to
> minimize chroma-luma crosstalk. Also most sets did not use the
> NTSC primary phosphors so a lot of the advantages of NTSC were
> lost for a few decades. When integrated circuits became
> available, dual bandwidth chroma decoders started appearing as
> well as comb filters to separate the luminance and chroma
> signals. More accurate phosphors were also gradually used in
> sets. The result was a major improvement in picture quality with
> the original 1953 broadcast standards. No such receiver
> improvement was possible with the PAL system. Regarding VITS,
> that was introduced, but very few sets used it.

Really? Entire chipsets were made to use it and they reduced the
cosst to build new TVs. Just because it wasn't etched on the CRT's
face doesn't mean it wasn't used.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 14 of 15 ==
Date: Sun, Jan 9 2011 10:37 pm
From: "Michael A. Terrell"

"Geoffrey S. Mendelson" wrote:
>
> mm wrote:
> > But thoss were in the analog signals. When they went to digital, why
> > didn't they stop using PAL or stop using NTSC? That is my point.
>
> Because they could. :-)
>
> Seriuosly the digital standards were developed with keeping the old systems
> in play, even if they were no longer needed.
>
> > What tied them to both PAL and ntsc at the same time?
> >
> > Regional pride?
> >
> > Or was it because they wanted current analog tvs to be able to receive
> > digital signals that went through a set-top digital to analog
> > converter, and some tvs wanted 50 cycle and others 60 cycle, so if the
> > air-borne signal was the same, it couldnt' be converted to one of 50
> > or 60?
> >
>
> It really did not matter. Maybe in 1983 when digtially encrypted HBO satellite
> receviers were designed, but in 2005 when the US conversion started, it was
> simple enough to use anything they wanted and produce NTSC or PAL or computer
> RGB output or all three on a set top box.

There were no 'digtially encrypted HBO satellite receviers' in 1983.
An external 'Video Chiper II' was used with recievers on a small list
that were tested to work with the 'Video Chiper II'. Most commercial
grade C-bnad receivers had a low pass filter in the video amplifier that
prevented them from working. The interesting thing was that the cheaper
equiment that was barely better than consumer grade made up most of that
list. United Video Cablevision in Cincinatti, Ohio was one of the
systems picked to do field testing before the system went live. I
modified all our Collins-Rockwell receivers to work with the 'Video
Chiper II' test units. They freaked out when I sent them the test data
and told them what hardware I was using. BTW, the test unit serial
number was 16.

It wasn't until combo consumer grade recievers wer built that the
'Video Chiper II' was changed into a plug in module so it could be
replaced or upgraded as the securtiy software changed.

Also, note that the original 'Video Chiper' was full digial
scrambling built for the military, while the 'Video Chiper II' digitized
the audio and inverted the sync on the video. VC units cost over a
million dollars each. HBO wanted a way to turn off the feed to CATV
systems who were late, or didn't even try to pay thier bills. A well
known MSO in the early '80s was over six months behind on everything
except their payroll and utility bills. HBO wanted to make them catch
up, and stay that way.

> The actual encoding is not PAL or NTSC anyway. H.264 which is the current
> standard for high end compression does not have a fixed frame rate. I mentioned
> that in a previous posting.
>
> With a fast enough decoder chip you can take any resoltuion and frame rate
> and put out anything else. My Western Digitial TV Live unit will take
> almost any compressed video file up to 1080P60 (1080x720 60 frames a second)
> and put it out on the fly, with audio in sync from 480i60 (standard NTSC),
> or 560i50 (standard PAL), in composite, 480P60 or 560P60 in component,
> or digital in HDMI with several choices in between.
>
> Why you could not slap an ATSC or DVB-T or the Japanese standard tuner
> chip (or all three) on it instead of a USB port or ethernet is more of a
> matter of product placement than anything else.
>
> Geoff.
> --
> Geoffrey S. Mendelson N3OWJ/4X1GM
> Those who cannot remember the past are condemned to misquote it.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 15 of 15 ==
Date: Sun, Jan 9 2011 10:37 pm
From: "Michael A. Terrell"

stratus46@yahoo.com wrote:
>
> On Jan 9, 8:18 am, "William Sommerwerck" <grizzledgee...@comcast.net>
> wrote:
> > > 1) NTSC I and Q color difference, PAL R-Y, B-Y
> > > 2) Different primaries, especially green. PAL had a smaller color
> > > gamut.
> > > 3) Different color bandwidth for different colors. NTSC had 1.3
> > > MHz for I and 0.5 MHz for Q. PAL was equal for R-Y and B-Y.
> > > 4) Excellent interleaving of chroma-luminance frequency
> > > components which was largely destroyed by the phase alteration.
> >
> > That isn't immediately clear to me. How badly would pahse alteration affect
> > the frequency components of the subcarrier?
> >
> > You left out 3.5. The I and Q primaries' color and bandwidth are based on
> > how the eye actually perceives color. NTSC not only transmits more color
> > information, but uses the available bandwidth more effectively.
> >
> > > As a note, much of the advantage of points 2), 3) and 4) was lost
> > > on early sets which just used 0.5 MHz bandwidth for decoding both
> > > chroma components and bandwidth limiting the luminance signal to
> > > minimize chroma-luma crosstalk.
> >
> > Actually, most early sets (at least RCA) had full-bandwidth color. RCA
> > continued to offer such sets for two or three years. I suspect many current
> > sets using digital processing are full-bandwidth, but there's no easy way to
> > know which is which.
> >
> > > When integrated circuits became available, dual bandwidth chroma
> > > decoders started appearing...
> >
> > Not that I'm aware of. Such sets require a second delay line, which runs up
> > the cost.
> >
> > > as well as comb filters to separate the luminance and chroma
> > > signals.
> >
> > Correct.
> >
> > > More accurate phosphors were also gradually used in
> > > sets. The result was a major improvement in picture quality with
> > > the original 1953 broadcast standards. No such receiver
> > > improvement was possible with the PAL system.
> >
> > Oh? Why?
>
> WHO CARES? Analog is thankfully gone.

And digitial TV is a waste of time.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

==============================================================================
TOPIC: OT: scope recommendations?
http://groups.google.com/group/sci.electronics.repair/t/945010a432810e85?hl=en
==============================================================================

== 1 of 2 ==
Date: Sun, Jan 9 2011 6:36 pm
From: Smitty Two

In article <igdd1o$oil$1@news.eternal-september.org>,
mike <spamme9@gmail.com> wrote:

> The point was, ditch the strobe.
>
> I know zip about this, beyond the 15 minutes I spent googling and
> two hours thinking about it...but I never let incompetence stop me
> from pontificating...
>
> I just picked some round numbers to make the math easy, but it scales
> for whatever real numbers you're using.
>
> At 50 FPS, you have 20ms per frame. If you use 1000 pixels acquisition
> and you want to keep the image smear to one pixel, you have 20us flash
> duration
> at 1000X intensity. Assuming your digitizer can handle that level of
> peak intensity and behave linearly, all you have left to worry about
> is synchronizing a mechanical system with the video detector and the
> flash. If there's 10mm between frames, all you need is 10um mechanical
> stability in the film transport mechanism from frame to frame.
>
> Much easier if you can tolerate lower resolution and lots of image smear.
>
> No need to make the electronics any more capable than the weakest link.
>
> Also, your light source may not have been designed to run at 50Hz.
> forever. About 40 years ago, a guy at Tektronix did an experiment
> where he tested transistors under pulsed conditions. Turned out that
> at the rates we're talking about, you get full excursion of junction
> temperature and the life of devices was significantly reduced.
> That was a long time ago, and there are a LOT of variables.
> Dunno if it still applies to current devices.
>
> Sounds like a fun project.

At first I thought you meant ditch the strobe, but then for some reason
decided that wasn't what you meant. I asked him about that a month or so
back, and suggested a mechanical shutter. It turns out, he says, that
the light draws about 400 amps or something ridiculous like that, in
order to be bright enough since it's only on for a few microseconds as
you say. That's a bunch of current and heat to worry about if the light
was on constantly.

He's looked into and rejected a few different light types, and don't
recall offhand what he's settled on for now, but I agree that lots of
different problems could crop up.

Not sure whether I'd classify the project as fun or not. I admire his
determination, but I worry that his optimism is misguided. The
off-the-shelf flash scanners wouldn't cost 60k if they were easy to
design, engineer, and manufacture.

== 2 of 2 ==
Date: Sun, Jan 9 2011 9:58 pm
From: "Michael A. Terrell"

Gerard Bok wrote:
>
> On Sun, 9 Jan 2011 12:48:40 -0000, "N_Cook" <diverse@tcp.co.uk>
> wrote:
>
> >Gerard Bok <bok118@zonnet.nl> wrote in message
> >news:4d286e4d.3071872@News.Individual.NET...
> >> On Fri, 07 Jan 2011 06:24:12 -0800, Smitty Two
> >> <prestwhich@earthlink.net> wrote:
> >>
> >> >A friend is being coerced by circumstance into learning a bit of
> >> >electronics, and has need for a basic scope.
> >>
> >> For basics, I would advice him to run a soundcard-as-scope
> >> program on his PC. Freeware widely available and suitable for
> >> basic stuff.
> >> Let him note the limitations he observes and that will give him
> >> his 'shopping list' when buying a real scope.
>
> >I've never used a pc scope - is it easy for a novice (or absent minded
> >old-hand) putting the probe where he shouldn't and blowing up the whole pc ,
> >not just the input FETs
>
> What's cheaper, blowing a scope's input FETs or blowing a PC's
> soundcard ? And what's easier to repair / replace ?
> Imho scopes are both less foolproof and less forgiving than PCs.
>
> You may not agree, but I stand by my advice.
> I can only add, that --indeed-- some folks shouldn't be allowed
> to be to close to anything that has wires attached.
> For those folks: learn electronics by books only, don't try hands
> on ;-)

How many scopes have you blown up? I've used them for 45 years and
never blown up the input on one.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

==============================================================================
TOPIC: 12 volt automotive sealed beam lamps in series
http://groups.google.com/group/sci.electronics.repair/t/fbedfb20fe2856fd?hl=en
==============================================================================

== 1 of 2 ==
Date: Sun, Jan 9 2011 9:54 pm
From: "Michael A. Terrell"

Spehro Pefhany wrote:
>
> On Tue, 04 Jan 2011 17:22:27 -0500, the renowned "Michael A. Terrell"
> <mike.terrell@earthlink.net> wrote:
>
> >
> >klem kedidelhopper wrote:
> >>
> >> I have a 24 volt military truck that I use for snow plowing. In the
> >> past I've had trouble finding 6000 series 24 volt sealed beam lamps
> >> for the plow frame.. And when I did I have found them to be very
> >> expensive. So I came up with a circuit using a DPDT switch in which
> >> both the high and low circuit lamp filaments are wired in series when
> >> power is applied. I was very careful to initially select two lamps
> >> that drew exactly the same current when tested on my bench power
> >> supply. The arrangement has worked flawlessly for the past few years.
> >> The other night I had occaision to look at the lights from outside the
> >> truck while it was running. Charging voltage on a 24 volt system can
> >> run as high as 28 volts on a typical 24 volt system. Although I didn't
> >> try to measure the voltage accross each lamp, I noticed that one lamp
> >> is slightly brighter than the other on the low circuit. I'm assuming
> >> that filament is getting weaker and thinner and will likely fail
> >> shortly. And of course when that happens I'll lose the low circuit. I
> >> can rematch two more lamps but before I do the thought occurred to me
> >> if there was any practical easy way the equalise the voltage accross
> >> both lamps in order to compensate for any minute differences in
> >> filament resistance. I think that the total current, (two lamps in
> >> series) is about 5.0 amps. Thanks for any suggestions. Lenny
> >
> >
> > How about a 24 V to 12 V converter to power the headlamps? National
> >Semiconductor makes the 'Simple Switcher' series of regulators.
>
> You could also just buy a DC-DC converter.. 24:12 at 200W will run
> around $170, in stock at Mouser.
>
> http://www.meanwell.com/search/SD-200/SD-200-spec.pdf
>
> Looks expensive compared to the raw components, perhaps, but I'll bet
> most parts for your truck cost more than that.
>
> There's enough adjustment range that you can set it to 13.8VDC or
> whatever you think should be nominal. It will also run the lights at
> full brightness with the motor off (at the expense of some battery
> life, of course).

Probably, but it's 14 years old and I've not spent more than $100 in
repairs in the 3 years I've owned it. :)

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 2 of 2 ==
Date: Sun, Jan 9 2011 9:55 pm
From: "Michael A. Terrell"

klem kedidelhopper wrote:
>
> On Jan 5, 1:30 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
> wrote:
> > D Yuniskis wrote:
> >
> > > On 1/5/2011 12:20 AM, Michael A. Terrell wrote:
> > > >> Klem Kedidelhopper was a comediene of 1950's vintage I think.that he
> > > >> was the brain child of Red Skelton. When my son persuaded me to open
> > > >> an email account many years ago after I repeatedly told him that I
> > > >> would never have any use for one I had to pick a screen name.
> > > >> Never really thinking that this would ever even go anywhere and not
> > > >> fully taking this whole computer thing seriously at the time anyway, I
> > > >> chose the name of one of my favorite TV characters. Well these days I
> > > >> use email a lot, Klem is still on the job, I still think computers are
> > > >> a royal pain in the ass, and surprisingly most people have no idea as
> > > >> to who he was. Lenny.
> >
> > > Not *the* Lenny Bruce?? ;-)
> >
> > > > He was a 'County Bumpkin' character perfomed by Red Skelton on his TV
> > > > variety show. Along with 'The mean widdle Kid', a bum named 'Freddy the
> > > > Freeloader' and other characters.
> >
> > > Gertrude and Heathcliff
> >
> > The silly seagulls..
>
> Wasn't he also on the Jackie Gleason show?

As a guest? Probably.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

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