sci.electronics.repair - 26 new messages in 9 topics - digest

sci.electronics.repair
http://groups.google.com/group/sci.electronics.repair?hl=en

sci.electronics.repair@googlegroups.com

Today's topics:

==============================================================================
TOPIC: Help with wiring colors on old headphones
http://groups.google.com/group/sci.electronics.repair/t/f8481990f5c47309?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, May 19 2011 12:09 am
From: "Phil Allison"

"isw"
>
>>Some Wanker wrote:
>>
>> I'll check my books on acoustics about this.
>
> Check your physics book, too, recalling (as Phil said), that a speaker
> is a mechanical system operating *above resonance*.
>
> You can simulate this by hanging a fairly heavy weight from a rubber
> band. Hold the other end of the band (with the weight hanging down,
> stretching the rubber but *not too much*). Move your hand up and down.
> Below resonance, the weight follows your hand, with constant
> displacement, no matter the frequency. Above resonance, your hand goes
> down while the weight is coming up, and the faster you move your hand,
> the smaller the weight's excursion gets. That's the domain a speaker
> works in.
>
> It is this reduction in excursion as frequency increases that makes a
> speaker *automatically* have a constant volume velocity (constant output
> level) regardless of frequency. The cone excursion drops by a factor of
> four for every octave increase in frequency.

** Give this man a Kewpie doll ......

> But insofar as speaker phasing is concerned, as long as they are both
> the same, it doesn't matter much, because in general, you have no idea
> what happened to the signals before they got stuck on that CD (or
> whatever).

** Some hi-fi whackos like to pretend it is possible to get "absolute
phase" from their systems - but few even know the above fact.

BTW:

The situation is different for most headphones and electrostatic speakers -
where diaphragm movement is resistance dominated rather than mass dominated.

Plus different again for a condenser microphone where diaphragm excursion
does not vary with frequency and the output voltage wave is a direct replica
of its displacement from zero.

.... Phil

==============================================================================
TOPIC: Randall RG100G3 powerFET amp
http://groups.google.com/group/sci.electronics.repair/t/57d83a13c4840b3c?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, May 19 2011 2:03 am
From: "N_Cook"

"no name", not Hitachi ,2Sk1058 failed in low power practise use. Securing
screw to h/s was fine . Known problem of Randall using suspect devices?
probably 2006 PbF/RoHS labels

==============================================================================
TOPIC: What happened to my hard drive?
http://groups.google.com/group/sci.electronics.repair/t/5638540b7e458b4e?hl=en
==============================================================================

== 1 of 9 ==
Date: Thurs, May 19 2011 2:29 am
From: mike

Meat Plow wrote:

> The BIOS should recognize a drive regardless of the state of the drives
> partitioning, formatting etc. The BIOS via int13 says hello to the
> drive's electronics and it reports back its CHS, LBA etc.. If this
> doesn't occur it is a problem with the drive electronics. I've verified
> this by taking two identical Seagate 160 GB drives. One that failed to be
> seen in BIOS and one that was making some weird noises. Both were out of
> satellite DVRs. Swapped the drive electronics and the drive that could
> not be seen by BIOS now showed up and functioned properly for a year
> after. Just an FYI.

That reminds me, I have an identical drive lying around here
somewhere, so
at least can swap the electronics and see what happens - thanks.

== 2 of 9 ==
Date: Thurs, May 19 2011 3:01 am
From: mike

On May 18, 8:10 pm, Jeff Liebermann <je...@cruzio.com> wrote:

> What kills drives is turning them on and off repeatedly. I have
> machines where the drive is running 24x7, and they last many years. I
> have an ancient Conner 1GB 1060S drive running in my SCO Unix 3.2v4.2
> server since about 1985 without difficulties.

In 85 that would be a humongous sized drive. Sounds like a record in
the making, if not already...
>

> >Or XP setup didn't recognize it, because it did show up correctly and
> >quickly on the startup screen as the
> >system booted
>
> OK. The BIOS recognizes the drive, but Windoze does not.

Ok, that was approximately the situation before I deleted the non-NTFS
partitions - after deleting those partitions
it just sits there when the machine is turned on, it spins up but
there are no sounds of the heads
seeking anything, and the bios finally times out and says there is
nothing on the IDE channel it's plugged
into - it just sits there, brick-like...

> There's
> a chance that the drive can be revived if you wipe it clean.

Ah, there is still hope, then, I'll see if those programs will touch
it like it is.

> Try one of the numerous disk wipe type of programs.
> <http://www.dban.org/about> (what I use)
> <http://www.diskwipe.org>
> Stuff in the Windoze XP CD and boot it. It should ask to partition
> and format the disk. After it's done, it will install XP. Much
> easier with a clean HD.
>
> >> Try Seatools and see if it finds anything:
> >> <http://www.seagate.com/www/en-us/support/downloads/seatools>
> >> It probably won't if the BIOS can't find it, but it's still possible.
>
> >I tried a couple different versions of Seatools, I guess when the bios
> >doesn't see it, other programs can't either.
>
> Make up your mind please.

Sorry for the confusion - what I mean is that after the drive became
brick-like,
I tried out Seatools 1.09 and 3.04 with the drive plugged in but
undetected,
and neither version was able to see the drive.

> When you go into the CMOS setup, does the
> drive show up and is it correctly identified as an ST340810A drive?

No, not any more
>if so, the BIOS sees it. If not, it's dead.

So far it's RIP ded.

Thanks again,
Mike

== 3 of 9 ==
Date: Thurs, May 19 2011 3:18 am
From: mike

On May 19, 1:12 am, Franc Zabkar <fzab...@iinternode.on.net> wrote:
> On Wed, 18 May 2011 07:03:45 -0700 (PDT), mike
> <mlight...@survivormail.com> put finger to keyboard and composed:
>
> >I'm wondering can anyone give me some clues as to what happened to
> >this Seagate 40 Gb hard drive I was messing around with the other day.
>
> >I was using Clonezilla to try to get a newly cloned XP system to boot
>
> <snip>
>
> >The XP partition was the only one recognized by the XP CD, so I used
> >Part Ed Magic to delete the non-NTFS partitions, thinking that would
> >fix it, but instead the hdd acts like a brick now, and worse than a
> >brick, since whichever IDE channel it's plugged into, it prevents
> >that channel from detecting itself and any other device on that
> >channel (jumpers set to cable select), causing big time delay in boot
> >while the BIOS trys and fails to detect said items.
>
> It could be that the drive has a weak head or bad media.
>
> There is a reserved System Area (SA) on the platters which stores the
> runtime (ATA) firmware, defect lists, SMART data, etc. When the drive
> starts up, it executes a POST and some minor bootstrap code on the
> PCB, and then proceeds to retrieve the firmware from the SA. If the SA
> is unreadable, then the drive won't come ready.

Interesting details, thanks...
>
> You could try a DOS based diagnostic such as MHDD. This can access the
> drive directly, without going though BIOS:http://hddguru.com/software/2005.10.02-MHDD

I did try MHDD, when I hit F2 to get the hdd info the result was
"drive not ready" - but I'll go back in
there and look into this ENABLEPRIMARY switch you mention - I'll have
to read some more of the docs.

>
> Be sure to use the ENABLEPRIMARY switch if the drive is the master on
> the primary IDE channel:http://66.14.166.45/whitepapers/compforensics/danalysis/MHDD%20Docume...http://66.14.166.45/whitepapers/compforensics/danalysis/MHDD%20Manual...
>
> Otherwise you could access the drive via its serial terminal interface
> using a program such as SeDiv. Let me know if you need more details

Ok, I'll look into SeDiv, but I have a feeling that communicating via
a serial
terminal interface is gonna be above my pay grade, I'll let you
know :).

Thanks for the pointers and links Frank,
Mike
>
> - Franc Zabkar
> --
> Please remove one 'i' from my address when replying by email.

== 4 of 9 ==
Date: Thurs, May 19 2011 3:48 am
From: Franc Zabkar

On Thu, 19 May 2011 03:18:23 -0700 (PDT), mike
<mlightner@survivormail.com> put finger to keyboard and composed:

>I did try MHDD, when I hit F2 to get the hdd info the result was
>"drive not ready" ...

That could mean that the drive is stuck in the BSY state.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

== 5 of 9 ==
Date: Thurs, May 19 2011 4:37 am
From: mike

Franc Zabkar wrote:
> On Thu, 19 May 2011 03:18:23 -0700 (PDT), mike
> <mlightner@survivormail.com> put finger to keyboard and composed:
>
> >I did try MHDD, when I hit F2 to get the hdd info the result was
> >"drive not ready" ...
>
> That could mean that the drive is stuck in the BSY state.

Hmm, that may be so, at least at the top of the MHDD screen the BSY
indicator is lit

Thanks,
Mike

== 6 of 9 ==
Date: Thurs, May 19 2011 6:38 am
From: Mysterious Traveler

On 05/19/2011 12:12 AM, Franc Zabkar wrote:
> On Wed, 18 May 2011 07:03:45 -0700 (PDT), mike
> <mlightner@survivormail.com> put finger to keyboard and composed:
>
>> I'm wondering can anyone give me some clues as to what happened to
>> this Seagate 40 Gb hard drive I was messing around with the other day.
>>
>> I was using Clonezilla to try to get a newly cloned XP system to boot
>
> <snip>
>
>> The XP partition was the only one recognized by the XP CD, so I used
>> Part Ed Magic to delete the non-NTFS partitions, thinking that would
>> fix it, but instead the hdd acts like a brick now, and worse than a
>> brick, since whichever IDE channel it's plugged into, it prevents
>> that channel from detecting itself and any other device on that
>> channel (jumpers set to cable select), causing big time delay in boot
>> while the BIOS trys and fails to detect said items.
>
> It could be that the drive has a weak head or bad media.
>
> There is a reserved System Area (SA) on the platters which stores the
> runtime (ATA) firmware, defect lists, SMART data, etc. When the drive
> starts up, it executes a POST and some minor bootstrap code on the
> PCB, and then proceeds to retrieve the firmware from the SA. If the SA
> is unreadable, then the drive won't come ready.
>
> You could try a DOS based diagnostic such as MHDD. This can access the
> drive directly, without going though BIOS:
> http://hddguru.com/software/2005.10.02-MHDD
>
> Be sure to use the ENABLEPRIMARY switch if the drive is the master on
> the primary IDE channel:
> http://66.14.166.45/whitepapers/compforensics/danalysis/MHDD%20Documentation.pdf
> http://66.14.166.45/whitepapers/compforensics/danalysis/MHDD%20Manual.pdf
>
> Otherwise you could access the drive via its serial terminal interface
> using a program such as SeDiv. Let me know if you need more details.
>
> - Franc Zabkar
My suggestion is that you take a close look at the pins where
the IDE cable plugs in and you'll probably find at least one
pin is bent and isn't plugging into the IDE cable.

== 7 of 9 ==
Date: Thurs, May 19 2011 8:20 am
From: mike

On May 19, 9:38 am, Mysterious Traveler <mysterious.trave...@dot.net>
wrote:

>
> My suggestion is that you take a close look at the pins where
> the IDE cable plugs in and you'll probably find at least one
> pin is bent and isn't plugging into the IDE cable.
>
> --
OK, next chance I get I'll do that, though I think its unlikely that
that's the problem (knock on wood :)

== 8 of 9 ==
Date: Thurs, May 19 2011 8:33 am
From: Jeff Liebermann

On Thu, 19 May 2011 03:01:06 -0700 (PDT), mike
<mlightner@survivormail.com> wrote:

>it just sits there when the machine is turned on, it spins up but
>there are no sounds of the heads
>seeking anything, and the bios finally times out and says there is
>nothing on the IDE channel it's plugged
>into - it just sits there, brick-like...

1. Try it with just the power applied and no IDE cable connected.
Can you now hear the heads seeking? The IDE interface on the
motherboard might be fried.
2. You might not be able to hear the heads seeking (actually
self-calibrating) on power on if the machines fans are noisy. I use a
stethoscope.

>Sorry for the confusion - what I mean is that after the drive became
>brick-like,
>I tried out Seatools 1.09 and 3.04 with the drive plugged in but
>undetected,
>and neither version was able to see the drive.
>(...)
>> When you go into the CMOS setup, does the
>> drive show up and is it correctly identified as an ST340810A drive?
>
>No, not any more

Seatools should detect a drive that's not formatted, but does show up
in the BIOS. However, if the drive does NOT appear in the BIOS, it's
dead.

MeatPlow suggested juggling PCB's on the drive. That might be worth
the effort as drives that don't appear in the BIOS are usually PCB
failures, not HDA failures.

>>if so, the BIOS sees it. If not, it's dead.
>
>So far it's RIP ded.

Seagate and Western Dismal have made my life interesting. Prior to
about 2005, WD drives had horrible premature failures and Seagate were
surviving much longer than WD. After about 2008, the situation was
reversed, with Seagate drives failing miserably, and WD doing much
better. That's also the current situation. With only two players
left in the commodity retail drive biz, it's becoming rather scarey.
All I can hope for is that the SSD drive makers take over quickly.
Hopefully, they'll last longer than 3-5 years but too soon to tell.
<http://en.wikipedia.org/wiki/List_of_defunct_hard_disk_manufacturers>

--
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

== 9 of 9 ==
Date: Thurs, May 19 2011 8:46 am
From: Adrian C

On 19/05/2011 16:33, Jeff Liebermann wrote:
> Seagate and Western Dismal have made my life interesting. Prior to
> about 2005, WD drives had horrible premature failures and Seagate were
> surviving much longer than WD. After about 2008, the situation was
> reversed, with Seagate drives failing miserably, and WD doing much
> better. That's also the current situation. With only two players
> left in the commodity retail drive biz, it's becoming rather scarey.
> All I can hope for is that the SSD drive makers take over quickly.
> Hopefully, they'll last longer than 3-5 years but too soon to tell.
> <http://en.wikipedia.org/wiki/List_of_defunct_hard_disk_manufacturers>
>

Good grief, reading that have noted Seagate have recently lept into bed
with Samsung (trouble free drives in my TiVo), and WD has just gobbled
up Hitachi GST. Billion dollar plus deals.

--
Adrian C

==============================================================================
TOPIC: Are faulty APC UPS's easy repairs or is it throw in the trash?
http://groups.google.com/group/sci.electronics.repair/t/afd84408acb5d795?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, May 19 2011 3:43 am
From: "Stephen"

Hi, I have two faulty APC BackUPS CS500's each with a different fault.

The first unit will switch to battery when there is a power cut. However,
when the power is restored, it will not switch back to mains power, it
remains on the battery till it goes flat.

The 2nd one will not power up when pressing the on/off button on the front
of the unit.

I have a third working identicial UPS and I have tried the battery out of
this one in the two faulty units and its NOT the battery.

Are these likely to be an easy repair or shall I flog them on Ebay for
spares?

Stephen

== 2 of 2 ==
Date: Thurs, May 19 2011 8:56 am
From: Jeff Liebermann

On Thu, 19 May 2011 11:43:53 +0100, "Stephen" <i.want.spam@spam.com>
wrote:

>Hi, I have two faulty APC BackUPS CS500's each with a different fault.
>
>The first unit will switch to battery when there is a power cut. However,
>when the power is restored, it will not switch back to mains power, it
>remains on the battery till it goes flat.

Hmmm... that shouldn't be too difficult. Is there a relay that does
the switching on the CS 500? If so, see if it's working, or if the
contacts are fried.

>The 2nd one will not power up when pressing the on/off button on the front
>of the unit.

Bad ribbon cable connection on the insulation displacement connector
going to the main board.

>I have a third working identicial UPS and I have tried the battery out of
>this one in the two faulty units and its NOT the battery.
>
>Are these likely to be an easy repair or shall I flog them on Ebay for
>spares?

No. They're a PITA to repair. There are some schematics at:
<http://www.eserviceinfo.com/index.php?what=search2&searchstring=APC>
but I couldn't find anything on the CS500. I've done some seat of the
pants fixes on various APC UPS's but it was more luck than knowledge
that resulted in a repair. Mostly, what I found are bad crimps on the
spade lugs, bad insulation displacement ribbon connector "crimps" to
the front panel, and fried electrolytics when run in backup mode for
too long (high ripple current).

The CS500 sells for $85 to $120, so putting more than about 1-2 hrs
into this is problematic. Google find some vendors that offer APC UPS
repair services, but I have no experience with any of these.

Incidentally, the local recycler constantly complains about the large
number of UPS's that he gets. He has to remove the battery from the
UPS, which burns his time. If you do decide to recycle, please remove
the battery and recycle it separately.

--
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

==============================================================================
TOPIC: Tempest / BatterySpec AGM batteries?
http://groups.google.com/group/sci.electronics.repair/t/9ab59c9b0f69f30d?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, May 19 2011 4:50 am
From: Bill Sloman

On May 19, 6:39 am, notme <no...@notme.org> wrote:
> > rest assured that's some no-name chinese battery and quality wasn't a
> > design concern, at all.
>
> > Stick with panasonic or yuasa if you care about quality. Some of those are
> > from china now, but are less bogus than the rest of the stuff out there.
>
> [CL]
>
> A statement full of prejudice and innuendo.

It's certainly full of prejudice, but that's our stock in trade around
here. If you work in electronics for a couple of decades you build up
useful prejudices without explicitly knowing what they are based on.
It's unscientific, but science is a tolerably expensive way of
building up a body clearly connected facts, while prejudice is cheaper
and less reliable, but a great deal better than nothing, particularly
when science hasn't got around to quantify what you need to know.

As for innuendo

http://en.wikipedia.org/wiki/Innuendo

there's nothing indirect about opinion being presented - its a plain
statement of opinion, without any obvious hidden agenda.

--
Bill Sloman, Nijmegen

> Facts?

==============================================================================
TOPIC: Recycling electronic waste.
http://groups.google.com/group/sci.electronics.repair/t/da679f4848b11be7?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, May 19 2011 6:42 am
From: "Ian Field"

"b" <reverend_rogers@yahoo.com> wrote in message
news:058eb586-4a80-4d09-a7dc-3d5213dc7010@x3g2000yqj.googlegroups.com...
On May 17, 10:28 pm, "Ian Field" <gangprobing.al...@ntlworld.com>
wrote:
> Taking your e-waste to the council tip doesn't allways mean it will be
> recycled in a lawful manner!
>
> http://www.bbc.co.uk/iplayer/episode/b0116gw0/Panorama_Track_My_Trash/

this video by artist chris jordan has some extremely disturbing points
on the shameful wastefulness of the so-called developed world:

What I'd like to know is how to make some of the scrap PCs come my way.

Firstly I could probably find something better than I've got.

Secondly I could aquire more HDDs to store all the stuff I download.

Thirdly I could make some cash refurbishing and selling any surplus.

==============================================================================
TOPIC: Shorted Computer Power Supply
http://groups.google.com/group/sci.electronics.repair/t/326dbb3fa5e1a293?hl=en
==============================================================================

== 1 of 4 ==
Date: Thurs, May 19 2011 7:17 am
From: KenO

Hi Jeff,

Thanks for your link ATX Power Supply Schematic <http://
www.google.com/search?q=atx+power+supply+schematic&hl=en&prmd=...>

Could not find any schematic for ilssan model ISP 120SI

When I searched used
http://www.google.com/search?as_q=ilssan+atx+power+supply+schematic&hl=en&biw=1440&bih=706&tbm=isch&btnG=Google+Search&as_epq=&as_oq=&as_eq=&imgtype=&imgsz=&imgw=&imgh=&imgar=&as_filetype=&imgc=&as_sitesearch=&as_rights=&safe=images&as_st=y
but also found No ilssan schematics.

Ken

== 2 of 4 ==
Date: Thurs, May 19 2011 9:01 am
From: Jeff Liebermann

On Thu, 19 May 2011 07:17:36 -0700 (PDT), KenO <kenitholson@yahoo.com>
wrote:

>Thanks for your link ATX Power Supply Schematic <http://
>www.google.com/search?q=atx+power+supply+schematic&hl=en&prmd=...>
>
>Could not find any schematic for ilssan model ISP 120SI
>
>When I searched used
>http://www.google.com/search?as_q=ilssan+atx+power+supply+schematic&hl=en&biw=1440&bih=706&tbm=isch&btnG=Google+Search&as_epq=&as_oq=&as_eq=&imgtype=&imgsz=&imgw=&imgh=&imgar=&as_filetype=&imgc=&as_sitesearch=&as_rights=&safe=images&as_st=y
>but also found No ilssan schematics.

I doubt if you're going to find the specific schematic for a Ilssan
whatever. Open the case, and identify the regulator chip. Then, dig
through the mess of schematics that Google finds and see if you can
find a similar schematic that uses the same chip. You won't get the
exact schematic but it will be close.

"Notes on the Troubleshooting and Repair of Small Switchmode Power
Supplies"
<http://repairfaq.ece.drexel.edu/sam/smpsfaq.htm>

--
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 4 ==
Date: Thurs, May 19 2011 9:35 am
From: "larry moe 'n curly"

KenO wrote:

> I tried to connect a hard drive while the [power supply] was turned on and [it] blew.
>
> When I inspected the [power supply] components and PC board, found the fuse did
> Not blow and only visible damage was a short section of burned wire of
> one inductor coil. If you tell me how will post photos of the [power supply] for
> your examination.

Try a photo posting place, like Flickr.com , PhotoBucket.com , or, if
you don't want to register with the site, try TinyPic.com or
ImageShack.us .

Really, really good FAQ about electronics repair: www.RepairFAQ.org

Unplug the AC power cord before opening the power supply, and don't
even test it unless its cover is fully installed (all screws
tightened).

I'm no expert, but I've never seen a fusible resistor inside a common
PC power supply, except maybe the large rectangular ceramic ones.
Fusible resistors are more common on motherboards, near the ports for
the keyboard, mouse, and USB, and on hard drives (usually next to a
zener to protect against overvoltage, and if it triggers, the fuse
associated with it pops). When regular resistors open up (higher than
rated resistance), they usually show burn marks or cracks, but fusible
resistors usually open up without showing damage.

The only coils that tend to burn in power supplies are those for the
automatic power factor correction (high voltage side) and the output
filters (low voltage side), and I think your problem is related to the
latter because those coils run hot, and those coils vary a lot in
size, depending not only on power ratings but also on the quality. If
the affected coil is in the low voltage section, maybe you can
separate its wires from one another in the burned area and coat them
with varnish. Do NOT do this if the coil handles high voltage.
Typically when a PC power supply fails and its fuse doesn't pop, the
problem is in the low voltage section, such as a shorted diode or
MOSFET or a worn electrolytic capacitor. Use only low-ESR capacitors
for replacement, preferrably of the same diameter (tight fit in
there). Any replacement diode or MOSFET has to be of the same type
(diode should be Schottky) and meet the same minimum ratings for amps,
volts, and watts. To remove anything attached to a heatsink, it's
usually necessary to unsolder everything, including the heatsink.

== 4 of 4 ==
Date: Thurs, May 19 2011 9:39 am
From: "larry moe 'n curly"

KenO wrote:

> Could not find any schematic for ilssan model ISP 120SI

Reepair.net/en or ElektroTanya.com may have something, but more likely
you'll have
to find the controller chips and rely on data sheets and applications
notes from the makers of those chips.
But generally, to fix an ATX power supply you just look for physical
damage, bad solder joints, and check
diodes and transistors with a meter.

==============================================================================
TOPIC: another puzzler
http://groups.google.com/group/sci.electronics.repair/t/b80657d8be4c22cd?hl=en
==============================================================================

== 1 of 6 ==
Date: Thurs, May 19 2011 7:54 am
From: Carey Carlan

spamtrap1888 <spamtrap1888@gmail.com> wrote in news:88df2861-f695-449b-
a558-e3d119b1cb3b@34g2000pru.googlegroups.com:

> Let's look at the case of the ignorant host.
>
> There are three possibilities at the start of the game. The
> probability of each is 1/3
>
> _1 2 3_
> aCGG
> bGCG
> cGGC
>
> Let us say door 1 represents the contestant's pick. The host can pick
> either door 2 or door 3
> Case a: Host picks Door 2. Result: Goat. Contestant switches to Door
> 3, loses.
> ..............Host picks Door 3 Result Goat. Contestant switches to
> Door 2, loses.
> Case b: Host picks Door 2. Result Car. Contestant loses
> ..............Host picks Door 3. Result Goat. Contestant switches to
> Door 2, wins
> Case c: Host picks Door 2. Result Goat. Contestant switches to Door 3,
> wins
> ..............Host picks Door 3 Result Car. Contestant loses.
>
> Of the six possible scenarios, the contestant loses four times. If the
> contestant does not switch after the ignorant host opens a door, the
> contestant loses four times. If we discard the times the host opens a
> door with a car behind it, the contestant wins two out of four times
> when he switches, and two out of four times when he doesn't switch.
> Therefore, switching picks has no effect on the odds when the host
> randomly opens one of the other doors.

Then go back to the original where the host knows where the car is and
the contestant switches.

Case a: Host picks Door 2. Result: Goat. Contestant switches to Door 3,
loses.
..............Host picks Door 3 Result Goat. Contestant switches to
Door 2, loses.
Case b: Host picks Door 3. Result Goat. Contestant switches to Door 2,
wins
Case c: Host picks Door 2. Result Goat. Contestant switches to Door 3,
wins

Or the contestant doesn't switch.

Case a: Host picks Door 2. Result: Goat. Contestant keeps Door 1, wins.
..............Host picks Door 3 Result Goat. Contestant keeps Door 1,
wins.
Case b: Host picks Door 3. Result Goat. Contestant keeps Door 1, loses
Case c: Host picks Door 2. Result Goat. Contestant keeps Door 1, loses

After the Host opens the door the odds are even. Makes no difference if
the contestant changes doors or not. This is the same as there only
being two doors.

The original claim was that the odds remained 1 in 3 even after the Host
opened the door. I still don't see it.

== 2 of 6 ==
Date: Thurs, May 19 2011 9:03 am
From: spamtrap1888

On May 19, 7:54 am, Carey Carlan <gulf...@hotmail.com> wrote:
> spamtrap1888 <spamtrap1...@gmail.com> wrote in news:88df2861-f695-449b-
> a558-e3d119b1c...@34g2000pru.googlegroups.com:
>
>
>
> > Let's look at the case of the ignorant host.
>
> > There are three possibilities at the start of the game. The
> > probability of each is 1/3
>
> > _1 2 3_
> > aCGG
> > bGCG
> > cGGC
>
> > Let us say door 1 represents the contestant's pick. The host can pick
> > either door 2 or door 3
> > Case a: Host picks Door 2. Result: Goat. Contestant switches to Door
> > 3, loses.
> > ..............Host picks Door 3 Result Goat. Contestant switches to
> > Door 2, loses.
> > Case b: Host picks Door 2. Result Car. Contestant loses
> > ..............Host picks Door 3. Result Goat. Contestant switches to
> > Door 2, wins
> > Case c: Host picks Door 2. Result Goat. Contestant switches to Door 3,
> > wins
> > ..............Host picks Door 3 Result Car. Contestant loses.
>
> > Of the six possible scenarios, the contestant loses four times. If the
> > contestant does not switch after the ignorant host opens a door, the
> > contestant loses four times. If we discard the times the host opens a
> > door with a car behind it, the contestant wins two out of four times
> > when he switches, and two out of four times when he doesn't switch.
> > Therefore, switching picks has no effect on the odds when the host
> > randomly opens one of the other doors.
>
> Then go back to the original where the host knows where the car is and
> the contestant switches.
>
> Case a: Host picks Door 2. Result: Goat. Contestant switches to Door 3,
> loses.
> ..............Host picks Door 3 Result Goat. Contestant switches to
> Door 2, loses.
> Case b: Host picks Door 3. Result Goat. Contestant switches to Door 2,
> wins
> Case c: Host picks Door 2. Result Goat. Contestant switches to Door 3,
> wins
>
> Or the contestant doesn't switch.
>
> Case a: Host picks Door 2. Result: Goat. Contestant keeps Door 1, wins.
> ..............Host picks Door 3 Result Goat. Contestant keeps Door 1,
> wins.
> Case b: Host picks Door 3. Result Goat. Contestant keeps Door 1, loses
> Case c: Host picks Door 2. Result Goat. Contestant keeps Door 1, loses
>
> After the Host opens the door the odds are even. Makes no difference if
> the contestant changes doors or not. This is the same as there only
> being two doors.
>
> The original claim was that the odds remained 1 in 3 even after the Host
> opened the door. I still don't see it.

Without switching, the contestant has a 1/3 chance of winning:
Case a: Contestant picked door with car. Host can open either door,
his choice, to reveal goat.
Case b: Contestant picked door with goat. Host must open Door 3 to
reveal goat.
Case c: Contestant picked door with goat. Host must open Door 2 to
reveal goat.

With switching, the contestant now has a 2/3 chance of winning:
Case a: Host can open either door, his choice. Contestant switches to
unopened door, loses.
Case b: Host opens Door 3, contestant switches to Door 2, wins.
Case c: Host opens Door 2, contestant switches to Door 3, wins.

== 3 of 6 ==
Date: Thurs, May 19 2011 9:16 am
From: spam@spam.com (Don Pearce)

On Wed, 18 May 2011 08:44:57 -0500, "David" <someone@somewhere.com>
wrote:

>"Don Pearce" wrote in message
>news:4dd3548d.36447387@news.eternal-september.org...
>>The host acts as a leak of information. It might help to imagine
>>an
>>alternate game, where the host does not know the contents of the
>>doors,
>>and the game is void if the host reveals the car. This version
>>puts you
>>back to 50/50 when the host reveals a goat, whether you switch
>>doors or
>>not.
>>***
>>Not true. When the host reveals a goat whether he guessed or
>>knew
>>it was there makes absolutely no difference. You should still
>>switch doors.
>>
>>David
>>
>
>If the host does not know, he might quite as easily reveal the
>car.
>You then can't win it. Do you guarantee yourself 2/3 odds by
>switching
>then? No. If the host reveals a goat by chance, the odds do
>indeed
>drop to 50/50.
>
>d
>***
>Sorry, I disagree. Yes the host could reveal a car if he is
>unaware of the situation. If this happens, the game was defined
>as void. If the host instead reveals a goat, there is no
>difference whether he guessed or knew the goat was there.
>
>David
>
>

Void is not one of the permitted outcomes. Suppose the host
accidentally revealed the car - to be equivalent to the intentional
goat revelation, he would then have to say "never mind, take the car
anyway". That would leave you in the 1/3 2/3 situation. If he reveals
a goat by chance the game degenerates to the simple situation - the
host has chosen one of the three, and you get to pick between the
remaining two, always assuming that he did not pick the car.

The point of the intentional revelation is that by switching you get -
in effect - both doors, not just the one.

== 4 of 6 ==
Date: Thurs, May 19 2011 10:21 am
From: "David"

"Don Pearce" wrote in message
news:4dd54100.162501046@news.eternal-september.org...

On Wed, 18 May 2011 08:44:57 -0500, "David"
<someone@somewhere.com>
wrote:

>"Don Pearce" wrote in message
>news:4dd3548d.36447387@news.eternal-september.org...
>>The host acts as a leak of information. It might help to
>>imagine
>>an
>>alternate game, where the host does not know the contents of
>>the
>>doors,
>>and the game is void if the host reveals the car. This version
>>puts you
>>back to 50/50 when the host reveals a goat, whether you switch
>>doors or
>>not.
>>***
>>Not true. When the host reveals a goat whether he guessed or
>>knew
>>it was there makes absolutely no difference. You should still
>>switch doors.
>>
>>David
>>
>
>If the host does not know, he might quite as easily reveal the
>car.
>You then can't win it. Do you guarantee yourself 2/3 odds by
>switching
>then? No. If the host reveals a goat by chance, the odds do
>indeed
>drop to 50/50.
>
>d
>***
>Sorry, I disagree. Yes the host could reveal a car if he is
>unaware of the situation. If this happens, the game was defined
>as void. If the host instead reveals a goat, there is no
>difference whether he guessed or knew the goat was there.
>
>David
>
>

>Void is not one of the permitted outcomes. Suppose the host
>accidentally revealed the car - to be equivalent to the
>intentional
>goat revelation, he would then have to say "never mind, take the
>car
>anyway". That would leave you in the 1/3 2/3 situation. If he
>reveals
>a goat by chance the game degenerates to the simple situation -
>the
>host has chosen one of the three, and you get to pick between
>the
>remaining two, always assuming that he did not pick the car.
>
>The point of the intentional revelation is that by switching you
>get -
>in effect - both doors, not just the one.
>
>d
***
Start at the beginning of this post and read all of the quoted
stuff. The initial assumption is that 'void' IS a permitted
outcome. If the void assumption is changed , I concede.
David

== 5 of 6 ==
Date: Thurs, May 19 2011 10:28 am
From: "William Sommerwerck"

I don't know why people make the Monty Hall Paradox so complex. I've
explained it simply, twice.

All you have to do is understand why the initial probability of getting the
big prize is 1/3 -- and everything else falls out in a completely
straightforward manner.

== 6 of 6 ==
Date: Thurs, May 19 2011 10:28 am
From: Ron Capik

On 5/19/2011 10:54 AM, Carey Carlan wrote:
> spamtrap1888<spamtrap1888@gmail.com> wrote in news:88df2861-f695-449b-
> a558-e3d119b1cb3b@34g2000pru.googlegroups.com:
>
>> Let's look at the case of the ignorant host.
>>
>> There are three possibilities at the start of the game. The
>> probability of each is 1/3
>>
>> _1 2 3_
>> aCGG
>> bGCG
>> cGGC
>>
>> Let us say door 1 represents the contestant's pick. The host can pick
>> either door 2 or door 3
>> Case a: Host picks Door 2. Result: Goat. Contestant switches to Door
>> 3, loses.
>> ..............Host picks Door 3 Result Goat. Contestant switches to
>> Door 2, loses.
>> Case b: Host picks Door 2. Result Car. Contestant loses
>> ..............Host picks Door 3. Result Goat. Contestant switches to
>> Door 2, wins
>> Case c: Host picks Door 2. Result Goat. Contestant switches to Door 3,
>> wins
>> ..............Host picks Door 3 Result Car. Contestant loses.
>>
>> Of the six possible scenarios, the contestant loses four times. If the
>> contestant does not switch after the ignorant host opens a door, the
>> contestant loses four times. If we discard the times the host opens a
>> door with a car behind it, the contestant wins two out of four times
>> when he switches, and two out of four times when he doesn't switch.
>> Therefore, switching picks has no effect on the odds when the host
>> randomly opens one of the other doors.
>
> Then go back to the original where the host knows where the car is and
> the contestant switches.
>
> Case a: Host picks Door 2. Result: Goat. Contestant switches to Door 3,
> loses.
> ..............Host picks Door 3 Result Goat. Contestant switches to
> Door 2, loses.
> Case b: Host picks Door 3. Result Goat. Contestant switches to Door 2,
> wins
> Case c: Host picks Door 2. Result Goat. Contestant switches to Door 3,
> wins
>
> Or the contestant doesn't switch.
>
> Case a: Host picks Door 2. Result: Goat. Contestant keeps Door 1, wins.
> ..............Host picks Door 3 Result Goat. Contestant keeps Door 1,
> wins.
> Case b: Host picks Door 3. Result Goat. Contestant keeps Door 1, loses
> Case c: Host picks Door 2. Result Goat. Contestant keeps Door 1, loses
>
> After the Host opens the door the odds are even. Makes no difference if
> the contestant changes doors or not. This is the same as there only
> being two doors.
>
> The original claim was that the odds remained 1 in 3 even after the Host
> opened the door. I still don't see it.

OK, try this: blow the game up to 100 doors. Your chance of picking
the winning door on the first try is 1 out of 100. Stick with that
choice and each time a zonk is revealed the chance of the prize being
in the remaining group increases. When you get down to two doors the
chance of the prize being behind the other door is 99 out of 100.
The chance of your first pick being correct is still 1 out of 100.

Later...
Ron Capik
--

==============================================================================
TOPIC: Is MTS audio a victim of the latest cable company upgrading?
http://groups.google.com/group/sci.electronics.repair/t/60a2fa68004f3c17?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, May 19 2011 9:55 am
From: "Deke"

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:6LidnZ823trqFUnQnZ2dnUVZ_r-vnZ2d@earthlink.com...
>
> Deke wrote:
>>
>> "Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
>> news:3MWdnWgnBvoUFUzQnZ2dnUVZ_oidnZ2d@earthlink.com...
>> >
>> > Deke wrote:
>> >>
>> >> Michael A. Terrell wrote:
>> >> >
>> >> > What storm?
>> >> >
>> >> The one that gives you signal disrupting heavy fog for three straight
>> >> days?
>> >
>> >
>> > You've never lived in Florida, or you would know that you don't need
>> > a storm to have heavy fog.
>> >
>> >
>> > --
>> > You can't fix stupid. You can't even put a Band-AidT on it, because
>> > it's
>> > Teflon coated.
>>
>> OK. But three days of fog heavy enough to disrupt satellite service?
>> Can't find anything on Google to support that. Must have been a bad
>> installation.
>
>
> Prove it, and why would that instance be on Google? Can you find
> anything about the heavy smoke & fog that blanketed this area for months
> after one hurricane?
>
>
Me, prove it? I believe you were the one who said you had fog so thick it
blocked satellite service for three days. Prove it, use what ever search
engine you want, or are capable of using.

>> BTW, there's no T in band-aid.
>
>
> BTW, get a real news client instead of that crappy Microsoft Windows
> Mail 6.0.6002.18197, so you can see things other than the most basic
> ASCII characters. That piece of crap is only good for old ladies to
> exchange pickle recipies.
> --
And yet it works well enough to respond to your posts. Imagine that.

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