sci.electronics.repair - 19 new messages in 11 topics - digest

sci.electronics.repair
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Today's topics:

==============================================================================
TOPIC: Picture tube degaussing
http://groups.google.com/group/sci.electronics.repair/t/a6f0cc34cbf52c0b?hl=en
==============================================================================

== 1 of 5 ==
Date: Thurs, Apr 22 2010 11:01 am
From: bz

"William R. Walsh" <wm_walsh@hotmail.com> wrote in news:976ab687-72ed-487d-
826d-ea5359e01050@z3g2000yqz.googlegroups.com:

> Hi!
>
>> Have your friend hide the magnets from the kids. The internal
>> degauss should take care of the remaining spots provided it
>> works.
>
> Sometimes it isn't stout enough to do the job. Some years back, my
> younger brothers managed to put a faint "blob" on a MAG Innovision 17"
> CRT. No amount of degaussing with the monitor's built in coil would do
> the job. Even though the coil came on at every power up, it just
> didn't seem to have the oomph. Operating it manually through the
> monitor's menu did not help.
>
> Being busy at the time, I took a quick look and decided that they'd
> damaged the monitor's picture tube. And then, after a while, I managed
> to acquire a large electric bulk eraser, which I eventually decided to
> try using as a degaussing wand for this monitor.
>
> It worked brilliantly. I started from several feet away by turning it
> on and moved very slowly toward the CRT itself. Then I ran it slowly
> around the CRT face, maintaining several inches worth of distance.
> When I was satisfied, I moved away the same several feet and shut the
> coil off.
>
> William

I have successfully degaussed CRT monitors using an old magnetron magnet
suspended from a stout rubber band fastened to a bent wire in the a hole in
the center of the magnet.

I would wind up the magnet/rubber band combo and let it spin rapidly
Holding it near the monitor and slowly moving it away as it spun.

Any strong and rapidly spinning magnet that is aligned so that the magnetic
field alternates directions should work.

Some 'bulk erasers' spin a magnet using an electric motor.

--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

== 2 of 5 ==
Date: Thurs, Apr 22 2010 12:15 pm
From: Meat Plow

On Thu, 22 Apr 2010 14:47:11 -0400, Ron Weston <RonW@nosuch.com>wrote:

>Thanks for the replies so far. My friend is a senior citizen and lives
>alone, so no children have been near the TV. There have been lightning
>storms so that may be what caused her TV problem.
>
>I have a bulk tape eraser. When I visit again first I'll try my
>degaussing coil on the side of the TV as well as the front, and if
>that doesn't work I'll try the eraser.
>
>I'll report back what happens.

Do you know how to use a degauss coil?

== 3 of 5 ==
Date: Thurs, Apr 22 2010 12:27 pm
From: "William Sommerwerck"

> Some 'bulk erasers' spin a magnet using an electric motor.

Zenith once made one with a small magnet you spun by hand. It was intended
for small blotches.

== 4 of 5 ==
Date: Thurs, Apr 22 2010 12:34 pm
From: AZ Nomad

On Thu, 22 Apr 2010 14:47:11 -0400, Ron Weston <RonW@nosuch.com> wrote:
>Thanks for the replies so far. My friend is a senior citizen and lives
>alone, so no children have been near the TV. There have been lightning
>storms so that may be what caused her TV problem.

>I have a bulk tape eraser. When I visit again first I'll try my
>degaussing coil on the side of the TV as well as the front, and if
>that doesn't work I'll try the eraser.

With the eraser, turn it on and off at least 5' away from the TV.
Walk slowly to the tv waving it around then back off. Be careful; the
things are very powerful and you might be able to damage the shadow
mask if you get closer than needed.

== 5 of 5 ==
Date: Thurs, Apr 22 2010 3:11 pm
From: "Arfa Daily"

"William R. Walsh" <wm_walsh@hotmail.com> wrote in message
news:976ab687-72ed-487d-826d-ea5359e01050@z3g2000yqz.googlegroups.com...
> Hi!
>
>> Have your friend hide the magnets from the kids. The internal
>> degauss should take care of the remaining spots provided it
>> works.
>
> Sometimes it isn't stout enough to do the job. Some years back, my
> younger brothers managed to put a faint "blob" on a MAG Innovision 17"
> CRT. No amount of degaussing with the monitor's built in coil would do
> the job. Even though the coil came on at every power up, it just
> didn't seem to have the oomph. Operating it manually through the
> monitor's menu did not help.
>
> Being busy at the time, I took a quick look and decided that they'd
> damaged the monitor's picture tube. And then, after a while, I managed
> to acquire a large electric bulk eraser, which I eventually decided to
> try using as a degaussing wand for this monitor.
>
> It worked brilliantly. I started from several feet away by turning it
> on and moved very slowly toward the CRT itself. Then I ran it slowly
> around the CRT face, maintaining several inches worth of distance.
> When I was satisfied, I moved away the same several feet and shut the
> coil off.
>
> William

Back in't' day, we wuz taught to have the TV switched on, and go around the
four sides of the CRT using circular motions, and to keep those motions
going all the same way. Then to come up to the CRT face, and again use
circular motions, again keeping them in the same direction, and spiraling
slowly away from the face. At a distance of a couple of feet, when the field
from the coil was no longer having any noticeable effect on the picture, the
coil was quickly turned through 90 degrees, and powered off.

As to what caused the problem on this particular TV, could be all sorts of
things. One of the favourites, as I recall, was customers switching off the
vacuum cleaner when near to the TV. You can also get suddenly appearing
purity patches from shadowmask displacement when the spring expansion mounts
move out of place, or spot welds on the shadowmask frame give out. However,
mechanical issues such as these, would not reasonably be expected to cure by
manually degaussing, so I would say that the problem here is magnetic.

Arfa

==============================================================================
TOPIC: Safety of microwave cooking
http://groups.google.com/group/sci.electronics.repair/t/52932f2e95be2ee9?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, Apr 22 2010 12:33 pm
From: zekfrivo@zekfrivolous.com (GregS)

In article <7fidnWTKZaq1EE3WnZ2dnUVZ_vgAAAAA@posted.isomediainc>, "Paul Hovnanian P.E." <paul@hovnanian.com> wrote:
>Jeff Liebermann wrote:
>
>> On Thu, 15 Apr 2010 20:17:39 GMT, mzenier@eskimo.com (Mark Zenier)
>> wrote:
>>
>>>And if you google "french frys cancer" you get refered to Acrylamide.
>>
>> Anti-Cancer Drugs in French Fries: Good Idea?
>>
><http://www.diet-blog.com/archives/2009/12/23/anti-cancer_drugs_in_french_fries
>_good_idea.php>
>>
>> Most of the links I read quoted the original 2002 study in Sweden that
>> eventually showed *NO* correlation between acrylamide and cancer in
>> rodents.
>>
>> "Further, the International Journal of Cancer found no link
>> between acrylamide consumption and cancer of the oral cavity,
>> pharynx, esophagus, larynx, large bowel, breast and ovaries."
>>
>> However, there are plenty of dietary reasons to justify avoiding fried
>> foods.
>
>Better to feed the fries to the rats and then eat the rats.
>

I don't know if its still true. but I like to buy Ca. oranges vs Florida since
Florida put cancer causing orange dye on the fruit.
I sometime eat skins.

Ca. seems knowlegable about that. One of those Ca. things.
Ca. did not put any dye on the orange, but I have got some real orange oranges lately.

greg

== 2 of 2 ==
Date: Thurs, Apr 22 2010 12:45 pm
From: Jeff Liebermann

On Thu, 22 Apr 2010 10:54:10 -0700, "Paul Hovnanian P.E."
<paul@hovnanian.com> wrote:

>You hold him down while I feed this stuff to him. Then we'll see if its safe
>or not.
>;-)

No need. I have a microwaved bacon and rabbit food omelette, with
greasy fries, last night for a combination breakfast, lunch, and
dinner. I'll let you know if I'm still alive tomorrow.

--
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: Detectron Geiger Counter
http://groups.google.com/group/sci.electronics.repair/t/172aa0a4a231f69a?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, Apr 22 2010 1:20 pm
From: Sjouke Burry

Chris F. wrote:
> I recently bought an old Detectron model DG-7 geiger counter. This is from
> the early 50's and has three 1U5 tubes inside. Power requirements are 90
> volts for the B+, two "D" cells for the tube filaments, and a 4.5 volt bias
> supply.
> I went over the unit, replacing a selenium rectifier and testing the
> tubes. The unit powers up, but generates a steady stream of pulses on it's
> own, even with the probe detached. The frequency of the oscillation varies
> with the range selector knob. The probe is working - when brought near a
> source (a bunch of vaseline marbles) it will produce extra clicks in
> addition to the stray ones generated by the unit.
> I've checked all the other components - resistors, capacitors, etc. The
> only thing I couldn't check is a very small tube, which looks like a
> cold-cathode rectifier of some kind. I've also tried varying the B+ and bias
> voltages. And I can't find a schematic, which makes matters worse.
> I'm not sure what to do next. Any ideas?
>
>
When the b+ becomes to high, the gas-discharge tubes start
oscillating, producing a steady stream of pulses.

So start with lowering b+ to zero, and then increase, until
either back at 90 volts, or the pulses re-appear.
At that point lower the voltage a bit, and re-check with your
radiation source.
Also there should be a capacitor across the tubes somewhere,
If so, check their quality(leakage and value).

== 2 of 2 ==
Date: Thurs, Apr 22 2010 5:10 pm
From: Jeff Liebermann

On Thu, 22 Apr 2010 10:41:19 -0700, "Chris F." <zappyman@hotmail.com>
wrote:

> I recently bought an old Detectron model DG-7 geiger counter.

Schematic of the DG-9 model:
<http://www.curtcass.com/detectron/dg9-sch.jpg>
Probably quite similar to the DG-7.

> I went over the unit, replacing a selenium rectifier

Replace it with what? Is silicon, the B+ is probably too high.

At that age, 99.999999% of the electrolytic cazapitors have high ESR.
However, looking at the schematic, there are none. Weird.

>and testing the tubes.

How? With a tube tester? I sometimes work on ancient Motorola radios
with pencil tubes. I have to make my own adapter to work in the tube
tester.

>The unit powers up, but generates a steady stream of pulses on it's
>own, even with the probe detached.

Ok, something is oscillating. I have some guesses based on the
schematic, but the right way is to get a scope, with a high voltage
probe (i.e. 100x) and sniff around for which section is oscillating.
My best guess is that since the beast doesn't have any power supply
filter capacitors on any of the batteries, and you've probably
assembled a mess of power supplies, batteries, and junk to simulate
the batteries, you have a fairly high impedance on the power supply
lines. Rather than fixing it with a proper battery, find a big fat
capacitor (with a suitable high voltage rating), and put it across the
power supply leads as close to the circuit (not as close to the
battery) as possible. The magic buzzword is "motorboating".

>The frequency of the oscillation varies
>with the range selector knob. The probe is working - when brought near a
>source (a bunch of vaseline marbles) it will produce extra clicks in
>addition to the stray ones generated by the unit.

Good, it's working.
<http://www.youtube.com/watch?v=U6x5mSp0PeA>
0.2mr/hr, about the same as background radiation. (I have the same
counter and the one in the video seems a bit insensitive).

> I've checked all the other components - resistors, capacitors, etc. The
>only thing I couldn't check is a very small tube, which looks like a
>cold-cathode rectifier of some kind.

Nope. Probably a neon lamp used as a regulator. Photo?

>I've also tried varying the B+ and bias
>voltages. And I can't find a schematic, which makes matters worse.
> I'm not sure what to do next. Any ideas?

Google for "Detectron Schematic".
<http://www.curtcass.com/detectron>
<http://www.curtcass.com/detectron/index2.html>

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

==============================================================================
TOPIC: Panasonic KX-TG2382 Cordless Phone Hookswitch Troubles
http://groups.google.com/group/sci.electronics.repair/t/eb9eb83bbb1a48c0?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Apr 22 2010 3:22 pm
From: Franc Zabkar

On Wed, 14 Apr 2010 20:09:15 -0500, "William R. Walsh"
<newsgroups1@idontwantjunqueemail.walshcomptech.com> put finger to
keyboard and composed:

>At first I suspected the handsets, but they're working fine. So I looked
>inside the base unit and started tracing the circuit, as that's where the
>actual "hookswitch" event would probably be handled. There's a transistor on
>the board in the base unit that appears to do the job, marked "A1625" on its
>casing. From what I can tell, it should be a "KSA1625" high voltage
>switching transistor.
>
>Am I right in thinking that little transistor might be failing after many
>years of helping to answer calls?

I would suspect the relay (?) before I would suspect the transistor. I
have seen modems where the reed relay contacts have stuck closed.
Yours appears to be stuck in the open state. If you can configure your
base unit for pulse dialing mode, try dialing a bunch of zeros and
listen for clicking.

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

==============================================================================
TOPIC: Telephone extensions
http://groups.google.com/group/sci.electronics.repair/t/11b67b07a95a1f0a?hl=en
==============================================================================

== 1 of 3 ==
Date: Tues, Apr 20 2010 5:12 pm
From: M.Joshi

Hello,

What is the easiest way to connect three separate telephone extensions
to a BT main socket?

The BT socket is an NTE5 i.e. One half can be removed to connect
extensions.

I am considering using a junction box as it is unlikely that 3
telephone extensions will all connect to the IDC terminals on the NTE5.

--
M.Joshi

== 2 of 3 ==
Date: Thurs, Apr 22 2010 4:35 pm
From: M.Joshi

Dave Plowman (News);2407075 Wrote:
> In article M.Joshi.6140636@diybanter.com,
> M.Joshi M.Joshi.6140636@diybanter.com wrote:-
> What is the easiest way to connect three separate telephone
> extensions
> to a BT main socket?-
> -
> The BT socket is an NTE5 i.e. One half can be removed to connect
> extensions.-
> -
> I am considering using a junction box as it is unlikely that 3
> telephone extensions will all connect to the IDC terminals on the
> NTE5.-
>
> They are designed to take three lots of wires.
>

I was told today that the standard IDC terminals on BT sockets will
each reliably take 2 wires and that a third will fall out?

--
M.Joshi

== 3 of 3 ==
Date: Fri, Apr 23 2010 12:19 am
From: "Dave Plowman (News)"

In article <M.Joshi.616a935@diybanter.com>,
M.Joshi <M.Joshi.616a935@diybanter.com> wrote:
> > They are designed to take three lots of wires.
> >

> I was told today that the standard IDC terminals on BT sockets will
> each reliably take 2 wires and that a third will fall out?

Not so - they were designed from the start for 'in' 'out' and 'spur'. But
of course only if using the correct cables.

--
*With her marriage she got a new name and a dress.*

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

==============================================================================
TOPIC: rj12 crimp punch
http://groups.google.com/group/sci.electronics.repair/t/341e92153ce9086c?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Apr 22 2010 5:35 pm
From: vjp2.at@at.BioStrategist.dot.dot.com

When you crimp and rj11 connector, you are really pushing in the six
contacts and the thing that holds the cable in. Ths crimper should
therefore be able to be made into a screwdriver sized punch that you
can just push in those things. DOes such an rj12 crimp punch exist?

- = -
Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
http://www.panix.com/~vjp2/vasos.htm
---{Nothing herein constitutes advice. Everything fully disclaimed.}---
[Homeland Security means private firearms not lazy obstructive guards]
[Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]

==============================================================================
TOPIC: Crimpable Rj12 female
http://groups.google.com/group/sci.electronics.repair/t/66e093a0733b9e7f?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Apr 22 2010 5:40 pm
From: vjp2.at@at.BioStrategist.dot.dot.com

How come i've never seen female crimpable rj11 connectors?

==============================================================================
TOPIC: ir receiver module, testing and identifying
http://groups.google.com/group/sci.electronics.repair/t/9883c0a53be9e325?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Apr 22 2010 5:54 pm
From: Brian

I have a Onkyo TX-8211. It's become unresponsive to both the factory
remote and a universal remote that was programmed to control it. I
popped it open to inspect the receiver module. I couldn't see any
markings on it (without removing it from the pcb, anyway). I measured
5V on the supply line. On the output line I could see a digital signal
that was about 120mV peak-to-peak when I sent an IR signal from one of
the remotes.

Anyone know if this is typical of the output? Should the signal be
larger? If the module needs to be replaced, how would I identify a
replacement?

Since it is generating a signal I'm wondering if some other part has
failed. There's an electrolytic cap wired to it, which I'm eying
suspiciously.

==============================================================================
TOPIC: cheap Gucci bag saler (paypal payment)( http://www.brandtrade10.com )
http://groups.google.com/group/sci.electronics.repair/t/30da1c60c1334e1c?hl=en
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==============================================================================
TOPIC: Fender Twin reverb from 1979
http://groups.google.com/group/sci.electronics.repair/t/5ed19ff4ba61ec1a?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Apr 22 2010 7:43 pm
From: "Phil Allison"

"Nutcase _Kook"

> Assuming I cannot get 1.5 inch long UNC 8/32 bolts in the UK, other than a
> hundred or stupid min order quotes, any suggestions. ? I cannot return
> this
> amp , despite repair, as it is unsafe. The 4 vertically mounted screws
> that
> litterally hold the amp into the cab are stripped to next to useless. Not
> captive nuts , nor spire nuts in the chassis part, sort of combination of
> both.

** A 1979 Fender Twin Reverb is the 135 watt model - with ultra-linear
output stage.

The chassis looks like this:

http://www.tru-solutions.jp/Fender_Twin_Reverb_79_JBL_04.jpg

The black steel U-clips take the thread of the four top bolts - they will
also accept ordinary self tapping screws of the right size.

The three holes in the back edge take self tapping screws driven into the
top of the cabinet and will hold the chassis solidly in place *on their
own*.

> The
> owners mistreat the amp and can keep the originals along with the all too
> tempting-to-turn rear voltage selector knob . Fine for USA but out and out
> safety hazzard in the UK, especially the way this lot abuse their kit.
> Removed and plated off over the spindle and knob fitted internally inside
> the amp for any later purists.

** The red voltage selector knob merely has to be removed to eliminate the
hazard.

..... Phil

==============================================================================
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http://groups.google.com/group/sci.electronics.repair/t/1d559dc84df019d7?hl=en
==============================================================================

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