Toshiba TV29C90 problem; Image fades to black...

[Dave Platt]

In article <n9g7445fdmof3nohavnt74eghlh02mb0je@4ax.com>,
JW <none@dev.nul> wrote:

I think I'll try option 2 with a U441.

Yeah... that's certainly the sensible thing to do, unless you find
that the device *really* needs very specific selection for various
parameters.

Now for my dumb/ignorant question: The schematic does not show source and
drain - how do I determine which is which when I replace the part?

For an N-JFET, the source goes towards the more negative voltage...
in this schematic, it looks as if the downward side would be the
lower-voltage side per the normal convention, and thus the drain's on
the top and the source is on the bottom.

JFETs tend to be fairly symmetrical, and will often work if you swap
the source and drain, but since the source/gate and drain/gate
capacitances may not be identical you should probably keep the part in
its preferred orientation.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[bz]

Tim <tim@tim.tim> wrote in news:MPG.22adfa799165188989706@news.aliant.net:

OK, this is a problem with a 19" Citizen TV. It is just over a year old.

If the set is put on a stand that has a metal object (like a Satellite
Receiver on a shelf) mounted within 8 inches below the set, the pic has
a very noticeable purity problem all the way across the bottom and about
1/2 way up each side. If I raise the set up, the purity problem will
diminish, but even up at 8" away from the console stand, it still has
slight purity issues.

Raising the set up on boxes is problematic, as the space is very
limited. I would like to shield whatever it is. I am not sure if it is a
reflection from the set or radiated magnetic fields from the equipment
below.

The console is in a travel trailer, so I cannot move everything away
from the tv, as most of the electronics are in this one console, with
the TV on top of it.

Any helpful suggestions are appreciated.

I assume that this is a CRT tv, not a LCD or plasma tv.

Sounds like the 'metal object' contains a strong magnet or has been
magnetized.
I have some magnets that will effect a CRT from over 2 feet away.

A transformer can also radiate a[n AC] magnetic field that disrupts nearby
devices.

If you can find the source of the magnetic field and move THAT away from
the TV, it should fix the problem.

It is possible that putting the set in place and then 'degaussing'
everything in the vicinity will 'fix' the problem.

Does your Satellite receiver have a built in hard drive for recording
programs? It is possible that the drive is 'leaking' a strong magnetic
field [but most hard drives confine the field very well]






--
bz 73 de N5BZ k

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

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[Dave Platt]

In article <ovfeh5-8ue.ln1@remote.clifto.com>,
clifto <clifto@gmail.com> wrote:

I went to the web site of my first thought:

http://www.danssmallpartsandkits.net/

and found:

DUE TO A BAD ACCIDENT DAN'S SMALL PARTS AND KITS IS CLOSED UNTIL FURTHER
NOTICE!!!
DAN WILL BE BACK

Seconded. Dan is (has been, at least) a great source of interesting
obscure parts - a really wonderful resource.

I hope that he and his are OK!

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[Dave Platt]

In article <ovfeh5-8ue.ln1@remote.clifto.com>,
clifto <clifto@gmail.com> wrote:

I went to the web site of my first thought:

http://www.danssmallpartsandkits.net/

and found:

DUE TO A BAD ACCIDENT DAN'S SMALL PARTS AND KITS IS CLOSED UNTIL FURTHER
NOTICE!!!
DAN WILL BE BACK

Seconded. Dan is (has been, at least) a great source of interesting
obscure parts - a really wonderful resource.

I hope that he and his are OK!

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[DaveM]

"Beloved Leader" <Kim_Jong_Il@volcanomail.com> wrote in message
news:edfafa3c-fe5b-4fe3-be05-8482cde82903@w7g2000hsa.googlegroups.com...

Is there a site with the tube complement of ancient Tektronix 'scopes,
the ones from the 50s and 60s? I thinking of the 514 and the 516 in
particular. There may be other Teks with those model numbers, but
these are getting way back there. The 516 has the traditional blue,
rounded on top, side panels that swing open, but the 514 is really a
dinosaur. The innards slide forward from the case for maintenance. The
case is squared off on all edges. I'm not inclined to download a
schematic, as all I want to know is which tubes are common to both.

Thanks.

Why not download the manuals for both of these instruments? Too lazy? Want
someone else to do your work?
Both manuals are available for free download at
http://bama.edebris.com/manuals/tek/.
The ball is in your court.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Experience: What you get when you don't get what you want

 

[DaveM]

"Beloved Leader" <Kim_Jong_Il@volcanomail.com> wrote in message
news:edfafa3c-fe5b-4fe3-be05-8482cde82903@w7g2000hsa.googlegroups.com...

Is there a site with the tube complement of ancient Tektronix 'scopes,
the ones from the 50s and 60s? I thinking of the 514 and the 516 in
particular. There may be other Teks with those model numbers, but
these are getting way back there. The 516 has the traditional blue,
rounded on top, side panels that swing open, but the 514 is really a
dinosaur. The innards slide forward from the case for maintenance. The
case is squared off on all edges. I'm not inclined to download a
schematic, as all I want to know is which tubes are common to both.

Thanks.

Why not download the manuals for both of these instruments? Too lazy? Want
someone else to do your work?
Both manuals are available for free download at
http://bama.edebris.com/manuals/tek/.
The ball is in your court.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Experience: What you get when you don't get what you want

 

[N_Cook]

Baron <baron.nospam@linuxmaniac.nospam.net> wrote in message
news:g23kp1$rdv$1@registered.motzarella.org...

msg Inscribed thus:

James Sweet wrote:


msg wrote:

This Saturday I replaced seven popped Nichicon electrolytics
in my iMac G5; it took me nearly five hours of intense battling
with too-tight hole sizes and high-thermal conductivity planes
but the job got done and the fix worked. Has anyone worked
on this planar and can comment? What wattage and tip sizes
worked for you? I used a 65 watt iron and ground the tip into
various chisels and angled points, used excess solder and flux
and tried an amount of preheating but it really was a _bitch_
to do. I kinda doubt the board was made for repairing.

Michael



The heatsinking effect of planes can be a real issue. I use a 140W
Weller soldering gun for motherboard capacitor replacement, it's the
only thing I've found that puts down enough heat to remove the caps
without ripping up traces.

Indeed. I neglected to mention that I cranked up the wattage with
a variac to about 90W but that is nowhere near what you use

Michael

Hot air preheating works wonders. I use a hot air paint stripper gun to
preheat an area first before then desoldering the cap. Usually they
come out of the board quite cleanly but some manufacturers bend the
leads after insertion into the pcb, which can be a pain.

--
Best Reagrds:
Baron.

My tool for that is a dart with a bolt exchanged for the flight.
Without heating, excavate around the solder with the dart until you can
lever the pin up.
But then I continue on , using the hot-air only.
Another recently discovered aid for this process.
I saw a plumber using some woven glass mat to protect a cupboard before
soldering.
As I had plenty of GRP grade woven mat I glued together 4 bits of sheet of
that , using contact adhesive (discolours but holds together on hot air
heating).
Cut a hole to match the area of interest and lightly clamp the mat to the
board , mounted in a vice with protected jaws.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[bz]

James Sweet <jamessweet1@trashmail.net> wrote in news:Lye1k.2159$Yx.1418
@trndny08:

Baron wrote:
msg Inscribed thus:

James Sweet wrote:

msg wrote:

This Saturday I replaced seven popped Nichicon electrolytics
in my iMac G5; it took me nearly five hours of intense battling
with too-tight hole sizes and high-thermal conductivity planes
but the job got done and the fix worked. Has anyone worked
on this planar and can comment? What wattage and tip sizes
worked for you? I used a 65 watt iron and ground the tip into
various chisels and angled points, used excess solder and flux
and tried an amount of preheating but it really was a _bitch_
to do. I kinda doubt the board was made for repairing.

Michael


The heatsinking effect of planes can be a real issue. I use a 140W
Weller soldering gun for motherboard capacitor replacement, it's the
only thing I've found that puts down enough heat to remove the caps
without ripping up traces.
Indeed. I neglected to mention that I cranked up the wattage with
a variac to about 90W but that is nowhere near what you use

Michael

Hot air preheating works wonders. I use a hot air paint stripper gun to
preheat an area first before then desoldering the cap. Usually they
come out of the board quite cleanly but some manufacturers bend the
leads after insertion into the pcb, which can be a pain.



That's a great idea, I'll have to give it a try next time. Just have to
be careful not to overdo it and cause SMT parts to drop off the board.

I have built dams out of paper to protect nearby parts from the hot air.
Held the paper on the board with alligator clips.

Works fine. Also a good temperature indicator. If the paper chars too much,
your air is too hot.

caveat: I was playing with an old pcb, stripping it of parts with my hot
air gun. One of the electrolytic caps got caught in the guns nozzle.

Before I could shake it out, BANG. Small jet of flames. Shell of cap
flying across the room.

In other words "avoid overheating electrolytics, they can explode."







--
bz 73 de N5BZ k

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

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[bz]

Tim <tim@tim.tim> wrote in
news:MPG.22af3e66c44ceb15989707@news.aliant.net:

In article <Xns9AB18DEB06E2DWQAHBGMXSZHVspammote@130.39.198.139>,
bz+ser@ch100-5.chem.lsu.edu says...
Tim <tim@tim.tim> wrote in
news:MPG.22adfa799165188989706@news.aliant.net:

OK, this is a problem with a 19" Citizen TV. It is just over a year
old.

If the set is put on a stand that has a metal object (like a
Satellite Receiver on a shelf) mounted within 8 inches below the set,
the pic has a very noticeable purity problem all the way across the
bottom and about 1/2 way up each side. If I raise the set up, the
purity problem will diminish, but even up at 8" away from the console
stand, it still has slight purity issues.

Raising the set up on boxes is problematic, as the space is very
limited. I would like to shield whatever it is. I am not sure if it
is a reflection from the set or radiated magnetic fields from the
equipment below.

The console is in a travel trailer, so I cannot move everything away
from the tv, as most of the electronics are in this one console, with
the TV on top of it.

Any helpful suggestions are appreciated.

I assume that this is a CRT tv, not a LCD or plasma tv.

Sounds like the 'metal object' contains a strong magnet or has been
magnetized.
I have some magnets that will effect a CRT from over 2 feet away.

A transformer can also radiate a[n AC] magnetic field that disrupts
nearby devices.

If you can find the source of the magnetic field and move THAT away
from the TV, it should fix the problem.

It is possible that putting the set in place and then 'degaussing'
everything in the vicinity will 'fix' the problem.

Does your Satellite receiver have a built in hard drive for recording
programs? It is possible that the drive is 'leaking' a strong magnetic
field [but most hard drives confine the field very well]


Yes the TV is CRT, and no, the receiver does not have a HD in it, nor
does it have a large transformer. The purity problem is static, that is
it does not change colour, so I don't think it's a transformer, as that
would cause a rainbow effect.

Maybe I'll try rearranging the "stack" of components to see if one of
the other devices cause less magnetic radiation, or reflection if that's
the case.

It would be nice if this set had a manual degaussing option, but alas it
doesn't. I don't even hear the coils buzz when the set comes on, but
there are no other purity issues, so they must be functional. I'll take
my tape eraser down with me, and try that to see if the problem returns
after zapping the screen.

Lacking an eraser, if you can hang a magnet on a string so that you can
spin it, you can sometime degauss with that.

I had a nice heavy magnet from an old radar magnetron that had a hole in
just the right spot.
I had a loop of copper wire threaded through the hole and hung the
contraption from a piece of string.
I would wind it up good and let it spin, slowly moving it away from the
monitor.
Did a good job of degaussing.

Sometimes, for a joke, I would spin it on the other side of a wall, near
someones monitor.
They would come running out of their office "something strange is happening
to my monitor. The picture is wobbling all over the place and changing
colors!"


--
bz 73 de N5BZ k

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

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[GregS]

In article <6c2b44tqpbdgcbcujf4anctqhcnt7erv65@4ax.com>, acuffe@gmail.com wrote:

On Mon, 02 Jun 2008 14:11:32 -0500, msg <msg@_cybertheque.org_> wrote:

This Saturday I replaced seven popped Nichicon electrolytics
in my iMac G5; it took me nearly five hours of intense battling
with too-tight hole sizes and high-thermal conductivity planes
but the job got done and the fix worked. Has anyone worked
on this planar and can comment? What wattage and tip sizes
worked for you? I used a 65 watt iron and ground the tip into
various chisels and angled points, used excess solder and flux
and tried an amount of preheating but it really was a _bitch_
to do. I kinda doubt the board was made for repairing.

Michael

I wouldn't even attempt to do this without a temperature controlled
soldering station. You need a lot of power, but with no temperature
control, you're likely to over heat the board and lift traces. It's
also critical to have a clean properly tinned tip.
Andy Cuffe

acuffe@gmail.com

Having a Weller miniature iron with 80 watts is sure nice. Sometimes I combine heats from
the 3 outputs. Desolder, solderer, and hot air. I have used 2 irons before.
For the rough things sometimes I also use a Bic lighter against the iron for a afterburner effect.
The RS 250 watt gun, then the torch.

I got so tired of watching the game last night, I got to the point I just wanted anybody to win so it was all
over....

greg

Lets go Pens

 

[N_Cook]

powerampfreak <powerampfreak@hotmail.com> wrote in message
news:220a9a3f-1e0e-4ad2-9989-f14d349cafb6@j22g2000hsf.googlegroups.com...

Hi all. I had a shorted driver stage (MJE15032/33) in one of the
channels which resulted a lot of open resistors in the output stage,
Some components in the clip-detector circuit blew too. After replacing
all the broken stuff, the channel operates, but with high frequency
ringing superimposed on the fundamental sinewave. Does anyone have a
specific tip for this failure? Some of the compensation capacitors
gone bad? Thanks a lot for any advice!
Regards
Steve

Assuming a constant hf then a matter of divining, by literally floating your
hand/finger over, until zeroing in.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[gareth magennis]

"powerampfreak" <powerampfreak@hotmail.com> wrote in message
news:220a9a3f-1e0e-4ad2-9989-f14d349cafb6@j22g2000hsf.googlegroups.com...

Hi all. I had a shorted driver stage (MJE15032/33) in one of the
channels which resulted a lot of open resistors in the output stage,
Some components in the clip-detector circuit blew too. After replacing
all the broken stuff, the channel operates, but with high frequency
ringing superimposed on the fundamental sinewave. Does anyone have a
specific tip for this failure? Some of the compensation capacitors
gone bad? Thanks a lot for any advice!
Regards
Steve

Yes, you haven't found all the broken stuff yet. Don't start guessing,
trying to link symptoms with components, you'll be there all day and get
nowhere. Go back and check very carefully all the components from the
output transistors back as far as it is possible for the damage to have
gone.

One technique I use is to use the diode check function on my multimeter,
giving a reading of forward voltage drop. This gives an indication of
resistance and semiconductor junction integrity at the same time. As this
is a stereo amp you can directly compare the working channel with the faulty
one.

Check each transistor junction and all the components using BOTH test lead
polarities, starting from the power devices backwards. (You may be measuring
a base emitter junction with a 100K resistor between the two. In one
direction you will read 100k, the other you will read a 0.6V diode).

Investigate any discrepancies between channels, allowing for changing
readings due to charged/charging capacitors. Both sides should read and
behave the same. This may seem at first to be a very labour intensive
procedure, but with practice can be carried out surprisingly quickly, and
discrepancies easily located.


Gareth.

 

[gareth magennis]

"powerampfreak" <powerampfreak@hotmail.com> wrote in message
news:220a9a3f-1e0e-4ad2-9989-f14d349cafb6@j22g2000hsf.googlegroups.com...

Hi all. I had a shorted driver stage (MJE15032/33) in one of the
channels which resulted a lot of open resistors in the output stage,
Some components in the clip-detector circuit blew too. After replacing
all the broken stuff, the channel operates, but with high frequency
ringing superimposed on the fundamental sinewave. Does anyone have a
specific tip for this failure? Some of the compensation capacitors
gone bad? Thanks a lot for any advice!
Regards
Steve

Yes, you haven't found all the broken stuff yet. Don't start guessing,
trying to link symptoms with components, you'll be there all day and get
nowhere. Go back and check very carefully all the components from the
output transistors back as far as it is possible for the damage to have
gone.

One technique I use is to use the diode check function on my multimeter,
giving a reading of forward voltage drop. This gives an indication of
resistance and semiconductor junction integrity at the same time. As this
is a stereo amp you can directly compare the working channel with the faulty
one.

Check each transistor junction and all the components using BOTH test lead
polarities, starting from the power devices backwards. (You may be measuring
a base emitter junction with a 100K resistor between the two. In one
direction you will read 100k, the other you will read a 0.6V diode).

Investigate any discrepancies between channels, allowing for changing
readings due to charged/charging capacitors. Both sides should read and
behave the same. This may seem at first to be a very labour intensive
procedure, but with practice can be carried out surprisingly quickly, and
discrepancies easily located.


Gareth.

 

[William Sommerwerck]

Have you compared the components, waveforms, etc in the good channel with
the "bad" one?

It might be less trouble to simply shotgun the components you haven't
already replaced.

There is also the remote possibility that the amp was behaving this way
before it failed.

 

[Gareth Magennis]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:t4-dnY1aquET7tvVnZ2dnUVZ_v7inZ2d@comcast.com...

Have you compared the components, waveforms, etc in the good channel with
the "bad" one?

Note that if you do add a dummy load you well may find that you get very
different waveforms than your nice sine wave with a little hash on top -
this could be very misleading at this time. You could even destroy some
more transistors, so I wouldn't bother since you know the amp is still
faulty anyway.

It might be less trouble to simply shotgun the components you haven't
already replaced.

Yep.

There is also the remote possibility that the amp was behaving this way
before it failed.

Very true. Make sure you don't just repair the symptoms!



Gareth.

 

[William Sommerwerck]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com>
wrote in message news:48467E45.F488F1BA@hotmail.com...

Do you know what I mean by the "output Zobel network"?

A Zobel network is used for impedance compensation -- usually to make a
circuit look more resistive.

An amp with such a network at its output might very well be unusually
load-sensitive.

 

[Gareth Magennis]

"powerampfreak" <powerampfreak@hotmail.com> wrote in message
news:033c6761-f388-4d76-86d0-570d32d4d042@m45g2000hsb.googlegroups.com...
On 4 Juni, 13:36, Eeyore <rabbitsfriendsandrelati...@hotmail.com>
wrote:

powerampfreak wrote:
Eeyore wrote:
powerampfreak wrote:
Hi all. I had a shorted driver stage (MJE15032/33) in one of the
channels which resulted a lot of open resistors in the output stage,
Some components in the clip-detector circuit blew too. After
replacing
all the broken stuff, the channel operates, but with high frequency
ringing superimposed on the fundamental sinewave. Does anyone have a
specific tip for this failure? Some of the compensation capacitors
gone bad? Thanks a lot for any advice!

At all power levels ?

Actually, I run it without the dummy load for initial testings, in
order to operate the amp more safely.. until I get a decent output
signal.
Then I go for power tests.
I think I drove the amp up to somewhere 30-40V rms and the high
frequency oscillation is riding on top of my sinewave test signal.

But at lower levels ?

The OK channel doesn't behave like this, if anyone may think it's just
because I've no dummyload connected.
Besides, there seems to be different version of the M1400, since my
schematic isn't exactly like the amp...
Maybe anyone has a few schematics for this unit in PDF?

Ooooh, I did at one time I think. I'll look.

But anyway, do you know what I mean by the 'output zobel network' ? An RC
series combination. The R should be of several watts rating. Do make sure
that
the R isn't burnt out (open).

Graham- Dölj citerad text -

- Visa citerad text -

The Zobel network is all fine.




Can you clarify whether you have tested and got these waveforms with a dummy
load or not?

You said earlier: "The OK channel doesn't behave like this, if anyone may
think it's just
because I've no dummyload connected".



Gareth.

 

[Mark D. Zacharias]

"davidlaska" <Davidlaska@gmail.com> wrote in message
news:2bd0e1df-f6de-4f6a-aadf-9cae8e20dadd@b9g2000prh.googlegroups.com...

I have had it for decades but I do not want to give it up because it
works fine withstand the popping and hissing it does in all modes
except off. Is it over for it?

It's fixable - get it to a shop that knows these things. Likely it's only
doing it on one channel, and this in turn would most likely be a noisy
transistor - they had a few problems with those, like 2SC458 and 2SC1213 and
the like. Can also be caused by a bad coupling capacitor, or if it's making
the static on both channels, could be an arcing power switch - although this
would cause interference on nearby AM radios and cause the dial lights to
flash and dim.


Mark Z.

 

[Michael Kennedy]

"webpa" <webpa@aol.com> wrote in message
news:ae99156e-9d42-4907-b8b7-e9fd7196a417@d45g2000hsc.googlegroups.com...

On Jun 1, 9:03 pm, gruv2...@gmail.com wrote:
Hello All,
My laptop no longer charges the battery. I need a motherboard
schematic or at least somebody that knows what 'normally' dies in that
circuit. There is a current sense resistor in the charge path, and
some FETs that i cannot find a datasheet for. There must be some
comparators somewhere in there controlling the FETs. Dose anybody know
about this circuit,or have a schematic??

Thanks!!!
-Stephen

Most likely failure: Broken solder joints on the DC input connector.
Fix: disassemble enough to reach the solder side, re-solder. It is
much easier to find instruction on disassembly than a schematic. If
you REALLY need a schematic, then the machine is not repairable.

Sounds like the OP has a general knowledge about electronics and would know
if it was just a bad solder joint in the power connector. A picture of the
board might help someone help you.

Stephen.. I didn't see your original post because you are posting through
google groups. Me and a lot of other people are blocking all messages from
google groups because of all of the spam an porn that they are spewing onto
USENET. You should look into using a real NNTP server if you want people to
see your messages.. Just a friendly tip.

Check out
http://improve-usenet.org/
http://www.teranews.com/
http://schmidt.devlib.org/usenet/free-news-servers.html

 

[bz]

philsvintageradios <philsvintageradios@yahoo.ca> wrote in news:d0401b14-
67ae-409a-a50d-c5705fe65f27@z24g2000prf.googlegroups.com:

On Jun 3, 7:02 pm, Tim <t...@tim.tim> wrote:
In article <e1c9e6e0-ff27-4723-8918-91eb929d51d6
@c65g2000hsa.googlegroups.com>, hrhofm...@att.net says...
.....

try putting a sheild between, see what you can find, a sheet of
alunimum might be enough. sheet of tin that is grounded might be even
better.
I have screwed up a couple of TV's by playing with magnets near them,
never had much success with degaussing them that way but I am sure it
is possible

Shielding against a DC magnetic field REQUIRES a ferris material. The
stronger it is picked up by a magnet, the better.

Mu-metal is the best kind of shielding.

Aluminum, whether grounded or not, will have no effect. Neither will
copper.
You need something that will 'short out' and 'contain' the magnetic field.

On the other hand A conductor WILL give some shielding for AC magnetic
fields. The degree of shielding depends on the frequency of the AC.
The higher the frequency, the easier it is to shield against an AC field
with a GOOD conductor of any kind.




--
bz 73 de N5BZ k

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

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap