MessageView 421F schematic

[Don Cleveland]

"pdmtr" <pdmtr@yahoo.com> wrote in message
news:1118091823.471227.24610@g49g2000cwa.googlegroups.com...

I have a HP 8567A (very similar to HP 8568A/B) spectrum analyzer that
has an error code flashing every 2 seconds on screen. "YTO unlock"
message comes on and at the same time the Green SWEEP Led on the 85662
Display unit flashes instantly. I have figure out that this is related
to the Yig Tuning Oscillator (Y.T.O.) that is the main sweep osc of the
spectrum analyzer. Inside the RF/IF section I have seen that the A6 YTO
PHASE LOCK board has the "YTO UNLOCKED" led permanent on while the "YTO
LOOP CLOSED" led is mostly lit and goes instantly out (whenever the
message on screen comes on). The exact same off time of it the "LOW"
led located on the A22 FREQ CONTROL Board comes on. The analyzer has a
sweeped display with a VERY low refresh rate (a refresh every time the
error message comes on) and has a working RF input, checked for level
with a R&S SMS generator... I can see the R&S output signal but
spectrum show a difference on carrier frequency of aprox: 13.6MHz lower
than the actual input freq. The 100MHz are showing (using the MARKER)
as 86.4MHz!
Anyone know something about that problem? I cant find even the manual
of the HP 8567A spectrum analyzer (while i have found where to buy the
manual for the 8568A/B model), so any help will be greatly appreciated.
My regards
Sotris Pdmtr
pdmtr@NOSPAMyahoo.com

Here's a link to the manual:

http://cp.literature.agilent.com/litweb/pdf/08567-90001.pdf

Don Cleveland

 

[Glenn]

I don't remember well and I don't have a set of schematics in front of me,
but a couple of suggestions:

It's unlikely that you are running without *any* 10 MHz reference. That
reference goes into locking everything in the box and even if the
instrument were in ext ref mode with that loop unlocked, the error is
probably small enough that the other loops wouldn't have a problem.
Normally the 10M tuning range is only a few ppm.

The YTO loop, (the "outer loop") probably needs several other properly
locked references to operate correctly. In fact, it's "YTO unlock" error
may only be a logical OR of inner loops. The idea being that if any of
those other loops are not locked properly, the YTO signal cannot be
trusted either. Oven Cold and Ext Ref are certainly affiliated with the
precsion 10MHz reference and probably a detector circuit that looks for
10MHz external signal.

Are there rear panel BNCs on that instrument with adjacent "10M out" and
"10M in" labels that should have a short jumper cable that is missing?
That might almost explain all of your problems.

The slow refresh rate is probably related to error reporting of the
unlocked condition. It will probably go to normal rate once all the loops
are properly closed. I wouldn't be surprised if test mode ignores the
warnings so that diagnosis can proceed more or less normally.

Glenn

 

[John Miles]

In article <1118153600.092161.134340@g47g2000cwa.googlegroups.com>,
pdmtr@yahoo.com says...

Trying to figure out if thats a hardware failure of the YIG Osc, or a
failure of the ,master time base TCXO, as it looks like only the
refresh rate is "blocked" or delayed for some reason.

It sounds like a problem with the diagnostic circuits. Or: "Oven Cold"
could imply a bad oven-control circuit in a 10811 OCXO module, if it has
one. That's a pretty common fault, usually caused by a thermal fuse
that's opened up due to old age.

I'd be somewhat surprised if the 8567A had a 10811 OCXO, though. If it
has a TCXO with no oven, then the presence of the "Oven Cold" message
makes me wonder if there's an interconnect problem between the 8567A and
85662A. It shouldn't be possible to get that message on an analyzer
without an oven-controlled timebase, so that'd be an important clue.

It's almost certainly not the YIG oscillator, if the analyzer works OK
in all spans in Shift-w mode.

But also it might
be a mis-programming fault, and not a hardware failure... Also I'm
thinking that the error it may be located on the 85662 display unit and
not on the RF/IF base unit, as it looks that the display unit provides
the RF unit some synchronizing signals thru the Bus cable and also some
IF signals thru the Multi-Coaxial Interconnection. Not sure where the
main TCXO is located

It'll be in the RF section.

, but it looks its on the 85662 unit and not on the
RF/IF base... So if the refresh problem is related to the locking of
the YTO that will lead to a TCXO REF fault. The EXT REF input is
located on the 85662 unit

Hmm, are you sure? That should be on the RF unit, not the display unit,
if I remember correctly.

If you find something related (anything really) it would be a great
help, as the basic working philosophy behind the 8568 (8567) & 8566
Spectrum Analyzers should be the same!!! )

Will do.

-- jm

------------------------------------------------------
http://www.qsl.net/ke5fx
Note: My E-mail address has been altered to avoid spam
------------------------------------------------------

 

[Glenn]

Sotris wrote:

Switched on external reference and checked with a +3dbm 10MHz sinewave
. When i applied the +3dbm signal it works like with the switch on
internal position. When i removed the signal from input, all system
freezed... So the internal ref must at least works. Dont know about
the freq accuracy of it yet (I'll measure it), but its working. So
thats good.

Correct, sounds like it is using either the internal or external 10 MHz

reference.

Do you have the service manual of the 8567? If you have it, can you
make some copies of specific parts of it (I'll pay all the cost for
them of course)?
Sorry, I don't. I'm doing all this from very old memory!


Yes thats should be true. However I still cannot locate a 10MHz TCXO
inside that instrument. Have download some service (verification &
Given the symptoms, I wouldn't worry about that at the moment. Since it

works in "Int 10 MHz" position, it's finding something.

Oven Cold and all other messages except the "YTO unlock" are only come
on during the error correction routine. At normal operation mode, only
"YTO unlock" & VERY slow refresh rate of sweep are the symptoms. Even
at that refresh rate can make measurements of an input signal... I
understand the YTO loop as you explain it. The strange thing is that
during the test mode almost all measurements of inputs signals are
correct both for frequency and amplitude. I have also checked an AM &
an FM modulated carrier up to 1250MHz. And I say almost because I've
noticed that when I set a Span <1.000MHz cannot find the input
signal. Increasing again the span at >1.001MHz signal appears again...

I think that may be a clue. Narrow spans probably use somewhat
different phaselock circuits, in order to improve phasenoise
characteristics close to the carrier. The 8568 was very different from
the 8566, as someone (John Miles? Hi John de n6gn) has already noted.

The 8568 used a "pilot channel" which was sort of a twin of the main
signal path but there only to allow improving the phasenoise of the LO.
I wouldn't be at all surprised if things are switched differently for
narrow spans where narrow RBW filters mean that the improved phase noise
was important.
However, the fact that it sweeps slowly and issues an unlocked error on
wider sweeps leads me to suspicion that there is still something more
general wrong with the YO loop.

There is a BNC for 1st Local out and another one for frequency
refference IN/OUT depending on an INT/EXT switch aside of it. I've set
it on Internal position under normal operation.

Judging from what you've written, I'm shifting focus away from
suspecting the 10M reference.

I agree with you that you really need at least an accurate functional
block diagram so you can unravel things.

Sorry I don't have any documentation and that I can't remember more detail.

Glenn

 

[John Miles]

In article <a6ece70a.0506080214.200ada8d@posting.google.com>,
pdmtr@yahoo.com says...

It'll be in the RF section.

Yes it should be there!!! Only thing is I cannot find it! )

Sounds like there's a TCXO module buried somewhere, instead of the
standard 10811-60111 oven. I wouldn't worry about it any further.

If you find something related (anything really) it would be a great
help, as the basic working philosophy behind the 8568 (8567) & 8566
Spectrum Analyzers should be the same!!! )

In the case of my broken 8566B, the problem turned out to be A20C7, a 10
uF electrolytic that was open. The YTO main-coil driver circuit was
oscillating at about 1 MHz, which kept the outer YTO control loop from
locking up.

I started troubleshooting by verifying that the M/N and 20/30 MHz
synthesizers were both working properly, using a frequency counter.
That meant the problem had to be the YIG or its driver circuitry,
including the pretuning DAC. I went through the YTO loop adjustments
section in the tests/adjustments manual (which should be freely
downloadable from Agilent), and found that while the pretune DAC
adjustments were OK, I couldn't bring the actual YTO output frequencies
into range. There was a 1 MHz oscillation in the voltage-to-current
driver circuit that clearly didn't belong there, so I poked around with
an ESR meter and found an open electrolytic (A20C7). Replacing it and
recalibrating A20 took care of the issue.

My major problem is that here in Greece we don't have a lot of HP
support and to find something (used or not) we must take our chances
with the "SLR" (shipping lose risk) parameter as I call it Have
allready lost 3 manuals for test equipments ordered from US and
another one delivered to me after 5 months from shipment!!! And mostly
here, there is a total lack of (second hand) spare parts sources for
things like test instruments...
I have seen in the past, your tracking generator for the 8566. Nice
mod you've done there on the 86222A plug-in. Will something similar
work with 8567A/8568?

Thanks! Spare parts are a problem everywhere, unfortunately. I was
glad that I didn't actually have a bad YTO, or I would have been in
trouble. The 1.5-GHz analyzers are pretty different with regard to
their tuning/conversion schemes, so no, the 86222A mod won't work with
the 8567/8 directly. Check out the article linked from the DKD
Instruments page at http://www.dkdinst.com/products/TGdescrip.html for a
good discussion of what it takes to track an 8567/8.

-- jm

------------------------------------------------------
http://www.qsl.net/ke5fx
Note: My E-mail address has been altered to avoid spam
------------------------------------------------------

 

pinpassion <mjdrum@comcast.net> wrote:

I need to know the connection scheme for this transformer so I can
put it to use.

For help on figuring out unknown transformers:

http://groups-beta.google.com/group/sci.electronics.components/browse_thread/thread/6a594e9fd8bb4a00/3c9fffff00c587c3

http://groups-beta.google.com/group/rec.antiques.radio+phono/browse_thread/thread/c3aca0be99f82432/63550f1c6f904ad8

I don't have the issue of 73 magazine, and I don't even know
if this is the same transformer that may have been part of the
construction article.

You might ask over in one of the rec.radio.amateur newsgroups (maybe
..equipment or .homebrew) - somebody over there might at least be able to
give you the info from the magazine article.

Matt Roberds

 

[Todd H.]

howardkinsd@yaEXPUNGEhoo.com (Howard Knight) writes:

I get the shock when I touch any part of the back of my computer or
wires, and also touch the metal part of the cable that comes in and
connects to my cable modem. Here's the deal:

I live in an older house that is not grounded. The ground prong on
the outlets isn't connected to ground or anything else.

Red flag. This is problem #1. This isn't a ground loop. This is an
absence of ground. The former is an inconvenience, the latter can
kill ya.

Also, I've determined that the coax cable coming in to my cable
modem is grounded.

Typically staked at the junction box by the cable company.

Somthing seems to be making the ground prong on my outlet hot. I've
narrowed down the problem to my power strip. I've unplugged
everything from my outlet and I check the outlet for voltage.
Neutral to hot gives me 110V. Neutral to ground give me nothing
(actually, for some odd reason, there does seem to be a slight
voltage (less than 2V).

The odd reason is that if we believe what you're telling us (i.e. that
your ground on your outlet is completely floating) I'd believe any
voltage you'd tell me between ground and the neutral of the outlet.

Hot to ground also gives me nothing. As one would expect.

As one would expect in Danger World where ground is left completely
floating.

In the Safe World, neutral and ground should be the same potential
with 0V, and hot to ground should measure in the 110-120V range.

Now, if I plug in a power strip and do the same check on one of the
outlets on the power strip, I get: neutral to hot 110V,

Good.

Neutral to ground around 60V

Wee! This is a Big Problem.

and hot to ground around 60V. Is this right?

Oy. No.

You gotta remember here, your ground in your outlets is completely
floating, and someone should tell you this is Very Bad.

I've checked this with two power strips and I get the same results.
What would cause this? Is the polarity on my outlet wrong? Or, am
I just a dummy and am misintepreting what is going on. This
misterious 60V is what give me the shock.

Call an electrician. Today. You've got potentially lethal problems
with your home's electric wiring. You may also have some power
strips in need of replacement.

60V on your third wire ground is Not Good (tm). Since your computer
is a metal enclosed 3-wire appliance, it's presenting allcomers with
60V ready to shock the crap out of em.

Most aren't aware that surge suppressing power strips do nothing
without a real third wire ground, and it appears that they might also
be creating a rather hazardous situation. I suspect that these may be
surge suppressing power strips with some circuitry that is potentially
faulty (burned out MOV's for instance) and is therefore creating a
more hazardous situation than you have at your outlet to begin with
because your outlet is heinously miswired.

Don't take offense, but do call an electrician.

Best Regards,
--
/"\ ASCII Ribbon Campaign | Todd H
\ / | http://www.toddh.net/
X Promoting good netiquette | http://triplethreatband.com/
/ \ http://www.toddh.net/netiquette/ | "4 lines suffice."

 

[Howard Knight]

Todd H. (bmiawmb@toddh.net) wrote:
: ...your outlet is heinously miswired.

Not miswired, just wired 40+ years ago with no ground. Couldn't I
just ground the outlet myself? Run a wire from the ground in the
outlet to a water pipe outside? Would that solve my problems?

Howard

 

[CJT]

Howard Knight wrote:

Todd H. (bmiawmb@toddh.net) wrote:
: ...your outlet is heinously miswired.

Not miswired, just wired 40+ years ago with no ground. Couldn't I
just ground the outlet myself? Run a wire from the ground in the
outlet to a water pipe outside? Would that solve my problems?

Howard

There are electrical codes with which you should comply.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.

 

[MetalHead]

Howard Knight wrote:

Todd H. (bmiawmb@toddh.net) wrote:
: ...your outlet is heinously miswired.

Not miswired, just wired 40+ years ago with no ground. Couldn't I
just ground the outlet myself? Run a wire from the ground in the
outlet to a water pipe outside? Would that solve my problems?

Howard,
First, I think you should replace that outlet strip. They have MOV's
between the hot and ground and neutral and ground. When an MOV gets a
big surge, they start leaking current that they would have blocked
before the damage. Because your ground is floating, the leakage of the
two sets of MOV's has made a voltage divider between hot and neutral
with the ground at the midpoint. Grounding the outlet feeding your
computer is a good idea, but it may trip breakers or blow fuses if the
outlet strip is really hammered.

You might think about getting your house wiring brought up to modern
configuration, proper grounding and GFI outlets add a lot to the
electrical safety of a house. It would probably add to the resale value
as well. If you are in a rental house, good luck.

Bob

 

[Rich Grise]

On Fri, 10 Jun 2005 21:39:09 +0000, Howard Knight wrote:

First, let me tell you that I'm a retard when it comes to electronic
stuff. Anyway...

I was fiddling around behind my computer and got a nice shock. I'm
trying to figure out this problem and am hoping you folks could
help me out.

I get the shock when I touch any part of the back of my computer or
wires, and also touch the metal part of the cable that comes in and
connects to my cable modem. Here's the deal:

I live in an older house that is not grounded. The ground prong on
the outlets isn't connected to ground or anything else.

Then get that fixed by a qualified professional before you burn
your house down or kill one of your children.

Sorry,
Rich

 

[Rich Grise]

On Fri, 10 Jun 2005 23:31:57 +0000, Howard Knight wrote:

Todd H. (bmiawmb@toddh.net) wrote:
: ...your outlet is heinously miswired.

Not miswired, just wired 40+ years ago with no ground. Couldn't I
just ground the outlet myself? Run a wire from the ground in the
outlet to a water pipe outside? Would that solve my problems?

Use #10 AWG solid bare copper, and if you can't afford to have it

done by a qualified professional, at least have it inspected by
a qualified professional.

Don't murder your children.

Good Luck!
Rich

 

[Gary Schafer]

On Fri, 10 Jun 2005 21:39:09 -0000, howardkinsd@yaEXPUNGEhoo.com
(Howard Knight) wrote:

First, let me tell you that I'm a retard when it comes to electronic
stuff. Anyway...

I was fiddling around behind my computer and got a nice shock. I'm
trying to figure out this problem and am hoping you folks could
help me out.

I get the shock when I touch any part of the back of my computer or
wires, and also touch the metal part of the cable that comes in and
connects to my cable modem. Here's the deal:

I live in an older house that is not grounded. The ground prong on
the outlets isn't connected to ground or anything else. Also, I've
determined that the coax cable coming in to my cable modem is
grounded. Somthing seems to be making the ground prong on my outlet
hot. I've narrowed down the problem to my power strip. I've
unplugged everything from my outlet and I check the outlet for
voltage. Neutral to hot gives me 110V. Neutral to ground give me
nothing (actually, for some odd reason, there does seem to be a
slight voltage (less than 2V). Hot to ground also gives me nothing.
As one would expect.

Now, if I plug in a power strip and do the same check on one of the
outlets on the power strip, I get: neutral to hot 110V, neutral to
ground around 60V and hot to ground around 60V. Is this right?
I've checked this with two power strips and I get the same results.
What would cause this? Is the polarity on my outlet wrong? Or,
am I just a dummy and am misintepreting what is going on. This
misterious 60V is what give me the shock.

Howard

The doom and gloomers sure do come out of the woodwork.
There is probably nothing at all wrong with your power strips. If they
have surge protective devices in them what you are reading may be
normal. Some power strips have capacitors from hot to ground and
neutral to ground in addition to mov's. Mov's by themselves have some
capacitance and can act like a voltage divider as one poster
mentioned. The fact that you measure 60 volts would indicate that both
devices are acting in the same manor and dividing the voltage equally,
so they are probably ok. However because of the nature of the devices
it puts some voltage on your items that are tied to the ground of the
power strip.

You should run a ground wire from the ground pin on the outlet back to
the power service panel (breaker/fuse panel). The service panel should
have a ground wire going to a ground rod already.

Running your outlet ground wire to a ground of its own would be better
than nothing but the correct way to do it is to run it right to your
service panel.

Regards
Gary K4FMX

 

[Jim Adney]

On Fri, 10 Jun 2005 21:21:55 -0400 Gary Schafer
<gaschafer@comcast.net> wrote:

The doom and gloomers sure do come out of the woodwork.

Yep, I completely agree. It's rather clear that no one before Gary had
much of a clue as to what was really going on here.

What you are seeing is the completely normal result of having a home
system with no ground, a power strip with surge protection, and a
voltmeter with a high imput impedance.

You can leave things just the way they are, but the best thing would
be to update the house wiring and give yourself some good grounds. In
the meantime, your surge protector only gives your computer limited
protection.

A proper ground is applied at the service entrance (where the AC power
enters the house) and follows the wiring out to each outlet from
there. An alternate ground can still protect you from electrical shock
if it is well done, but it may cause other problems and may not allow
your surge limiters to protect your equipment as well.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[w_tom]

Rather scary that so many know so much as to reply ...
without first learning electrical basics.

The wall receptacle safety ground must have a dedicated wire
connection to breaker box safety ground. Not to earth; to
safety ground. And definitely not a connection to pipes.

Wire connection to pipes must be to remove electricity from
that pipe. Never make a connection intended to dump
electricity into pipes. A worst case scenario, a pipe
connection might only electrify a wet human in a shower or
bath. Wet is the worst time to touch electricity.

Connection to earth ground also does nothing useful. The
important connection to earth must be from breaker box only.
A receptacle safety ground must connect to breaker box so that
a wiring fault does trip the circuit breaker. No way around
that grounding (bonding) requirement.

The wall receptacle, power strip, or computer need not be
miswired to obtain leakage voltage. Without a safety ground,
then leakage currents might cause the chassis to 'feel'
electrically hot. Not a danger to a dry human. However
leakage can cause damage to interconnected computer components
and cause other irritating problems.

Easiest solution is to have an electrician route a properly
earthed wire to that receptacle. Electricians have fancy toys
that make 'impossible to route' wires simple.

If a receptacle is not safety grounded, then the circuit
should be GFCIed. GFCI is a minimum necessary correction.

Better power strip is typically about $3+, no nonsense surge
protector or filter components inside, AND the power strip
must include a 15 amp circuit breaker. The breaker being
important for human safety - for reasons not discussed here.

Howard Knight wrote:

Todd H. (bmiawmb@toddh.net) wrote:
: ...your outlet is heinously miswired.

Not miswired, just wired 40+ years ago with no ground. Couldn't I
just ground the outlet myself? Run a wire from the ground in the
outlet to a water pipe outside? Would that solve my problems?

Howard

 

[Robert Baer]

pinpassion wrote:

Hi Gang,

I have a large and heavy power supply transformer
that is part of a high current power supply project
that was featured in 73 magazine back in 1973. It
was started by a ham radio operator and was never
finished. I am going to finish it, if I can. I am
trying to identify the transformer leads. This is
for a 12 volt, 40 to 60 amp output. Here are the markings:

This transformer was made by ADC and is marked 541-010 REV H.
There is a marking on it that says 3-19470 and what I think
is a date code of 7438. There are terminal connections on one
side that are numbered 1 - 6. On the other side the connections
are numbered 7 - 14. I need to know the connection scheme for
this transformer so I can put it to use. I contacted who I
thought was the manufacturer "ADC" for information, and that
did not help.

I don't have the issue of 73 magazine, and I don't even know
if this is the same transformer that may have been part of the
construction article. I can take pictures and post them if that
might help.

Anybody have any ideas?

Thanks a lot.

Mike

1) Ohm the leads out to identify windings and center-taps.

2) Use a 40 watt light bulb in series with thehighest resistance winding
to (partly) energize the transformer.
Measure the voltage across that "input" winding, and then of all of
the other windings (write the readings down).
This gives you the volrtage ratios between the windings, and will
give you a clue as to which one was to be the 115VAC primary.

 

[Dimitrios Tzortzakakis]

--
Tzortzakakis Dimitrios
major in electrical engineering, freelance electrician
FH von Iraklion-Kreta, freiberuflicher Elektriker
dimtzort AT otenet DOT gr
? "Todd H." <bmiawmb@toddh.net> ?????? ??? ??????
news:8464wm7wn5.fsf@ripco.com...

howardkinsd@yaEXPUNGEhoo.com (Howard Knight) writes:
I get the shock when I touch any part of the back of my computer or
wires, and also touch the metal part of the cable that comes in and
connects to my cable modem. Here's the deal:

I live in an older house that is not grounded. The ground prong on
the outlets isn't connected to ground or anything else.

Red flag. This is problem #1. This isn't a ground loop. This is an
absence of ground. The former is an inconvenience, the latter can
kill ya.

Is this legal in USA?Here, there are people who put shucko-plugs in old

fashioned three-prong receptacles, with the result, abcence of ground (the
appliance works, but is not grounded).Modern computers that work in the GHz
range need very good grounding, because their case becomes hot otherwise
from induced high-frequency currents.

Also, I've determined that the coax cable coming in to my cable
modem is grounded.

Typically staked at the junction box by the cable company.

Somthing seems to be making the ground prong on my outlet hot. I've
narrowed down the problem to my power strip. I've unplugged
everything from my outlet and I check the outlet for voltage.
Neutral to hot gives me 110V. Neutral to ground give me nothing
(actually, for some odd reason, there does seem to be a slight
voltage (less than 2V).

The odd reason is that if we believe what you're telling us (i.e. that
your ground on your outlet is completely floating) I'd believe any
voltage you'd tell me between ground and the neutral of the outlet.

In my house:hot to neutral and hot to ground 225 volts (3:10 pm)and, of

course, neutral to ground 0 volts.I have checked every inch of the
installation myself, because I think that electricity is quite a good
friend,but canbecome dangerous sometimes.

Hot to ground also gives me nothing. As one would expect.

As one would expect in Danger World where ground is left completely
floating.

In the Safe World, neutral and ground should be the same potential
with 0V, and hot to ground should measure in the 110-120V range.

Notice however that neutral even having a potential of 0 volts is run by

large enough currents to cause problems in bad installations (neutral bars
in distribution panels and neutrals in electric ranges e.g. tend to burn to
be charcoaled completely).

Now, if I plug in a power strip and do the same check on one of the
outlets on the power strip, I get: neutral to hot 110V,

Good.

Neutral to ground around 60V

Wee! This is a Big Problem.

and hot to ground around 60V. Is this right?

Oy. No.

You gotta remember here, your ground in your outlets is completely
floating, and someone should tell you this is Very Bad.

I've checked this with two power strips and I get the same results.
What would cause this? Is the polarity on my outlet wrong? Or, am
I just a dummy and am misintepreting what is going on. This
misterious 60V is what give me the shock.

Call an electrician. Today. You've got potentially lethal problems
with your home's electric wiring. You may also have some power
strips in need of replacement.

60V on your third wire ground is Not Good (tm). Since your computer
is a metal enclosed 3-wire appliance, it's presenting allcomers with
60V ready to shock the crap out of em.

Most aren't aware that surge suppressing power strips do nothing
without a real third wire ground, and it appears that they might also
be creating a rather hazardous situation. I suspect that these may be
surge suppressing power strips with some circuitry that is potentially
faulty (burned out MOV's for instance) and is therefore creating a
more hazardous situation than you have at your outlet to begin with
because your outlet is heinously miswired.

Don't take offense, but do call an electrician.

Best Regards,
--
/"\ ASCII Ribbon Campaign | Todd H
\ / | http://www.toddh.net/
X Promoting good netiquette | http://triplethreatband.com/
/ \ http://www.toddh.net/netiquette/ | "4 lines suffice."

 

[Vidar Lřkken]

Dimitrios Tzortzakakis wrote:

Is this legal in USA?Here, there are people who put shucko-plugs in old
fashioned three-prong receptacles, with the result, abcence of ground (the
appliance works, but is not grounded).Modern computers that work in the GHz
range need very good grounding, because their case becomes hot otherwise
from induced high-frequency currents.

Bullshit. The potential at the case is power leaked in the psu, not
_any_ other parts in the computer. The psu has a filter on the input,
which leaks tiny currents to ground/chassis. This has nothing to do with
the cpu or any other thing. It has nothing to do with induction afaik.


--
MVH,
Vidar

www.bitsex.net

 

[colin]

"Howard Knight" <howardkinsd@yaEXPUNGEhoo.com> wrote in message
news:11ak23tensjvm95@corp.supernews.com...

I live in an older house that is not grounded. The ground prong on
the outlets isn't connected to ground or anything else.

if you want to carry on living i sugest you get this problem rectified
imediatly. if you were living in the UK the wiring would be condemed by the
power company as soon as they were aware of it.

Colin.

 

[CJT]

Jim Adney wrote:

On Fri, 10 Jun 2005 21:21:55 -0400 Gary Schafer
gaschafer@comcast.net> wrote:


The doom and gloomers sure do come out of the woodwork.


Yep, I completely agree. It's rather clear that no one before Gary had
much of a clue as to what was really going on here.

What you are seeing is the completely normal result of having a home
system with no ground, a power strip with surge protection, and a
voltmeter with a high imput impedance.

But ... that combination can be deadly. If you don't believe me,
google "guitar amp death caps."

You can leave things just the way they are, but the best thing would
be to update the house wiring and give yourself some good grounds. In
the meantime, your surge protector only gives your computer limited
protection.

A proper ground is applied at the service entrance (where the AC power
enters the house) and follows the wiring out to each outlet from
there. An alternate ground can still protect you from electrical shock
if it is well done, but it may cause other problems and may not allow
your surge limiters to protect your equipment as well.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

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