"sparky is a MORON "


** **** off

- you brainless PARROTING ****wit !!



..... Phil

In article , "Leonard Caillouet" wrote:
Please see page 2.

http://www.cbtricks.com/miscellaneou...e/floating.pdf

I swear I have seen documented procedures lifting the ground of an oscilloscope.
I though it was Tektronix, but I don't remember the details.

I like using battery scopes and also differential probes.

greg

In article , Meat Plow wrote:
On Fri, 1 Jan 2010 12:22:41 +1100, "Phil Allison"
wrote:

** Standard procedure for servicing any unit with an unknown fault is to
FIRST see what happens when plugged into a normal AC outlet - ie one with
neutral and ground linked at the service box.

Funny that was never on any service literature or diagnostic procedure
documentation I ever read. Nor would I have ever made it my own
practice as a first step thinking back 30 through 30 years.

But then again this is an internationally mirrored forum so I don't
really try to pawn off my particular service procedures as the gospel
where the diagnostics flow chart may be much different in certain
regions of the globe.



I have hooked things up with isolation and later found things like a motor short.
Works fine with the transformer.

I didn't always first check the customers explanation and plug something
in right away before doing anything, but I do it now.


greg

In article , Andy wrote:
On Dec 2, 12:03 pm, (GregS) wrote:
In article , "Dave Plowman (News)"
wrote:



In article ,
GregS wrote:
In article , sbnjhfty
wrote:
I'm looking for an isolation transformer for repairing small (less
than 1000W) power supplies. I see loads of them on ebay and some are
medical grade and inexpensive. Are these usable for what I want?
Other than that, any tips on where to get a good deal on one? I
don't want to spend a load as this is hobby work only.

Just an 'isolation transformer" means NOTHING for what you want. Most
all isolation transformers sold have the secondary tied to ground. You
need a service isolation transformer. You can usually get inside and
remove a secondary "neutral" connection.

That's interesting. I've never seen any transformer with the secondary
tied to ground - unless as part of an installation. The word 'isolation'
means just that. Sure you're not thinking of an auto transformer?

I have been thinking about it. The MAIN purpose of an isolation transformer
is to make it non isolated by making a NEW neutral close to the device
being powered. The main purpose of an isolation transformer is noise control.

Now we have us tecks who all our lives have learned isolation and that stuff.
I taliked to the people at Tripplite and verified ALL their isolation
transformers ARE grounded. Read the paragraph, and yet it says above,
"Complete
line
Isolation"http://www.tripplite.com/en/products/model.cfm?txtSeriesID=325&EID=1
3...
Also look
throughhttp://www.tripplite.com/en/keyword-search.cfm?q=isolation%20transforme
r
The isolator you buy from MCM is very unlikely to have the secondary
grounded, but
I really can't verify that.

In reading PC Power Protection by Mark Waller, he
pointed out their is a NEC requirment for this grounding.
I have not found an exact description in the code. There is about 75
references
in that book, but no index marks. Man, I should sell that book !!!! Big
Bucks.

greg

On an isolation transformer (single phase), the primary side is always
grounded because the neutral leg is always bonded in the distribution
panel. This is a code requirement. If the secondary is also grounded
(I am pretty sure this is also a requirement), the two sides are still
electrically isolated. The current leaving the secondary hot leg must
return to the neutral (grounded) leg of the secondary. There is no
path from the secondary hot to the primary neutral. The secondary has
to leave the hot leg and return on the secondary neutral leg. The
secondary current cannot go any where except through secondary loop.
Any noise on the high side (from nearby VFDs or other) must pass
through the primary winding in order to induce a current onto the
secondary. The winding itself is a low pass filter, so much of the
noise on the primary is dissipated as heat.

I would agree with this except you also state then, there is no path from
secondary hot to primary neutral, which makes no sense in your
explanation. In electronic servicing you don't want to ground the
secondary making a new neutral. You got to get away from the code to do it.

greg

"GregS"
Meathead Plonker
"Phil Allison"

** Standard procedure for servicing any unit with an unknown fault is to
FIRST see what happens when plugged into a normal AC outlet - ie one
with
neutral and ground linked at the service box.

Funny that was never on any service literature or diagnostic procedure
documentation I ever read. Nor would I have ever made it my own
practice as a first step thinking back 30 through 30 years.


I have hooked things up with isolation and later found things like a motor
short.
Works fine with the transformer.

I didn't always first check the customers explanation and plug something
in right away before doing anything, but I do it now.


** Its important for a tech to see any symptoms the customer is complaining
about, first hand.

You gotta plug it in to do that.



..... Phil

Phil Allison wrote:


** Its important for a tech to see any symptoms the customer is complaining
about, first hand.

You gotta plug it in to do that.



.... Phil



Customer says his unit was emitting smoke and smells. You look at the
unit and it smells crisp on first inspection. Are you really going to
tell me your going to plug it in first???

Customer says there is sparks from the AC cord where there pet rabbit
might have chewed it. You look at it and see bare copper.
Your going to plug that in first?

Customer brings in unit that has had liquid poured into it.
Are your going to plug that in without tearing it down first?

Most of the time you will plug it in to verify faults. But there are
times a visual and smell no power inspection will tell you a lot.

bob

"bob"
( snip smartarse drivel )


** This above utter fool does not bother to read more than one post in a
thread before jerking himself off in public.


Examples he missed from ME in this thread:


" There are a host of other checks and inspections a service tech needs to
do
on and around the AC wiring, fusing devices and any AC power leads and
plugs attached to a unit. Any parts that are damaged, worn out or otherwise
seem unsafe must be repaired or replaced.

I go through a LOT of AC plugs, fuses and fuse holders in my work. "

And:

" My post does NOT say that it is the very first step.

It does say that with an unknown but possible PSU fault - connection to a
normal RCD protected AC outlet should be done FIRST - before using an
isolation tranny.

Obviously, visual inspection comes very first, including carefully checking
of the AC plug, lead and fuse if accessible. If the AC fuse is missing or
blown, then a major fault is likely.

In the latter case, MY procedure is to install a suitable new AC fuse and
gradually bring up the item using a variac - all the time monitoring the
current draw from the AC supply with meter specially built for that purpose.
If the AC current becomes unusually large ( or the RCD trips) as the AC
voltage rises - game over.



..... Phil

Jamie t wrote in
:

Nice vanity call you have there Mr. N5BZ..

Thanks! Former call was WA5DQP.
My 'sine' has been 'bz' (my initials) since my first contacts as WN5DQP/0.

For some reason I have a vision of seeing you on slow scan?

Sorry, no. Played with tty many years ago. A bit of playing with packet
stuff. Occasional FM and SSB.

CW is my favorite mode.

73

--
bz 73 de N5BZ k

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

In article 39, bz wrote:
Jamie t wrote in
:

Nice vanity call you have there Mr. N5BZ..

Thanks! Former call was WA5DQP.
My 'sine' has been 'bz' (my initials) since my first contacts as WN5DQP/0.

For some reason I have a vision of seeing you on slow scan?

Sorry, no. Played with tty many years ago. A bit of playing with packet
stuff. Occasional FM and SSB.

CW is my favorite mode.

73


I was just tapping out you call sign. Its been a while since I did that.
A really long while for the straight key.
I remembering trying to tap code while I was in the Army barracks
with a temporary setup. I was using two pieces of wire ! That was
40 years ago.

Seems my hand goes balistic on your letters. I need some practice
though. It was a lot easier doing mine. N6GS.

greg

bz wrote:

Jamie t wrote in
:


Nice vanity call you have there Mr. N5BZ..


Thanks! Former call was WA5DQP.
My 'sine' has been 'bz' (my initials) since my first contacts as WN5DQP/0.


For some reason I have a vision of seeing you on slow scan?


Sorry, no. Played with tty many years ago. A bit of playing with packet
stuff. Occasional FM and SSB.

CW is my favorite mode.

73

ah, CW, 30 WPM myself!
I can send faster!

(GregS) wrote in
:

In article 39, bz
wrote:
Jamie t wrote in
:

Nice vanity call you have there Mr. N5BZ..

Thanks! Former call was WA5DQP.
My 'sine' has been 'bz' (my initials) since my first contacts as
WN5DQP/0.

For some reason I have a vision of seeing you on slow scan?

Sorry, no. Played with tty many years ago. A bit of playing with packet
stuff. Occasional FM and SSB.

CW is my favorite mode.

73


I was just tapping out you call sign. Its been a while since I did that.
A really long while for the straight key.
I remembering trying to tap code while I was in the Army barracks
with a temporary setup. I was using two pieces of wire ! That was
40 years ago.

Seems my hand goes balistic on your letters. I need some practice
though. It was a lot easier doing mine. N6GS.


Try tapping out 'BENS BEST BENT WIRE' followed by the 'shave and a hair
cut' rhythm. It has a cool beat.



--
bz 73 de N5BZ k

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

In article 39, bz wrote:
(GregS) wrote in
:

In article 39, bz
wrote:
Jamie t wrote in
:

Nice vanity call you have there Mr. N5BZ..

Thanks! Former call was WA5DQP.
My 'sine' has been 'bz' (my initials) since my first contacts as
WN5DQP/0.

For some reason I have a vision of seeing you on slow scan?

Sorry, no. Played with tty many years ago. A bit of playing with packet
stuff. Occasional FM and SSB.

CW is my favorite mode.

73


I was just tapping out you call sign. Its been a while since I did that.
A really long while for the straight key.
I remembering trying to tap code while I was in the Army barracks
with a temporary setup. I was using two pieces of wire ! That was
40 years ago.

Seems my hand goes balistic on your letters. I need some practice
though. It was a lot easier doing mine. N6GS.


Try tapping out 'BENS BEST BENT WIRE' followed by the 'shave and a hair
cut' rhythm. It has a cool beat.


Oh this could go on and on !!