开云体育

Generally, for use in the national standards labs, we used Labsphere units.

For some good practical information, theory & technical guides on integration spheres, see:

a)

b)

c)



Or:



rick

Got it!

--
Michael Lynch
Dardanelle, AR

So, on the old version, where is Vc to 'tap' into , ... & has anyone done that ? !

It's a front panel jack, just to the left of the the position knob.

Cheers
Peter

I got bit unplugging my 485 a few years ago I have no idea how it happened. Now I use linesman's
pliers lined with rubber so to not damage anything, to pull the lead out. I do wear leather gloves
when
taking HV measurements.

You do have to be somewhat careful. There is usually a very high resistance between the connector and
the CRT - some tens of megs - and the DAG coating is also resistive. So although a belt from the
stored charge in the CRT feels alarming, the current is tiny - in the tens of microamp region. The
really dangerous ones are in the 500 series of tubed/valved oscilloscopes, because some of the
voltages to do with anode/plate supplies are potentially lethal because of the hundreds of mA current
available.

Whatever I'm doing with higher voltages that pack a punch I use the old trick of keeping one hand in
my pocket - so you can't get a current flowing from one hand to the other via your chest and beating
heart.

And the other way to prevent damage for those who don't happen to have linesman's pliers is to use a
section of bicycle inner tyre wrapped around what you are trying to pull apart and regular pliers.
That is the standard way of disassembling fountain pens without damaging the parts.

Craig

I think that Jeff makes a good point here. There is no reason to test like that. You are very
likely to
burn up some good components through feedback, excess current or over-voltage. Causing any sort
of high voltage supply to jump an arc requires a much higher voltage than is found in a normal
circuit.
For example, a car coil that may send 4-6kV across a good spark plug can be forced to produce 10
times
as much voltage when made to jump a large gap, but they will not last long doing that. There are
simply too many delicate parts in one of these scopes to use that method of testing.

--
Michael Lynch
Dardanelle, AR

What on earth is the matter with this list at the moment - do you not all read English? Read my
original mail, and my shouty point by point explanation!!!!!

Craig

then short the exposed tip (which is at the end of the red lead that
goes to the crt) to metalwork. If there is a spark, then the CRT is
receiving the output from the multiplier

No. That is not proper procedure, this is not a lawn mower. You let that ultor voltage arc you are
beating the shit out of a bunch of precision resistors in the chain for the CRT bias, stressing old
unobtainium parts and once some of that shorts out you'll be sorry. If it is already shorted the
voltage
does not build up, if you make it so it can, the stress on the rest of it will be more severe as the
capacitance discharges.

The arc method of testing is fine on an old "Madman Muntz", but not for Tek scopes.

So, sorry, I disagree.

You clearly did not read what I said. You short the exposed tip OF THE CRT to ground. The CRT is a
capacitor which stores the charge from the multiplier for a long time.

1. YOU TURN THE SCOPE OFF - OK? You might unplug it from the mains just to be sure.
2. Then you disconnect the HT CONNECTOR BETWEEN THE MULTIPLIER AND CRT - got that? You know - THE LONG
WHITE PLUG AND SOCKET WITH THE RED WIRES COMING OUT.
3. THEN YOU SHORT THE EXPOSED TIP OF THE CRT WIRE TO GROUND. I just hope I don't need to draw a
picture.

So absolutely nothing at all gets stressed! I'm sorry to shout, but you really should have read and
understood my post before rubbishing the procedure.

Craig

On Mon, Jun 25, 2018 at 09:56 pm, Ed Breya wrote:

Jeff, I have to disagree with your disagreement - when you short the PDA lead
of a scope CRT to ground, you are (rapidly) discharging the filter capacitance
of the internal carbon DAG or metallization to the outside coatings or
surfaces like the (grounded) mu-shield. It is a common safety procedure to
keep it safe during later work or CRT handling, and has nothing to do with the
cathode circuit. There are risks though, like getting zapped yourself, or
slipping during unplugging, letting the Alden connector tip accidentally hit
circuitry instead of ground. It would be safer, but less exciting to discharge
it in a less intense way via a high resistance, but when you only have two
hands, each holding one end of a recently unplugged connector set, it's hard
to add components to your situation. Direct shorting to ground is the most
expedient method.

Sometimes the Aldens are tight after years of sitting, and are difficult to
pull apart, then all of a sudden let loose easily. Before attempting
disengagement, twist one end against the other to break the surface adhesion -
especially if one part is silicone rubber, which tends to hang on tightly.
Once the housings are free from each other, the main thing holding is the
contacts. Then carefully apply the pulling force between the halves. When you
feel it snap loose, you can slowly withdraw and expose the hot tip and touch
it to the chassis.

I have done it plenty of times, and gotten zapped a bit approximately once,
but it's harmless as long you're not surprised and lose control. My method
nowadays is to wear leather work gloves, and grab the connector halves between
the thumb and index finger of each hand, and levering between the thumb
knuckles. The gloves soften up the forces on the thumbs, and help spread the
arc if you happen to screw up. With practice, this can give very good control.

Now, TV CRTs are a different story - usually higher voltage, and lots more C.
For those I use a BFS with the shank connected to the outer DAG ground return
wiring net via an alligator clip lead. Just shove the tip under the ultor boot
and up and in until solid contact is made.

Ed

I got bit unplugging my 485 a few years ago I have no idea how it happened. Now I use linesman's pliers lined with rubber so to not damage anything, to pull the lead out. I do wear leather gloves when taking HV measurements.

On Mon, 25 Jun 2018 21:08:10 -0700, you wrote:

On Mon, Jun 25, 2018 at 08:40 pm, Jeff Urban wrote:

On Mon, Jun 25, 2018 at 07:45 pm, Jim Ford wrote:

then short the exposed tip (which is at the end of the red lead that goes to
the crt) to
metalwork. If there is a spark, then the CRT is receiving the output from

the

multiplier

No. That is not proper procedure, this is not a lawn mower. You let that ultor
voltage arc you are beating the shit out of a bunch of precision resistors in
the chain for the CRT bias, stressing old unobtainium parts and once some of
that shorts out you'll be sorry. If it is already shorted the voltage does not
build up, if you make it so it can, the stress on the rest of it will be more
severe as the capacitance discharges.

The arc method of testing is fine on an old "Madman Muntz", but not for Tek
scopes.

It may not work here, but a way to test for high voltage was to test
for the leakage from the HV line, or the magnetic fields. Take an old
neon lamp (or perhaps a small CCFL lamp. tape it to an insulating
stick or plastic rod. Do NOT hold any of the metallic conductors, and
bring it close to the HV transformer or the HV lead. You may see some
activity. You're not touching any of the leads to any other lead,
you're looking for a field to perhaps ionize the neon.

May work, may not. Worked on old TV sets, but that was far more HV.

Harvey

So, sorry, I disagree.

I think that Jeff makes a good point here. There is no reason to test like that. You are very likely to burn up some good components through feedback, excess current or over-voltage. Causing any sort of high voltage supply to jump an arc requires a much higher voltage than is found in a normal circuit. For example, a car coil that may send 4-6kV across a good spark plug can be forced to produce 10 times as much voltage when made to jump a large gap, but they will not last long doing that. There are simply too many delicate parts in one of these scopes to use that method of testing.

Jeff, I have to disagree with your disagreement - when you short the PDA lead of a scope CRT to ground, you are (rapidly) discharging the filter capacitance of the internal carbon DAG or metallization to the outside coatings or surfaces like the (grounded) mu-shield. It is a common safety procedure to keep it safe during later work or CRT handling, and has nothing to do with the cathode circuit. There are risks though, like getting zapped yourself, or slipping during unplugging, letting the Alden connector tip accidentally hit circuitry instead of ground. It would be safer, but less exciting to discharge it in a less intense way via a high resistance, but when you only have two hands, each holding one end of a recently unplugged connector set, it's hard to add components to your situation. Direct shorting to ground is the most expedient method.

Sometimes the Aldens are tight after years of sitting, and are difficult to pull apart, then all of a sudden let loose easily. Before attempting disengagement, twist one end against the other to break the surface adhesion - especially if one part is silicone rubber, which tends to hang on tightly. Once the housings are free from each other, the main thing holding is the contacts. Then carefully apply the pulling force between the halves. When you feel it snap loose, you can slowly withdraw and expose the hot tip and touch it to the chassis.

I have done it plenty of times, and gotten zapped a bit approximately once, but it's harmless as long you're not surprised and lose control. My method nowadays is to wear leather work gloves, and grab the connector halves between the thumb and index finger of each hand, and levering between the thumb knuckles. The gloves soften up the forces on the thumbs, and help spread the arc if you happen to screw up. With practice, this can give very good control.

Now, TV CRTs are a different story - usually higher voltage, and lots more C. For those I use a BFS with the shank connected to the outer DAG ground return wiring net via an alligator clip lead. Just shove the tip under the ultor boot and up and in until solid contact is made.

Ed

On Mon, Jun 25, 2018 at 07:45 pm, Jim Ford wrote:


then short the exposed tip (which is at the end of the red lead that goes to
the crt) to
metalwork. If there is a spark, then the CRT is receiving the output from the
multiplier

No. That is not proper procedure, this is not a lawn mower. You let that ultor voltage arc you are beating the shit out of a bunch of precision resistors in the chain for the CRT bias, stressing old unobtainium parts and once some of that shorts out you'll be sorry. If it is already shorted the voltage does not build up, if you make it so it can, the stress on the rest of it will be more severe as the capacitance discharges.

The arc method of testing is fine on an old "Madman Muntz", but not for Tek scopes.

So, sorry, I disagree.


On Mon, Jun 25, 2018 at 09:08 pm, Mlynch001 wrote:

On Mon, Jun 25, 2018 at 08:40 pm, Jeff Urban wrote:

On Mon, Jun 25, 2018 at 07:45 pm, Jim Ford wrote:

then short the exposed tip (which is at the end of the red lead that goes

to

the crt) to
metalwork. If there is a spark, then the CRT is receiving the output from

the

multiplier

No. That is not proper procedure, this is not a lawn mower. You let that

ultor

voltage arc you are beating the shit out of a bunch of precision resistors

in

the chain for the CRT bias, stressing old unobtainium parts and once some of
that shorts out you'll be sorry. If it is already shorted the voltage does

not

build up, if you make it so it can, the stress on the rest of it will be

more

severe as the capacitance discharges.

The arc method of testing is fine on an old "Madman Muntz", but not for Tek
scopes.

So, sorry, I disagree.

I think that Jeff makes a good point here. There is no reason to test like
that. You are very likely to burn up some good components through feedback,
excess current or over-voltage. Causing any sort of high voltage supply to
jump an arc requires a much higher voltage than is found in a normal circuit.
For example, a car coil that may send 4-6kV across a good spark plug can be
forced to produce 10 times as much voltage when made to jump a large gap, but
they will not last long doing that. There are simply too many delicate parts
in one of these scopes to use that method of testing.

--
Michael Lynch
Dardanelle, AR

Ok. You can't just leave it there. How do you discharge the CRT? ?\_(ツ)_/?

On Mon, Jun 25, 2018 at 08:40 pm, Jeff Urban wrote:

On Mon, Jun 25, 2018 at 07:45 pm, Jim Ford wrote:

then short the exposed tip (which is at the end of the red lead that goes to
the crt) to
metalwork. If there is a spark, then the CRT is receiving the output from

the

multiplier

No. That is not proper procedure, this is not a lawn mower. You let that ultor
voltage arc you are beating the shit out of a bunch of precision resistors in
the chain for the CRT bias, stressing old unobtainium parts and once some of
that shorts out you'll be sorry. If it is already shorted the voltage does not
build up, if you make it so it can, the stress on the rest of it will be more
severe as the capacitance discharges.

The arc method of testing is fine on an old "Madman Muntz", but not for Tek
scopes.

So, sorry, I disagree.

I think that Jeff makes a good point here. There is no reason to test like that. You are very likely to burn up some good components through feedback, excess current or over-voltage. Causing any sort of high voltage supply to jump an arc requires a much higher voltage than is found in a normal circuit. For example, a car coil that may send 4-6kV across a good spark plug can be forced to produce 10 times as much voltage when made to jump a large gap, but they will not last long doing that. There are simply too many delicate parts in one of these scopes to use that method of testing.

--
Michael Lynch
Dardanelle, AR

On Mon, Jun 25, 2018 at 06:27 pm, musicamex wrote:

Good to hear. Ive read that the 460 is known for leaky caps on the adq
board. I just grabbed a working 460a with a screen that says "passed self
test". For under $100. I wont pick it up till my next trip north.

On Monday, June 25, 2018, <toby@...> wrote:

On 2018-06-25 8:23 PM, musicamex@... wrote:

Was the 460a an improvement over the 460 regarding the leaking

electrolytic capacitors? What is the general opinion of the 460a?

I REALLY like mine! But I can't compare to any other DSO's; it's the
only one I've used.

I haven't had any problems with it yet, capacitors or otherwise. Touch
wood.

--Toby

Thanks

--
Good judgement comes from experience; experience comes from bad judgement.

99 times out of 10 a blown fuse is not due to a bad fuse.....

I have a TDS460A and recently took the case off, just to look at it, fearing the dreaded leaky caps. Mine was a later 90's model from the dates on the CRT and other components and the inside looks great, no evidence of deteriorated caps. It is my understanding that the Caps made in the mid and later 90's were not as big a problem as the earlier ones. This scope seems to bear this out. I really like the 460A and use it as my primary scope , I also have a 360, but find the 460 to be superior in almost every respect. I bought mine for $75 "As Is, needs repairs" and it passes self check with flying colors. Voltage and timing Calibration seems good and everything works as it should.

--
Michael Lynch
Dardanelle, AR

Jim Yanik used an old computer ? Why am I not quite taken aback by this ? LOL

If he's dead then he's dead, but at least he is remembered. If he is alive his health could be to the point where he might not be able to participate on the net anymore.

We all gotta go sometime.

On Mon, Jun 25, 2018 at 07:45 pm, Jim Ford wrote:

then short the exposed tip (which is at the end of the red lead that goes to
the crt) to
metalwork. If there is a spark, then the CRT is receiving the output from the
multiplier

No. That is not proper procedure, this is not a lawn mower. You let that ultor voltage arc you are beating the shit out of a bunch of precision resistors in the chain for the CRT bias, stressing old unobtainium parts and once some of that shorts out you'll be sorry. If it is already shorted the voltage does not build up, if you make it so it can, the stress on the rest of it will be more severe as the capacitance discharges.

The arc method of testing is fine on an old "Madman Muntz", but not for Tek scopes.

So, sorry, I disagree.

I think I have a few low voltage supplies to check before getting to the HV stuff.
Thanks.


Sent from my Verizon, Samsung Galaxy smartphone

No, no ticking.? ?The scope loks and sounds exactly the same plugged in to the mains or not, power switch on or off.


Sent from my Verizon, Samsung Galaxy smartphone

Yep, set for 120 VAC.? I did move the jumper to Mid voltage.
I will try a night light in series as soon as I can.?
Thanks, Jeff


Sent from my Verizon, Samsung Galaxy smartphone

Good to hear. Ive read that the 460 is known for leaky caps on the adq
board. I just grabbed a working 460a with a screen that says "passed self
test". For under $100. I wont pick it up till my next trip north.

--
Good judgement comes from experience; experience comes from bad judgement.

99 times out of 10 a blown fuse is not due to a bad fuse.....

On 2018-06-25 8:23 PM, musicamex@... wrote:

Was the 460a an improvement over the 460 regarding the leaking electrolytic capacitors? What is the general opinion of the 460a?

I REALLY like mine! But I can't compare to any other DSO's; it's the
only one I've used.

I haven't had any problems with it yet, capacitors or otherwise. Touch wood.

--Toby

Thanks

Was the 460a an improvement over the 460 regarding the leaking electrolytic capacitors? What is the general opinion of the 460a?

Thanks