开云体育

On Mon, 16 Jul 2018 13:37:12 -0700, you wrote:

On Sun, Jul 15, 2018 at 08:45 AM, David Hess wrote:

They were using stories from actual science fiction writers. Larry
Niven wrote Inconsistent Moon which was episode 12 of season 2.

AAAAHHHH, I think I remember that one. the guy from Family Ties was on it and he was a scientist who figured the sun had gone nova, but it turned out to be a solar flare. He had the hots for this Woman and was a bit shy to approach her but when he thought the world was gong to end he went for her. She got a little bit miffed over that but got over it. the shockwave at the speed of sound hit them and the flare did kinda FUBAR the Earth but it did not kill everyone. he was kinda thinking when he wanted to cook all the food they had because the utilities were bound to go off.

There was a short story that this was based on, IIRC>

It had a bit more of a human touch than I prefer in scifi but not too bad. Even with Star Trek, which I cut my teeth on, the ones that are like a soap opera are not my favorite to say the least. I don't really even watch DS9 because of that. not that it is bad, it is just not my taste.

Berman. Piller. Sheer Evil.....

<never mind>

When I was a kid, 7 when it came out nobody was allowed to talk when it was on. We had the choice, shut up, outside or hell broke loose, maybe locked in a closet or something. My Parents were not really abusive at all. Tough, but then so was I. But the olman was allowed to talk and he made some jokes about it that literally had me on the floor rolling in laughter. I mean to the point where I missed part of the show. But they did reruns so all was not lost.

That series was great, as well as some that followed, but I have to say, the new Outer Limits actually beat them.

IIRC, even darker than the original. And the original? Very FEW
episodes were positive.... Not that I remember.

YMMV.

Harvey

On Mon, 16 Jul 2018 13:12:56 -0700, you wrote:

I've seen a standardization to several end destinations. One is that
the voltage rating seems to determine the size of the barrel
connector. That's now, from what I can see.

Secondly, there's a current limit that's also imposed. I have an HP
that wants higher current for the supply, and does not have the (older
standard) 5.5/2.1 (whichever *is* the "standard")) connector. It's
actually smaller in the barrel.

I'm going to conclude that there's an evolving standard out there, and
I have no idea of what it is.

Now, that is completely screwed up by the "DELL" standard, which
apparently includes some HP laptops.

Dell has a 3 wire cable to the power supply brick. The inner pin is
apparently an I2C connector. The inner and outer shells are power and
ground (suggest that the outer is ground). In a DELL computer, if the
power block does not identify itself as a "genuine" power adaptor,
then the battery will not charge.

Those adaptors (and don't ask me what I think of them) work with a
different standard. Not sure what the effective voltage and current
limits are in this case.

Bottom line, there *is* somewhat of a standard (don't know what it is)
that is now applied to barrel and pin diameters for different voltage
limits.

Harvey

They do seem to be approaching some modicum of standardization finally. My sister had 2 laptops different brands and the power supplies were interchangeable, and my Gateway supply runs them as well. They are all about 19 volts and it seems the polarity has been matching. I noticed an older Gateway adapter would not work on my newer Gateway and I suspect it is because it pulls more current. Maybe not running but it might charge faster. The diameter of the whole thing is the same but the pin in the middle is larger.

Right now I have the whole Toshiba motherboard for sale but you don't want it for just that. It works so I don't want to turn it into a parts mule. the older laptop is going to be my music server on the garage if I can ever get the wireless to work on it. you might look around for a laptop that has been dropped or something, you are not going to do mass production, right ?

Another idea might be a music store that sells electric, they likely also have effects pedals and many of them run of a wall wart. I worked at a music store like that for a bit and they had 2 boxes full of wall warts, one box of AC and one box of DC. they migth have some pedals that they can't fix. You can just try the plug, not even powering it up. The voltage doesn't matter, as long as it makes the connection.

Also for a one off (that's what engineers call them I think) you can just cut the wire and put on any connector you please.

This is hardly relevant, but it might be of interest to note that many TVS diodes exhibit negative resistance section.

I have made a proof-of concept oscillator that uses a TVS as an oscillator. Probably one of the simplest oscillators you can make.



Leo

On Tue, Jul 10, 2018 at 07:22 PM, Michael A. Terrell wrote:

That so called radio station looked like something from what 'Sanford & Son'
would have tossed out.

Yeah. It was a small town AM radio station with maybe 10,000 watts. What gets me is how he pushed microwaves through that tower that was clearly not built for it, and at a strength to reach pretty far into outer space. Oh, and no propagation delay either.

I like picking scifi apart like that. Some say I overanalyse but I say they underanalyse.

I've actually written a bit of scifi and it is not easy to create new futuristic science. I can't reveal it because of reasons, but I got good reviews on it. And then the timeline. I ran out of timeline. I had to go back and change things, pain in the (_|_).

I had a half decent science background, but many authors don't. The depend on research and whatever, themselves or assistants.

But all in all I think scifi is a good thing. I mean real scifi, not this magic bullshit like Harry Potter. I consider the pollution. But if kids watch real scifi it can stimulate their interest in real science. I can't say for sure if that happened to me but I think it likely.

My story ? A guy wakes up 396 years on the future. He is a kinky person and an engineer. After more contemporary education he is again and engineer and does well financially. He takes 2 Wives, and each give him 2 kids. And what brought him to the future had nothing to do with time travel, it was suspended animation. After 396 years they did figure out time travel.

i was like in another world when I was writing it. And I had to read what I wrote the day before to keep continuity. I know how difficult it can be to write really good scifi, and I don't consider what I wrote all that good. OK but not great.

If I bored you with this, sorry, but this is an off topic non political thread so I figure I have some license here.

Was this meant to be in the Tek Scopes list ?

Thanks for your input

I am using a short 50ohm bnc to bnc and it displays the correct wave on my other scopes. I just tried a second 2ft bnc to bnc and get the same result.

The attenuators such as c36 and c37 will not correct this much deviance. Nor will the compensation pots on the preamp. I have not tried much else.

But are you saying this could all be corrected with calibration? I am working on getting the correct hardware to calibrate but I wold like to get the square wave visually square, even if it is not calibrated. If there is still a issue, I believe there is, then I wont be able to calibrate until it is corrected.

On Sun, Jul 15, 2018 at 08:45 AM, David Hess wrote:

They were using stories from actual science fiction writers. Larry
Niven wrote Inconsistent Moon which was episode 12 of season 2.

AAAAHHHH, I think I remember that one. the guy from Family Ties was on it and he was a scientist who figured the sun had gone nova, but it turned out to be a solar flare. He had the hots for this Woman and was a bit shy to approach her but when he thought the world was gong to end he went for her. She got a little bit miffed over that but got over it. the shockwave at the speed of sound hit them and the flare did kinda FUBAR the Earth but it did not kill everyone. he was kinda thinking when he wanted to cook all the food they had because the utilities were bound to go off.

It had a bit more of a human touch than I prefer in scifi but not too bad. Even with Star Trek, which I cut my teeth on, the ones that are like a soap opera are not my favorite to say the least. I don't really even watch DS9 because of that. not that it is bad, it is just not my taste.

When I was a kid, 7 when it came out nobody was allowed to talk when it was on. We had the choice, shut up, outside or hell broke loose, maybe locked in a closet or something. My Parents were not really abusive at all. Tough, but then so was I. But the olman was allowed to talk and he made some jokes about it that literally had me on the floor rolling in laughter. I mean to the point where I missed part of the show. But they did reruns so all was not lost.

That series was great, as well as some that followed, but I have to say, the new Outer Limits actually beat them.

The land line is $60/month here now. Anyone recommend a system keypad, main system board with cellphone
function, and monitoring service that is low cost for the cell phone line charge and the monitoring?

Oh, and your post would not be considered off topic in TestgearNotTekscopes. A computer is definitely test gear. Actually so are amplifiers if you work on tuners, CD DVD players, tape decks. A tuner can be a source for a test signal if you are working on an amp. The only thing that is not acceptable there is Tek scopes because I do not want to divert any traffic from this group. It is just too nice.

And any home brew test gear is VERY welcome.

Just so you know.

They do seem to be approaching some modicum of standardization finally. My sister had 2 laptops different brands and the power supplies were interchangeable, and my Gateway supply runs them as well. They are all about 19 volts and it seems the polarity has been matching. I noticed an older Gateway adapter would not work on my newer Gateway and I suspect it is because it pulls more current. Maybe not running but it might charge faster. The diameter of the whole thing is the same but the pin in the middle is larger.

Right now I have the whole Toshiba motherboard for sale but you don't want it for just that. It works so I don't want to turn it into a parts mule. the older laptop is going to be my music server on the garage if I can ever get the wireless to work on it. you might look around for a laptop that has been dropped or something, you are not going to do mass production, right ?

Another idea might be a music store that sells electric, they likely also have effects pedals and many of them run of a wall wart. I worked at a music store like that for a bit and they had 2 boxes full of wall warts, one box of AC and one box of DC. they migth have some pedals that they can't fix. You can just try the plug, not even powering it up. The voltage doesn't matter, as long as it makes the connection.

Also for a one off (that's what engineers call them I think) you can just cut the wire and put on any connector you please.

On Mon, Jul 16, 2018 at 01:02 PM, Craig Cramb wrote:

I would say your probe is the causing this problem not the scope.

I would say the same thing. But after

"I have changed some of the attenuator settings and even tried adjusting the compensation from the preamp board but it has little effect."

I would think more work will need to be done.

I would say your probe is the causing this problem not the scope.

On Sun, Jul 15, 2018 at 04:52 PM, Raymond Domp Frank wrote:

Good luck!

If it is cyanoacrylate on nylon hell need it. I have never had luck gluing nylon. Even Plas-T-pair did nothing. If any glue works on it it seems like it works as a filler, Filling knurling or grooves or whatever and that is what makes it work at all. As far as actually bonding to nylon, I have never found anything that could do that and I have tried things. Not sure if I ever tried toluene but that is only a solvent like the Plas-T-pair, but they gave you some powdered resin with it.

I asked my Mother who is somewhat of an expert on such things because of her job, and she said there are glues that work well on nylon but they are expensive.

I hope it works out for the OPer, all I can say is use an ample amount, without spillage or over whatever and hope for the best. If it is not nylon then forget everything I just wrote...

On Mon, Jul 16, 2018 at 11:11 AM, Timothy wrote:

I am in the process of accumulating these devices and plan to learn to
calibrate my scopes. Although I know they wont be certified they at least will
be usable.

At the moment I have a 60mhz function/arbitrary wave generator. I am using
that for my square wave. I have other scopes that are putting the same square
wave up correctly.

What I used to set up my 465 was... PG506, assorted attenuators, 50ohm through termination, 20pf standardizer, 50ohm cables, the manual and surely I'm missing something. Everything done in order as laid in the manual.

I dont want to post bad info. I was up until 2am last night and I thought I had it licked before I went to bed.

I just powered up the scope and when I switch from channel one to channel two it is back in add mode. After about 20-30 sec this clears up and it works normally.

Could it be that it was in fact the capacitor that was at fault and the 1kv substitute is not responding as quickly as the 150v?

I want this scope to work perfectly. Its a very nice and clean scope.

Working on these scopes is like working on a classic car both rewarding and frustrating!

I am in the process of accumulating these devices and plan to learn to calibrate my scopes. Although I know they wont be certified they at least will be usable.

At the moment I have a 60mhz function/arbitrary wave generator. I am using that for my square wave. I have other scopes that are putting the same square wave up correctly.

On Mon, Jul 16, 2018 at 10:28 AM, Timothy wrote:

I have a 465B that had a intermittent beam. 90% of the time the screen was
blank. I ended up changing the multiplier (although I am not sure that was the
problem) and the vertical output board and now my trace is back but there is a
problem that is the same on both channels. The problem is on all divisions to
a degree. I have changed some of the attenuator settings and even tried
adjusting the compensation from the preamp board but it has little effect.
Does anyone have any familiarity with this issue or can at least point me in
the direction I should look first?

/g/TekScopes/photo/56677/12?p=Name,,,20,1,0,0
/g/TekScopes/photo/56677/13?p=Name,,,20,1,0,0

Something strange I have noted is when I probe say test point 1 (the resistor
coming out of the attenuator box) or TP2 @ CR1193 on the vertical preamp the
trace on the broken scope blurs so much you cant even see it anymore, the
screen just becomes brighter and the test scope gets a blurred out trace, its
there, just fat. When I test the diode at point 9 I get a clean trace and the
damaged scope does not blur. Im not sure if this is related or if I am doing
something wrong. I was probing a 465 (not B) last night and did not have any
of these problems.

Another question about the manual. The arrows to the test points in the Figure
8-11 diagram dont seem to point to a definite spot. i have been looking at the
schematic to try and determine where exactly I am supposed to probe. Am I
doing this right?

Do you have the equipment to make these adjustments you made? Normalizers,attenuators,fast rise square wave? Without the equipment its next to impossible to make these adjustments.

Hello Colin,
I think I've reached my limit here to what I can understand / suggest, regarding a scope I don't own and don't have previous experience with.
I can't understand very well how can the jitter be less at right-hand side of the screen, and worse on the left side... I could even think of it as a side-effect of the pre-trig visualization... but first of all, I think this step of the calibration is done in the "post-trig" visualization... and second, it would take an appreciable amount of variation of the sampling rate (in comparison to the "play" rate, being D-to-A converted and displayed)... Which I don't think it's the case.. .but this AD / DA is too intricate to understand it by just quick reading the manual.
For what it's worth, it did cross my mind about an hypothesis... What would happen if the sample rate is not being correctly adjusted accordingly by the sweep time/div dials?
Since this scope works with a fixed 50 samples/div concept, I suppose that it needs to adjust the sampling rate in accordance to the position of this selector... and I imagine that being operated by leaf switches, that it can be undersampling at some speeds, leading to increased jitter...
Since the same fault would be affecting the play-back of the waveform, such a fault would not turn itself in easily (with less detailed waveforms).
Hope it helps somehow.
KRgrds,
Fabio




On Fri, Jul 6, 2018 at 02:48 PM, Colin Herbert wrote:

Hi Fabio,
I have now completed the "STORAGE HORIZONTAL" section of the Calibration
procedure. Absolutely everything checked out as well within tolerance, until I
got to the item 4 "Check Jitter Correction". This all checked out good, too,
except that while there was no jitter generally on the right-hand side of the
screen, it could be seen for the first two or so cycles. This was most obvious
when using 50 kHz sinewave, 20 us/DIV, 2 mV/DIV, and X10 MAG. Again the centre
part of the display was within specification, but the first two or so full
cycles showed noticeable jitter.
Colin.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Fabio
Trevisan
Sent: 05 July 2018 23:35
To: [email protected]
Subject: Re: [TekScopes] 468 DSO Calibration/troubleshooting

OK Collin,
Now it makes some sense that there's no instruction to set the "NON STORE" to
Off.
It's set to off at Section #2, step i, when it asks to set storage mode to
"NORM".
Fine then... it means that during this step the scope is in full "digital"
mode, and the waveform we're looking at is the digitized one.
regarding your triggering problem... well it does seem that it's being caused
by something else, because if we think of the entire STORAGE triggering check
/ calibration instructions, it's rather minimalist.
It basically covers checks of the storage window mode (post trig and pre trig)
and the A and B gates, and this one and only adjustment (for Storage NORM DC
Bal).
I don't think the jitter is caused anywhere here, and from your description of
when you try to align the rising edge of the 50KHz signal to the 2nd graticule
line. that it comes out of trigger, that doesn't really make sense.
This fact alone suggests that the triggering point of the digital section is,
level wise, completely unmatched to the analog section... Because, if you
display this very same 50KHz in analog mode in this time base of 0.1ms, and
set the trigger point of the 1st cycle at the 0 crossing... the 6th cycle will
be dead on the correct spot (and so every one of the displayed cycles will be
crossing the center line exactly at each of the HOR minor divisions).

And talking about your jitter / alias... Well, at 50 points per division (as
the storage mode is expected to acquire/display), this 50KHz signal at
0.1ms/div would still have a healthy 10 points / cycle so, a jitter of +- 1
sample would be 1/10th of a minor division and, at this acquisition speed,
much lower than the limit of the scope, I wouldn't expect nothing worse than
+-1 sample.
Definitely there shouldn't be aliasing at play here either (with this healthy
10 sample / cycle). If much, a jitter of +- 0.05 div.

I will try to dig a little bit on the circuitry to see if I can come with any
suggestion... but basically, from this point on, I don't think you're getting
the calibration instructions wrong...or that you're missing something. It
really seems that something is not working well on the digital triggering
section.

KRgrds,

Fabio


On Thu, Jul 5, 2018 at 12:03 pm, Colin Herbert wrote:

Hi Fabio,
The difficulty with looking at a 50-KHZ at 0.1 ms/div is that the triggering
is really not that great and some aliasing is evident. I do see your point,
though and I have given it a go, but the jitter doesn't help and I can't get
any of the rising edges to align with the second vertical graticule line

using

the A trigger level. What I have just noticed, though, is that the stable
triggering only takes place between the zero crossing and just after the

next

crest and, oddly, it seems to be the wrong slope! That is, with the slope
switch in the + position, triggering is on the falling edge and vice versa.
The non-storage triggering is exactly the way it should be. I think there

may

be something wrong, here.

With regard to the storage/non-storage buttons. They are all latched.

Pushing

any of the storage buttons (Norm, Envelope, Avg and Save) releases any of

the

other three and the Non-stope button. Pushing Non-store releases the storage
buttons. I think that's what you might expect.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Fabio
Trevisan
Sent: 05 July 2018 19:29
To: [email protected]
Subject: Re: [TekScopes] 468 DSO Calibration/troubleshooting

Hi Collin,
You're welcome... It's more challenging to solve puzzles when you're not
actually on the driver's seat.

Right out of the box I can't see a flaw in your reasoning... I confess I
didn't make the math that 50KHz at 0.1ms/div would give something like 50
cycles...
I agree it seems really silly to try to adjust the crossing of the waveform

at

that particular cross-hair, with such dense waveform. 20us/div would really
make more sense in that respect.
Or maybe... they really meant it to be densely packed with cycles, so that

we

could "disregard" the rising edge slope (at that density, the rising edge is
almost a vertical line, that we would only need to make sure is aligned to

the

vertical graticule).
If there's no mistake in the instructions, it should have - at least -
mentioned that we should be aligning the leading edge of the 6th displayed
cycle, and not just "Align the leading edge"... that's too vague to say the
least.

Now, regarding my doubt whether the procedure is meant to be carried out in
storage mode or not, I have a doubt: How does the "NON STORE" button mode
works (mechanically)?
Is that when we press some of the STORAGE MODE buttons (say, NORM, ENVELOPE,
AVG, or SAVE), does it make the "NON STORE" button to pull out?
That would explain why there's no instruction to explicitly set the "NON
STORE" button to OFF (out).

KRgrds,

Fabio





On Thu, Jul 5, 2018 at 10:07 am, Colin Herbert wrote:

Hi Fabio,

Firstly, thank you for giving this some thought. Some of my observations:

1. Check STORAGE WINDOW Operation. This all works fine, except that when

going

to "d. set STORAGE WINDOW PRE TRIG" the triggering jitter becomes

quite

noticeable; it is less so in POST TRIG.
2. Check A and B+ GATES.
Set NON-STORE On; A TIME/DIV 0.1 ms; B TIME/DIV 20 us. All works as

expected,

except for the jitter when in NORM storage mode - Non-storage there is a
rock-solid trace with no jitter at all.
3. Check/Adjust Storage NORM Trigger DC Balance (R126)
Set CH1 VOLTS/DIV 5mV; HORIZ DISPLAY A. Remember that the A sweep is

still

at 0.1 ms/DIV and so there are some 50 full cycles of a 50-kHz sine-wave.
Trying to set anything with the A TRIGGER LEVEL is nigh on impossible. I

think

the sweep should be A at 20 us/DIV, showing ten full cycles. The problem

now

is that trying to align the leading edge with the second vertical

graticule

line at the horizontal centre graticule line results in loss of

triggering.

This alignment can be done using the horizontal position control, however.
When aligned in this way, switching between AC and DC Trigger coupling of

the

A sweep shows no movement.

Have I achieved what is required, or am I again missing something?

It is a pity that Reed Dickinson hasn't seen this thread, as I think he is

a

bit of an expert on the 468 and he certainly holds them in some respect.
However, I repeat my thanks to you, Fabio.

Regards, Colin.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Fabio
Trevisan
Sent: 05 July 2018 17:09
To: [email protected]
Subject: Re: [TekScopes] 468 DSO Calibration/troubleshooting

Hello Collin,

Regarding my last statement (the P.S.), that this check should be made in
"non-store" mode, I'm giving second thoughts at it.
I`m not sure yet, but I just found out that there are two "NORM triggering

DC

balance" adjustments... one on the analog side and another one on the

storage

side...
So, it seems weird that we could even be able to adjust the STORAGE NORM
triggering DC balance in any mode that isn't a storage mode.

On the other hand, I may still be correct on my initial assumption,

because

the flow of the instructions and the explicit instruction to set "NON

STORE"

to ON, at Section #2, step g.
I`m only not sure if that adjustment (R126) would be even doable while in

NON

STORE mode...

I`ll get back to it as soon as I can dig a little bit more on the manual.

Rgrds,

Fabio



On Thu, Jul 5, 2018 at 08:23 am, Fabio Trevisan wrote:

Hello Colin,

I don't own a 468 and have no particular experience with it, but I have

the

manuals (in PDF form) and since your doubt is related to understaing of

the

instructions, I decided to give it a try and see if I could make sense

out

of

this part of the instruction that you're doubtful at.

At this step, the only thing that doesn't seem really clear to me is why

it

asks specifically to align the leading edge of the sine-wave to the 2nd
graticule line (why the 2nd.???)..
But, regardless of not understanding that, I think the purpose of this
calibration step is clear... Is to make a "differential" assessment of

the

triggering level shift, between using AC triggering coupling and DC

triggering

coupling...
So, basically what it is asking for, is for you to make sure that the
triggering point doesn't move between AC and DC coupling, when you're

actually

feeding a signal that already swings about 0V...
I mean, if the input signal is swinging about 0V (i.e. if it doesn't

contain

a

DC level), changing the triggering coupling from AC to DC should not

make

any

difference, and therefore, the triggering point, whatever it was set to

before

switching to DC, the wave form must remain in the same position.
If the waveform shifts horizontally, than it means that the triggering

point

"seen" by the triggering circuit have changed when switching over from

AC

to

DC, which it shouldn't.

Giving second thoughts to the instruction, it's not much different than
adjusting the Norm DC triggering balance of a 464 (which I own), and

probably

the same as the 465 (more common).
the only difference is that, for the 464, we're asked for looking at the

very

beginning of the sweep, and not at the 2nd vertical graticule line (i.e.

1

division after the sweep actually started).
This difference in procedure (from the non store scope), doesn't

actually

matter to what the DC balance adjustment is doing (which is nothing more

than

shifting the DC level of the actual signal being fed to the triggering

input

buffer, with the intent to making it match with the level of the same

signal

when AC coupled).
The only reason I think they're doing that (adjusting at the 2nd

vertical

graticule line iso at the beginning of the sweep), is because this point

is

about the actual point on the display where the triggering point of the
digital stored signal is supposed to be displayed.

P.S. Also note that, although this adjustment step is called "Check /

Adjust

STORAGE NORM Trigger DC balance", by following the instructions coming

from

the previous steps, I understand (it's my conclusion though) that this
adjustment is not meant to be performed in storage mode.
The previous section, "#2 Check A and B+ gates", at step g. it asks you

to

set the "NON STORE" button to ON position... and then it doesn't ever

ask

you

to change it to OFF, so, by the flow of the procedure, the #3 check is

to

be

performed in NON STORE mode.
Therefore, this jitter that you mentioned you're getting on storage mode
should not interfere with you performing this adjustment (because it's

done

in

NON STORE mode).

Now, talking about this jitter... I don't think it has any relation to

this

adjustment, and it's probably not going to be fixed by setting this

adjustment

right.

I hope I was able to help you somehow.

KRgrds,

Fabio




On Tue, Jul 3, 2018 at 10:08 am, Colin Herbert wrote:

I have got through the calibration/adjustment procedure up to "Storage
Triggering". My problems now are twofold. I can't understand Section

#3

-

"Check/Adjust Storage NORM Trigger DC Balance" (P4-89 in the manual).

Apart

from the fact that the storage triggering has a deal of jitter, I

can't

get

step (e) to make sense. I am supposed to "use the A TRIGGER LEVEL to

align

the

point where the sine-wave's leading edge intersects the center

horizontal

graticule line with the 2nd vertical graticule line". Because of the

the

jitter and the fact that the triggering fails when I adjust the A

TRIGGER

LEVEL, this is impossible. Am I doing something wrong (quite

possible),

or

is

the manual giving me the wrong information? Help!
If anyone has an idea of how I can eliminate the jitter, that would be

nice,

too. There is no jitter in "NON STORE" operation. I was hoping it

would

just

be something simple like a switch needing cleaning, or an IC needing
reseating, but nothing has given me any clues so far...
Colin.

On Fri, Jul 6, 2018 at 02:48 PM, Colin Herbert wrote:

Hi Fabio,
I have now completed the "STORAGE HORIZONTAL" section of the Calibration
procedure. Absolutely everything checked out as well within tolerance, until I
got to the item 4 "Check Jitter Correction". This all checked out good, too,
except that while there was no jitter generally on the right-hand side of the
screen, it could be seen for the first two or so cycles. This was most obvious
when using 50 kHz sinewave, 20 us/DIV, 2 mV/DIV, and X10 MAG. Again the centre
part of the display was within specification, but the first two or so full
cycles showed noticeable jitter.
Colin.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Fabio
Trevisan
Sent: 05 July 2018 23:35
To: [email protected]
Subject: Re: [TekScopes] 468 DSO Calibration/troubleshooting

OK Collin,
Now it makes some sense that there's no instruction to set the "NON STORE" to
Off.
It's set to off at Section #2, step i, when it asks to set storage mode to
"NORM".
Fine then... it means that during this step the scope is in full "digital"
mode, and the waveform we're looking at is the digitized one.
regarding your triggering problem... well it does seem that it's being caused
by something else, because if we think of the entire STORAGE triggering check
/ calibration instructions, it's rather minimalist.
It basically covers checks of the storage window mode (post trig and pre trig)
and the A and B gates, and this one and only adjustment (for Storage NORM DC
Bal).
I don't think the jitter is caused anywhere here, and from your description of
when you try to align the rising edge of the 50KHz signal to the 2nd graticule
line. that it comes out of trigger, that doesn't really make sense.
This fact alone suggests that the triggering point of the digital section is,
level wise, completely unmatched to the analog section... Because, if you
display this very same 50KHz in analog mode in this time base of 0.1ms, and
set the trigger point of the 1st cycle at the 0 crossing... the 6th cycle will
be dead on the correct spot (and so every one of the displayed cycles will be
crossing the center line exactly at each of the HOR minor divisions).

And talking about your jitter / alias... Well, at 50 points per division (as
the storage mode is expected to acquire/display), this 50KHz signal at
0.1ms/div would still have a healthy 10 points / cycle so, a jitter of +- 1
sample would be 1/10th of a minor division and, at this acquisition speed,
much lower than the limit of the scope, I wouldn't expect nothing worse than
+-1 sample.
Definitely there shouldn't be aliasing at play here either (with this healthy
10 sample / cycle). If much, a jitter of +- 0.05 div.

I will try to dig a little bit on the circuitry to see if I can come with any
suggestion... but basically, from this point on, I don't think you're getting
the calibration instructions wrong...or that you're missing something. It
really seems that something is not working well on the digital triggering
section.

KRgrds,

Fabio


On Thu, Jul 5, 2018 at 12:03 pm, Colin Herbert wrote:

Hi Fabio,
The difficulty with looking at a 50-KHZ at 0.1 ms/div is that the triggering
is really not that great and some aliasing is evident. I do see your point,
though and I have given it a go, but the jitter doesn't help and I can't get
any of the rising edges to align with the second vertical graticule line

using

the A trigger level. What I have just noticed, though, is that the stable
triggering only takes place between the zero crossing and just after the

next

crest and, oddly, it seems to be the wrong slope! That is, with the slope
switch in the + position, triggering is on the falling edge and vice versa.
The non-storage triggering is exactly the way it should be. I think there

may

be something wrong, here.

With regard to the storage/non-storage buttons. They are all latched.

Pushing

any of the storage buttons (Norm, Envelope, Avg and Save) releases any of

the

other three and the Non-stope button. Pushing Non-store releases the storage
buttons. I think that's what you might expect.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Fabio
Trevisan
Sent: 05 July 2018 19:29
To: [email protected]
Subject: Re: [TekScopes] 468 DSO Calibration/troubleshooting

Hi Collin,
You're welcome... It's more challenging to solve puzzles when you're not
actually on the driver's seat.

Right out of the box I can't see a flaw in your reasoning... I confess I
didn't make the math that 50KHz at 0.1ms/div would give something like 50
cycles...
I agree it seems really silly to try to adjust the crossing of the waveform

at

that particular cross-hair, with such dense waveform. 20us/div would really
make more sense in that respect.
Or maybe... they really meant it to be densely packed with cycles, so that

we

could "disregard" the rising edge slope (at that density, the rising edge is
almost a vertical line, that we would only need to make sure is aligned to

the

vertical graticule).
If there's no mistake in the instructions, it should have - at least -
mentioned that we should be aligning the leading edge of the 6th displayed
cycle, and not just "Align the leading edge"... that's too vague to say the
least.

Now, regarding my doubt whether the procedure is meant to be carried out in
storage mode or not, I have a doubt: How does the "NON STORE" button mode
works (mechanically)?
Is that when we press some of the STORAGE MODE buttons (say, NORM, ENVELOPE,
AVG, or SAVE), does it make the "NON STORE" button to pull out?
That would explain why there's no instruction to explicitly set the "NON
STORE" button to OFF (out).

KRgrds,

Fabio





On Thu, Jul 5, 2018 at 10:07 am, Colin Herbert wrote:

Hi Fabio,

Firstly, thank you for giving this some thought. Some of my observations:

1. Check STORAGE WINDOW Operation. This all works fine, except that when

going

to "d. set STORAGE WINDOW PRE TRIG" the triggering jitter becomes

quite

noticeable; it is less so in POST TRIG.
2. Check A and B+ GATES.
Set NON-STORE On; A TIME/DIV 0.1 ms; B TIME/DIV 20 us. All works as

expected,

except for the jitter when in NORM storage mode - Non-storage there is a
rock-solid trace with no jitter at all.
3. Check/Adjust Storage NORM Trigger DC Balance (R126)
Set CH1 VOLTS/DIV 5mV; HORIZ DISPLAY A. Remember that the A sweep is

still

at 0.1 ms/DIV and so there are some 50 full cycles of a 50-kHz sine-wave.
Trying to set anything with the A TRIGGER LEVEL is nigh on impossible. I

think

the sweep should be A at 20 us/DIV, showing ten full cycles. The problem

now

is that trying to align the leading edge with the second vertical

graticule

line at the horizontal centre graticule line results in loss of

triggering.

This alignment can be done using the horizontal position control, however.
When aligned in this way, switching between AC and DC Trigger coupling of

the

A sweep shows no movement.

Have I achieved what is required, or am I again missing something?

It is a pity that Reed Dickinson hasn't seen this thread, as I think he is

a

bit of an expert on the 468 and he certainly holds them in some respect.
However, I repeat my thanks to you, Fabio.

Regards, Colin.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Fabio
Trevisan
Sent: 05 July 2018 17:09
To: [email protected]
Subject: Re: [TekScopes] 468 DSO Calibration/troubleshooting

Hello Collin,

Regarding my last statement (the P.S.), that this check should be made in
"non-store" mode, I'm giving second thoughts at it.
I`m not sure yet, but I just found out that there are two "NORM triggering

DC

balance" adjustments... one on the analog side and another one on the

storage

side...
So, it seems weird that we could even be able to adjust the STORAGE NORM
triggering DC balance in any mode that isn't a storage mode.

On the other hand, I may still be correct on my initial assumption,

because

the flow of the instructions and the explicit instruction to set "NON

STORE"

to ON, at Section #2, step g.
I`m only not sure if that adjustment (R126) would be even doable while in

NON

STORE mode...

I`ll get back to it as soon as I can dig a little bit more on the manual.

Rgrds,

Fabio



On Thu, Jul 5, 2018 at 08:23 am, Fabio Trevisan wrote:

Hello Colin,

I don't own a 468 and have no particular experience with it, but I have

the

manuals (in PDF form) and since your doubt is related to understaing of

the

instructions, I decided to give it a try and see if I could make sense

out

of

this part of the instruction that you're doubtful at.

At this step, the only thing that doesn't seem really clear to me is why

it

asks specifically to align the leading edge of the sine-wave to the 2nd
graticule line (why the 2nd.???)..
But, regardless of not understanding that, I think the purpose of this
calibration step is clear... Is to make a "differential" assessment of

the

triggering level shift, between using AC triggering coupling and DC

triggering

coupling...
So, basically what it is asking for, is for you to make sure that the
triggering point doesn't move between AC and DC coupling, when you're

actually

feeding a signal that already swings about 0V...
I mean, if the input signal is swinging about 0V (i.e. if it doesn't

contain

a

DC level), changing the triggering coupling from AC to DC should not

make

any

difference, and therefore, the triggering point, whatever it was set to

before

switching to DC, the wave form must remain in the same position.
If the waveform shifts horizontally, than it means that the triggering

point

"seen" by the triggering circuit have changed when switching over from

AC

to

DC, which it shouldn't.

Giving second thoughts to the instruction, it's not much different than
adjusting the Norm DC triggering balance of a 464 (which I own), and

probably

the same as the 465 (more common).
the only difference is that, for the 464, we're asked for looking at the

very

beginning of the sweep, and not at the 2nd vertical graticule line (i.e.

1

division after the sweep actually started).
This difference in procedure (from the non store scope), doesn't

actually

matter to what the DC balance adjustment is doing (which is nothing more

than

shifting the DC level of the actual signal being fed to the triggering

input

buffer, with the intent to making it match with the level of the same

signal

when AC coupled).
The only reason I think they're doing that (adjusting at the 2nd

vertical

graticule line iso at the beginning of the sweep), is because this point

is

about the actual point on the display where the triggering point of the
digital stored signal is supposed to be displayed.

P.S. Also note that, although this adjustment step is called "Check /

Adjust

STORAGE NORM Trigger DC balance", by following the instructions coming

from

the previous steps, I understand (it's my conclusion though) that this
adjustment is not meant to be performed in storage mode.
The previous section, "#2 Check A and B+ gates", at step g. it asks you

to

set the "NON STORE" button to ON position... and then it doesn't ever

ask

you

to change it to OFF, so, by the flow of the procedure, the #3 check is

to

be

performed in NON STORE mode.
Therefore, this jitter that you mentioned you're getting on storage mode
should not interfere with you performing this adjustment (because it's

done

in

NON STORE mode).

Now, talking about this jitter... I don't think it has any relation to

this

adjustment, and it's probably not going to be fixed by setting this

adjustment

right.

I hope I was able to help you somehow.

KRgrds,

Fabio




On Tue, Jul 3, 2018 at 10:08 am, Colin Herbert wrote:

I have got through the calibration/adjustment procedure up to "Storage
Triggering". My problems now are twofold. I can't understand Section

#3

-

"Check/Adjust Storage NORM Trigger DC Balance" (P4-89 in the manual).

Apart

from the fact that the storage triggering has a deal of jitter, I

can't

get

step (e) to make sense. I am supposed to "use the A TRIGGER LEVEL to

align

the

point where the sine-wave's leading edge intersects the center

horizontal

graticule line with the 2nd vertical graticule line". Because of the

the

jitter and the fact that the triggering fails when I adjust the A

TRIGGER

LEVEL, this is impossible. Am I doing something wrong (quite

possible),

or

is

the manual giving me the wrong information? Help!
If anyone has an idea of how I can eliminate the jitter, that would be

nice,

too. There is no jitter in "NON STORE" operation. I was hoping it

would

just

be something simple like a switch needing cleaning, or an IC needing
reseating, but nothing has given me any clues so far...
Colin.

Some months ago I had a similar problem on my 465.
Turned out that the plastic pin/cam in the inner (B) shaft that engages the B drum was broken (fatigue and age).
I solved the problem in the same exact manner describer here:

I dismantled the drum assembly, recovering the broken parts parts of the cam and making it rebuild in brass by a mechanic specialized in precision parts.
Another similar problem was cured in a different manner, as in the link below:

Hope it can help

Max

I have a 465B that had a intermittent beam. 90% of the time the screen was blank. I ended up changing the multiplier (although I am not sure that was the problem) and the vertical output board and now my trace is back but there is a problem that is the same on both channels. The problem is on all divisions to a degree. I have changed some of the attenuator settings and even tried adjusting the compensation from the preamp board but it has little effect. Does anyone have any familiarity with this issue or can at least point me in the direction I should look first?

/g/TekScopes/photo/56677/12?p=Name,,,20,1,0,0
/g/TekScopes/photo/56677/13?p=Name,,,20,1,0,0

Something strange I have noted is when I probe say test point 1 (the resistor coming out of the attenuator box) or TP2 @ CR1193 on the vertical preamp the trace on the broken scope blurs so much you cant even see it anymore, the screen just becomes brighter and the test scope gets a blurred out trace, its there, just fat. When I test the diode at point 9 I get a clean trace and the damaged scope does not blur. Im not sure if this is related or if I am doing something wrong. I was probing a 465 (not B) last night and did not have any of these problems.

Another question about the manual. The arrows to the test points in the Figure 8-11 diagram dont seem to point to a definite spot. i have been looking at the schematic to try and determine where exactly I am supposed to probe. Am I doing this right?