Date   

Re: Tek 7854 intermittent issues

Albert Otten
 

Hi Nick,

I watched your video https://www.youtube.com/watch?v=o7OC9Qm7inE and again some earlier videos and photos.
As far as I can see your calibrator is OK in analog mode? Photo _MG_2320 in https://groups.io/g/TekScopes/album?id=252782 shows 40 mV amplitude in analog mode.
But in AVG photo _MG_2318 the amplitude is 20 mV; also mainly 20 mV in _MG_2323 except for an "outlier" and the right most part.
You didn't show where the zero level is. My guess is that the zero input values are digitized to 20 mV in stead of 0 mV. Except for the "outlier" and right most part where correctly 0 mV is displayed.
If you repeat things with the calibrator at 0.4 V or 4 V and the scope at 0.1 mV/div or 1 V/div you might see other anomalies.
Could be a digitizer problem but also RAM problem I think.

Albert

On Thu, Sep 3, 2020 at 09:55 AM, Nick Corvid wrote:


Alright, sorry for the quality I had it on the bench rather than in a rack so
my angle is quite bad (looking down from the top) but, I have a video of the
behavior!

Video: https://www.youtube.com/watch?v=o7OC9Qm7inE

If you have time watch the whole thing, it shows some strange artifacts as it
goes, if not have some time stamps of the more interesting things.

Immediately after power up: 00:00

Switch to stored: 00:05

Start of first AQR: 00:08

Things start happening: 02:11

End of first AQR: 02:25

Final result after 3 more AQR's: 02:32


My P7001 connected to a modern PC - need more infos about the original

Holger Lübben
 

Hi everybody!

I've managed to connect my DPO to a modern PC - here is a video of the working system:

https://youtu.be/ki-5oDWhn4g

This is the overlay-card I'm using:
http://w140.com/tekwiki/images/7/77/P7001_program_overlay_card.jpg

To get the look & feel correctly I need some more input ;-)
Does anyone have any information about the programs which were available with the DPO?
Listings, printouts, descriptions, pictures, own experiences, ...?

I've shared all my information about the system on the tekwiki page:
http://w140.com/tekwiki/wiki/P7001

Thanks
Holger


Re: Tek 7854 intermittent issues

Albert Otten
 

Ah, I meant Hi Paul (not Nick) in my previous message. Albert.


Re: Tek 7854 intermittent issues

Albert Otten
 

Hi Nick,
My 7854 is an earlier version. Strange, if that makes any difference I would expect the newer version to have a faster sampling rate.
Albert

On Thu, Sep 3, 2020 at 04:48 AM, Paul wrote:

Albert -
Yep, those are the steps I'm following. Oddly though, my 0.5ms/div works as
reported at 512 P/W, and fails gracefully as described at 0.2ms/div, but at
1024 P/W, it works at 2ms/div & fails at 1ms/div. I never get the immediate
error. I've got a 'newer' model w/ combined RAM/ROM board, you?

Nick -
Happy to poke around & take readings for ya - let me know if I can be of help.


Re: Tek 7854 intermittent issues

Nick Corvid
 

Alright, sorry for the quality I had it on the bench rather than in a rack so my angle is quite bad (looking down from the top) but, I have a video of the behavior!

Video: https://www.youtube.com/watch?v=o7OC9Qm7inE

If you have time watch the whole thing, it shows some strange artifacts as it goes, if not have some time stamps of the more interesting things.

Immediately after power up: 00:00

Switch to stored: 00:05

Start of first AQR: 00:08

Things start happening: 02:11

End of first AQR: 02:25

Final result after 3 more AQR's: 02:32


Re: HAPPY 20th BIRTHDAY TEKSCOPES!!!

Glydeck
 

Dennis,

I’m very thankful for this online community, especially now. I miss Stan, one of the originals.

Thank you!

George

On Sep 2, 2020, at 4:11 PM, Morris Odell <vilgotch1@gmail.com> wrote:

Thanks for the mention Dennis and your efforts as a moderator. I've really enjoyed being a member of this group and look forward to the daily digest I receive. The knowledge and helpfulness of the other members here is a great resource. I also enjoy helping other when I can too.

I hope this group continues for a long tiome to come!

Morris Odell VK3DOC locked down in Melbourne, Australia



Re: Tek 7854 intermittent issues

Nick Corvid
 

It seems like my issue might be thermal related. When it cold starts (everything is at room temperature) it almost always is missing parts of the digital waveform, but if I set it to AQR (and since parts are missing it won't complete) and watch it in stored mode, after a few minutes the missing parts start to fill with noise then the correct data starts to fill in a short while after that, once that has occurred, it seems (most of the time) that the digital side will capture properly until I turn it off and it cools down for a while again. When I'm able I'd like to capture a video of this in action to better describe what's happening.

Also I genuinely didn't know you were supposed to use a specific plugin for AQS until just now, when I very first set up this machine to test it, it would AQS for anything, in auto trigger mode, using just a 7B85 in the left horizontal slot, at any time per div I selected. When this stopped I thought there was an issue.

Finally have the power supply slid out as well so I can finally make some measurements to see if I'm getting some noise or something that's messing with everything until it's "warmed up". Though the fact that the issue disappears randomly makes me not very confident in any correct looking readings.

Still have some occasional other issues as well, like the cal out reading (both on the scope and on another scope) around 2.6 times what it should, but only for a few minutes and SUPER intermittently (like I might not see it for 20 or 30 power cycles or more)

This thing causes me great confusion.


Re: 1S1 sampling unit; (also 7B53AN & 7A18 plugins)

snapdiode
 

Oh and you might want an extender cable too, for when you need to repair it (and you will).

I recommend you read the circuit description of the manual and study the schematics.

Use this PDF

http://bama.edebris.com/download/tek/1s1/Tek1S1_Manual_print.pdf

Text-searchable and nice clear schematics and graphs.


Re: Tek 7854 intermittent issues

Paul
 

Albert -
Yep, those are the steps I'm following. Oddly though, my 0.5ms/div works as reported at 512 P/W, and fails gracefully as described at 0.2ms/div, but at 1024 P/W, it works at 2ms/div & fails at 1ms/div. I never get the immediate error. I've got a 'newer' model w/ combined RAM/ROM board, you?

Nick -
Happy to poke around & take readings for ya - let me know if I can be of help.


Re: 1S1 sampling unit; (also 7B53AN & 7A18 plugins)

Jim Ford
 

I believe it, Harvey.  A former coworker had experimented with tubes, and he said that while you can run the filaments from A.C., try D.C. for audio; you'll like it.Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Harvey White <madyn@dragonworks.info> Date: 9/2/20 7:01 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] 1S1 sampling unit; (also 7B53AN & 7A18 plugins) I once had a Heathkit OM3, which had a horrible hum problem (eventually).  I solved it by running the filaments off DC.  If you ever have that problem, I can suggest it.  The IO-14 was billed as a lab scope, I think.HarveyOn 9/2/2020 9:19 PM, David Collier wrote:> Hi Garth,> I'm in Canberra (Oz).> Some US sellers won't ship to Oz, a few charge ridiculous shipping of US$400 to 500, which is where they hope to profit!> A Heathkit IO-14 from USA is costing me US$50 carriage via the Global Shipping Program, which seems very inexpensive.> David C.>> >>


Re: 1S1 sampling unit; (also 7B53AN & 7A18 plugins)

Harvey White
 

I once had a Heathkit OM3, which had a horrible hum problem (eventually).  I solved it by running the filaments off DC.  If you ever have that problem, I can suggest it.  The IO-14 was billed as a lab scope, I think.

Harvey

On 9/2/2020 9:19 PM, David Collier wrote:
Hi Garth,
I'm in Canberra (Oz).
Some US sellers won't ship to Oz, a few charge ridiculous shipping of US$400 to 500, which is where they hope to profit!
A Heathkit IO-14 from USA is costing me US$50 carriage via the Global Shipping Program, which seems very inexpensive.
David C.



Re: 1S1 sampling unit; (also 7B53AN & 7A18 plugins)

 

Thanks Thomas,
Happy to swap my HP1740A for a Tek!


Re: 1S1 sampling unit; (also 7B53AN & 7A18 plugins)

 

Hi Garth,
I'm in Canberra (Oz).
Some US sellers won't ship to Oz, a few charge ridiculous shipping of US$400 to 500, which is where they hope to profit!
A Heathkit IO-14 from USA is costing me US$50 carriage via the Global Shipping Program, which seems very inexpensive.
David C.


Re: HAPPY 20th BIRTHDAY TEKSCOPES!!!

Morris Odell
 

Thanks for the mention Dennis and your efforts as a moderator. I've really enjoyed being a member of this group and look forward to the daily digest I receive. The knowledge and helpfulness of the other members here is a great resource. I also enjoy helping other when I can too.

I hope this group continues for a long tiome to come!

Morris Odell VK3DOC locked down in Melbourne, Australia


Re: TWD 120's FREE

Thomas Garson
 

Charlie,

Well, I have SCSI adapters galore, and an operating PC running Windows 98, necessary for operation of a legacy DSP analyzer (PC bus hardware). So, I have a system that could PROBABLY work with it. There is already a Tek analog scope on that bench, but the storage capability could be handy.

If no one more needy puts up their hand, I would take one of those.
Zip code 97520.

Thomas Garson
Aural Technology, Ashland, OR
By my calculation, the dynamic range of the universe is roughly 679dB,
which is approximately 225 bits, collected at a rate 1.714287514x10^23 sps.

On 9/2/20 1:24 PM, Charlie Conger wrote:
I just found one, maybe two, complete TWD120's while unpacking after a move. These had been missing for years. These are 100 Mhz 2channel Digital Storage Digitizers originally made for GE medical. They require a PC to act as a display to be fully functional. As I last recall these were fully functional the last time I used them.
see here for more details
http://w140.com/tekwiki/wiki/TWD120
If anyone is interested PM me and I will be happy to send for cost of shipping.


Re: TWD 120's FREE

Charlie Conger
 

It only uses SCSI. At the bottom of the WIKI here is a link to guy who has sorted out the OS issues and fixes for them. It is a mixed bag but free is a very good price. It has basically the same functionality as the old TDS400 scopes which were my favorite low cost TDS.


Re: TWD 120's FREE

G Hopper
 

Looks like an interesting bit of hardware.

Does it use all three interfaces to communicate with the PC (as listed in
the wiki)? or just the SCSI: " Adaptec ASPI SCSI driver is required for
the software to communicate with the digitizer. SCSI configuration can be
tricky." and the serial and parallel were for other things?

That it was designed to work with windows 3.1 and becomes a tough thing to
keep operational as OSes progressed is why these PC based scopes are such a
mixed bag. Makes me glad I have older hardware based scopes. :-)

On Wed, Sep 2, 2020 at 1:24 PM Charlie Conger <ctconger@gmail.com> wrote:

I just found one, maybe two, complete TWD120's while unpacking after a
move. These had been missing for years. These are 100 Mhz 2channel Digital
Storage Digitizers originally made for GE medical. They require a PC to act
as a display to be fully functional. As I last recall these were fully
functional the last time I used them.

see here for more details
http://w140.com/tekwiki/wiki/TWD120

If anyone is interested PM me and I will be happy to send for cost of
shipping.




Re: Strange Tek2440 issue

Vince Vielhaber
 

On 09/02/2020 02:50 PM, Siggi wrote:
On Wed, Sep 2, 2020 at 2:07 PM Vince Vielhaber <vev@michvhf.com> wrote:

I had actually done that last nite, but didn't have the parts layout
handy to see which probe was on which pin (I had them on the diodes>.

Here they are with voltage measurements:

http://www.hamradio.fun/pix/2440.html

Uh, this makes no sense to me.
The base of Q870 should be pulled toward +15V unreg through R864(? hard to
read on the schematic), and the two op amps shunt it towards ground when
they detect too high voltage or too high current, respectively. Whichever
of pins 1/7 is lower is the op-amp in control of the output.

... time passes ...

Yeah, still doesn't make sense to me. I'm going to guess that either the
op-amps are (pins 1/7 are) reversed on the schematic, or that your channel
designations are.
Double checked, followed the foil, Channel 2 is definitely on pin 1.

I got the power supply board out right now so it's definitely going to see some new caps. I'll also take a real close look at Q870 and Q879.

I measured R478 with a 4 wire ohmmeter and it's 10.01. Haven't checked any of the other ... yet.

I did look at the +8 and _15v rails as well as the 5V unreg and the +10 ref. All were ok with both the voltmeter and the scope. While the board's out I'm also going to track down U870's inputs to see if something's backward in the schematic.

More later!
Thanks!
Vince.


Even so, it still doesn't make sense, as the voltage-control op-amp starts
dialing more voltage (Channel 2 normal at 5.54V rises to 16.94V), while the
current limit op-amp goes on the limit (Channel 1 normal at 16.76V dips to
6.16V). What doesn't make sense here is that the current control op-amp is
dialing a voltage that exceeds the voltage control's usual/normal voltage.
I haven't done the maths, but as there's a bias on the current limit
op-amp's feedback input, it might be that it's simply kicking in because
the output voltage has sagged.

I think you need to look further afield, how's the +8V rail doing,
the +-15V rails, raw and regulated? How is the -5V rail doing? Any other
rails you can find...

If you can't find a bad rail, start looking at the biasing for Q870 & Q879,
have the resistors drifted? If R864(?) or R478 have drifted significantly
upward, that'd explain why the transistors can't meet the current demand.
If the biasing is OK, you need to look at the transistors themselves. If
their gain is down, that'd also explain things. You can measure the base
current to Q879 indirectly by the voltage drop over its base resistor. Even
looking at what's happening on Q870's emitter under collapse - is that
transistor going to saturation, indicating that Q879 is dozing off on the
job?

Good luck!

--
K8ZW http://www.metalworkingfun.com http://www.hamradio.fun


TWD 120's FREE

Charlie Conger
 

I just found one, maybe two, complete TWD120's while unpacking after a move. These had been missing for years. These are 100 Mhz 2channel Digital Storage Digitizers originally made for GE medical. They require a PC to act as a display to be fully functional. As I last recall these were fully functional the last time I used them.

see here for more details
http://w140.com/tekwiki/wiki/TWD120

If anyone is interested PM me and I will be happy to send for cost of shipping.


Re: HAPPY 20th BIRTHDAY TEKSCOPES!!!

n4buq
 

Hmmm. Mine shows I joined 09/30/03 (Account -> Identity - Account Profile). I must've been a lurker for a while.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Dave Daniel" <kc0wjn@gmail.com>
To: TekScopes@groups.io
Sent: Wednesday, September 2, 2020 2:49:40 PM
Subject: Re: [TekScopes] HAPPY 20th BIRTHDAY TEKSCOPES!!!

Oh. Duh. The date is on the “personal” under “Account Settings”.

On Sep 2, 2020, at 15:45, n4buq <n4buq@knology.net> wrote:

I searched for my member ID. Apparently I joined on or about April 7,
2004.

I smile when I see that I asked my first Tek question and the second reply
was from none other than Stan Griffiths. Then I see my reply to his
saying "Yes, you are correct". How embarrassing. I didn't know who he
was at the time.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Dave Daniel" <kc0wjn@gmail.com>
To: TekScopes@groups.io
Sent: Wednesday, September 2, 2020 2:40:10 PM
Subject: Re: [TekScopes] HAPPY 20th BIRTHDAY TEKSCOPES!!!

Is there a way to figure out when one joined the original (Yahoo groups)
list?

DaveD

On Sep 2, 2020, at 14:06, Dennis Tillman W7pF <dennis@ridesoft.com>
wrote:

Michael Dunn started TekScopes 20 years ago on August 31, 2000. There was
just one post that day from Walter Shawlee who joined that same day and
he
has been an active member ever since.

To Walter: Thank you for 20 years of contributions to TekScopes and for
all
the parts and instruments you have on your web site!

* Three days later Stan Griffiths W7NI (RIP) joined.
* Three more members, including Tom Gootee, joined in October, 2000.
* By the end of 2000 there were 13 members.
* A year later it was clearly important: there were 68 members and >150
posts each month. John Miles and Morris Odell joined TekScopes in that
first
year.

To John and Morris: Thank you for your regular contributions over the 19
years you have been members!

* I was a late comer. When I joined in mid-November 2002 there were
already
250 members. I was looking for something like this for a long time and I
jumped right in with my first post that same day. Apparently I have been
busy ever since I joined - I just noticed this will be my 5,000th post
since
I joined.

Today we have over 8,000 members worldwide and there are 500 to 1500
posts
per month.

Thank you, Michael Dunn, for realizing the need for a Tektronix support
group, for all you did to keep it going the first 17 years, and for being
there for me when I need occasional help and/or guidance as I continue to
moderate it.

Dennis Tillman W7pF







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