Date   

Re: GPIB using Win98 and a NI GPIB-PCII/IIA ISA card to talk to my TDS540B?

craig.belcher@...
 

I'm just about to head down the ISA path and I'm reading this, got a recommendation on a USB interface?


Calibration of the Measure Function on a TDS220

Steve Hendrix
 

I'm new to the group, so please forgive any faux pas on my part!

I have long used a TDS220 and still like it a lot. I note that the Measure function, specifically displaying a DC voltage numerically, has always had a nontrivial offset that seems larger than it should be. I even sent it out to a Tek cal lab, and it seemed to be unchanged afterward. Here are examples of the offset from ideal (zero) with the ground clip clamped directly on the probe tip, standard x10 probe:

V/Div VDC
50 2.96
20 1.14
10 0.377
5 -0.012
2 0.111
1 0.055
0.5 0.021
0.2 0.001
0.1 -0.007
0.05 -0.005
0.02 0.005

Are these numbers reasonable for the instrument, or is there some adjustment I can make?

Steve Hendrix


Re: Dumont knock off of Tek

greenboxmaven
 

On 6/22/19 2:20 PM, ken chalfant wrote:
Greetings,



Initially Dumont was probably the leader in oscilloscope technology for a few years, but Tektronix quickly took the lead.
By the mid 1960s, Dumonts were easy to find and not expensive for high school kids with "pump gas-cut grass-throw papers" money. The low frequency response made them less than ideal for TV shop work, and useless for repairing the color circuits in TVs. A Heathkit, Eico, or perhaps RCA might be within reach, but a Tektronix was a dream most of us had to wait some time for.


I believe Dumont was eventually acquired by Fairchild. I actually owned a dual beam, four channel Fairchild/Dumont scope. I also owned a number of other Dumont scopes. They really weren???t knock-offs.
I was given a monsterous Dumont dual beam scope that did not work. I restored it and used it mostly for audio. I think it might have made it to 500KC.

Interestingly, a company named Lavoie made ???exact??? (well sort-of) Tek knock-offs of the 53x and maybe the 54x scopes. The story I heard told that this opportunity came about because the military was pressured to open bid for scopes meeting the Tektronix specifications. I have used some Lavoie scopes a long time ago. From the outside they looked almost exactly like the Tek scope they copied, but the knobs were different. However, they were not the same level of quality construction on the inside as the Tek scopes.
I used them in the Air Force. The ones we had were "clones" of the 524. They worked ok, but just were not the "real thing". There was indeed an effort to avoid relying on one maker for a while. One of the most interesting was the Eldeco copy of the Collins KWM-2 transceiver


Bruce Gentry, KA2IVY

That???s my two cents, FWIW.

Regards,

Ken






Problomatic (broken) 464 storage scope.

mark@...
 

Ok,.. I am looking for some pointers if you would be so kind,... I have a broken 464 scope... the symptoms are as follows:-
1) The scope powers up,.. but the beam is not running correctly,.. ie as it was failing the beam was going back in time in a curly pattern,...
2) Beam finder does bring the beam in though
3) Fan does not make a continuous tone/noise... ie speed changes.
A) So far I have checked for magic smoke and burnt etc,.. so far nothing!
B) Have measure main voltages,.. And this is where things start going to pot:

5 volts DC measures 5.58v,.. with more ripple than I can measure
-8 Volts DC measures in at -8.4v again with loads of ripple.
+15 Volts DC measures in at 15.8v,. with loads of ripple
+65 Volts measures in at 68v and loads of ripple
140 Volts measures in at 134v with loads of ripple.

So clearly, ( I assume ) the power supply looks suspect,...

I sort of suspected failed input electrolytics.... but reading further forum stuff this seems unlikely as they are essentially Mil. grade components,.. so probably not the source of my problem.
I have also seen other utube video where the voltages are measured ,.. and mine are no where near close or as stable as these....
My other thoughts then go of to the Tant caps... are there are lots of them,.. the ones in the supply do not appear as short,.. as the is measurable resistance...(less than 10 ohms,.. is this normal?).

Now I'm thinking there may be issues on another board which is dragging the main supply down,.. causing the massive ripple and cycling,.. ( do not have a second scope,.. which makes life more difficult for sure ), But I think the supply may be in a cycle of dipping in and out,.. and failing to get to normal operation ,.. because of some down stream fault.

As the failing supply with also give the timebase scans trouble as there is nothing stable,.. I also noted prior to complete failure was that vertical calibration had gone to pot,.. simple DC signals of 5v did not show as 5v on the scope... so everything seemed to be in a cascade failure,.. but all leading be back to the power supply,.. but is this correct.

Before I start jumping in a stripping things apart,... isolating boards etc,... does anyone on have any pointers for me,.. as I am hoping someone may be able to offer some more informed paths to tread and try ,.. before I jump in with a soldering iron and spanners
many thanks


Re: Dumont knock off of Tek

cksamsung.ck@...
 

I'm new to this tekscope group. I was referred by someone at QRZ forum and
I hope I'm not being out of line. Does anyone know Dan Shores in Portland.

Chris K

On Fri, Jun 21, 2019, 7:54 PM Dave Seiter <d.seiter@...> wrote:

Funny how things come in groups; I've never seen a transistorized Dumont
scope in the flesh, but I literally stumbled on one this morning at an
estate sale. An R1062. I would have never given it a second look, except
for this post. It was clean, undamaged, and the guy offered it to me for
$5.... After digging up the proper HP power cord, I found out that it
actually works, so I'm going to donate it to my buddy until I get the 7603
working.
Anyone ever seen a service manual or schematics for the 1062? I took a
quick look at the interior, and I don't remember any of the pots being
labeled. The trace rotation and horizontal width need help.
The panel layout could have been greatly improved- the horizontal
centering is no where near the other horizontal controls, the delayed
trigger controls are prominent while the normal trigger is almost hidden,
and it took me forever to find the trigger source selector. That's what
you get when playing with a rackmount scope on a tabletop!
-Dave
On Thursday, June 20, 2019, 6:06:24 PM PDT, Bill Higdon via Groups.Io
<willard561=aol.com@groups.io> wrote:

I found this on the Seattle Craigslist

https://seattle.craigslist.org/oly/ele/d/olympia-dumont-766-series-oscilloscope/6913548974.html
Bill






Re: still trying to track down 2216 manuals

n7bfs
 

I have one of the 2216's and the original owners manual (in poor condition) and would love to find a service manual (electronic preferred).
If there are any updates on this thread it would be appreciated.
Also I have the rack mount 'ears' but the 'inserts' that go into the side 'holes' that hold the scope into the brackets are missing.
Does anyone have pictures or source of these little guys?
Looks like there are four per bracket.

Thanks for any tidbits on this nice 'digitizing' analog scope :)

Doug C


Re: Dumont knock off of Tek

Jim Potter
 

I'm guessing that scope didn't have any amplifiers or sweep. That meant you had to have big enough voltage signals to deflect the beam directly. It would be interesting to see more detailed specifications.

Jim

At 05:45 PM 6/22/2019, Brad Thompson wrote:
Bob Albert via Groups.Io wrote:

 The story I heard was that Dumont himself said that his company would always be the leader in oscilloscpes, somewhat akin to the president of Ford saying the Japanese could never erase the 20 year lead that Ford had.
Mr. Dumont didn't face reality. Then we see that his company made a Tek clone. I recall LaVoie for one doing that. Or was that LeCroy? Then Fairchild did it but they were the same as Dumont I think. I owned one and it was a good performer.
This corporate ball of snakes really puts so many at a disadvantage. Greed certainly turns out to be an enemy, but it's human nature apparently.
    On Saturday, June 22, 2019, 02:46:19 PM PDT, Richard Knoppow <dickburk@...> wrote:

   A strange decision for DuMont since they were deeply involved
with television.

On 6/22/2019 2:28 PM, Richard Solomon wrote:

From what I was told back in the 60's,
it was a Marketing decision.

Dumont believed there was no market
for high frequency scopes so they
concentrated on low frequency (500 Kc
max) high sensitivity (microvolts in some
cases) scopes.

Tektronix held the opposite belief (high
frequency).

We all know who made the right decision.

73, Dick, W1KSZ

Hello--

And before that, in 1934 General Radio offered an oscilloscope
(the model 687) with "useful" response to 130 MHz:

https://www.ietlabs.com/genrad_history/genrad_museum

Quoting from the museum site: "...GR decided not to make more oscilloscopes deciding that they were not precise enough for laboratory use and only useful in the radio service shop. Needless to say, that was a lost opportunity. However in 1938 they did make an advanced oscilloscope, the type 770, known as “Big Berthaâ€&#65533;, but it was only used internally and never sold...."

...Which begs an obvious question: given GR's reputation for building precision
instruments, why didn't someone on the staff tackle the "precision problem" and
make a good oscilloscope?

73--

Brad AA1IP

James M. Potter, PhD, President
JP Accelerator Works, Inc.
2245 47th Street
Los Alamos, NM 87544

TEL: 505-690-8701


Re: Dumont knock off of Tek

Brad Thompson
 

Bob Albert via Groups.Io wrote:

  The story I heard was that Dumont himself said that his company would always be the leader in oscilloscpes, somewhat akin to the president of Ford saying the Japanese could never erase the 20 year lead that Ford had.
Mr. Dumont didn't face reality.  Then we see that his company made a Tek clone.  I recall LaVoie for one doing that.  Or was that LeCroy?  Then Fairchild did it but they were the same as Dumont I think.  I owned one and it was a good performer.
This corporate ball of snakes really puts so many at a disadvantage.  Greed certainly turns out to be an enemy, but it's human nature apparently.
     On Saturday, June 22, 2019, 02:46:19 PM PDT, Richard Knoppow <dickburk@...> wrote:

      A strange decision for DuMont since they were deeply involved
with television.

On 6/22/2019 2:28 PM, Richard Solomon wrote:

From what I was told back in the 60's,
it was a Marketing decision.

Dumont believed there was no market
for high frequency scopes so they
concentrated on low frequency (500 Kc
max) high sensitivity (microvolts in some
cases) scopes.

Tektronix held the opposite belief (high
frequency).

We all know who made the right decision.

73, Dick, W1KSZ

Hello--

And before that, in 1934 General Radio offered an oscilloscope
(the model 687) with "useful" response to 130 MHz:

https://www.ietlabs.com/genrad_history/genrad_museum

Quoting from the museum site: "...GR decided not to make more oscilloscopes deciding that they were not precise enough for laboratory use and only useful in the radio service shop. Needless to say, that was a lost opportunity. However in 1938 they did make an advanced oscilloscope, the type 770, known as “Big Bertha”, but it was only used internally and never sold...."

...Which begs an obvious question: given GR's reputation for building precision
instruments, why didn't someone on the staff tackle the "precision problem" and
make a good oscilloscope?

73--

Brad  AA1IP


Re: 7CT1N

Harvey White
 

On 6/22/2019 6:45 PM, Dave Brown wrote:
Been some time (several years, now retired) since I used mine and loaned it
to a friend a few days back to check out-he thought he might buy it- but he
reckons it's got too low a refresh rate-something I don't recall. Yet to get
it back-could be a week or so- but wondered if there may be something
wrong with it that could cause this complaint? Any thoughts?
Not so much a problem, but that the traces are running at about a 60 hz rate, so 10 traces refreshes about 6 times a second (or less, since it's a half cycle).  That's where the flicker/refresh rate comes in.  On a 7904, I have not seen an objection from my point of view, but that's just me.

The refresh rate is inherent in the collector supply voltage.

Harvey



DaveB, NZ







Re: Dumont knock off of Tek

Bob Albert
 

The story I heard was that Dumont himself said that his company would always be the leader in oscilloscpes, somewhat akin to the president of Ford saying the Japanese could never erase the 20 year lead that Ford had.
Mr. Dumont didn't face reality.  Then we see that his company made a Tek clone.  I recall LaVoie for one doing that.  Or was that LeCroy?  Then Fairchild did it but they were the same as Dumont I think.  I owned one and it was a good performer.
This corporate ball of snakes really puts so many at a disadvantage.  Greed certainly turns out to be an enemy, but it's human nature apparently.

On Saturday, June 22, 2019, 02:46:19 PM PDT, Richard Knoppow <dickburk@...> wrote:

    A strange decision for DuMont since they were deeply involved
with television.

On 6/22/2019 2:28 PM, Richard Solomon wrote:
From what I was told back in the 60's,
it was a Marketing decision.

Dumont believed there was no market
for high frequency scopes so they
concentrated on low frequency (500 Kc
max) high sensitivity (microvolts in some
cases) scopes.

Tektronix held the opposite belief (high
frequency).

We all know who made the right decision.

73, Dick, W1KSZ
--
Richard Knoppow
dickburk@...
WB6KBL


7CT1N

Dave Brown
 

Been some time (several years, now retired) since I used mine and loaned it
to a friend a few days back to check out-he thought he might buy it- but he
reckons it's got too low a refresh rate-something I don't recall. Yet to get
it back-could be a week or so- but wondered if there may be something
wrong with it that could cause this complaint? Any thoughts?
DaveB, NZ


Re: Dumont knock off of Tek

Richard Knoppow
 

A strange decision for DuMont since they were deeply involved with television.

On 6/22/2019 2:28 PM, Richard Solomon wrote:
From what I was told back in the 60's,
it was a Marketing decision.
Dumont believed there was no market
for high frequency scopes so they
concentrated on low frequency (500 Kc
max) high sensitivity (microvolts in some
cases) scopes.
Tektronix held the opposite belief (high
frequency).
We all know who made the right decision.
73, Dick, W1KSZ
--
Richard Knoppow
dickburk@...
WB6KBL


Re: Dumont knock off of Tek

Richard Solomon <dickw1ksz@...>
 

From what I was told back in the 60's,
it was a Marketing decision.

Dumont believed there was no market
for high frequency scopes so they
concentrated on low frequency (500 Kc
max) high sensitivity (microvolts in some
cases) scopes.

Tektronix held the opposite belief (high
frequency).

We all know who made the right decision.

73, Dick, W1KSZ

On Sat, Jun 22, 2019 at 11:20 AM ken chalfant <kpchalfant@...> wrote:

Greetings,

I’m not sure it is fair to call a Dumont scope a Tek knock-off.

Allen B. Dumont opened his company in the 1930’s and was producing an
oscilloscope around 1943.

Tektronix was founded in 1946.

HP, founded in 1939 produced its first scope, the HP-130A, on or about
1956.

Initially Dumont was probably the leader in oscilloscope technology for a
few years, but Tektronix quickly took the lead.

The competition between Tek and HP was good for the industry in general
and Tek and HP specifically. Dumont was unable to keep pace. Perhaps
because Mr. Dumont was not as open to new ideas as was Tektronix and
Hewlett Packard leaders.

I believe Dumont was eventually acquired by Fairchild. I actually owned a
dual beam, four channel Fairchild/Dumont scope. I also owned a number of
other Dumont scopes. They really weren’t knock-offs.

Interestingly, a company named Lavoie made “exact” (well sort-of) Tek
knock-offs of the 53x and maybe the 54x scopes. The story I heard told
that this opportunity came about because the military was pressured to open
bid for scopes meeting the Tektronix specifications. I have used some
Lavoie scopes a long time ago. From the outside they looked almost exactly
like the Tek scope they copied, but the knobs were different. However,
they were not the same level of quality construction on the inside as the
Tek scopes.

That’s my two cents, FWIW.

Regards,

Ken


On 21Jun, 2019, at 8:54 PM, Dave Seiter <d.seiter@...> wrote:

Funny how things come in groups; I've never seen a transistorized Dumont
scope in the flesh, but I literally stumbled on one this morning at an
estate sale. An R1062. I would have never given it a second look, except
for this post. It was clean, undamaged, and the guy offered it to me for
$5.... After digging up the proper HP power cord, I found out that it
actually works, so I'm going to donate it to my buddy until I get the 7603
working.
Anyone ever seen a service manual or schematics for the 1062? I took a
quick look at the interior, and I don't remember any of the pots being
labeled. The trace rotation and horizontal width need help.
The panel layout could have been greatly improved- the horizontal
centering is no where near the other horizontal controls, the delayed
trigger controls are prominent while the normal trigger is almost hidden,
and it took me forever to find the trigger source selector. That's what
you get when playing with a rackmount scope on a tabletop!
-Dave
On Thursday, June 20, 2019, 6:06:24 PM PDT, Bill Higdon via Groups.Io
<willard561=aol.com@groups.io> wrote:

I found this on the Seattle Craigslist
https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fseattle.craigslist.org%2Foly%2Fele%2Fd%2Folympia-dumont-766-series-oscilloscope%2F6913548974.html&amp;data=02%7C01%7C%7C876efc5d49cb441305b208d6f6bce83b%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636967688537380724&amp;sdata=ZIv42ESyeEsQzekSauGT9UL28m0giBBp77fSyuKQdTk%3D&amp;reserved=0
Bill








Tdr cable 015-1023-00

NigelP
 

I have just acquired one of the above 1ns cables for the s-6 & s-52 & 7s12. Does anybody have info about how to use this cable..... Specifically about bending (or not !) ?


Re: Dumont knock off of Tek

Dave Brown
 


Re: 2467B Focus and A5 issues

satbeginner
 

Hi all,

again some progress today:

I had to rebuild the entire DAC reference circuit using new resistors -flying wire style- because they were all toast and many traces were either gone or disconnected somewhere.
But, at least it will start now, but of course it gave a "Test 4 Fail 11" message.

I first tried to deactivate the electrolyte using sodium-bicarbonate (baking soda), but in the end cleaning it with Lidl W5 kitchen degreasing spray, a soft toothbrush and warm water worked super!

After the rebuild, the weird thing was, that although I could move the traces from top to bottom, the readout was only about 4 divisions apart, so not at the top and bottom of the screen.
Using the two trimpots on the a5 board would move them, but only like a half division max.

That turned out to be a damaged 155-0137-00 Vertical Out (U600), so that was an existing problem, but not visible previously.
These are still (more or less) available, so that can be resolved later.
For now, I consider myself lucky, because I was able to temporarily solder the one broken contact, and for now it is working again.

Being the optimist, I started with a first attempt to calibrate, but after the CRT adjustments and entering Cal-1 I realized there was more fun ahead, noe of the number of markers per graticule made sense.
It looks af is there is a factor of 5 error in the timebase, (the picture is showing 1kHz markers) so that will be the next thing to look at, but for now I am quite happy with the result so far :-)

Again, some pictures here: https://groups.io/g/TekScopes/album?id=92199

To be continued,

Un saludo,

Leo


TM-506 TM-515 mainframes free to good home

ebayatessnh
 

I have two TM-506 and one TM-515 mainframes that I am parting with. All in good (for their age) condition, and worked last time they were powered up (about 10 years ago).They are free, but you will have to pay for shipping from southern NH and boxing up at a UPS store. Or local pickup would be even better, I'm sure you would leave with more than just the mainframes. Email me off list if you are interested.


Re: Dumont knock off of Tek

ken chalfant
 

Greetings,

I’m not sure it is fair to call a Dumont scope a Tek knock-off.

Allen B. Dumont opened his company in the 1930’s and was producing an oscilloscope around 1943.

Tektronix was founded in 1946.

HP, founded in 1939 produced its first scope, the HP-130A, on or about 1956.

Initially Dumont was probably the leader in oscilloscope technology for a few years, but Tektronix quickly took the lead.

The competition between Tek and HP was good for the industry in general and Tek and HP specifically. Dumont was unable to keep pace. Perhaps because Mr. Dumont was not as open to new ideas as was Tektronix and Hewlett Packard leaders.

I believe Dumont was eventually acquired by Fairchild. I actually owned a dual beam, four channel Fairchild/Dumont scope. I also owned a number of other Dumont scopes. They really weren’t knock-offs.

Interestingly, a company named Lavoie made “exact” (well sort-of) Tek knock-offs of the 53x and maybe the 54x scopes. The story I heard told that this opportunity came about because the military was pressured to open bid for scopes meeting the Tektronix specifications. I have used some Lavoie scopes a long time ago. From the outside they looked almost exactly like the Tek scope they copied, but the knobs were different. However, they were not the same level of quality construction on the inside as the Tek scopes.

That’s my two cents, FWIW.

Regards,

Ken

On 21Jun, 2019, at 8:54 PM, Dave Seiter <d.seiter@...> wrote:

Funny how things come in groups; I've never seen a transistorized Dumont scope in the flesh, but I literally stumbled on one this morning at an estate sale. An R1062. I would have never given it a second look, except for this post. It was clean, undamaged, and the guy offered it to me for $5.... After digging up the proper HP power cord, I found out that it actually works, so I'm going to donate it to my buddy until I get the 7603 working.
Anyone ever seen a service manual or schematics for the 1062? I took a quick look at the interior, and I don't remember any of the pots being labeled. The trace rotation and horizontal width need help.
The panel layout could have been greatly improved- the horizontal centering is no where near the other horizontal controls, the delayed trigger controls are prominent while the normal trigger is almost hidden, and it took me forever to find the trigger source selector. That's what you get when playing with a rackmount scope on a tabletop!
-Dave
On Thursday, June 20, 2019, 6:06:24 PM PDT, Bill Higdon via Groups.Io <willard561=aol.com@groups.io> wrote:

I found this on the Seattle Craigslist
https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fseattle.craigslist.org%2Foly%2Fele%2Fd%2Folympia-dumont-766-series-oscilloscope%2F6913548974.html&amp;data=02%7C01%7C%7C876efc5d49cb441305b208d6f6bce83b%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636967688537380724&amp;sdata=ZIv42ESyeEsQzekSauGT9UL28m0giBBp77fSyuKQdTk%3D&amp;reserved=0
Bill





TDS520B - the screen gradually expands and then darkens in about 20 mins

unclebanjoman
 

Hi all,

I got that dam'd TDS520 to repair. Powered up, it works perfectly.
Then, the screen gradually expands and then darkens in about 20 mins. The process initially is very inappreciable, and gradually accelerates over time.

I dismantled the display board and its associated CRT to make it work out of the oscilloscope (it's connected to the main chassis with a flat cable only).

Searching for some component in thermal runaway, using coolant spray give me no result. Mumble...

I made some voltage measurement. The A20 board uses only the +24 V supply from the main PSU and uses an LM317 to step down to +21 V.
When the screen starts to expand visibly (and darkens) the +21 V decreases rapidly down to +15/16 V and the LM317 becomes damn hot! Surely and excessive current is drawn from it.

I've changed the C308 speed-up capacitor (base of Q205) with no results.
I'll check the Q205 drive signal to see if it changes over time but I'm strongly oriented toward a failure in the flyback transformer T225.

I know already know that this transformer model is practically unobtainable (120-1841-00).
I wonder that an equivalent or similar transformer cannot be found that can be adapted. I don't think it's such a so critical component!

What is your opinion?

Thanks,

Max


Re: HP 547a Current Tracer probe useful in finding shorted Capacitors ... was ... Most common capacitor spot failure in 7K scopes?

 

That 4270A contains lots of other
sweets, like a nixie tube display!
Oops, almost wandering off to the other side!

Raymond