Date   

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@ix.netcom.com
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@msn.com> 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@att.net> 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@att.net> 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


Re: PG-506 Calibration Generator parts needed

Craig Cramb
 

I have some PG506 modification kits that that are new parts and include this transistor. Contact me off list electronixtoolbox@gmail.com if you are interested.

Craig


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

 

On Sat, Jun 22, 2019 at 04:31 PM, Harvey White wrote:


Some probes had the BNC on them, those were meant to be used with the early
logic analyzers which had 5 volts on a BNC at the back
...and for troubleshooting the HP 4270A Automatic Capacitance Bridge, which to my surprise contains a 5V BNC socket inside, marked "Logic Probe"...
That 4270A contains lots of other sweets, like a nixie tube display!

Raymond


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

Harvey White
 

On 6/21/2019 10:32 PM, Dave Seiter wrote:
Was the clip-on logic probe part of the same family? (the one that clips on to a 14/16 pin DIP and auto senses the power pins) The pouch I have for the probe set also has a pocket for the clip-on probe.  A very cool tool, but I haven't used it since about 1985.
There were several sets.  3 probes, logic clip (maybe) in a pouch.  Ditto  (minus the current probe but definitely with the clip) in a box, optimized for TTL.  Much larger box with a clip on logic analyzer dongle that does individual chips.

Note that there were several varieties of logic probe and pulser, one optimized for TTL, one general use.  (T on the end of the model number)

Some probes had the BNC on them, those were meant to be used with the early logic analyzers which had 5 volts on a BNC at the back (I'll never understand why HP decided that back was good for short cables...)

the grabbers that will work are the ones with round pins, such as the ones for the very early LA's such as 1600, 1610, or so.

Harvey



-Dave
On Friday, June 21, 2019, 11:11:28 AM PDT, Jack Reynolds <jackandladyreynolds@gmail.com> wrote:
Finding these for sale seems to be nearly impossible.  They appear to be
relatively low part count large component devices. It has also
apparently been quite a few years since they were for sale.  Hasn't
anyone copied them and made them for sale under another name by now.  Or
is this another case of so few people wanting to do component level
troubleshooting any more that there is no market?

Jack Reynolds

On 6/21/2019 1:19 PM, garp66 wrote:
Sometimes I use a common 9V battery cell with clip leads to independently power up the HP 547a Current Tracer, independent of the PCB that I am testing, thus isolating the PCB board power( with PCB either On or Off). The Logic Pulser HP 546a can also be powered independently with a 9V cell. Of course one can also connect  the 9V battery neg. terminal to the PCB-under-test, Or not, depending on various test issues, TBD, that one encounters.

These two small simple bits of HP test gear have well proven their worth-in-weight for many many years.

An HP AP Note  (.pdf) # 163-2, on these probes is available:
http://hpmemoryproject.org/an/pdf/an_163-2.pdf

A HP Bench Brief (.pdf)  is also useful:
http://hparchive.com/Bench_Briefs/HP-Bench-Briefs-1977-09-10.pdf

rick








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

tekscopegroup@...
 

Yes the logic clip is part of the set:

HP545A = Logic Probe
HP546A = Logic Pulser
HP547A = Current Trace Probe
HP548A = Logic Clip

You can find them sometimes as a set on ebay, but usually selling north of $400-600. I think this set sold new back when at around $1000 (or more), the 547A alone was around $400. But on rare occasions the price of a set on ebay will be extremely good. About 1.5 years ago I finally found a set of the 3 probes with the carry case all in very good condition from a seller in Germany for about EUR 160, shipping included. At the same time there was also a logic clip for sale from a US seller at $45 so I got it as well to complete the set. The case actually has a separate pocket just to slip in the clip.

The Logic clip is very versatile, just clip it onto the IC and it will automatically figure out which pin is Vcc and GND and start to operate. Used mine just last night along logic probe and pulser to test a counter design in building process. The pulser is a work of art, with all the choices of different pulse stream rates that can be selected just by a single push button.

More recently about a year ago there was again on ebay a set of the 3 probes with the case for a mere $100 Buy It Now. I was about to get it as well but then tough to leave it for someone else. The set was gone in the next 10 minutes. And just a few weeks ago there was another set that was sold for $135 BIN. This time I saw the listing on the results page as still available and decided to go after it, but when I went to the actual listing it was already listed as sold. Then just to confirm went back to the results page and it was still there, so I guess the ebay database was just taking its time to update.

BTW the light bulbs used in both the logic and current probe (5V 60mA "Grain of Wheat") are still available cheaply at Mouser for about a dollar a piece if I remember correctly. I bought 10 just in case for any foreseeable future needs and then some. At the time there where still 180 available in stock. If anyone needs the Mouser PN just let me know. Not that these bulbs are going to burn out any time soon, but I figured that the filament or the bulb might break if the probe is accidentally dropped. But hopefully not with the current sensor side hitting the ground as it would then be toast for good and no more bulb needed.

Alex


PG-506 Calibration Generator parts needed

henasau@...
 

I had misfortune and snapped off transistor's leg beyond repair. Tektronix part number 151-1108-00
Unfortunately this is enhanced N-Channel Mosfet Q758 (VN99AK) in high amplitude section.
Some parameters according to data sheet: VDS 90V, IDS 2A, VGS is low 0.8-2v with RDS 5 ohm.
I would imagine, it would be very hard to get one. Any idea if I could use something modern instead.
Perhaps someone has PG-506 parts unit and could sell this transistor to me.

Any help is appreciated.


Re: TG-506 generator plug-in part needed.

tom jobe <tomjobe@...>
 

Is there such a thing as a TG-506?

On 6/22/2019 12:01 AM, henasau@hotmail.com wrote:
I had misfortune and snapped off transistor's leg beyond repair.
Unfortunately this is enhanced N-Channel Mosfet Q758 (VN99AK) in high amplitude section.
Some parameters according to data sheet: VDS 90V, IDS 2A, VGS is low 0.8-2v with RDS 5 ohm.
I would imagine, it would be very hard to get one. Any idea if I could use something modern instead.
Perhaps someone has PG506 parts unit and could sell this transistor to me.
Any help is appreciated.


Re: TG-506 generator plug-in part needed.

tom jobe <tomjobe@...>
 

Perhaps if you provided the Tektronix part number your luck would improve?
Also do a search of the Internet using the Tek part number.

On 6/22/2019 12:01 AM, henasau@hotmail.com wrote:
I had misfortune and snapped off transistor's leg beyond repair.
Unfortunately this is enhanced N-Channel Mosfet Q758 (VN99AK) in high amplitude section.
Some parameters according to data sheet: VDS 90V, IDS 2A, VGS is low 0.8-2v with RDS 5 ohm.
I would imagine, it would be very hard to get one. Any idea if I could use something modern instead.
Perhaps someone has PG506 parts unit and could sell this transistor to me.
Any help is appreciated.


Re: 7603 center slot connector issue (was Dead 7603)

Vintage Test
 

Hi Jim,

I remember offering you a connector back when you first asked, but you never sent me your address! Strangely, I was clearing out my lab and found the connector, packed up and ready to go! Would you still like it?

Cheers,
Mel

--
you can never have enough oscilloscopes, DMMs, valve testers or soldering irons . . .


Re: 7603 center slot connector issue (was Dead 7603)

hpxref
 

Jim, had these come off on a 7603   years ago,

mine weren't broken just bowed.  On the 7603 I used a pencil eraser, the large draftsman type

and pushed/wedged  it between the shell and the adjacent PC board. This held the shell against the contacts

and its still working many years later.  I would send you a pix, but I plugged my 7L14 into my 7603  a year ago

as a permanent fixture and just found it jammed in and cant unplug it without fear of breaking the pull tab

Many plug ins inserted and removed b4 that with no probs.

The 7603 had an LHS  plug in shell  come off too, and since there is no pc board adjacent that I fixed a small

Al bracket on the frame to hold that one in with the  compressed eraser.

I used hi quality erasers , Staedler, which have stood the test of time , maybe hard to get now with the demise of

penciled/ inked  drafting?  Maybe you could use two to press in both glued halves?

Cheap and quick enough to give it a go

Rgds

John


Re: Most common capacitor spot failure in 7K scopes?

Dave Seiter
 

If you have a dead logic analyzer probe laying around, the individual probe tips might have the same square ID/OD as the probe power pins.  
-Dave

On Friday, June 21, 2019, 6:51:54 AM PDT, Carsten Bormann <cabocabo@gmail.com> wrote:

On Jun 21, 2019, at 13:20, george edmonds via Groups.Io <G6HIG=yahoo.com@groups.io> wrote:

The original HP547A was designed to use mini grabbers to power it up, the pulser is a 546A and there was also a logic probe in the same familly.
Yes.  I’m trying to put together a more permanent way to supply the probe; it would be great to find the connectors mating to the ones that go into the grabbers now (and that would also allow me to apply a better ground lead to the pulser, which seems to have the same connector).

(Sorry if this is too off-topic for tekscopes, maybe I should have asked on the HP group.)

Grüße, Carsten

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