Date   

Re: 475A for sale

DaveH52
 

I recently brought my 2465 back from the dead thanks, in large part, to my 465M that I also brought back from the dead. I learned early, while bringing a 510, 511 and 511A back from the dead in my teens (c. 1968) , that you can't troubleshoot a bad scope with itself, you need another scope.
The marker might clean up with alcohol or mineral spirits, CH2 might need a new capacitor somewhere, and the mag switch could probably use a dose of contact cleaner if you can get it in there. A general cleaning and close inspection inside might instill a sense of reverence for the instrument.
The 475 is a fine 200MHz scope and I used one for years in a small production shop, until I got my hands on a 350 MHz 485 to use


NEW SUBJECT: Comprehensive list of Phosphors WAS: Blue phosphor scopes

 

The BEST (and as far as I know the ONLY) extremely comprehensive reference list of CRT phosphors I have ever found is the one compiled by Patrick Jankowiak KD5OEI from many different sources. It includes:
* The RMA/EIA phosphor designations (e.g. P1, P7, P11...).
* The International E.U. phosphor designations (e.g. GK, WW, YX...).
* Samples of each phosphor’s fluorescence and phosphorescence emission color.
* Each phosphor’s peak wavelength, wavelength range, persistence, and/or decay times.
* Each phosphor’s chemical composition.
* The applications each phosphor was developed for or used on.
You can download your own copy of this comprehensive reference on CRT phosphors at:
http://www.bunkerofdoom.com/tubes/crt/crt_phosphor_research.pdf

While you are there I recommend that you take a look at the rest of the unique and fascinating site where this CRT phosphor reference is located. This is the "Bunker of DOOM". It contains all sorts of "Timeless Information for Retro-Tech Hobbyists and Hardware Hackers... We continue to offer the finest and most Obscure Classical Electronics information we can find, and recent items of possible interest".
Patrick Jankowiak KD5OEI is the mastermind of this site. As he says "There is only one original and true Bunker of DOOM and this is it":
http://www.bunkerofdoom.com/

Be careful. Before you know it an hour has passed and you still haven't explored more than a fraction of Patrick's fascinating collection of information.
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Reginald Beardsley via groups.io
Sent: Thursday, June 25, 2020 10:20 PM
To: TekScopes@groups.io
Subject: [TekScopes] Blue phosphor scopes

Did anyone other than Tek make scopes with blue phosphors? I was chatting with a friend and neither of us could think of anyone. All either of us had seen was green CROs.

Have Fun!
Reg





--
Dennis Tillman W7pF
TekScopes Moderator


sw503

John Ferguson
 

The  SW503 seems scarce.  Does anyone have a working unit which they might part with for a modest price?

If this is a goofy request, let me know why.


Re: Genealogy

Dale H. Cook
 

Sorry abut that folks - I still haven't mastered my new email client - that should have gone to Miles and not to the list.
--
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
https://plymouthcolony.net/starcity/radios/


Re: Blue phosphor scopes

Bert Haskins
 

On 6/26/2020 8:12 PM, Harvey White wrote:
Thanks, got it almost right.

I think that the "black trace" was calcium chloride, BTW.

Now for fun, has anyone heard of a 3DP7?  I had one once.

Harvey


On 6/26/2020 7:25 PM, Kurt Swanson wrote:
My 545 way back when had a blue trace that was almost certainly P11.  Very hard on the eyes.

Some scopes prior to WWII had white P4 traces, while others had light blue P5 for fast photography.  Most had green P1, though, until P31 was invented, which is almost burn proof.

The tri-color TV CRT is P22, while the "black" trace CRT is P10.  I have a 4AP10 in my collection, and I have been scheming about powering it up one of these days...

Regards - Kurt

I have a NOS RCA 3WP1 with a mu metal shield that I bought new many years ago.

I bought it for a backup for a scope I was traveling with, and never even powered it up.

This is about the lowest deflection voltage crt ( no PDA ) that was made.

I wonder if there would be anyone interested in it.

I have a bunch of other types also.

Some are P7.

--  Bert



Re: Genealogy

Dale H. Cook
 

On 6/27/2020 11:16 AM, you wrote:

I'm not familiar with the USGenWeb project. After some chores today I will look into it.
Miles -

It is the largest volunteer genealogy project in the country. The site for West Springfield is at:

https://sites.rootsweb.com/~mahampde/towns/westspringfield/index.html

but there is not much information there. You might find other resources at the Hampden Co. page:

https://sites.rootsweb.com/~mahampde/index.htm

I worked in West Springfield a couple of times when I was in my 20s and living in Amherst.
--
Dale H. Cook, Member, NEHGS, AGS, MA Soc. of Mayflower Descendants;
Plymouth Co. MA Coordinator for the USGenWeb Project
Administrator of https://plymouthcolony.net


Re: (OT) repair tools: Autotransformers/variacs

Dave Voorhis
 

On 27 Jun 2020, at 15:37, Dale H. Cook <bridgewaterma@...> wrote:


On 6/26/2020 10:54 PM, Jim Ford wrote:

You can always correct it. That's the beauty of it.
The ugly of it is that someone else can uncorrect it.
True, but Wikipedia trends over time toward correctness.

The problem with printed and non-editable Web-based encyclopaedias is that their wrongness is set in stone.


Re: Tektronix 2230

satbeginner
 

Hi,

Try this very good document of Håkan :

http://www.hakanh.com/dl/docs/troubleshooting_tips_on_2200_ps.pdf

If you remove the switching transistor, you can feed a 43VDC into the scope to temporarily bypass the grid power supply.
That way you can eliminate possible overloads further down into the scope.

Succes,

Leo


Genealogy

Roy Morgan <k1lky68@...>
 

Dale,

I notice your deep involvement in genealogy.

I am a descendant of MilesMorgan who settled West Springfield (1600's)..there is a statue of him in Court Square.

I'm not familiar with the USGenWeb project. After some chores today I will look into it.

See
Morganhomesite.com
For developments about Justin Morgan of horse fame

Roy Morgan
K1LKY Western Mass

On Jun 27, 2020, at 10:37 AM, Dale H. Cook wrote
...
--
Dale H. Cook, Member, NEHGS, AGS, MA Soc. of Mayflower Descendants;
Plymouth Co. MA Coordinator for the USGenWeb Project
Administrator of https://plymouthcolony.net


Tektronix 2230

Saroj Pradhan
 

Hi everybody
I have a tektronix 2230 that I got from one of my friends and that was
lying with me for one year. Last week I tried to put on it. But
unfortunately the ac line tripped. I opened the scope and with tedious
effort got access to the power supply section. Checked it with multimeter
found the following:
Two bridge rectifiers shorted.
Q9070 shorted
CR907 shorted
Q908 shorted
R909 opened
U930 cracked
CR908 shorted

I replaced all the defective components and all electrolytic and other
fixed capacitor capacitors in both inverter section and low voltage side. I
have not changed the capacitor in the line filter, C908, C904, C922 and
C919.
After doing that I again put on the scope this time it took away q9070
Cr907and all the rectifier diode.
Then checked the resistance between tp950 and tp940 it was very low around
8Ohms.it turned out that cathode and anode of Q935 was shorted. I did not
have the correct replacement so just desoldered Q935. According to the
manual this transistor protects the power supply from high voltage at tp950
and hi current of Q946 and Q947.
After replacement of other burnt components I put on the scope this time
with current limiter bulb.i experienced following behaviour:
Bulb was flashing with a ticking sound at the frequency of around 60 times
in one minute. I could see two of the small bulbs in the main board also
flashing in same frequency.
Measured some voltages at different points
At every points of measurement voltages were jumping.
Measurements are as follow:
Voltage at C906 varies from around 130 to 285v
Voltage across C925 varies from 12 to 20v
Voltage across tp950 and tp940 varies from 1 to 9v
U930 pin voltages with respect to u930 ground pin
Pin 1 0v
Pin 2 0.1 to 0.8v
Pin 3 0 to 0.3v
Pin4 0v
Pin5 almost 0v
Pin6 0 to 1.5v
Pin 8 12 to 20v
Pin 9 5 to 7v
Pin 10
Sent from my Huawei phone


Tektronix 2230

Saroj Pradhan
 

Hi everybody
I have a tektronix 2230 that I got from one of my friends and that was lying with me for one year. Last week I tried to put on it. But unfortunately the ac line tripped. I opened the scope and with tedious effort  got access to the power supply section. Checked it with multimeter found the following:
Two bridge rectifiers shorted.
Q9070 shorted
CR907 shorted
Q908 shorted
R909 opened
U930 cracked
CR908 shorted

I replaced all the defective components and all electrolytic and other fixed capacitor capacitors in both inverter section and low voltage side. I have not changed the capacitor in the line filter, C908, C904, C922 and C919.
After doing that I again put on the scope this time it took away q9070 Cr907and all the rectifier diode.
Then checked the resistance between tp950 and tp940 it was very low around 8Ohms.it turned out that cathode and anode of Q935 was shorted. I did not have the correct replacement so just desoldered  Q935. According to the manual this transistor protects the power supply from high voltage at tp950 and hi current of Q946 and Q947.
After replacement of other burnt components I put on the scope this time with current limiter bulb.i experienced following behaviour:
Bulb was flashing with a ticking sound at the frequency of around 60 times in one minute. I could see two of the small bulbs in the main board also flashing in same frequency.
Measured some voltages at different points
At every points of measurement voltages were jumping.
Measurements are as follow:
Voltage at C906 varies from around 130 to 285v
Voltage across C925 varies from 12 to 20v
Voltage across tp950 and tp940 varies from 1 to 9v
U930 pin voltages with respect to u930 ground pin
Pin 1 0v
Pin 2 0.1  to 0.8v
Pin 3 0 to 0.3v
Pin4 0v
Pin5 almost 0v
Pin6 0 to 1.5v
Pin 8 12 to 20v
Pin 9 5 to 7v
Pin 10 0 to 3v
Pin 11 12 to 20v
Pin12 0 to 6.6
Pin 14  0 to 1.8v
Pin 15 0v
Pin 16 0v
I red some where to test u930 with external power supply so I wanted to checked the voltages at u930 pins with externally applying voltage across C925 so I put off the scope and connected external power supply across C925 and increased the voltage at around 23v I could see few milliamp in the display of external power supply. I then decreased the voltage to 14 volt and did measure voltages at different pins of u930 and they are as follow
Pin1 0v
Pin2 4.37v
Pin3 0v
Pin4 0v
Pin5 1.66v
Pin6 3.57v
Pin8 13.9v
Pin9 12.6v
Pin10 11.78v
Pin11 13.9v
Pin12 13.9v
Pin13
Pin14 4.9v
Pin16 0v
As suggested in u930 testing document there was no pulse in pin5 and pin10.
I have 50 MHz keysight. Till now I was hesitating to scope around tek 2230 because I do not have isolation transformer. Because u935 was supplied with external supply I Scoped at test point 44 and 45.At point I got the ramp and 56KHz pulses at 44 with 94%duty cycle.
I will put Q935 once I have the proper replacement. People are using mcr72 scr as Q935. I have some tyn series scr shall I select one with proper voltage and current rating and replace for Q935?
And please some suggest and me to rectify my issue with tek2230.
By the way for cr908 I used 1n4148 and for cr908 I used 1n4007.
Sent from my Huawei phone


Re: 2215 CRT problem, PSU filtering?

 

First, do you have any LED lamps in the near area? Some of them radiate a lot of trash.

Make sure the CRT shield has a good ground connection.

It probable is a good idea to check/replace the PS filter caps while you are in there. See manual for what to order.

The probe waveform is a negative 0.5 volts. See waveform #34 in the service manual.

Regards,

Tom

On 6/26/2020 1:28 PM, Maxsimmonds1337@... wrote:
Hi Everyone,

I have just bought a scope (tek 2215) which initially would not power on. I was able to fix this (it was a simple faulty power switch). Everything seems to be working except that there's a distinct rippled on both channels - even when they're set to ground!

Does anyone know what's the first thing I should look into? My guess is some sort of power supply filtering caps need replacing - but a visual inspection doesn't show any blow electrolytics. Here's an image of the ripple I'm talking about:

https://imgur.com/a/Yc4GrBi

You can see it's about 20mV ripple, at around 125KHz.


On another note, should the probe adjust output be negative? I'm sure it's showing a -500mV square wave?!

Thanks in advance!

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


Re: (OT) repair tools: Autotransformers/variacs

snapdiode <snapdiode@...>
 

That's a mighty jaundiced eye you got there.


Re: (OT) repair tools: Autotransformers/variacs

Dale H. Cook
 

On 6/27/2020 12:49 AM, Dennis Tillman wrote:

I have a booklet GR produced for the Strobotac with many classic pictures Doc Edgerton took of things frozen at the critical instant in time when something remarkable just happened.
I met Doc when I was a student in the MIT High School Studies Program in the mid '60s. Early on I spent some time wandering around and familiarizing myself with campus. In one corridor there were display cases with many of those photos and prototypes and production models of the Strobotac. A man walked out of an office, saw me intently looking at the cases, and introduced himself - it was Doc.
--
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
https://plymouthcolony.net/starcity/radios/


Re: (OT) repair tools: Autotransformers/variacs

Dale H. Cook
 

On 6/26/2020 10:54 PM, Jim Ford wrote:

You can always correct it.  That's the beauty of it.
The ugly of it is that someone else can uncorrect it.
--
Dale H. Cook, Member, NEHGS, AGS, MA Soc. of Mayflower Descendants;
Plymouth Co. MA Coordinator for the USGenWeb Project
Administrator of https://plymouthcolony.net


Re: (OT) repair tools: Autotransformers/variacs

n4buq
 

Coincidentally, I've been looking at getting one of those over the last few days. Unfortunate what the bulbs cost for them these days. I suppose if I watch long enough...

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Dennis Tillman W7pF" <dennis@...>
To: TekScopes@groups.io
Sent: Friday, June 26, 2020 11:49:10 PM
Subject: Re: [TekScopes] (OT) repair tools: Autotransformers/variacs

I have a GR Strobotac. It is fascinating instrument to have when studying
repetitive mechanical motion. I know how brilliant Doc Edgerton is as well.
I have a booklet GR produced for the Strobotac with many classic pictures
Doc Edgerton took of things frozen at the critical instant in time when
something remarkable just happened.

I used to put on stroboscope demonstrations in my daughter's elementary
school. For the grand finale I connected a WaterPik "massage" shower head to
the sink in her classroom. The shower head had a few different settings that
made the water pulse or rotate out of different nozzles. By synchronizing
the strobe with the shower head the water pulses coming out of the shower
head could be gradually slowed down and brought to a standstill in front of
their eyes. And then I would very gradually increase the strobe speed just a
little more to make the pulses of water defy gravity and go backwards up
into the shower head.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Richard
Knoppow
Sent: Thursday, June 25, 2020 9:46 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] (OT) repair tools: Autotransformers/variacs

A nit-pik: Harold Edgerton was a professor at MIT. There is a short bio
at:
<https://en.wikipedia.org/wiki/Harold_Eugene_Edgerton>
GR developed the stroboscope, based on Edgerton's patents, commercially.
GR was known for the Strobotac and other strobe instruments almost as
much as the Variac.
Edgerton formed a company with a couple of MIT grad students to develop
his inventions. See:
<https://en.wikipedia.org/wiki/EG%26G>
Beside the stroboscope Edgerton was responsible for the single flash
strobe lights which became so common in photography.
The earliest ones were made by Eastman Kodak under the name Kodatron. These
were large units meant for studio use. At the time Kodak was promoting
Kodachrome, initially a very slow film, so the availability of high
intensity strobe lights was highly desirable to them.

On 6/25/2020 8:55 AM, Dale H. Cook wrote:
On 6/25/2020 11:02 AM, Dennis Tillman wrote:

Eduard Karplus, along with 2 other GR Engineers, created the famous
GR-874 connector which also had a long useful life because of its
outstanding bandwidth and its unique sexless design.
Like the Variac, the GR-874 connector is simple and reliable.
Dennis -

Thank you for the information about Eduard Karplus. I enjoyed learning
that he was involved in the design of two GR lines that I frequently
use - the Variac and 874 connectors. I have a large tackle box holding
the many 874 standards, adapters, filters, cables, and accessories
that I use in the shop and in the field with many GR instruments.

The only GR engineers whose work I am fairly familiar with are Harold
Edgerton (whom I met while in high school) and Henry Hall (I own some
of the bridges he designed).

General Radio, like Tektronix, was a company where the engineers were
known for creating outstanding products.
I think that was also true of HP in its heyday. The vast majority of
the instruments that I own are GR, HP, and Tek, and some of them still
see frequent (and many others occasional) use in the field. Other
instruments from those three see regular use in my shop.
--
Richard Knoppow
dickburk@...
WB6KBL






--
Dennis Tillman W7pF
TekScopes Moderator




Re: TDS series: cleaning buttons and 'flex board'

Siggi
 

Þann lau., 27. jún. 2020 kl. 06:19 skrifaði Roger Evans via groups.io
<very_fuzzy_logic@...>:

A year or two back I was playing with one of the 'Nokia LCD display
modules' that are sold very cheaply for use with Arduinos and other
microprocessor projects. Some adhesive failed and the LCD itself parted
company with the PCB that provides the interface to the user accessible
pins. The LCD ribbon cable was neither soldered to the PCB or went to a
proper socket but was simply sandwiched to the 'user' PCB with a small
strip of black foam rubber, the PCB contact tracks were the same pitch as
the LCD ribbon tracks and the rubber clearly connected each track to its
partner but not to the adjacent tracks. I checked this assmption by
measuring for continuity directly across the foam and then to a mm or so of
misalignment. I hadn't come across this 'one dimensional conductor' before
and I still haven't found the proper term to search for it online and find
how it is manufactured.

https://en.wikipedia.org/wiki/Elastomeric_connector?


Re: TDS series: cleaning buttons and 'flex board'

Roger Evans
 

Thanks for the eBay link to the button repair kits, I am intrigued by how they work since they have no knowledge of the geometry of the conductors that they have to bridge when the button is pressed.

A year or two back I was playing with one of the 'Nokia LCD display modules' that are sold very cheaply for use with Arduinos and other microprocessor projects. Some adhesive failed and the LCD itself parted company with the PCB that provides the interface to the user accessible pins. The LCD ribbon cable was neither soldered to the PCB or went to a proper socket but was simply sandwiched to the 'user' PCB with a small strip of black foam rubber, the PCB contact tracks were the same pitch as the LCD ribbon tracks and the rubber clearly connected each track to its partner but not to the adjacent tracks. I checked this assmption by measuring for continuity directly across the foam and then to a mm or so of misalignment. I hadn't come across this 'one dimensional conductor' before and I still haven't found the proper term to search for it online and find how it is manufactured. I am very tempted to buy one of these kits if I can find a European seller, postage from the US can be prohibitive.

Regards,

Roger


Re: TDS series: cleaning buttons and 'flex board'

Colin Herbert
 

Thanks for the clarification, John. What had me puzzled was the mention of "gold foil"
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of John Crighton
Sent: 27 June 2020 01:49
To: TekScopes@groups.io
Subject: Re: [TekScopes] TDS series: cleaning buttons and 'flex board'

Hello Colin,

we are at cross purposes here.
You are are talking about contacts on the 7000 series and TM series
plug-ins.
The flexible rubber membrane behind the push buttons of the TDS series is
different.

Just like you, I could not see a problem using a cotton bud and ISO
until I ruined the flexible membrane.

How to safely clean the rubbery flexible membrane contacts is what Roger
wants to know.

Regards,
John Crighton
Sydney


----- Original Message -----
From: "Colin Herbert via groups.io"
<colingherbert@...>
To: <TekScopes@groups.io>
Sent: Saturday, June 27, 2020 4:07 AM
Subject: Re: [TekScopes] TDS series: cleaning buttons and 'flex board'


I often give the gold-plated edge contacts of 7000-series and TM-series
plug-ins that I have just purchased a wipe with IPA (isopropanol) on a
cotton-bud. I have never had a problem. So what on earth were you doing that
was different to what I do?
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of John
Crighton
Sent: 26 June 2020 14:48
To: TekScopes@groups.io
Subject: Re: [TekScopes] TDS series: cleaning buttons and 'flex board'

Hello Roger,
I swapped some bits and pieces of old test equipment for a non working
TDS320 oscilloscope.
The power supply is dead.

On YouTube there was a man describing how he restored a TDS??? oscilloscope
back to
working order by cleaning the dirty power switch contacts.

With enthusiasm, I jumped into to my TDS320 with a cotton bud soaked in ISO
and
with two strokes of the bud I had ruined the delicate contacts of the flex
board.
The gold leaf looking contacts had vanished and my cotton bud was black.

If I ever find the circuit diagram of the switch mode power supply for this
TDS320 and
get it working, I would be happy to use an external push button for the
power ON/OFF
switch. So all is not lost yet.

Roger, cotton buds and ISO, on that delicate gold leaf, I learnt the hard
way.

Did I rub too hard? I felt as though I was using a light touch.
Too much ISO on the cotton tip, so that the black carbon material under the
gold leaf
dissolved? Probably.
Find some cleaning liquid that does not dissolve the black stuff.

Regards,
John Crighton
Sydney


----- Original Message -----
From: "Roger Evans via groups.io" <very_fuzzy_logic@...>
To: <TekScopes@groups.io>
Sent: Thursday, June 25, 2020 8:40 PM
Subject: [TekScopes] TDS series: cleaning buttons and 'flex board'


I have recently acquired a TDS744A which is working fine but I have minor
concerns about the front panel buttons. The 'clear menu' button needs a
much firmer push than its neighbours around the screen and the Start/Stop
button near the large rotary control was originally not working at all but
cleared itself after I had struggled to get the chassis out of the (slightly
dented) cabinet!

There are warnings in the service manual about not touching either the
carbon points on the buttons or the flex board that the buttons mate
against. One of the very few references I have been able to find suggests
the traces on the flex board may be carbon / graphite. I am sure that many
TDS owners must have cleaned worn and dirty buttons and flex boards so can
anyone offer advice on solvents and techniques. I do have to hand a
conductive paint which is an aqueous solution of colloidal graphite (50
years ago it came under the tradename of Aquadag).

Many thanks,

Roger



---
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https://www.avg.com


Re: TDS7104 hard disk dead and blank screen

JOE
 

I am using one of the Windows 7 upgrades available on Ebay. Works great. I had some issues setting it up initially. The support from the seller was amazing. Note, no affiliation with the seller, just a satisfied customer.

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