TekScopes@groups.io

Re: 465 Scan Expansion Mesh

[email protected]

I believe you're right, Stan.  I'd heard both explanations.
Actually, the geometry story doesn't pan out well if you've ever seen
one of the guns outside of the jug.  the mesh is hemispherical in
shape.  If it dealt with geometry, I'd expect an odd shape to
compensate for the extremes of the rectangular screen.  For those who
have never seen one, it is interesting.  Very, very delicate, and so
fine that when you hold it up to the light, it's like a diffraction
grating, splitting the light up into different colors.  It's also so
fine that it will hold water.  One little puff of air and you dimple
it permanently.  I send a piece of a mesh to friend Dale Johnson
(used to work for Tek in the Dallas Service center, but at the time
was working for a company that serviced scanning electron
microscopes.  He put the piece of mesh under a scope and the view was
really interesting.  It's quiet obvious that it's etched and not a
woven screen that one first envisions.  I don't know whatever
happened to the Polaroid of that scan that I had.  It should would
make for an interesting post, but that was 25 years ago!

Sometimes, during manufacturing, a little dirt gets inside the jug
and finds its way to the mesh.  The resulting display is a small spot
on the CRT that just can't be illuminated by the beam because of the
shadow effect it creates.  I was rather irritated one time when a new
465B came in with that exact problem and the factory wasn't going to
honor a warranty replacement of the jug because it was "still within
all specifications of CRT anomolies".  I put myself in the customer's
shoes and decided that I wouldn't put up with a something like that
in the windshield of a new car.  Why should the customer put up with
a manufacturing defectlike that in his $3500 scope?  We replaced the
CRT anyway and shoved the old one down factory's throat.  Tek was
starting to change from a very customer-oriented organization to a
very money-conscious outfit.

And Stan, I don't know that I agree 100% about the mesh being a bad
deal compared to what the 535 had.  I've never seen a burned CRT in a
scope with a mesh and you can't say that about the old ones.  The
mesh diffused the beam enough that the CRT was pretty burn
resistant.  To me, the ±1 digit bobble of a digital scope is far
worse to look at than the fuzzy trace of a 465.

Dean

Tek 2230 Digital scope options

#225

Does anyone know where I can pick up the GPIB OPT 10 for the Tek 2230 
or the RS232 option?
Thanks,
Vince Coppola

Re: Tek 7904 Display Problem

Don Crano

#224

Hi Mark,

Yeah I remember posting a list of the YaHoo groups I belong to.

I know what you mean about the older scopes and their fine trace lines. My
old 453 is still on of my favorites, I can sync it on anything I feed into
it.<g>  Under it sits a 475A with it's mixed mode delay is nice, but does
not have the fine trace of the ol 453. On a Tekmobile 3 I have the 7904,
with the two lower shelfs each holding a TM504A, and both fully loaded with
plug-ins. So it is my mobile work bench, I can take it any where around the
layout as need be.<g> I really do not have a count of the 7K and TM plug-ins
I have and what works and does not work. But I am sure I do not have them
all. Then on my bench I have a 2230 for what ever analog/digital I might
need.

Don

  Remember Always Have Fun and Enjoy!,
  Don Crano   Akron, Oh   NMRA #096211
  mailto:donc@...
               Visit    Model Railroading with DCC at:
                          
               Join     Model Railroading with DCC Web Ring.

Show quoted text

----- Original Message -----
From: Mark Gurries <gurriesm@...>
To: <TekScopes@...>
Sent: Thursday, April 19, 2001 6:12 PM
Subject: Re: [TekScopes] Tek 7904 Display Problem

BTW Hi Mark Gurries glad to see you on the list.
Hi Don.

Been watching the list for a while.  It was from one of your email on the
DCC list that I learned about this list.  Anyway...

I told Jim Williams here at Linear Tech about this list.  (My Lab bench
is next to his.)  But he is not one to use PC's.  That Jim for ya.  For
those who are not familiar with Jim, he is one of out treasured assets at
the company.  Hi writes many application notes for our IC and tackling
problems and parts that cause most of us to glaze over our eyes in terms
of the accuracy or noise level requirements.  Things like how do you
verify all 24 bits of a 24 bit DAC!

The trick around here to getting a Tek scope fixed and checked out by Jim
Williams is to get an old 500 or 400 series scope in the lab.  Tell Jim
about it, and the fact that it does not work annoys Jim to no end.
Before you know it, he is digging into the scope and fixing everything.
Not that we cannot fix out own scopes mind you, but, Jim does a faster
and better job than anyone I know.  It fun to watch him and of course you
learn along the way the history and debug tricks.

We have about every make of Tek scope at the company labs.  We have lots
of 547's working in parallel with the latest Tek Scopes.  We just got
around to setting up an old 556 dual beam on another engineers lab bench.
 454's are another favorite.  A few of the guys have 7K stuff like yours.
  One of my employees has every 7K plug in made including some test
adapters if I recall correctly.  It amazing to see the latest scopes
setup right next to an old classic.  The biggest reason we like the old
400 and 500 series scopes is the very fine trace and excellent noise
floor.  When Jim sets up his 556 with two 1A4 plugins showing 8 traces
that are all beautifully detailed (4 of the traces are on a different
time base to boot)  published in a App note, we sometimes get letters and
calls about the scope photo alone!  How did you do that?

We think that our lab is one of the biggest consumers of electricity in
Silicon Valley with all these Tube Tek scopes on and possibly the source
of all the blackouts here in California.  We already went though one air
conditioner!  ;-0

Best Regards,

Mark Gurries
gurriesm@...

---------------------------------------------------------
Promotor of the DCC Standard for Model trains.
Model Railroad Club and NMRA DCC presentations are at:

--------------------------------------------------------
Audio Enthusiast (Love SAE equipment)

----------------------------------------------------------

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Re: 465 Display Help Needed

Stan or Patricia Griffiths

#223

CRT Mesh comment below:

dhuster@... wrote:

A few comments on what has been offered so far.

The characteristic fuzziness of a 465/475 and 7K scopes over their
earlier cousins (and which apparently is NOT your problem since you
describe major "focus" problems) is due to the inclusion of a scan
expansion mesh within the jug through which the electron beam has to
pass, causing a small amount of beam scatter.  The mesh is there to
improve geometry.My understanding of the reason an expansion mesh was used in 465 and later
vintage tubes was really to improve the vertical and horizontal sensitivity
of the CRT such that expensive transistors would no longer be necessary in
the vertical and horizontal scope amplifiers.  It was mostly a manufacturing
cost reduction measure with a spot size tradeoff.  Not a good tradeoff, in my
opinion.

Compare the output stages of the 547, 453, and 454 scopes to what you see in
the 465 and 475 and you will see what I am talking about.

Stan
w7ni@...

Re: 465 Display Help Needed

[email protected]

#222

A few comments on what has been offered so far.

The characteristic fuzziness of a 465/475 and 7K scopes over their 
earlier cousins (and which apparently is NOT your problem since you 
describe major "focus" problems) is due to the inclusion of a scan 
expansion mesh within the jug through which the electron beam has to 
pass, causing a small amount of beam scatter.  The mesh is there to 
improve geometry.

If oscillations within the vertical system is the problem, then 
inputting a sine wave will show  a thicker trace at the peaks and a 
thinner trace at the zero-crossing points.  Also, you'll see the 
signal from the vertical deflection plate pins on back to the source 
of oscillation.

Open elements inside the jug can cause defocusing.

Don't forget that astigmatism and focus interact and one may be the 
problem where the other is not.  If you can "round up" an unfocused 
stationary dot on the CRT with the astigmatism control, then focus is 
your problem.  If not, the astigmatism circuit may be at fault.

Make sure the LV power supplies are clean, correct and ripple-free.

Re: 465 Display Help Needed - another thought

#220

--- In TekScopes@y..., ashtonb@j... wrote:
--- In TekScopes@y..., Kurt Graber <kurtg@s...> wrote:


billw101@a... wrote:

Hello, I have been pulling problems out of a 465 that I recently
acquired. The last remaining problem is the inability to get a sharp
focus on the trace with any combination of intensity, focus or
astigmatism. I have checked everything in the CRT circuits with the
exception of the high voltage, crt bias and cathode bias, until I 
get
the use of an HV probe. Can anyone tell me if I am looking in the
right area or suggest any common failure modes? The low voltage
supplies all check good and noise free. Thanks for any help.
...........................................



Your use of Yahoo! Groups is subject to 

A common problem or failure is the opening of the voltage divider circuit
that the focus and astig tap into.
I am unfamilier with your particular scope but the chances are good 
that one
of the resistors has opened up. I have seen many cases !!! youdon't 
need a
HV probe , just take your meter and ohm them out. They will not appear burned
but they have a tendancy to open up due to the high voltage.......this will
cause an unsharp trace and many cases no trace at all (just a haze)...Good
LuckAnother point: the 46x, 47x series just wasn't as sharp as the tube 
scopes!  or even and especially - the 454, 454A.  Some engrs. think 
the 454A best 150 MHz scope ever (2mV/DIV, all the delaytriggering) 
or sometimes ~ 200 MHz if all went well on that assembly..  

I can see the  clear difference bewtween say, a 475A and the 454As- 
tiny wiggles just visible on 54-A disappear into the thick trace of 
475 (or 465).

Just in case you're trying to do better than it Can!


AshtonAShton, yes I have heard that same thing about the 465, however after 
troubleshooting I am further able to describe the problem. The 
transition of the trace either falling or rising is poorly defined 
and instead of one sharp edge I see almost a centimeter of blur. I 
have been through the video output amplifier from one end to the
other but I still have the symptom that any capacitance such as a 
scope lead hung on either vertical deflection output causes the 
amplifier to go into high freq. oscillation and the trace becomes a 
fog. I will press on but there is definitely something wrong with
this thing.

Bill

Re: 465 Display Help Needed - another thought

Stan or Patricia Griffiths

#221

billw101@... wrote:

AShton, yes I have heard that same thing about the 465, however after
troubleshooting I am further able to describe the problem. The
transition of the trace either falling or rising is poorly defined
and instead of one sharp edge I see almost a centimeter of blur. I
have been through the video output amplifier from one end to the
other but I still have the symptom that any capacitance such as a
scope lead hung on either vertical deflection output causes the
amplifier to go into high freq. oscillation and the trace becomes a
fog. I will press on but there is definitely something wrong with
this thing.

BillHi  Bill,

I would take a close look at the input FET's to make sure they are the
original type.  Sometimes they will short or open and the repair techinician
will use whatever FET is handy and not bother with the correct part.  This
can cause all sorts of oscillation problems and stuff like you are seeing.

Stan
w7ni@...

Re: 465 Display Help Needed - another thought

[email protected]

#219

--- In TekScopes@y..., Kurt Graber <kurtg@s...> wrote:


billw101@a... wrote:

Hello, I have been pulling problems out of a 465 that I recently
acquired. The last remaining problem is the inability to get a sharp
focus on the trace with any combination of intensity, focus or
astigmatism. I have checked everything in the CRT circuits with the
exception of the high voltage, crt bias and cathode bias, until I get
the use of an HV probe. Can anyone tell me if I am looking in the
right area or suggest any common failure modes? The low voltage
supplies all check good and noise free. Thanks for any help.
...........................................



Your use of Yahoo! Groups is subject to 

A common problem or failure is the opening of the voltage divider circuit
that the focus and astig tap into.
I am unfamilier with your particular scope but the chances are good that one
of the resistors has opened up. I have seen many cases !!! youdon't 
need a
HV probe , just take your meter and ohm them out. They will not appear burned
but they have a tendancy to open up due to the high voltage.......this will
cause an unsharp trace and many cases no trace at all (just a haze)...Good
LuckAnother point: the 46x, 47x series just wasn't as sharp as the tube 
scopes!  or even and especially - the 454, 454A.  Some engrs. think 
the 454A best 150 MHz scope ever (2mV/DIV, all the delay triggering) 
or sometimes ~ 200 MHz if all went well on that assembly..  

I can see the  clear difference bewtween say, a 475A and the 454As - 
tiny wiggles just visible on 54-A disappear into the thick trace of 
475 (or 465).

Just in case you're trying to do better than it Can!


Ashton

Re: *Cheap* Equipment sources

[email protected]

#218

--- In TekScopes@y..., Michael Dunn <mdunn@c...> wrote:
    Just a little poll of sorts: I'm wondering where we all findold 
equipment -- at least the stuff we get for real cheap!

    I and a friend on this list have found pretty much all ourstuff 
at "garage sales" held at a local university.  We're talking REAL 
cheap.  C$10-$20 (U$7-14) for anything from a 502A to a 549 or 556! 
$5 for a plug-in.  Usually in very good condition.  How about you?
Hello Michael, and thanks for helping me get past the sign-on glitch. 
As you can see, posting now works too [I think - we'll see].

I started accumulating Teks (beyond a couple for use) ~ 3 years ago 
pre- eBay for me..  A fireman in LA had an ad in Nuts&Volts.. ended
up sending along an initial 10ish scopes (mostly 453s) and a year 
later, more things.  

Truck rate and such seems about only way to handle high ship'g cost, 
but that means ~ 300ish # to come out reasonably.  This may not be 
true in '01 (?).

Now I have to read some back posts.  I've mainly used Tek scopes 
forever - only lately repair / calibrate, but without the tricks that 
experience teaches (might tell about the 2430 with no warning about 
needing an extra fan - except buried in the Service Manual.  Ugh. 
All those labels about imploding CRTs but - not one saying "cool it - 
Now!")

Ashton Brown
Sonoma county, No. Calif.

Re: *Cheap* Equipment sources

Jams & Kandy Nunn

#217

I started my collection with a 535a that I purchased at a garage sale for $1.  The scope came with CA plug-in and a set of probes.   I always admired the Tek scopes from the 60's and thought that it would be fun to fix it or take it apart.   I ended up doing both and spending a lot more than a buck to get it working.   My other "sea story" is a 545a that I purchased from a TV station last year.  The scope was calibrated! has the "old" style cart, 4 probes, a CA and a M plug-in and a 1L5 (not working) all the original manuals and I found the original purchase order in the operators manual compartment, total cost was $60.   

Most of what I purchase I find on E-bay or the TRW swap meet  (I live in LA).

Jim Nunn

Re: 465 Display Help Needed

Kurt Graber

#216

billw101@... wrote:

Hello, I have been pulling problems out of a 465 that I recently
acquired. The last remaining problem is the inability to get a sharp
focus on the trace with any combination of intensity, focus or
astigmatism. I have checked everything in the CRT circuits with the
exception of the high voltage, crt bias and cathode bias, until I get
the use of an HV probe. Can anyone tell me if I am looking in the
right area or suggest any common failure modes? The low voltage
supplies all check good and noise free. Thanks for any help.

To unsubscribe from this group, send an email to:
TekScopes-unsubscribe@...



Your use of Yahoo! Groups is subject to A common problem or failure is the opening of the voltage divider circuit
that the focus and astig tap into.
I am unfamilier with your particular scope but the chances are good that one
of the resistors has opened up. I have seen many cases !!! you don't need a
HV probe , just take your meter and ohm them out. They will not appear burned
but they have a tendancy to open up due to the high voltage.......this will
cause an unsharp trace and many cases no trace at all (just a haze)...Good
Luck

Re: *Cheap* Equipment sources

Michael

#215

    I and a friend on this list have found pretty much all our stuff
at "garage sales" held at a local university.  We're talking REAL
cheap.  C$10-$20 (U$7-14) for anything from a 502A to a 549 or 556!
$5 for a plug-in.  Usually in very good condition.  How about you?Gee, half your luck! I've never seen any Tek stuff at garage sales (not that
I go to many), and paid A$600 (around US$1200) for my (as new) 7603; but I
was given a TM503 with a DM501A (faulty) and three plug-in kits in exchange
for a satellite TV receiver.  Meanwhile I have (mostly) fixed the DM501 and
keep looking... :)

Kind regards,
:)
Michael

Re: *Cheap* Equipment sources

ronald h. driggers

#214

I paid 25 for the 545a, most of the plugins cost 15 to 20, bought one on
ebay as well as some of my manuals, some of the stuff is in a salvage yard,
near by, but they run 25 to 45 dollars depending on the size and weight,
they look at the scrap value, bought the ca and the 130 lc meter this
weeking for 20 dollars for the two,  more than i want to spend but i am in a
bad area for old tek stuff. I have found others but can not pay shipping.
You seem to buy much cheaper than i can, the 556 i got was 20.00 dolllars,
may not be an easy repair though. Since this is a hobby cheaper would be
MUCH better for me. I have payed more for manuals than equipment.

Show quoted text

----- Original Message -----
From: Michael Dunn <mdunn@...>
To: <TekScopes@...>
Sent: Monday, April 23, 2001 10:17 AM
Subject: [TekScopes] *Cheap* Equipment sources


    Just a little poll of sorts: I'm wondering where we all find old
equipment -- at least the stuff we get for real cheap!

    I and a friend on this list have found pretty much all our stuff
at "garage sales" held at a local university.  We're talking REAL
cheap.  C$10-$20 (U$7-14) for anything from a 502A to a 549 or 556!
$5 for a plug-in.  Usually in very good condition.  How about you?


-----------------------------------------------------------------
Michael Dunn     | Surround Sound Decoder & Stereo Enhancer
Cantares         | Self-Amplified Speakers, Test Equipment
74 George St.    | Ambisonic Surround Sound CDs and Recording
Waterloo, Ont.   | (519) 744-9395 (fax: 744-7129)
N2J 1K7          | mdunn@...
Canada           | 
-----------------------------------------------------------------

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TekScopes-unsubscribe@...



Your use of Yahoo! Groups is subject to 

*Cheap* Equipment sources

Michael Dunn

#213

Just a little poll of sorts: I'm wondering where we all find old equipment -- at least the stuff we get for real cheap!

   I and a friend on this list have found pretty much all our stuff at "garage sales" held at a local university.  We're talking REAL cheap.  C$10-$20 (U$7-14) for anything from a 502A to a 549 or 556! $5 for a plug-in.  Usually in very good condition.  How about you?


-----------------------------------------------------------------
Michael Dunn     | Surround Sound Decoder & Stereo Enhancer
Cantares         | Self-Amplified Speakers, Test Equipment
74 George St.    | Ambisonic Surround Sound CDs and Recording
Waterloo, Ont.   | (519) 744-9395 (fax: 744-7129)
N2J 1K7          | mdunn@...
Canada           | 
-----------------------------------------------------------------

465 Display Help Needed

#212

Hello, I have been pulling problems out of a 465 that I recently 
acquired. The last remaining problem is the inability to get a sharp 
focus on the trace with any combination of intensity, focus or 
astigmatism. I have checked everything in the CRT circuits with the 
exception of the high voltage, crt bias and cathode bias, until I get 
the use of an HV probe. Can anyone tell me if I am looking in the 
right area or suggest any common failure modes? The low voltage 
supplies all check good and noise free. Thanks for any help.

Re: Tek 7104 readout problem

L. Mark Pilant

#211

I haven't ever looked at a 7100 scope, but I did have a 7904
with a very dim readout.  If you turned the trace intensity all
the way down and dimmed the lights, you could make out the
readout characters.

In my case, it turned out to be the Z-blanking board was way
out of calibration.  I went through the calibration procedure
until I got the the blanking board.  When I did the board, I
suddenly had the readout.  (And everything still worked as well :-)

Going through the rest of the calibration procedures showed the
rest of the 'scope wasn't that far out of spec.

I hope this helps.

- Mark

Tek 7104 readout problem

[email protected]

#210

I have a 7104 and now a 7103 that have the same readout problem.  The
readout is not visible unless the intensity knob is turned CW to the
"pulsed" position and then pushed against the stop.

On the 7104, I found that the TP1925 voltage was at -6.3V in the full CW
position, and I could make the readout go on by pulling it to about -11V,
so I tacked in a couple of resistors to change the range of the readout
intensity control.  (Note, another problem this scope has is that the A/B
intensity knob indicator lamps don't activate properly, but I have no idea
if that's related.)

I wasn't totally happy with the above hack, and now that I have a 7103
with the exact same problem, I would really like to find the underlying
cause... has anyone seen/fixed this?

Thanks...

Re: Tek 7904 Display Problem

Mark Gurries

#208

BTW Hi Mark Gurries glad to see you on the list.
Hi Don.

Been watching the list for a while.  It was from one of your email on the 
DCC list that I learned about this list.  Anyway...

I told Jim Williams here at Linear Tech about this list.  (My Lab bench 
is next to his.)  But he is not one to use PC's.  That Jim for ya.  For 
those who are not familiar with Jim, he is one of out treasured assets at 
the company.  Hi writes many application notes for our IC and tackling 
problems and parts that cause most of us to glaze over our eyes in terms 
of the accuracy or noise level requirements.  Things like how do you 
verify all 24 bits of a 24 bit DAC!

The trick around here to getting a Tek scope fixed and checked out by Jim 
Williams is to get an old 500 or 400 series scope in the lab.  Tell Jim 
about it, and the fact that it does not work annoys Jim to no end.  
Before you know it, he is digging into the scope and fixing everything.  
Not that we cannot fix out own scopes mind you, but, Jim does a faster 
and better job than anyone I know.  It fun to watch him and of course you 
learn along the way the history and debug tricks.

We have about every make of Tek scope at the company labs.  We have lots 
of 547's working in parallel with the latest Tek Scopes.  We just got 
around to setting up an old 556 dual beam on another engineers lab bench. 
 454's are another favorite.  A few of the guys have 7K stuff like yours. 
  One of my employees has every 7K plug in made including some test 
adapters if I recall correctly.  It amazing to see the latest scopes 
setup right next to an old classic.  The biggest reason we like the old 
400 and 500 series scopes is the very fine trace and excellent noise 
floor.  When Jim sets up his 556 with two 1A4 plugins showing 8 traces 
that are all beautifully detailed (4 of the traces are on a different 
time base to boot)  published in a App note, we sometimes get letters and 
calls about the scope photo alone!  How did you do that?

We think that our lab is one of the biggest consumers of electricity in 
Silicon Valley with all these Tube Tek scopes on and possibly the source 
of all the blackouts here in California.  We already went though one air 
conditioner!  ;-0


Best Regards,

Mark Gurries
gurriesm@...

---------------------------------------------------------
Promotor of the DCC Standard for Model trains.
Model Railroad Club and NMRA DCC presentations are at:        

--------------------------------------------------------
Audio Enthusiast (Love SAE equipment)


----------------------------------------------------------

Re: 127

Stan or Patricia Griffiths

#209

Hi Morris,

Well, Tek made TWO different silicon mod kits for the 127, depending upon the
serial number of your instrument.  For Serial Number 100-357, it is 040-0217-00
and for Serial Number 358-1409, it is 040-0282-00.  There are about 8 pages in
each instruction set.  So, if you tell me your Serial Number, I will get a copy
of the appropriate kit instructions for you.  It will cost you about $2 plus
postage.

Stan
w7ni@...

Stan or Patricia Griffiths wrote:

Show quoted text

Hi Morris,

I am sure Tek made a silicon replacement kit for those seleniums.  I am sure
I have a copy of it on microfiche.  I will check that out at my next free
moment and see about taking my microfiche to the local library and making you
a hard copy of the mod instructions for you.  I promise to keep the price of
my labor within reason . . .

Don't let me forget this . . . at age 62, things sometimes fall in the
cracks.

Stan
w7ni@...

morriso2002@... wrote:

I have picked up a 127 preamp power supply that is used to power a
couple of 1- or letter plugins for use as instrument amplifiers. It's
quite a boatanchor and seems to work OK but I want to replace the
selenium rectifiers in it with silicon for safety reasons.

There are 5 rectifiers in there. To save me a bit of measurement work,
does anybody have any info on function/ratings of the rectifiers or
whether Tek issued a bulletin on their replacement?

Morris

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100!!!

Michael Dunn

#207

Congratulations TekGroup!  We've hit 100 members!


-----------------------------------------------------------------
Michael Dunn     | Surround Sound Decoder & Stereo Enhancer
Cantares         | Self-Amplified Speakers, Test Equipment
74 George St.    | Ambisonic Surround Sound CDs and Recording
Waterloo, Ont.   | (519) 744-9395 (fax: 744-7129)
N2J 1K7          | mdunn@...
Canada           | 
-----------------------------------------------------------------

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