Date   

Tek 475 almost dead

richg_1998 <richg_1998@...>
 

Hello everyone
I have a Tek475 that is not dead, it is almost dead. It worked fine
last night. This morning I turned it on and no trace but indicator
lights work and the fan works. With no input and the intensity near
max, I can see a faint trace not in sync (more like a blur) at the
bottom half of the screen and the sweep sweep speed varies as the
horizontal speed is varied. Vertical gain and position have no
effect. The trace finder does not show anything when the switch is
pushed.
All the supplies are low. The +50v is only 44 volts and this affects
the other supplies. The adjustment pot has no effect though I do see
the voltage varying, as I turn the pot, at the op amp input and
output. The 9v ref. on one of the inputs is ok. The voltage regulator
appears to be limiting the voltage because of an overload. The
current being drawn is about 330ma which I suspect is high.
I have a manual which I am studying right now.
Anyone have any suggestions. Thank you in advance.

Richard Gagnon


fuzzy 465 and 475 traces, another issue to look at

 

we overhaul all the 400, 2000 and 7000 series pretty regularly, and
note that it is usally NOISE that affects spot size in the 400 series.

as the scopes age, there are many, many grounds (with dissimilar
metals) that get progressively worse. added to the loss of shielding
(sometimes missing, often loose or badly connected), and the rising
noise floor caused by so many aging interconnects, the
vertical/horizontal noise can become quite visible.

cleaning grounds, reseating and cleaning connectors, and reseating
semiconductors has a distinct and beneficial effect on this situation
(and many others).
you will often see a drastic difference in spot/trace size when
bandwidth limiting is on, this is a clear indication that various
spurious noise is entering the scope circuitry. this situation is
also made worse by bad HF adjustment, intermittent/noisy attenuators,
and a noisy HV supply.

these scopes also depend on many unobvious case grounds via metal
wipers that may have deteriorated, and need to be cleaned. some
scopes (esp. the early Sony/Tek scopes) have such bad ground loop
interference, they can only work correctly when all covers are in
place, which makes service a nightmare.

I don't doubt that the tube design and mesh dome affect spot size in
a bad way, and this is actually VISIBLE on the 2335/6, where the mesh
pattern is clearly visible inside the spot with a magnifier. But
beyond the tube dynamic behavior lies the presence of noise in a wide
bandwidth design, which also plays an important role.

In any case, keep in mind this is a general situation with many
causes, often appearing together at random, and some good work
practice is needed to keep it all under control. I doubt Tek really
intended these scopes to have a service life of over 30 years, so
some insight into the aging mechanisms of the scope is needed to keep
them alive and happy after so many years.

do you think your TV or computer monitor will look as good after 30
years?

all for now,
walter
http://www.sphere.bc.ca

Hey! I still have 6+ pounds of older 540 series parts and knobs for
anybody that wants them and will pay the shipping!


Tektronix 4696 looking for a new home

 

Can anyone use a Tektronix 4696 color ink-jet printer? This unit was
used with many pieces of test equipment and computer terminals. I
can't test the unit since the cartridge ran dry while it was in
storage. E-mail me for more details and photos. Best . . . Tom
Leedy <leedyt@aol.com>


Re: Fuzzy 465B trace revisited *correction*

donlcramer@...
 

I finally called Chris Curtin up tonight. As background, Chris had design
engineering roles for oscilloscope and computer terminal CRTs; and then was
Manufacturing Manager of the Tektronix CRT facility. From 1983 to 1988 he
was GM for the Display Device Division. He had guests, so couldn't spend too
much time on the phone, though he said he'd love to talk about CRTs. I got
some fast answers to some recent CRT questions, and then followed up with an
email which he said he would respond to later. (I also asked him to join
TekScopes!!!).

My apologies if I've "distorted" any answers.

He thought one key reason the 455/465/475 tubes had a wider spot size was the
increased deflection angle necessary with the bigger screens. He also
remembered that the 453 et al had a frame grid (!) scan expansion lens, while
the 465 et al had dome meshes. The latter blew up the beam in both axis,
plus there was some additional beam scattering due to the dome mesh (more
bits to interfere with the electron stream). He also mentioned that the
465/475 had higher bandwidths, which suggested the need for lower vertical
output voltages. Thus, there is more "scan expansion" with those tubes,
which negatively impacts the spot size.

Regarding the question of why the 465M had a completely different PN CRT than
the 465, his recollection is that the 465M program for the government was
very cost sensitive and Tek made little on those scopes. He thought the
specs were thus lower for the 465M tubes resulting in a different tube.

To my question of whether the "fuzzy" trace I see on my 465B is consistent
with a CRT defect, he speculated a misalignment in the gun structure. As an
aside, I've followed almost all suggestions made to me to diagnose this
problem and I cannot find an electronic defect, and the tube has plenty of
brights. (BTW, another thing I've noticed is that the fuzzy trace is cleaner
near the bottom of the screen and gets worse towards the top. Until I can
locate another good tube, I'm living with it--as another has suggested--and
it's relatively ok. A little disconcerting, but ok).

I didn't get to ask yet the reason there is a "double peak" when the tube is
worn out.... So many questions, so little time! Hopefully, more to come.

Don


In a message dated 7/8/02 1:56:31 PM Pacific Daylight Time,
w7ni@easystreet.com writes:

what is the REAL reason that 465's and 475's have
fat traces? It isn't simply the addition of the expansion mesh, like I
heard so many years ago, since we have several examples of CRT's with
expansion mesh and great spot size and some with expansion mesh and
not-so-good spot size. What is the real explanation of this . . . ?


Re: Fuzzy 465B trace revisited *correction*

jd_hurst <jdhurst@...>
 

The orignal post (Thu Jun 27, 2002) said, in part:
"The trace is fat, about 0.15 [divisions] wide regardless of whether
the 20MHz BW limit is engaged or not. This fuzzy trace isn't the
usual scan expansion mesh thing I don't think. It is odd in that a
sharper trace is visible within the fuzzier band, and the fuzzy bit
isn't necessarily symmetrical about this sharper trace. "

The way it is described, it seemed to me it could be noise.

So I looked at my machines to see what they do. I have a 455 that I
bought new in 1979 and has been well treated. I have a 7704a that I
bought used in 2001, but it looked to be in very good condition and
works well today. It has a 7A26 and a 7A24 amplifier units.

With no signal:
* The 455 shows a trace width of 1/3 minor divisions (I can fit 3
lines in one minor division)
* The 7A24 shows a trace width of 1/3 minor divisions
* The 7A26 show a trace width of 1/2 minor divisions at full
bandwidth and 1/3 minor divisons with bandwidth limited to 20Mhz

Another post (Fri Jun 28, 2002) suggested thicker than desired traces
may result from the amplifiers running at full gain internally. If
so, that may explain why my 7A26 has a fatter trace at full bandwidth
than when limited to 20Mhz.

I don't see any sign of fuzziness around the main trace on any of the
amplifiers. But then I also run a very most level of intensity (low
enough that there is no secondary emission lighting up the screen).

These machines (455 and 7704a) would have an expansion mesh in their
CRT's? I think so.

In any event, I am very happy with those two machines.

By the way, I was posting incorrectly and sending mail instead. Sorry
about that. .... John Hurst
__________________

--- In TekScopes@y..., "Stan & Patricia Griffiths" <w7ni@e...> wrote:
<snip> What I wanted to ask him
was, since that is true, what is the REAL reason that 465's and
475's have
fat traces? It isn't simply the addition of the expansion mesh,
like I
heard so many years ago, since we have several examples of CRT's
with
expansion mesh and great spot size and some with expansion mesh and
not-so-good spot size. What is the real explanation of
this . . . ? <snip>


Re: Fuzzy 465B trace revisited *correction*

Stan & Patricia Griffiths <w7ni@...>
 

This whole "fuzzy trace" issue has me somewhat confused. I thought I
understood it since I lived through the era when it orginally came up. It
was never an issue until the 465 was introduced and then, suddenly, it was
an issue . . . big time. I was selling 465's for Tek at the time in the
Boston Area (1970-1973) and I heard about it from customers all the time.
The explanation that came out of Beaverton was that the larger spot size and
fatter trace was due to the "expansion mesh" in the CRT. We all sort of
assumed (at least I did) that since previous scopes (453, 454, 485, 547,
etc.) did not seem to suffer from this problem, that the expansion mesh was
added at the time the 465 was developed and only then did the problem show
up.

Well, it seems that some of those earlier scopes also had the expansion mesh
but, somehow, managed to keep the small spot size and thin trace. I put in
a local phone call to Pete Keller to ask, once again, about this and had to
leave him a voice mail. He answered my voice mail with a voice mail of his
own and confirmed, like his book says, that the 453, 454, etc. (not the 547)
indeed does have the expansion mesh in the CRT. What I wanted to ask him
was, since that is true, what is the REAL reason that 465's and 475's have
fat traces? It isn't simply the addition of the expansion mesh, like I
heard so many years ago, since we have several examples of CRT's with
expansion mesh and great spot size and some with expansion mesh and
not-so-good spot size. What is the real explanation of this . . . ? I will
keep trying to reach Pete and have this one-on-one conversation with him and
share the results here when I get them. Boy, do I feel lucky that I can
just pick up a phone and make a local call to Pete Keller and he (and his
wife) actually know me when I call!

Stan
w7ni@easystreet.com

----- Original Message -----
From: <donlcramer@cs.com>
To: <TekScopes@yahoogroups.com>
Sent: Friday, June 28, 2002 12:09 PM
Subject: Re: [TekScopes] Fuzzy 465B trace revisited *correction*


You're right in that the 455/465/475 have fatter traces than the earlier
tubes. It's hard to explain the symptom without a photo but the fuzzy
trace
I see is unusual even for a 465B. We have others at work which I can
compare
mine to. With simple waveforms one could almost live with it, but more
complex waveforms really show how messed up it is.

This series does have a scan expansion mesh, but so does the 453/454
according to Pete Keller's CRT book. After reading his passages on scan
expansion, I've taken a mental note try to ask someone who should know and
understand why later scopes' traces were so much fatter than the earlier
ones. More later if I come up with anything.


Tek 488?

Michael <m_d_d@...>
 

Hi all, :)

Anyone ever hear of a Tek 488?

Anyone know of a definitive list of all Tek scope models ever made?

Might be a nice little project for someone...

cheers,
:)
Michael


Available 500 series parts for postage, charming little Tek 310

 

Noting that some list members are busy restoring (or trying to
restore) 500 series scopes, I though this might be useful.

I recently bought a big box of salvage from some Tek 500 series
scopes, just to get the knobs and a few pots. I still have a big
pile of good condition Tek rotary switches (some with precision
timing resistors, etc.), custom tapped power resistors, electrolytic
cans, connectors, other pots, etc., and all are looking for a new
home, I have more than enough Tek stuff already! There's also some
remains from a 564 storage scope available (including the power
transformer), if you can use it. I also have a big pile of 500
series knobs that somebody scrubbed, and they now look a bit gray,
not shiny black. they can can be yours too.

I can send you a pic to look at. it all weighs about 10-12 pounds
(excluding the 564 stuff), probably cost US$18-20 to ship by air.

also, I just got a Tek 310 3" portable from a private sale, and
everything works!!!! I am amazed, it came with the original manuals,
a spare 6au6, probe and line cord. US$20. the vertical cal is
slightly out, but so far, that's the biggest problem. what a cutie!
mind you, it throws off enough heat to act as a space heater, but
otherwise, it's very nice.

All the best,
walter
http://www.sphere.bc.ca


(No subject)

kk7iz <kk7iz@...>
 

Each pair of tubes are boxed together (except as noted) and have
matching test number / part number tags attached. All are plus
shipping.

12BY7 Tek P/N 157-0053-00 Selected pair, 4 pairs available
$15.00 Pair

6AU6 Tek P/N 157-0073-22 Selected pair, 4 pairs avasilable
$5.00 Pair

6AU6 Tek P/N 157-0073-00 Selected pair, 1 pair available
$5.00 pair

8136 Tek P/N 157-0082-00 Selected pair, 15 pair available
$5.00 pair
These tubes are in 2 styrofoam tube packers with holes
in them. Will be reboxed for sale as matched pairs per
the matching no on the tubes unless you buy either a pack
of 7 pairs or 8 pairs.

6197 Tek P/N 154-0146-00 4each individually boxed
$2.50 each

8608 Tek P/N 154-0491-00 1 ea boxed
$20.00

I have a large quantity of Tek and HP small parts, transistors,
diodes, modules etc. Will sort and sell individually or will consider
lot price for all. No inventory available as yet. If interested
contact me direct.

Lloyd Godsey KK7IZ
1315 N. Udall Circle
Mesa, Az 85203

480-495-5456 (cell)

kk7iz@cox.net


File - Posting Rules

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Michael Dunn
Moderator, TekScopes


Problem with tek 5113 high voltage circuit

tek5110lover
 

Hello all;
I recently purchased tek 5113(D13, dual beam storage) on ebay
auction, and it worked when arrived. But after 5min, beam disappeared
and I heard a high frequency pitch sound with a smell of burning some
parts in high voltage circuit of it. Does anyone have similar
experience? I would very much appreciate it if someone give me any
advice of where to start checking.
Regards


Re: How to decide - Restoration candidate or parts machine?

Michael Dunn <mdunn@...>
 

At 12:34 PM +0000 2002/7/1, excavatoree wrote:
However, it is complete (except for the missing pots and two 7788's
(expensive tube))
This is a parts unit, isn't it? I just can't bear to take apart a
unit with a trace.

I just finished "putting down" a 533... Your scope is certainly a better unit. It's a tough call... But, its parts might help in restoring a better box...


Re: How to decide - Restoration candidate or parts machine?

Craig Sawyers <c.sawyers@...>
 

However, I have a 545B that I am unsure about. It's dirty, has some
trim-pots broken on the Crt side, and the rotary swith contacts are
dark brown and very heavily corroded. The cosmetic condition of the
front and case panels does not justify the time and effort to restore
it.

However, it is complete (except for the missing pots and two 7788's
(expensive tube))

This is a parts unit, isn't it? I just can't bear to take apart a
unit with a trace.
Sad to say - I agree with you. The old girl seems to be at the end of her
life. Once the switches are worn out, in particular, it is time to give up.
If it has been used as long and hard as it seems, components will have
drifted in value (resistors in particular), electrolytics will be flakey,
and most of the valves (tubes) will be near end life.

Wipes a tear...

Craig


How to decide - Restoration candidate or parts machine?

excavatoree
 

Some old oscilloscopes (I'm speaking of the 500 series) are obviously
restoration candidiates - they are in good comsmetic shape, have a
trace, and only need minor repairs or adjustments.

Some of these are obviously parts units - bent, parts missing,
physically damaged to a great extent, etc.

However, I have a 545B that I am unsure about. It's dirty, has some
trim-pots broken on the Crt side, and the rotary swith contacts are
dark brown and very heavily corroded. The cosmetic condition of the
front and case panels does not justify the time and effort to restore
it.

However, it is complete (except for the missing pots and two 7788's
(expensive tube))

This is a parts unit, isn't it? I just can't bear to take apart a
unit with a trace.


556 transformer cancer

morriso2002 <morriso@...>
 

Hi all,

Unfortunately I need rewinding data for a couple of Tek HV
transformers for the 556. They are:

Part no 120-0432-00 and 120-0433-00

Does anyone have this info available? Stan, can you help?

Thanks,

Morris


P6046 Calibration

Miroslav Pokorni
 

Hello All,

Does anyone have picture, sketch, schematic or description of:

1. 067-0562-00 'P6046 Dual Input Adapter'

2. 067-0563-00 'P6046 Calibration Shield'

I embarked on probe calibration and those two items were listed. I can make
guesses, but would feel better if information came from a Tektronix
document.

Failing to find a sketch, schematic etc. would someone, please, confirm my
guesses:

The first item, 'dual input adapter' is a receptacle for both probe tips
connected together and fed to a BNC, to facilitate probe's common mode
drive.

The calibration shield looks to me as a single or double rail that holds
down stand-offs and thereby completes ground plane on the probe's PCB, which
Tektronix' layout people seem to have forgotten to do.

Regards

Miroslav Pokorni


7D11 digital delay module

petes7457 <pete.symons@...>
 

Hi,

Can anyone please explain the operation of the 7D11 module? I
recently purchased a 7834 which came with a 7D11 and 7B92A and I'm
trying to understand how the pair are meant to operate and how to get
the best from the 7D11.

Regards,

Pete


Re: Fuzzy 465B trace revisited *correction*

Don Black <jeans@...>
 

Hi Don, Try bypassing the deflection plates with a 0.1�f disk ceramic capacitor
and see if that has any effect on the trace. You could also try a capacitor
across the HV supply too if you can get one with sufficient voltage rating (in
case the ripple you're seeing is on the HV supply).
Don Black.

donlcramer@cs.com wrote:

You're right in that the 455/465/475 have fatter traces than the earlier
tubes. It's hard to explain the symptom without a photo but the fuzzy trace
I see is unusual even for a 465B. We have others at work which I can compare
mine to. With simple waveforms one could almost live with it, but more
complex waveforms really show how messed up it is.

This series does have a scan expansion mesh, but so does the 453/454
according to Pete Keller's CRT book. After reading his passages on scan
expansion, I've taken a mental note try to ask someone who should know and
understand why later scopes' traces were so much fatter than the earlier
ones. More later if I come up with anything.

I did check the vertical at the plates using a high speed Agilent Infinium
DSO. It showed about 100mvpp, 95MHz "ripple" on each plate, but the signals
were sometimes in phase, sometimes out of phase. If they were out of phase
all the time, the magnitude would correspond to about half the trace width I
see. By the way, disconnecting the vertical output amp from the plates
didn't make the flat line trace any thinner (in fact it made it a bit
worse....?)

I only have one more thing to check on the scope electronics end: the HV
multiplier output per a suggestion from another list member. Couldn't think
of how to get a HV probe to it last night, but have an idea this morning.
The other HV nodes (focus, cathode) were fine.

Thanks for the comments everyone.

Best rgds,

Don

In a message dated 6/28/02 4:40:27 AM Pacific Daylight Time,
rndmenke@lockhart.net writes:

I think all of these have a very fat trace. Without pulling
a manual, I think the vertical amplifier and attenuators
were set up so the gain was always maximum (or nearly so), plus
the fact that the CRT is larger (compared to a 453 or 453A).
I'm not sure if the CRT used a scan expansion mesh or not,
but a fat, fuzzy trace was/is a common complaint



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Re: Fuzzy 465B trace revisited *correction*

donlcramer@...
 

You're right in that the 455/465/475 have fatter traces than the earlier
tubes. It's hard to explain the symptom without a photo but the fuzzy trace
I see is unusual even for a 465B. We have others at work which I can compare
mine to. With simple waveforms one could almost live with it, but more
complex waveforms really show how messed up it is.

This series does have a scan expansion mesh, but so does the 453/454
according to Pete Keller's CRT book. After reading his passages on scan
expansion, I've taken a mental note try to ask someone who should know and
understand why later scopes' traces were so much fatter than the earlier
ones. More later if I come up with anything.

I did check the vertical at the plates using a high speed Agilent Infinium
DSO. It showed about 100mvpp, 95MHz "ripple" on each plate, but the signals
were sometimes in phase, sometimes out of phase. If they were out of phase
all the time, the magnitude would correspond to about half the trace width I
see. By the way, disconnecting the vertical output amp from the plates
didn't make the flat line trace any thinner (in fact it made it a bit
worse....?)

I only have one more thing to check on the scope electronics end: the HV
multiplier output per a suggestion from another list member. Couldn't think
of how to get a HV probe to it last night, but have an idea this morning.
The other HV nodes (focus, cathode) were fine.

Thanks for the comments everyone.

Best rgds,

Don

In a message dated 6/28/02 4:40:27 AM Pacific Daylight Time,
rndmenke@lockhart.net writes:


I think all of these have a very fat trace. Without pulling
a manual, I think the vertical amplifier and attenuators
were set up so the gain was always maximum (or nearly so), plus
the fact that the CRT is larger (compared to a 453 or 453A).
I'm not sure if the CRT used a scan expansion mesh or not,
but a fat, fuzzy trace was/is a common complaint


Re: Fuzzy 465B trace revisited *correction*

Ray Menke <rndmenke@...>
 

On Fri, Jun 28, 2002 at 01:00:15PM +1000, Robert Fincher wrote:

I have a 465 which displays exactly (!) the same
characteristics as yours. Like you, I've checked
everything I can think of, and all signals at the CRT
are clean. However, another common feature of our
I think all of these have a very fat trace. Without pulling
a manual, I think the vertical amplifier and attenuators
were set up so the gain was always maximum (or nearly so), plus
the fact that the CRT is larger (compared to a 453 or 453A).
I'm not sure if the CRT used a scan expansion mesh or not,
but a fat, fuzzy trace was/is a common complaint. However,
carrying a 547 or a 585 is a back-breaking task!
--
Ray Menke

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