Tektronix 465 Scope

[BFoelsch]

I recently gave away a 465 that was giving me fits. I don't know what
happened to it, but it had squirrelly problems all over. It was shipped to
Tek for repair in the early 1990's and Tek said it was unrepairable. Of
course I knew better.......

It was used extensively in field service, and was probably vibrated to
death, but it had the damndest problems I ever saw. The ones that really
killed me (other than the vertical attenuator switches) were an oscillation
in the Ch 1 vertical, inability to get a smooth leading edge on a fast rise
(fall was OK) and an intermittently failing intensified sweep. I spent about
100 hours on that thing and never did get it to work right. I don't know if
that had multi-layer boards or not, but it acted like some inaccessible
connections were intermittent. I checked and changed component after
component, and there would always be one more trouble. That was my weekend
for a few months; I would start and go througn the WHOLE calibration
procedure (including the stuff that everybody skips, like swinging the line
to check the power supply at high and low line conditions) to see how far I
could get this time. Undoubtedly I would stop at some point because the
adjustment didn't have enough range or some such. I'd fix that and next week
a different set of stuff wouldn't work. The problems were never expensive
stuff, just resistors and capacitors.

That was the ONLY Tek scope that ever stumped me. I even managed to keep a
647 running, and those NEVER worked.

Yes indeed. The perversity of the inanimate.

So I gave away the 465 and bought a TDS2012. Took a little getting used to,
but I've never looked back. Still have the old reliable 547 and a whole slew
of plug-ins in the corner, but they are going to need a new home before too
long.

 

[Bob Stephens]

So I gave away the 465 and bought a TDS2012. Took a little getting used to,
but I've never looked back. Still have the old reliable 547 and a whole slew
of plug-ins in the corner, but they are going to need a new home before too
long.

Tek won't fix the 2012 either

 

[BFoelsch]

Tek won't fix the 2012 either

Well, it did come with a three year warranty, and it does work well right
now, which is more than the 465 did. But I hear you. Time will tell.

 

[Jim Yanik]

I recently gave away a 465 that was giving me fits. I don't know what
happened to it, but it had squirrelly problems all over. It was
shipped to Tek for repair in the early 1990's and Tek said it was
unrepairable. Of course I knew better.......

It was used extensively in field service, and was probably vibrated to
death, but it had the damndest problems I ever saw. The ones that
really killed me (other than the vertical attenuator switches) were an
oscillation in the Ch 1 vertical, inability to get a smooth leading
edge on a fast rise (fall was OK) and an intermittently failing
intensified sweep. I spent about 100 hours on that thing and never did
get it to work right. I don't know if that had multi-layer boards or
not, but it acted like some inaccessible connections were
intermittent. I checked and changed component after component, and
there would always be one more trouble. That was my weekend for a few
months; I would start and go througn the WHOLE calibration procedure
(including the stuff that everybody skips, like swinging the line to
check the power supply at high and low line conditions) to see how far
I could get this time. Undoubtedly I would stop at some point because
the adjustment didn't have enough range or some such. I'd fix that and
next week a different set of stuff wouldn't work. The problems were
never expensive stuff, just resistors and capacitors.

That was the ONLY Tek scope that ever stumped me. I even managed to
keep a 647 running, and those NEVER worked.

Yes indeed. The perversity of the inanimate.

So I gave away the 465 and bought a TDS2012. Took a little getting
used to, but I've never looked back. Still have the old reliable 547
and a whole slew of plug-ins in the corner, but they are going to need
a new home before too long.

Trying to support a TEK product without the Tek selected transistors and
other specialized components is extremely difficult.
One of the first things I did when getting a unit that someone else had
tried to repair was to find and remove all the non-Tek xstrs,and replace
with the proper TEK parts.They were often causes of oscillations and bad HF
responses.Some scopes may have had ferrite beads used in some places lost
or not installed with the new transistors.One other common problem was a
black silver oxide growing on the tiny HF trimmer caps,especially on the
bottom of them,acting as an insulator and making the cap open and
ineffective.

IMO,the HF cam contacts used in the attenuators should be failing and no
longer repairable due to the plastic part that holds the gold contact to
the spring metal degrading and coming apart,or loss of spring tension.
That's a problem with using plastic parts,they outgass and eventually
degrade and lose strength.Some of the atten intermittents can be due to the
outgassing making a film on the contacts and pads.

 

[Jim Yanik]

Tek won't fix the 2012 either

TEK has a Long Term Product Support(LTPS) policy,where the item will be
serviceable by TEK X number of years after it's last sold in their catalog.
They have a list of whats supported and for how long on their website,IIRC.
"X" used to be 9 years,then got cut to 6,then some items are only ONE year.
That's why you have to check the list.
Also,repair prices climb in the last couple of years of "support",to
encourage you to buy a new unit.

AFTER the LTPS period is over,the item is no longer supported at all.
No exchange modules,and no parts support unless the part is used in a
current product.

 

[BFoelsch]

Trying to support a TEK product without the Tek selected transistors and
other specialized components is extremely difficult.
One of the first things I did when getting a unit that someone else had
tried to repair was to find and remove all the non-Tek xstrs,and replace
with the proper TEK parts.They were often causes of oscillations and bad
HF
responses.Some scopes may have had ferrite beads used in some places lost
or not installed with the new transistors.One other common problem was a
black silver oxide growing on the tiny HF trimmer caps,especially on the
bottom of them,acting as an insulator and making the cap open and
ineffective.

IMO,the HF cam contacts used in the attenuators should be failing and no
longer repairable due to the plastic part that holds the gold contact to
the spring metal degrading and coming apart,or loss of spring tension.
That's a problem with using plastic parts,they outgass and eventually
degrade and lose strength.Some of the atten intermittents can be due to
the
outgassing making a film on the contacts and pads.

Yes, this unit could indeed have had some non-Tek semiconductors in it. I
got the HF ocsillation to stop by putting a few gimmick capacitors, less
that 1 pF, at the output of the Ch 1 vertical amp. Didn't affect the
frequency response any, but the vertical output amp had a few extra time
constants visible on a leading edge that none of the adjustments would
control.

It was a real learning experience, but the patient died. One thing I DID
learn was that gold-plated sockets don't mean a thing if they mate with
tinned leads. When I first got that scope almost nothing worked, and major
recovery was effected by removing and replacing all the socketed
connectiions, which in that scope included virtually all of the
semiconductors. I also suspected that that scope was not a "complete"
instrument; seems to me that the versions and serial numbers didn't really
agree, as if someone tried to make one good scope out of parts from other
ones that were of varying vintages.

Anyway, I decided that I am out of the scope-fixing business. It's kind of
like changing the engine in a car, the first couple dozen are fun, and after
that its just plain work.

 

[budgie]

(snip)

Before introducing a new instrument, we went through a lengthy process
of building and testing prototypes, which I described some time ago in
this newsgroup. In one group, it was our practice to borrow some
assemblers from production to build the prototypes. One afternoon I was
looking at some units they had built, after they had left for the day,
and saw that the plastic of some switch bodies was very badly crazed --
they were covered with tiny cracks. Some experiments with bottles of
solvent we found in some of the assemblers' work areas pinned it down to
one particular liquid. The problem was one of the ingredients, which was
a relatively common solvent of the time. Unfortunately, I don't recall
which one -- it was something pretty mild as solvents go, like toluene
or Freon, not a relatively strong solvent like acetone, which we all
knew better than to use. We found out that the solvent had been banned
from production, but the assemblers kept a supply out of sight because
it was really good at removing flux.

May well have been toluene. It was often used as a cleaner in all sorts of
areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone
switchboards. Unfortunately proved to be a carcinogen and was banned, but it
WAS used to clean a myriad of hardware in a myriad of situations.

 

[Rick Frazier]

(snip)

May well have been toluene. It was often used as a cleaner in all sorts of
areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone
switchboards. Unfortunately proved to be a carcinogen and was banned, but it
WAS used to clean a myriad of hardware in a myriad of situations.

Banned? Perhaps from use as a general solvent in assembly areas, but if you walk
into most hardware stores (such as Ace), you can buy it in gallons in their paint
sections... Pretty cheap too!

It's at least a bit amazing that one industry may ban an item, yet another still
provides it...
It seems that you can't purchase lacquer paint for an automobile anywhere at this
point, yet can still buy gallons of lacquer thinner (and lacquer based paints for
wood) at the local hardware store... sigh...

--Rick AH7H

 

[John Miles]

Considering how longlasting and popular the 465 is,that's not a very smart
sentence.The same HF and LF cam switches were also used in the high-
performance 7000 series lab scopes.

True enough in the case of the 465. That model in particular seems to
have been very robust. You don't see many owners asking about how to
clean 465 switches.

485 switches, though, are another thing entirely. It's very rare to see
a 485 whose vertical attenuator switches aren't noisy. Perhaps gold-pad
abrasion has caught up to the instruments over time; however, I'm
personally aware of at least two anecdotal cases of noisy 485 switches
being fixed (at least for the time being) with contact cleaner.

It's possible there's more than one cause of switch degradation at work
in the 485 and other notorious "problem children." Either way, though,
the original designers were clearly not omniscient in all cases, or the
problems with certain models wouldn't be as widespread as they are. I
wish there were a sure-fire way to fix the 485's front-end switches; it
was my favorite Tek scope of the bunch otherwise.

-- jm

 

[John Woodgate]

May well have been toluene. It was often used as a cleaner in all sorts
of areas, some as pedestrian as the T/R/S plugs on old lamp-signalling
telephone switchboards. Unfortunately proved to be a carcinogen and was
banned, but it WAS used to clean a myriad of hardware in a myriad of
situations.

Toluene is one of the aromatics that is NOT carcinogenic. From the ATSDR
web site:

QUOTE
Studies in workers and animals exposed to toluene generally indicate
that toluene does not cause cancer. The International Agency for
Research on Cancer (IARC) and the Department of Health and Human
Services (DHHS) have not classified toluene for carcinogenic effects.
The EPA has determined that toluene is not classifiable as to its human
carcinogenicity.
ENDQUOTE

Toluene is available in small quantities as a solvent for contact
adhesive. It DOES attack some plastics, and those it attacks slowly can
exhibit surface dulling and crazing.

 

[Ralph Mowery]

May well have been toluene. It was often used as a cleaner in all sorts
of

areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone
switchboards. Unfortunately proved to be a carcinogen and was banned, but it
WAS used to clean a myriad of hardware in a myriad of situations.

It might have been carbon tet (tetracloride or however it is spelled). I
think it was taken off the market because of either liver or kidney failure
if the user had been drinking .

 

[Guy Macon]

Other than speed, is there any difference between a 465B and
a 475/475A that I should know about? I am looking for a
replacement but I want all or nearly all of the knobs to be
the same.

 

[Bill Janssen]

It might have been carbon tet (tetracloride or however it is spelled). I
think it was taken off the market because of either liver or kidney failure
if the user had been drinking .

When carbon tet was removed from telephone offices there was a story
about a technician spilling some
on a operator. The operator lost here hair and finger nails. Don't know
if that is true but we had to
remove all carbon tet from the cleaning supplies.

Bill K7NOM

 

[Jim Yanik]

True enough in the case of the 465. That model in particular seems to
have been very robust. You don't see many owners asking about how to
clean 465 switches.

485 switches, though, are another thing entirely. It's very rare to
see a 485 whose vertical attenuator switches aren't noisy. Perhaps
gold-pad abrasion has caught up to the instruments over time; however,
I'm personally aware of at least two anecdotal cases of noisy 485
switches being fixed (at least for the time being) with contact
cleaner.

It's possible there's more than one cause of switch degradation at
work in the 485 and other notorious "problem children." Either way,
though, the original designers were clearly not omniscient in all
cases, or the problems with certain models wouldn't be as widespread
as they are. I wish there were a sure-fire way to fix the 485's
front-end switches; it was my favorite Tek scope of the bunch
otherwise.

-- jm

Both 465 and 485 use the same HF cam switch contacts.

TEK used to have a repair kit that included both contacts,drill bits to
remove the securing rivets,and tiny nuts and bolts to secure the new
contacts.


They also had a repair kit for the LF contacts used in the timing
switch,with an alignment guide to get them straight.

Both are no longer available.

 

[Jim Yanik]

Other than speed, is there any difference between a 465B and
a 475/475A that I should know about? I am looking for a
replacement but I want all or nearly all of the knobs to be
the same.

Different input sensitivities on the vertical channels(knobs will not be
same as 465,IIRC),and 475 and /A have higher bandwidth.

IIRC,465 had 5mv V/div reading,and 475 had 2mv V/div

 

[Rich Grise]

When carbon tet was removed from telephone offices there was a story
about a technician spilling some
on a operator. The operator lost here hair and finger nails.

This is so stupid it's ludicrous.

Don't know
if that is true but we had to
remove all carbon tet from the cleaning supplies.

That's typical government wisdumb for you. Make laws based on hysteria.

Cheers!
Rich

 

[Rich Grise]

Toluene is one of the aromatics that is NOT carcinogenic. From the ATSDR
web site:

QUOTE
Studies in workers and animals exposed to toluene generally indicate
that toluene does not cause cancer. The International Agency for
Research on Cancer (IARC) and the Department of Health and Human
Services (DHHS) have not classified toluene for carcinogenic effects.
The EPA has determined that toluene is not classifiable as to its human
carcinogenicity.
ENDQUOTE

Toluene is available in small quantities as a solvent for contact
adhesive. It DOES attack some plastics, and those it attacks slowly can
exhibit surface dulling and crazing.

They banned it because it was the "active ingredient" in airplane glue,
which kids sniffed and got high.

Cheers!
Rich

 

[Roy Lewallen]

. . .

That's typical government wisdumb for you. Make laws based on hysteria.

Cheers!
Rich

Yeah, that's the stoopid guv'mint for ya! If they was just as smart as
we was, they wouldn't ban all this neat stuff.

According to a hazmat data sheet I have, carbon tet (which can be
absorbed by breathing, skin contact, or ingestion) causes damage to the
liver, kidneys, heart, adrenal glands, and nervous system, and is
particularly dangerous to people who have recently consumed alcohol, are
exceedingly fleshy or are undernourished, or have other problems like
hypertension. You can smell it at a concentration of 70 ppm; toxicity is
known at concentrations of 5 ppm.

I used the stuff quite a bit when I was a kid, and I'm just fine (I
think) so that's obvious proof that it's all a bunch of hogwash and a
government conspiracy.

Personally, I favor allowing anyone to buy and sell any kind of
hazardous chemical or object. By banning them, we've interfered with
natural selection, which seems to be resulting in a less and less
intelligent population. A sort of "unintelligent design" as it were.

Roy Lewallen, W7EL

 

[budgie]

Banned? Perhaps from use as a general solvent in assembly areas, but if you walk
into most hardware stores (such as Ace), you can buy it in gallons in their paint
sections... Pretty cheap too!

Different countries, different strokes.

 

[budgie]

Toluene is one of the aromatics that is NOT carcinogenic. From the ATSDR
web site:

(snip)

That was the reason used when it was banned here, merit notwithstanding.