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.



"Roy Lewallen" wrote in message
...
If there's any disagreement between what I say and what Jim says about
maintaining Tek scopes, listen to Jim and not me. He was there in the
trenches; I wasn't.

Roy Lewallen, W7EL

Jim Yanik wrote:

I worked for TEK for 21.5 years as a service tech in 2 of their field
offices;repaired and cal'd a lot of scopes and other TEK products.
. . .

On Wed, 22 Dec 2004 14:55:03 -0500, BFoelsch wrote:

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

"Bob Stephens" wrote in message
.. .
On Wed, 22 Dec 2004 14:55:03 -0500, BFoelsch wrote:

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

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.

"BFoelsch" wrote in
:

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
jyanik-at-kua.net

Bob Stephens wrote in
:

On Wed, 22 Dec 2004 14:55:03 -0500, BFoelsch wrote:

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

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.

--
Jim Yanik
jyanik-at-kua.net

"Jim Yanik" . wrote in message
.. .
"BFoelsch" wrote in
:

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.

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.





--
Jim Yanik
jyanik-at-kua.net

On Wed, 22 Dec 2004 05:15:23 -0800, Roy Lewallen wrote:

(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.

budgie wrote:

(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

In article ,
. says...

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

------------------------------------------------------
http://www.qsl.net/ke5fx
Note: My E-mail address has been altered to avoid spam
------------------------------------------------------

I read in sci.electronics.design that budgie wrote (in
) about 'Tektronix 465
Scope', on Thu, 23 Dec 2004:

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.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk