Tektronix 24xx series and U800 problems

[Jim Yanik]

mike <spamme0@juno.com> wrote in news:406869F6.4040006@juno.com:

TekMan wrote:


But I agree with jim: the 2465a/b are "must have" today if you wanna
do real good job in the home lab.

Andreas

I suppose you could come up with an application that could only be done
with a 2465, but you'd have to try really hard. "Must have" is a bit of
a reach.
I had one for two years. Couldn't justify the bench space and never
had occasion to take it out of the closet. If you don't need the
portability (home lab), a 7704A is MUCH greater bang for the buck.

mike

I consider the 2465 series the best -portable- scope TEK ever made,but it's
not a "must-have" by any means.Unfortunately,most if not all TEK analog
scopes are hindered by a lack of parts support like TEK-made ICs and both
HF and LF cam switch contacts that wear out.

For a bench scope,I'd much rather have a 7904(A) and a good set of PIs.
Then I'd have a curve tracer(7CT1N) and a spectrum analyzer(7L12,my
preference) in addition to a great scope with a differential amp PI(7A13).
You cannot beat the later TEK 7000 series lab scopes.

--
Jim Yanik
jyanik-at-kua.net

 

[Jim Yanik]

Jamie <jamie_5_not_valid_after_5_Please@charter.net> wrote in
news:106gua6h7fs6i52@corp.supernews.com:

ah, Ok, well that makes me feel better.
i haven't had any problems with the 485 and use that alot..
i do also keep it in an open place and cooled area.

Keep the air filter clean and the scope 'dirt-free'.



--
Jim Yanik
jyanik-at-kua.net

 

[Jeff W]

I have 2 485's, one working, one dead.

My 485 is my favorite scope; late production unit, pristine condition.
It is my favorite for nostalgia reasons; I started my career in 1981
as an engineering tech, and the owner of the small company had a new
485 that was his pride and joy, for which he paid a small fortune for.
He entrusted me with his "baby" and I enjoyed using it.

Jeff

On Sun, 28 Mar 2004 14:01:54 -0800, Jamie
<jamie_5_not_valid_after_5_Please@charter.net> wrote:

i own a 485 scope. does that make me old?
i also have a 465 and not sure about the specs on that one how ever.
all i know it works.



Jeff W wrote:

My personal experience is with an early 2465, I don't remember the
serial but it was around 20K or so. After sitting for perhaps 4
months of non-use, I turned it on and it ran for maybe one minute
before the readout started jumping, then flashing, then all display
was lost. For the next few times I turned it on, it would run for
maybe 30 seconds before losing the display. Pressing the beam find
button resulted in a minature display in the center of the screen,
which was wobbly & jumpy.

On investigation, the electrical failure seems to be that one of the
diff plate drive outputs of the U800 chip developed an internal
leakage path to its respective voltage rail, thereby pulling the
horizontal display off hard to one side.

Given that the scope was sitting for a long time, and developed the
fault early on start up, I don't think the primary failure mechanism
was due to heat. ( although it could have been weakened seriously by
past heat events, of course) So it appears to me that time alone may
be a key factor, which means that keeping your 2465 cool, using it
sparingly, etc, may not be a strategy that will preserve it in the
long run.

I really like 2465's, excellent performing scopes, but sold both my
2465's as a precaution.

Jeff

On Fri, 26 Mar 2004 15:10:10 +0100, "Jose V. Gavila" <eb5agv@ctv.es
wrote:


Hello!

After reading lots of old messages regarding Tektronix 24xx problems
(mainly on 2465 variants) with the dreaded U800 Horizontal Amplifier, I
have not yet found any definitive (if there is one ;-) ) answer to why
do they fail and the correlation with oscilloscope types, U800 reference
and failure rate.

I guess it could fail more in later units (2465A and B), as they have
perhaps higher requirements on the chip... but I am just guessing.

So I wonder if you could help me correlating all that information. I
think it would be fine to get info also on working units.

* Type (2465, 2465A, 2465B, 2445, ...)
* U800 reference (155-0241-01, 155-0241-02 or 155-0241-55, if known)
* Manufacture date (if known) or serial number (just first digits)
* If U800 is gone, how did it fail? (i.e. heat related (after long time
use), just after powering on?)
* Comments


Hope this helps to clarify a bit this recursive topic.

Thanks for your help and best regards,

JOSE

 

[Jeff W]

I couldn't agree more, Jim. While my 485 is my favorite scope (for
nostalgia reasons), my 7904 set-up makes for one powerful lab & blows
away the 2465s I used to have. (I never really used the on-screen
cursor measurement functions of the 2465, which admittedly is a cool
feature) I actually have two 7904's, one early & one late. I have a
boatload of plugins, including the 7CT1N you reference and a 7L5 (I
dabble in audio).

Jeff

On Mon, 29 Mar 2004 23:55:23 +0000 (UTC), Jim Yanik <jyanik@abuse.gov>
wrote:

mike <spamme0@juno.com> wrote in news:406869F6.4040006@juno.com:

TekMan wrote:


But I agree with jim: the 2465a/b are "must have" today if you wanna
do real good job in the home lab.

Andreas

I suppose you could come up with an application that could only be done
with a 2465, but you'd have to try really hard. "Must have" is a bit of
a reach.
I had one for two years. Couldn't justify the bench space and never
had occasion to take it out of the closet. If you don't need the
portability (home lab), a 7704A is MUCH greater bang for the buck.

mike





I consider the 2465 series the best -portable- scope TEK ever made,but it's
not a "must-have" by any means.Unfortunately,most if not all TEK analog
scopes are hindered by a lack of parts support like TEK-made ICs and both
HF and LF cam switch contacts that wear out.

For a bench scope,I'd much rather have a 7904(A) and a good set of PIs.
Then I'd have a curve tracer(7CT1N) and a spectrum analyzer(7L12,my
preference) in addition to a great scope with a differential amp PI(7A13).
You cannot beat the later TEK 7000 series lab scopes.