Tektronix 585a (tube-based) oscilloscope project

[zeitguy]

Does anyone have an old Tektronix scope similar to this? I just got it
from a surplus dump where it has been sitting in an unheated shed for a
few years. The tubes light up, and it gets a spot on the screen, but
the trace doesn't move at all, no matter what the settings are. I have
ordered an operators manual from the net, but it seems odd to me that
the trace won't even move, with or without a probe connected. I would
like to find someone with a similar scope who might be willing to share
some knowledge. I expect this is going to be a lengthy rehabilitation
project, if it is even possible.

The reason it might be worthwhile, is that the 585a was the last
production model of an all tube based scope in this range (85 mhz
rated, 100+ actual performance) and it is all hand built, with
components connected on ceramic strips. It was called a "Rolls Royce"
in one reference, and I would love to get it operational. But I will
need some guidance, I am sure.

 

[stickyfox@gmail.com]

There could be hundreds of opens due to corrosion on the contacts in
switches and any plug-in sockets. Have you given all the controls a
good workout, and removed and replaced the preamp? Not much else goes
wrong with these tube scopes, for the reasons you cited. Of course, you
could spend a day or two at an old-timey hardware store checking all
those tubes.

It should not be hard to find someone with a manual for that scope.
Don't pay some ebay crook 40 bucks for a photocopy.

 

[Arfa Daily]

"zeitguy" <zeitguy@gmail.com> wrote in message
news:1140207340.821215.29650@f14g2000cwb.googlegroups.com...

Does anyone have an old Tektronix scope similar to this? I just got it
from a surplus dump where it has been sitting in an unheated shed for a
few years. The tubes light up, and it gets a spot on the screen, but
the trace doesn't move at all, no matter what the settings are. I have
ordered an operators manual from the net, but it seems odd to me that
the trace won't even move, with or without a probe connected. I would
like to find someone with a similar scope who might be willing to share
some knowledge. I expect this is going to be a lengthy rehabilitation
project, if it is even possible.

The reason it might be worthwhile, is that the 585a was the last
production model of an all tube based scope in this range (85 mhz
rated, 100+ actual performance) and it is all hand built, with
components connected on ceramic strips. It was called a "Rolls Royce"
in one reference, and I would love to get it operational. But I will
need some guidance, I am sure.

If you've got no timebase, and no Y deflection either, then you should be

looking for a common reason, as these two pieces of circuitry, are pretty
much independent from each other. I would suggest starting by checking that
the HT supply for the tubes involved, is present. Could be something as
simple as an open circuit resistor, or short circuit decoupling cap ( or
possibly, both )

Arfa

 

[Jim Yanik]

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in
news:YArJf.12343$gB4.12112@newsfe4-gui.ntli.net:

"zeitguy" <zeitguy@gmail.com> wrote in message
news:1140207340.821215.29650@f14g2000cwb.googlegroups.com...
Does anyone have an old Tektronix scope similar to this? I just got
it from a surplus dump where it has been sitting in an unheated shed
for a few years. The tubes light up, and it gets a spot on the
screen, but the trace doesn't move at all, no matter what the
settings are. I have ordered an operators manual from the net,

You need a SERVICE manual.

but
it seems odd to me that the trace won't even move, with or without a
probe connected. I would like to find someone with a similar scope
who might be willing to share some knowledge. I expect this is going
to be a lengthy rehabilitation project, if it is even possible.

The reason it might be worthwhile, is that the 585a was the last
production model of an all tube based scope in this range (85 mhz
rated, 100+ actual performance) and it is all hand built, with
components connected on ceramic strips. It was called a "Rolls
Royce" in one reference, and I would love to get it operational. But
I will need some guidance, I am sure.

If you've got no timebase, and no Y deflection either, then you should
be looking for a common reason, as these two pieces of circuitry, are
pretty much independent from each other. I would suggest starting by
checking that the HT supply for the tubes involved, is present. Could
be something as simple as an open circuit resistor, or short circuit
decoupling cap ( or possibly, both )

Arfa

Well,the FIRST check should be all the power supply DC voltages,regulation
and ripple.

Just because there's a spot on the CRT does not mean that the PS voltages
are what they should be.

--
Jim Yanik
jyanik
at
kua.net

 

[n cook]

zeitguy <zeitguy@gmail.com> wrote in message
news:1140207340.821215.29650@f14g2000cwb.googlegroups.com...

Does anyone have an old Tektronix scope similar to this? I just got it
from a surplus dump where it has been sitting in an unheated shed for a
few years. The tubes light up, and it gets a spot on the screen, but
the trace doesn't move at all, no matter what the settings are. I have
ordered an operators manual from the net, but it seems odd to me that
the trace won't even move, with or without a probe connected. I would
like to find someone with a similar scope who might be willing to share
some knowledge. I expect this is going to be a lengthy rehabilitation
project, if it is even possible.

The reason it might be worthwhile, is that the 585a was the last
production model of an all tube based scope in this range (85 mhz
rated, 100+ actual performance) and it is all hand built, with
components connected on ceramic strips. It was called a "Rolls Royce"
in one reference, and I would love to get it operational. But I will
need some guidance, I am sure.

If relevant, I have a repair manual for the 585A
my email address on URL below

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Wild Bill]

I had some old Tek tube models similar to the one you described. My
memories of 'em are fairly vague, but I do remember admiring the
internal craftsmanship.

I kinda-sorta remember 2 jumper bars that were mounted within an
exposed insulated panel near the back of the cover (an opening in the
cover, near the back, visible with the scope cover on).

If my recollection is anywhere near accurate, the jumpers had to do
with the beam sweep. The jacks that the bars were inserted into were
just panel bananna jacks, and the jumper bars were just
bare/uninsulated plated bars with a bananna pin at each end.

I'm not sure that the bars' purpose was, but I seem to think that one
of the units wasn't operational, and that I noticed that the bars were
missing. Putting a set of bars in place, from another unit restored
operation.

Cheers
WB
..................

zeitguy wrote:

Does anyone have an old Tektronix scope similar to this? I just got it
from a surplus dump where it has been sitting in an unheated shed for a
few years. The tubes light up, and it gets a spot on the screen, but
the trace doesn't move at all, no matter what the settings are. I have
ordered an operators manual from the net, but it seems odd to me that
the trace won't even move, with or without a probe connected. I would
like to find someone with a similar scope who might be willing to share
some knowledge. I expect this is going to be a lengthy rehabilitation
project, if it is even possible.

The reason it might be worthwhile, is that the 585a was the last
production model of an all tube based scope in this range (85 mhz
rated, 100+ actual performance) and it is all hand built, with
components connected on ceramic strips. It was called a "Rolls Royce"
in one reference, and I would love to get it operational. But I will
need some guidance, I am sure.

 

zeitguy wrote:

Does anyone have an old Tektronix scope similar to this 585a ?

I had one for many years. Amazing device, BUT note:

(1) They're huge, heavy, and draw about 600 watts IIRC. Fine in the
winter, unbearable in the summer even with the workshop AC on.

(2)The fan is NOISY. Makes it hard (for me) to concentrate.

(3) There are about 50 tubes in there, each with 7 to nine pins, all
corroding away and making poor contact. There are a passel of wafer
switches, most of them NOT gold or silver plated, all contacts
corroding away. There's lots of redundancy in there, which means a good
10% of those contacts can go open circuit and the scope will still
kinda "work", but be totally out of specs.

(4) There's a tunnel diode or three in there which are easily burned
out (dont ask) and are very hard to find. Without them you have no
sweep and no scope.

(5) Even when it's working at 100%, the triggering is still mighty
iffy, at least compared to newer scopes. You can easily spend a minute
twiddling the trigger knobs before you get a stable trace. After doing
this a few huindred times, the charm wears off and most folks revert to
using a quieter, cooler, more portable, better triggering 465 or 475.

(6) Poking around in there can KILL you. There are many high-voltage
regulated power supplies.

----
Al that said it's an impressive beast, especially if you're used to a
5MHz heathkit scope.
If you have the time, $$, and patience, by all means go for it.

 

[Jorgen Lund-Nielsen]

zeitguy wrote:

Does anyone have an old Tektronix scope similar to this? I just got it
from a surplus dump where it has been sitting in an unheated shed for a
few years. The tubes light up, and it gets a spot on the screen, but
the trace doesn't move at all, no matter what the settings are. I have
ordered an operators manual from the net, but it seems odd to me that
the trace won't even move, with or without a probe connected. I would
like to find someone with a similar scope who might be willing to share
some knowledge. I expect this is going to be a lengthy rehabilitation
project, if it is even possible.

Here you find help:

http://groups.yahoo.com/group/TekScopes/

You have to became a member of yahoo-groups, but that's an easy task
and for free.

Jorgen