There is a suspect tantalum capacitor, which I did not replace, namely
C933, which is in the path that brings working voltage to the Delay Time Position control.... just as good measure, I
will replace that also...

-----Original Message-----
From: David C. Partridge
Sent: Thursday, April 18, 2019 1:43 AM

IIRC some flexible couplers in the 576 have the be insulating up to the
full voltage output of the 576.

I know that because I needed to replace one and luckily Hakan Hintze
had one on stock.

David

-----Original Message-----
From: Dennis Tillman W7PF
Sent: 18 April 2019 03:41

Hi Neil,
I had a slightly different problem but I think this might work for you.
But first, companies like McMaster-Carr (https://www.mcmaster.com/)
sell flexible couplers that can be substituted for the broken ones you
have. If they don't have one that will work for you try what I did
next:

What I have done in the past is taken a piece of heat shrink tubing
that is a close fit before shrinking. It should be long enough so about
a half inch of heat shrink is on the shaft on each side of where the
coupler used to be. I put a dab of epoxy all the way around each end of
heat shrink and then insert the heat shrink onto the two shafts. With a
heat gun I shrink the tubing. When the epoxy dries it is glued to each
end of the shaft. The small section of heat shrink tubing in the middle
where the coupler used to be should be nice and flexible and act like
the coupler did.

Dennis Tillman W7PF

-----Original Message-----
From: groups@...
Sent: Wednesday, April 17, 2019 8:32 AM
Subject: [TekScopes] 576 shaft repair

Apologies if this has come up before! I have a 576, and the plastic
couplers for the Intensity and Focus knobs are, of course, broken.
They look fairly hard to find, so I'm wondering what the best option
is - has anyone 3D printed replacements, for example? There's also a
video where a 577 has a similar repair accomplished with plastic
tubing (https://www.youtube.com/watch?v=wXiR01HLhUA).

One other thing - I've seen CRC 5-56 mentioned as the recommendation
for cleaning switches, but it no longer seems to be available -
instead replaced by CRC 05005. Is that an acceptable substitute, or
should I use something else?

Thanks,

Neil

--
Dennis Tillman W7PF
TekScopes Moderator

IIRC some flexible couplers in the 576 have the be insulating up to the
full voltage output of the 576.

I know that because I needed to replace one and luckily Hakan Hintze had
one on stock.

David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Dennis Tillman W7PF
Sent: 18 April 2019 03:41
To: TekScopes@groups.io
Subject: Re: [TekScopes] 576 shaft repair

Hi Neil,
I had a slightly different problem but I think this might work for you.
But first, companies like McMaster-Carr (https://www.mcmaster.com/) sell
flexible couplers that can be substituted for the broken ones you have. If
they don't have one that will work for you try what I did next:

What I have done in the past is taken a piece of heat shrink tubing that
is a close fit before shrinking. It should be long enough so about a half
inch of heat shrink is on the shaft on each side of where the coupler used
to be. I put a dab of epoxy all the way around each end of heat shrink and
then insert the heat shrink onto the two shafts. With a heat gun I shrink
the tubing. When the epoxy dries it is glued to each end of the shaft. The
small section of heat shrink tubing in the middle where the coupler used to
be should be nice and flexible and act like the coupler did.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
groups@...
Sent: Wednesday, April 17, 2019 8:32 AM
Subject: [TekScopes] 576 shaft repair

Apologies if this has come up before! I have a 576, and the plastic
couplers for the Intensity and Focus knobs are, of course, broken. They
look fairly hard to find, so I'm wondering what the best option is -
has anyone 3D printed replacements, for example? There's also a video
where a 577 has a similar repair accomplished with plastic tubing
(https://www.youtube.com/watch?v=wXiR01HLhUA).

One other thing - I've seen CRC 5-56 mentioned as the recommendation
for cleaning switches, but it no longer seems to be available - instead
replaced by CRC 05005. Is that an acceptable substitute, or should I
use something else?

Thanks,

Neil

--
Dennis Tillman W7PF
TekScopes Moderator

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
groups@...
Sent: Wednesday, April 17, 2019 8:32 AM
Subject: [TekScopes] 576 shaft repair

Apologies if this has come up before! I have a 576, and the plastic
couplers for the Intensity and Focus knobs are, of course, broken. They
look fairly hard to find, so I'm wondering what the best option is -
has anyone 3D printed replacements, for example? There's also a video
where a 577 has a similar repair accomplished with plastic tubing
(https://www.youtube.com/watch?v=wXiR01HLhUA).

One other thing - I've seen CRC 5-56 mentioned as the recommendation
for cleaning switches, but it no longer seems to be available - instead
replaced by CRC 05005. Is that an acceptable substitute, or should I
use something else?

Thanks,

Neil

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
groups@...
Sent: Wednesday, April 17, 2019 8:32 AM
Subject: [TekScopes] 576 shaft repair

Apologies if this has come up before! I have a 576, and the plastic
couplers for the Intensity and Focus knobs are, of course, broken. They
look fairly hard to find, so I'm wondering what the best option is -
has anyone 3D printed replacements, for example? There's also a video
where a 577 has a similar repair accomplished with plastic tubing
(https://www.youtube.com/watch?v=wXiR01HLhUA).

One other thing - I've seen CRC 5-56 mentioned as the recommendation
for cleaning switches, but it no longer seems to be available - instead
replaced by CRC 05005. Is that an acceptable substitute, or should I
use something else?

Thanks,

Neil

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Dave Daniel
Sent: Tuesday, April 16, 2019 11:39 AM
Subject: Re: [TekScopes] Absurdly simple way to get contact cleaner
into some Tek pots

would be interesting to submerge a "sealed" pot in a liquid and see
if the pot eventually fills up, just as an experiment to see just how
well these sealed pots are sealed.

Some time ago I had to submerge an unobtainium unsealed pot into a
beaker of IPA in order to free the shaft's rotation. It took a couple
of days of immersion to free up the shaft. I'm guessing that a "sealed"
pot would take much, much longer to absorb the fluid.

DaveD


On 4/16/2019 1:51 PM, Richard Solomon wrote:

My foolproof method is to drill
a small hole on the top side at
the rear. Pump in De-Oxit Fader
Lube and seal the hole with some
black tape.

73, Dick, W1KSZ

On Tue, Apr 16, 2019 at 10:45 AM Terry Gray via Groups.Io <tlgray42=
yahoo.com@groups.io> wrote:

I also have restored 100's of "sealed"? noisy controls by
pointing the control shaft straight up vertically, wrapping

something

around the bottom of the control to catch the excess contact
CLEANER/LUBE, spray around the base of the shaft where it goes into
the control, and "pump" the shaft up and down and give it time to
"pump" the contact cleaner/lube down into the control---remember
patience is a virtue. If at first it doesn't seem to be getting the
spray down the shaft, make a dam" just below the point where the
shaft enters into the control and try spraying a little additional
cleaner/lube into that area keeping it saturated and at the same

time

periodically "pumping' the shaft up and down to allow the
cleaner/lube to migrate along with capillary action down the shaft.
Allow the potentiometer shaft to remain pointed up vertically.
Sometimes it can take overnight or longer to get the cleaner/lube
down into the control but I have found over the last 50-60 years

that

it very, very rarely fails. Just be patient and I think this will
work for you, even for the difficult ones. I remember setting

upright

on their backs some of the big monster stereos and doing just that,

especially when the potentiometer access was not readily accessible
even with the long extended flexible tubing that sometimes came

with the contact cleaner/lube or that were also available at the

time. I

also remember running into some well sealed potentiometers and TV
tuners that we had to drill a small access hole into/through the
metal or plastic housing to get the cleaner/lube inside to do its
job. Just be very careful to not drill into the tuner or control
doing any internal damage. I remember disassembling throw-away pots
and tuners to learn where to drill the holes to prevent any internal

damage and you could then seal the hole

up with solder or glue when you completed the cleaning/lube process.

One

additional point, DO NOT use a contact cleaner with no lubricating
agent in its ingredients. Many years ago I attended a Channel Master
seminar on their contact cleaners and tuner (and switch)
cleaner/lubes. The company representative showed us under a fairly
high-powered microscope a video of what happens when you spray a
contact cleaner (with no lube) on the old TV tuner switch contacts
You completely wash away all lubrication from the individual contact
points and he showed us under the microscope what happens when you
rotate the switch thru the washed contacts. It scrapes the plating
off the contacts and now being unplated in that area it is oxidizes
and you end up with intermittent high resistance contacts down the
line(with time) that play havoc with your circuit. You think that

you

are "fixing" the intermittent switch contact(s) (or the intermittent
internal potentiometer wiper problem) but in reality you are totally

ruining (for the future) whatever you are so-called restoring by using
a non-lubricated

spray. I wish the video that the Channel Master rep showed us was

still

available>>>>it looked like a chisel scraping the plating off the
available>>>>contact
under the high-magnification microscope when all the lubrication had
been previously "cleaned" off the contact areas. He said DO NOT EVER
use a contact cleaner that has no lubrication in it or at least
follow up the "cleaning" process by spraying or adding some

additional lubrication to the

contact points. Hope this is helpful information to some of you,

it sure

was for me.
On Tuesday, April 16, 2019, 9:51:07 AM CDT, Bob Koller via
Groups.Io <testtech@...> wrote:

Try it sometime, I have literally done hundreds this way. Some

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Gary Robert Bosworth
Sent: Tuesday, April 16, 2019 7:42 AM
Subject: Re: [TekScopes] Absurdly simple way to get contact cleaner
into some Tek pots

Unless you squirt the contact cleaner in under pressure, I doubt that
much of it will find its way to the resistive element. What would be
better is to slightly loosen the other 3 screws and again squirt the
cleaner in under pressure. Some will find its way to the outside, so
be sure to wrap the potentiometer with tissue paper to block the
vapor's path.

Gary

On Mon, Apr 15, 2019 at 6:57 PM Dennis Tillman W7PF
<dennis@...>
wrote:

For years I've struggled with what to do about noisy pots. Until now
the best solution I have come up with is to remove the knob and drip
contact cleaner down the shaft. It only works a small percentage of
the time. And I'm not sure it can even work on ganged pots at all.
Plus it is quite messy since it is almost impossible to control the
burst of contact cleaner that comes out.

Faced with the same problem once again an idea struck me while I was
staring at the back side of one of the very common black square pots
(single or ganged). The ones I'm referring to have four tiny screws
holding them together from back to front.

SOLUTION: Remove one of the screws and squirt the contact cleaner

into

the hole. All four of the screws screw into a metal plate at the

front

of the pot. So the screw hole passes through every section of the pot
(or multiple pots regardless of how many there are.

It's too early yet to tell how effective this is. I only just
discovered it.

Dennis Tillman W7PF

--
Gary Robert Bosworth
grbosworth@...
Tel: 310-317-2247

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
redarlington
Sent: Tuesday, April 16, 2019 8:44 AM
Subject: Re: [TekScopes] More Complete List of Concept Series and
Measurements Concepts Books

I backed it up so it won't go away forever. What I don't have is a
place to dump it online with enough storage for even a quarter of it.

Downloaded: 37670 files, 136G in 14h 2m 14s (2.76 MB/s)

-Bob

On Sun, Apr 14, 2019 at 11:37 AM Roy Thistle
<roy.thistle@...>
wrote:

On Sat, Apr 13, 2019 at 09:25 AM, Dave Daniel wrote:

Does anyone know who the owner of this site is?

Hi:
I've seen that question asked on the forum before. IMHO, if people
keep asking, the site will soon disappear... like others, that were
once up, have.
Regards.

On Wed, 17 Apr 2019 07:06:19 -0700, you wrote:

I have been given this tool. I have a Tek 2246A and a Hitachi scope already. What can I do with this that I can't with the other scopes? I have never done anything with video nor intend to. Also, the trace is hiding deep lower left of CRT. Can't get it out of there.

If you're doing anything with baseband video, such as CCTV cameras for
surveillance systems, video tape recorders, etc., then you'll want
this.

On 2019-04-16 16:35, Alberto I2PHD wrote:

There is a suspect tantalum capacitor, which I did not replace, namely
C933, which is in the path that brings working voltage to the Delay Time Position control.... just as good measure, I
will replace that also...

Problem fixed. I replaced that suspect capacitor with a 4.7uF, 100V electrolytic, and now the delay time after which the B sweep starts is rock stable...

Now I have a suspect, which maybe somebody could confirm or deny... look at this photo of the replaced cap :

http://www.i2phd.org/public/tantalum2.2uF.jpg

Should the mark indicate the negative side of the cap, then it was soldered in reverse, with the marked side connected to +14V....
If instead it indicates the positive side, then no manufacturing errors....  I am not much familiar with the markings of the tantalum caps....

In any case, now my 475A is perfectly working, and this is what counts... :-)