Topics

Lots of corrosion on my new (newly aquired) Type 576 Curve Tracer


brentleew2003@...
 

Well, I bought it for parts and or not working. They said it would power up, and that the bulb was out. I assumed there was an issue with the display. It arrived this afternoon. It has a lot of corrosion. Must have been by the ocean near an open window. All the connectors, semiconductors, nuts, bolts, front panel. are suffering I might have done it differently had I known it's condition. But, I do like a challenge. Then after some working the switches I manged to get a nice bright trace, although very unstable, mostly due to VERY dry controls. Everything is very hard to turn Mosyt instability is due to the Display Invert and Display Offset Zero and Cal switched being super dryed out
I checked voltages and ripple. Very low ripple and all the voltages were nearly spot on.

It appears to have very light to little use, thankfully, but the corrosion.... Holy Cow. A lot of the zinc and or tin coatings on screws, connectors, rods, aluminum parts are really starting to get a corrosive film. Anything ferris is rusted. The anodised aluminum frames enclosing the blue side covers and front panels are very pitted. Not much I can do about that: sand em down and paint perhaps.

Also, the offset multiplier has lost (broken) its plastic retining bezel and fallen inward. I'll need to address that somehow. And the Polarity and Mode knobs are missing and cracked.

Can the corrosion be treated overall.
I couldn't afford the amount of De-ox needed to treat everything
I could pull each board and go at it slowly.


The readout works fine, As do the control lights. The knobs are all without any dirt between the splines and look like new. The aluminum rails adjacent to the front panel is damaged from corrosion and gray blisters are coming through the blue paint. The cosmetics I can accept and mitigate, but the wiring and potentiometers are in need of lubrication and surface protection from further decay. I just found a roll of solder attached to the plate between the low voltage regulator and the other boards. It's all there, too. You don't see that too often any more. Perhaps it was to use if you needed to rework the ceramic terminal strips.



Is there any easy way to get at the controls for lubrication. I have the manual, but it looks like you strip the knobs and pull the front off.
It looks like I'll need a lot of contract cleaner. Perhaps a larger container of De-Ox.



All in all, what an great instrument. I thonk most of the damage was from sitting and waiting. An IC date code check suggests 1979 But 1 board is dated 1980, perhaps it was the newest stocked part.


At this point I have ordered a spray can of deoxit and would lightly spray everything needing some protection and lube.
I"m open to suggestion on how to proceed,


Cheers,


Brent


ykochcal
 

Brent

If the CRT is ok then got something.

I have a few pieces of test equipment that have clearly been in the ocean
breeze for a long time and can have considerable corrosion. It can't remove
all the corrosion but I find simple green and brushing can clean things up
fairly well. If you increase the concentration from around 10% it takes more
stuff off, but then at some point you can lose some labels and paint. So
there is a balancing. With corrosion you always have the pitting in aluminum
and other metal parts.

Consider giving it a try on some smaller sub-assembly to see what you get.

You can search for other threads that have covered it in the past.

John

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, August 02, 2017 11:14 PM
To: TekScopes@yahoogroups.com
Subject: [TekScopes] Lots of corrosion on my new (newly aquired) Type 576
Curve Tracer

Well, I bought it for parts and or not working. They said it would power up,
and that the bulb was out. I assumed there was an issue with the display. It
arrived this afternoon. It has a lot of corrosion. Must have been by the
ocean near an open window. All the connectors, semiconductors, nuts, bolts,
front panel. are suffering I might have done it differently had I known
it's condition. But, I do like a challenge. Then after some working the
switches I manged to get a nice bright trace, although very unstable, mostly
due to VERY dry controls. Everything is very hard to turn Mosyt instability
is due to the Display Invert and Display Offset Zero and Cal switched being
super dryed out
I checked voltages and ripple. Very low ripple and all the voltages were
nearly spot on.

It appears to have very light to little use, thankfully, but the
corrosion.... Holy Cow. A lot of the zinc and or tin coatings on screws,
connectors, rods, aluminum parts are really starting to get a corrosive
film. Anything ferris is rusted. The anodised aluminum frames enclosing the
blue side covers and front panels are very pitted. Not much I can do about
that: sand em down and paint perhaps.

Also, the offset multiplier has lost (broken) its plastic retining bezel and
fallen inward. I'll need to address that somehow. And the Polarity and Mode
knobs are missing and cracked.

Can the corrosion be treated overall.
I couldn't afford the amount of De-ox needed to treat everything
I could pull each board and go at it slowly.


The readout works fine, As do the control lights. The knobs are all without
any dirt between the splines and look like new. The aluminum rails adjacent
to the front panel is damaged from corrosion and gray blisters are coming
through the blue paint. The cosmetics I can accept and mitigate, but the
wiring and potentiometers are in need of lubrication and surface protection
from further decay. I just found a roll of solder attached to the plate
between the low voltage regulator and the other boards. It's all there, too.
You don't see that too often any more. Perhaps it was to use if you needed
to rework the ceramic terminal strips.



Is there any easy way to get at the controls for lubrication. I have the
manual, but it looks like you strip the knobs and pull the front off.
It looks like I'll need a lot of contract cleaner. Perhaps a larger
container of De-Ox.



All in all, what an great instrument. I thonk most of the damage was from
sitting and waiting. An IC date code check suggests 1979 But 1 board is
dated 1980, perhaps it was the newest stocked part.


At this point I have ordered a spray can of deoxit and would lightly spray
everything needing some protection and lube.
I"m open to suggestion on how to proceed,


Cheers,


Brent











------------------------------------
Posted by: brentleew2003@yahoo.com
------------------------------------


------------------------------------

Yahoo Groups Links


Craig Sawyers <c.sawyers@...>
 

Mosyt instability is due to
the Display Invert and Display Offset Zero and Cal switched being super dryed out I checked
voltages
and ripple.
Is there any easy way to get at the controls for lubrication. I have the manual, but it looks
like you strip
the knobs and pull the front off.
It looks like I'll need a lot of contract cleaner. Perhaps a larger container of De-Ox.
The push button switches are notorious on the 576 and other instruments on which they are used. I
was lucky enough to get a 576 free from a guy who worked in the BBC Technical Centre in the UK. It
had a characteristic problem with the older 576 of epoxy potting on the HT transformer (yours is a
late instrument after Tek had gone across to silicone potting, so you're OK there). The BBC were
going to put it in the skip, so this guy hauled it home intending to fix it, never got around to it
and gifted it to me.

Anyhow, to cut a long story short, this 576 had had a really nice life in a dry air conditioned
environment. But the push switches were all intermittent.

To get to one set, you have to take out all some, or all horizontal and vertical boards. You have to
take the knobs off these and undo the switch securing nuts, then a screw at the back. You have to
unplug a great number of wires (use your phone to take lots of close up photos so you can put them
back correctly). If you have the manual there are clear diagrams which show which colour wires go
where too.

Once you get them out, you will see a board with the offending switches on it. Using the flexible
nozzle on a deoxit can you get a good squirt down the inside of each switch. Exercise each one a
lot, then a final squirt. Reassemble.

Good luck - these curve tracers are well worth saving!

Craig


Brent Watson <brentleew2003@...>
 

After a day of cleaning and lubing switches and contacts on the 576, it's not as bad as I thought. I used a small artists' brush and lightly coated a few circuit board  traces with DeOxit. Using De-ox on all the controls made a big difference. I was able to go through the familiarization procedure up to #51 with optimum results.Replaced a few rusted screws and went through initial test-set up  to #51 with optimum results.

Step 47 is the Step Generator.
After inserting an NPN transistor  and getting a minimum step amplitude, I can't get any steps.  I believe I saw some briefly yesterday, but can't get anything today. I got as far as putting my meter on  step generator IC U75 pins 9,1,3,5,  which respond to the "Number of Steps" switch. But have not been able to follow the path further.
I was hoping there might be someone here who knows these well enough to suggest where to suspect a problem. adapter doesn't support it, but didn't think it . I'm using an 013-069 adapter because that's what I have.  Here's a short video showing the issue.
https://www.youtube.com/watch?v=FdC9qWejY2M&feature=youtu.be


Cheers,
Brent

On Thursday, August 3, 2017, 12:29:15 AM PDT, 'Craig Sawyers' c.sawyers@tech-enterprise.com [TekScopes] <TekScopes@yahoogroups.com> wrote:

 
Mosyt instability is due to
the Display Invert and Display Offset Zero and Cal switched being super dryed out I checked
voltages
and ripple.
Is there any easy way to get at the controls for lubrication. I have the manual, but it looks
like you strip
the knobs and pull the front off.
It looks like I'll need a lot of contract cleaner. Perhaps a larger container of De-Ox.
The push button switches are notorious on the 576 and other instruments on which they are used. I
was lucky enough to get a 576 free from a guy who worked in the BBC Technical Centre in the UK. It
had a characteristic problem with the older 576 of epoxy potting on the HT transformer (yours is a
late instrument after Tek had gone across to silicone potting, so you're OK there). The BBC were
going to put it in the skip, so this guy hauled it home intending to fix it, never got around to it
and gifted it to me.

Anyhow, to cut a long story short, this 576 had had a really nice life in a dry air conditioned
environment. But the push switches were all intermittent.

To get to one set, you have to take out all some, or all horizontal and vertical boards. You have to
take the knobs off these and undo the switch securing nuts, then a screw at the back. You have to
unplug a great number of wires (use your phone to take lots of close up photos so you can put them
back correctly). If you have the manual there are clear diagrams which show which colour wires go
where too.

Once you get them out, you will see a board with the offending switches on it. Using the flexible
nozzle on a deoxit can you get a good squirt down the inside of each switch. Exercise each one a
lot, then a final squirt. Reassemble.

Good luck - these curve tracers are well worth saving!

Craig


Chuck Harris <cfharris@...>
 

Before you go too far, there are two capacitors
that are always bad in the 576. The 5V filter cap,
and a 3uf 150V wet tantalum cap.

-Chuck Harris

Brent Watson brentleew2003@yahoo.com [TekScopes] wrote:


After a day of cleaning and lubing switches and contacts on the 576, it's not as bad as I thought. I used a small artists' brush and lightly coated a few circuit board traces with DeOxit. Using De-ox on all the controls made a big difference. I was able to go through the familiarization procedure up to #51 with optimum results.Replaced a few rusted screws and went through initial test-set up to #51 with optimum results.

Step 47 is the Step Generator.
After inserting an NPN transistor and getting a minimum step amplitude, I can't get any steps. I believe I saw some briefly yesterday, but can't get anything today. I got as far as putting my meter on step generator IC U75 pins 9,1,3,5, which respond to the "Number of Steps" switch. But have not been able to follow the path further.
I was hoping there might be someone here who knows these well enough to suggest where to suspect a problem. adapter doesn't support it, but didn't think it . I'm using an 013-069 adapter because that's what I have. Here's a short video showing the issue.
https://www.youtube.com/watch?v=FdC9qWejY2M&feature=youtu.be


Cheers,
Brent

On Thursday, August 3, 2017, 12:29:15 AM PDT, 'Craig Sawyers' c.sawyers@tech-enterprise.com [TekScopes] <TekScopes@yahoogroups.com> wrote:


Mosyt instability is due to
the Display Invert and Display Offset Zero and Cal switched being super dryed out I checked
voltages
and ripple.
Is there any easy way to get at the controls for lubrication. I have the manual, but it looks
like you strip
the knobs and pull the front off.
It looks like I'll need a lot of contract cleaner. Perhaps a larger container of De-Ox.
The push button switches are notorious on the 576 and other instruments on which they are used. I
was lucky enough to get a 576 free from a guy who worked in the BBC Technical Centre in the UK. It
had a characteristic problem with the older 576 of epoxy potting on the HT transformer (yours is a
late instrument after Tek had gone across to silicone potting, so you're OK there). The BBC were
going to put it in the skip, so this guy hauled it home intending to fix it, never got around to it
and gifted it to me.

Anyhow, to cut a long story short, this 576 had had a really nice life in a dry air conditioned
environment. But the push switches were all intermittent.

To get to one set, you have to take out all some, or all horizontal and vertical boards. You have to
take the knobs off these and undo the switch securing nuts, then a screw at the back. You have to
unplug a great number of wires (use your phone to take lots of close up photos so you can put them
back correctly). If you have the manual there are clear diagrams which show which colour wires go
where too.

Once you get them out, you will see a board with the offending switches on it. Using the flexible
nozzle on a deoxit can you get a good squirt down the inside of each switch. Exercise each one a
lot, then a final squirt. Reassemble.

Good luck - these curve tracers are well worth saving!

Craig








------------------------------------
Posted by: Brent Watson <brentleew2003@yahoo.com>
------------------------------------


------------------------------------

Yahoo Groups Links




Brent Watson <brentleew2003@...>
 

Thanks Chuck,I'll plan to change them immediately
I don't suppose they could cause the step inop.
Brent

On Friday, August 4, 2017, 9:14:29 PM PDT, Chuck Harris cfharris@erols.com [TekScopes] <TekScopes@yahoogroups.com> wrote:

 
Before you go too far, there are two capacitors
that are always bad in the 576. The 5V filter cap,
and a 3uf 150V wet tantalum cap.

-Chuck Harris

Brent Watson brentleew2003@yahoo.com [TekScopes] wrote:

After a day of cleaning and lubing switches and contacts on the 576, it's not as bad as I thought. I used a small artists' brush and lightly coated a few circuit board traces with DeOxit. Using De-ox on all the controls made a big difference. I was able to go through the familiarization procedure up to #51 with optimum results.Replaced a few rusted screws and went through initial test-set up to #51 with optimum results.

Step 47 is the Step Generator.
After inserting an NPN transistor and getting a minimum step amplitude, I can't get any steps. I believe I saw some briefly yesterday, but can't get anything today. I got as far as putting my meter on step generator IC U75 pins 9,1,3,5, which respond to the "Number of Steps" switch. But have not been able to follow the path further.
I was hoping there might be someone here who knows these well enough to suggest where to suspect a problem. adapter doesn't support it, but didn't think it . I'm using an 013-069 adapter because that's what I have. Here's a short video showing the issue.
https://www.youtube.com/watch?v=FdC9qWejY2M&feature=youtu.be


Cheers,
Brent

On Thursday, August 3, 2017, 12:29:15 AM PDT, 'Craig Sawyers' c.sawyers@tech-enterprise.com [TekScopes] <TekScopes@yahoogroups.com> wrote:


Mosyt instability is due to
the Display Invert and Display Offset Zero and Cal switched being super dryed out I checked
voltages
and ripple.
Is there any easy way to get at the controls for lubrication. I have the manual, but it looks
like you strip
the knobs and pull the front off.
It looks like I'll need a lot of contract cleaner. Perhaps a larger container of De-Ox.
The push button switches are notorious on the 576 and other instruments on which they are used. I
was lucky enough to get a 576 free from a guy who worked in the BBC Technical Centre in the UK. It
had a characteristic problem with the older 576 of epoxy potting on the HT transformer (yours is a
late instrument after Tek had gone across to silicone potting, so you're OK there). The BBC were
going to put it in the skip, so this guy hauled it home intending to fix it, never got around to it
and gifted it to me.

Anyhow, to cut a long story short, this 576 had had a really nice life in a dry air conditioned
environment. But the push switches were all intermittent.

To get to one set, you have to take out all some, or all horizontal and vertical boards. You have to
take the knobs off these and undo the switch securing nuts, then a screw at the back. You have to
unplug a great number of wires (use your phone to take lots of close up photos so you can put them
back correctly). If you have the manual there are clear diagrams which show which colour wires go
where too.

Once you get them out, you will see a board with the offending switches on it. Using the flexible
nozzle on a deoxit can you get a good squirt down the inside of each switch. Exercise each one a
lot, then a final squirt. Reassemble.

Good luck - these curve tracers are well worth saving!

Craig




[Non-text portions of this message have been removed]



------------------------------------
Posted by: Brent Watson <brentleew2003@yahoo.com>
------------------------------------


------------------------------------

Yahoo Groups Links





[Non-text portions of this message have been removed]


Chuck Harris <cfharris@...>
 

The 5V filter is something like 11Kuf, and it dries out,
letting the 5V logic signals dance wildly. This will affect
most everything in the curve tracer.

The 3uf 150V, C719, is parth of the -75V regulator's
frequency compensation, and it can cause all of the voltages
to dance about if it is going bad. Mostly however, it likes
to leak sulfuric acid onto the board. It is essential
that it be a very low leakage capacitor, or it will cause
the voltages to drift. I replace them with a 3uF 200V mylar.
It is way too big, so with some creative lead bending, you
can fit it under the LV regulator board using the same holes
as the original. A little lead insulation is in order.

-Chuck Harris

Brent Watson brentleew2003@yahoo.com [TekScopes] wrote:

Thanks Chuck,I'll plan to change them immediately I don't suppose they could cause
the step inop. Brent


On Friday, August 4, 2017, 9:14:29 PM PDT, Chuck Harris cfharris@erols.com
[TekScopes] <TekScopes@yahoogroups.com> wrote:


Before you go too far, there are two capacitors that are always bad in the 576.
The 5V filter cap, and a 3uf 150V wet tantalum cap.

-Chuck Harris


ramzyelk00@...
 

I have a lot of parts for the trek 576. The die casting behind the front panel, the rear panel, some metalwork parts associated with the switch mountings, from panel overlay with switch bezels....cosmetic condition 85%. Also most of the step generator and display boards etc etc. I may be listing these on eBay in the near future. This is the first message that I have posted so I don't really know the form or correct procedure to do this. I also have a lot of replacement oem transistors for this unit. I live in the U.K. And my email address is ramzy.el.korashy@gmail .com
If you are interested feel free to communicate.