Tektronix 067-0532-00 Repair/Refurb

[Addicted2AnalogTek]

I just picked up an 067-0532-00 for uber cheap and intend on repairing it.

It appears the main reason why it was junked is because the shaft into the RF oscillator (119-01232-01) is broken.   It's a 3/8" x 6" shaft made of a material of unknown identity.   Does anyone see any reason why Derlin wouldn't work as a replacement? 

If I decide to repair and fully refurb the unit I will start adding photos and information to this thread.

[dave_k]

I don't know what Derlin is, but Delrin should work fine 

[Addicted2AnalogTek]

I don't know what Derlin is, but Delrin should work fine 

haha yeahhhh my fingers get dyslexia from time to time.   

I'm rather curious what the original material is... it seems like its made of some sort of stone. 
I'll take some 'before' pictures tomorrow and make this into a real repair/refurb thread.  It should be interesting considering the unit is serial number 000102...


  I may also make a thread for my Tek 106 refurb that I am almost finished with if anyone is interested in what diodes failed and what resistors were out of tolerance.

[TimFox]

The shaft material might be "Mycalex", a mica-stuffed machinable ceramic material with good electrical properties.

[Cyberdragon]

You can still buy mycalex. I've looked it up since I have a lot of antique gear with lots of mycalex parts. I have no idea how to cut or machine it or if you even can machine it, but it comes in squares from some manufacturers.

[TerraHertz]

I didn't know what a 067-0532-00 is, so googled. This is funny - a page from the schematics at tekwiki.
Is that a Tek addition, or some user's hack?

Interesting instrument, I hope you do post pics. Put them on http://w140.com/tekwiki/wiki/067-0532-00 too why don't you?

[Addicted2AnalogTek]

Those may be 'later modifications' like the schematic says, but mine definitely doesn't have those mods.  There is no "151-0150-00" or 2N3440 in it.   It's definitely strange how that schematic has the mods penciled in instead of the expected reprinted schematic with the modification date stamp.

I'll definitely get some pics up here tomorrow of the mess that is the '0532-00 - it's in pieces right now.
The unit is missing the power switch, tubes, and cover. I have all but the cover, which I will probably have made custom at some point.  I'm also attempting to buy the '01 version as well.

The following are the things I intend to do to this unit:

replace switch
replace oscillator main shaft
clean oscillator unit
replace 30D lytic caps
check/replace main filter caps
check/replace all CC resistors
replace all non-dogbone ceramic capacitors
refurb/check output head
thoroughly clean entire unit
have custom case made

[Addicted2AnalogTek]

I found a supplier of Mycalex that sells what I need - however it is $76 for a 12" piece of their lowest grade plus whatever extra they want to cut it to size for me and also shipping.   I'd probably be looking at about $100 for just that one piece. 

 I think I will try the $1 piece of Delrin first!  haha  If it doesn't end up working out I will buy the Mycalex rod.  It's definitely nice to know what it is though!!

[Addicted2AnalogTek]

Here are some preliminary pictures of the unit.  I forgot to take one before dismantling it though.

I was thinking of how the shaft could have gotten broken and why:

The shaft seems to be seized into the connector rings, so maybe they had a need to replace the 2C43 transmitter tube inside of the oscillator, and in their attempt to get the unit apart they broke the shaft off.  The other possibility is that it was dropped or hit, but I see no evidence of this on the front - then again it probably wouldn't take all that much force on the dial plate to snap that shaft, so it's possible I won't find any other damage.  I don't have any way of testing the tube, so I will have to just wait and see if it does or doesn't work.

As you can see, the oscillator capacitor plates are quite tarnished.  Does anyone think I should just leave them as-is?  Or should I take a silver polishing cloth to them and get them gleaming again?

I currently have the shaft pushed out as far as I can get it (as pictured), but it still isn't long enough to get away with.

The switch, shaft, and caps should be here by the end of the week.  I am also considering ordering a full set of replacement resistors - since it's highly likely that many are far out of tolerance - and since they are only going to be $40 total. 

[Addicted2AnalogTek]

these wouldn't fit in the last post.

[TerraHertz]

Silver tarnishing doesn't really matter. One of the reasons silver is used for plating HF components is that silver oxide is about the same conductivity as pure silver.

So reasonable amounts of oxidation don't change the electrical characteristics.
However if you try polishing it, and you wear through the silver plating, that will definitely screw things up.
Plus on a vane-air capacitor you don't want to bend the delicate blades at all, as that would affect scale linearity.

Some people recommend de-oxidisers like deoxit, but I've never tried it and so have no opinion on that.


Do you have all the pieces of that broken shaft? If so, have you considered just gluing it with superglue?
Line them up pressed into some kind of straight V-slot to get them exactly axial.

Delrin is slightly flexible, you may find the knob feels wonky with a thin delrin shaft.

[Addicted2AnalogTek]

Silver tarnishing doesn't really matter. One of the reasons silver is used for plating HF components is that silver oxide is about the same conductivity as pure silver.

So reasonable amounts of oxidation don't change the electrical characteristics.
However if you try polishing it, and you wear through the silver plating, that will definitely screw things up.
Plus on a vane-air capacitor you don't want to bend the delicate blades at all, as that would affect scale linearity.

Some people recommend de-oxidisers like deoxit, but I've never tried it and so have no opinion on that.


Do you have all the pieces of that broken shaft? If so, have you considered just gluing it with superglue?
Line them up pressed into some kind of straight V-slot to get them exactly axial.

Delrin is slightly flexible, you may find the knob feels wonky with a thin delrin shaft.

That's good to know- always learning something new here.   What about fingerprints though?  It looks like they have been there for quite some time since the tarnish has happened between the oil from the print..   If that isn't going to make any difference I will just leave it alone.   

I do have all of the pieces of the shaft and have contemplated just gluing or epoxying them back together, but the biggest problem with that is that I don't think I can get the pieces out of their seats without totally shattering them.  I have them soaking in PB blaster at the moment to try and get them loose, but one of the lock ring pieces is made of brass, so a penetrating fluid is unlikely to do much for that one.  Aside from using a torch to expand the metal pieces to retrieve the mycalex in whole, I don't know what I can do. 

I noticed that about the delrin. even at 3/8" it is still flexible enough that I don't want to use it if I don't have to.  Any ideas for breaking the pieces free without shattering them?

[TerraHertz]

That's good to know- always learning something new here.   What about fingerprints though?  It looks like they have been there for quite some time since the tarnish has happened between the oil from the print..   If that isn't going to make any difference I will just leave it alone.   

I don't know. Of course you could just leave it, fix all other problems and get the unit working, *then* decide if the discoloration is worth pursuing. Maybe the output frequency will track the dials well, and if so, who cares about surface color of interior things you can't see?
Or you may find it's unrepairable (dead unobtainium valve?) in which case the tarnish is also moot.

I do have all of the pieces of the shaft and have contemplated just gluing or epoxying them back together, but the biggest problem with that is that I don't think I can get the pieces out of their seats without totally shattering them.  I have them soaking in PB blaster at the moment to try and get them loose, but one of the lock ring pieces is made of brass, so a penetrating fluid is unlikely to do much for that one.  Aside from using a torch to expand the metal pieces to retrieve the mycalex in whole, I don't know what I can do. 

So, they are held in by more than just the grub screws I can see in the collars? They are glued in as well?
Wow, that sucks.

One possibility might be to press the pieces out. Can do even with just a bench vice. But if the pieces have irregular broken ends that's a problem. You don't want to damage those fracture surfaces, since to glue them they must fit exactly with the mating fracture face.

Could you make a jig to glue the pieces together while still in their respective collars and parts?
Bearing in mind that then the dial will probably be out of cal a bit.

Sorry, I forget - did you consider using fiberglass rod?  It comes in all sizes, and every company that sells electrical insulating materials will stock it. It's extremely rigid, but I don't know how much worse its high frequency dielectric parameters would be compared to the Mycalex.

[Addicted2AnalogTek]

I don't know. Of course you could just leave it, fix all other problems and get the unit working, *then* decide if the discoloration is worth pursuing. Maybe the output frequency will track the dials well, and if so, who cares about surface color of interior things you can't see?
Or you may find it's unrepairable (dead unobtainium valve?) in which case the tarnish is also moot.

Good point. I'll just leave it as-is unless I find that it doesn't function properly. I have enough to focus on to get this thing operational.

From what I can tell from the parts list and the internals of the oscillator (not on parts list), everything I need to repair it is obtainable.  The transmitter tube is a 2C43, which is still rather easy to get. All the inductors appear to be in good shape and I already have all the semiconductors and tubes in my stock.

So, they are held in by more than just the grub screws I can see in the collars? They are glued in as well?
Wow, that sucks.

One possibility might be to press the pieces out. Can do even with just a bench vice. But if the pieces have irregular broken ends that's a problem. You don't want to damage those fracture surfaces, since to glue them they must fit exactly with the mating fracture face.

Could you make a jig to glue the pieces together while still in their respective collars and parts?
Bearing in mind that then the dial will probably be out of cal a bit.

Sorry, I forget - did you consider using fiberglass rod?  It comes in all sizes, and every company that sells electrical insulating materials will stock it. It's extremely rigid, but I don't know how much worse its high frequency dielectric parameters would be compared to the Mycalex.

I really hope that no one got a wild hair up their butt and chose to glue the collars in place! I'm going to attempt to press out the part with the flat end from the dial plate assy - whether I have to use solvents to do so or not. If I do try solvents, I'll take a bottle neck and hot glue it in place for containment and hope that it holds so I don't destroy any paint or finishes.

I'm worried if I try to cement them together without having it all fully removed that I will end up cementing it to the outer housing and thus compounding my problem, but I suppose I can attempt it as a last resort - maybe try to put something in as a separator so that doesn't happen.

No, I haven't considered fiberglass actually... but it's worth looking into it's properties - or just giving it a shot.   I'll see if one of the local electrical supply houses has what I need tomorrow.

Once I wrap up this 106 square wave gen and finish calibrating the 468 I will be diving into the '0532 - hopefully within the next couple of days. Definitely by weeks end though.

[Addicted2AnalogTek]

I have managed to remove the pieces of the shaft without damaging them.  I used a steel punch with several layers of electrical tape to exert even pressure and avoid damage along with some pieces of PVC pipe as a non-marring surface to press against.  It worked perfectly. 

I have chosen a 2 part epoxy which specifically states that it is recommended for repairing ceramics. Hopefully the mycalex is porous enough to create a proper bond.  I will be cleaning the pieces thoroughly with IPA and heat drying them.  I will also be using a piece of angle-iron to make sure that the shaft sets true. 

I did a little bit of cleaning of the oscillator unit on the outer rim with Deoxit D5 as a test, and am very pleased with the results, so I think I will be cleaning the entire unit prior to reassembly.  There is a slight bit of buildup of some sticky substance on the inner edge of one of the plates that I would like to remove.  It appears that this oscillator had been opened and handled several times over it's life and has a large amount of dirt, gunk, and finger oils that I would like to remove.  There are comparison pictures of cleaned vs uncleaned attached below.

I have not yet ordered all of the new resistors. I will be testing all of the zener diodes and other semiconductors prior to an attempted power on.

Thank you for all of the pointers, ideas, and assistance with this restoration. I greatly appreciate it.  Once restored, I will be adding all of my info and pictures to the TekWiki site.

[Addicted2AnalogTek]

Cleaned up and ready for reassembly - pending curing of adhesive on Mycalex shaft.  Ended up using "Liquid Fusion" clear urethane glue and some super glue to fill in the chips and fine cracks.  After it fully cures I will sand the super glue smooth so there will be no areas left for anything to catch on and exert excess pressure on the break.

[Addicted2AnalogTek]

I didn't know what a 067-0532-00 is, so googled. This is funny - a page from the schematics at tekwiki.
Is that a Tek addition, or some user's hack?

Interesting instrument, I hope you do post pics. Put them on http://w140.com/tekwiki/wiki/067-0532-00 too why don't you?

Upon further inspection of my unit,  It appears that a small portion of the penciled in modifications have actually been performed.

I have attached a modified schematic below

[Addicted2AnalogTek]

The Mycalex shaft repair is finished. Pics attached.

I have measured all of the resistors, checked capacitors and semiconductors.
-Of course, many resistors are out of tolerance, but none seem to be out by any extreme magnitude.
-A few of the capacitors are trash - C42 (.0047uf 500V)  C236  (.01uf 500V)  and C88  (10uf 50V 'Lytic)
-Q237 (2n3702 / 151-0164-00) is 100% opened
All of the diodes and zener diodes seem to be fine.

I am going to place an order for all of the necessary resistors and caps so I can get everything into proper spec before I fully reassemble and test the unit.

Also adding a couple of pictures of the components before cleaning/replacements

[TerraHertz]

Coming along nicely!

A few points:
1. Hope you read this before swapping any parts on those ceramic insulator strips. I'm told that those absolutely require use of ONLY a special silver-based solder. Supposedly using tin-lead solder makes the metalization separate irreversibly from the ceramic.
I've never tried soldering those myself. Some others here on the forum are experts with old Tek gear and that issue.

2. The Mycalex shaft - if you reverse it, would the reglued section end up somewhere under no stress, and also isn't in the RF field? There are obvious advantages to this.

3. Some before and after pics of the Deoxit cleaned silver tarnish would be nice. Might motivate me to buy some. I'm poor, don't like to buy stuff I don't know whether will really work or not. People here keep mentioning it, but seeing is believing.

[Addicted2AnalogTek]

Coming along nicely!

A few points:
1. Hope you read this before swapping any parts on those ceramic insulator strips. I'm told that those absolutely require use of ONLY a special silver-based solder. Supposedly using tin-lead solder makes the metalization separate irreversibly from the ceramic.
I've never tried soldering those myself. Some others here on the forum are experts with old Tek gear and that issue.

Thank you!
Thanks for the heads up, but fortunately I read about that quite some time ago before I started repairing my first scope and purchased some Tek silver solder specifically for that.  I now have several rolls from various pieces of gear that I've bought, so I am good on that.   I've been wondering if any other types of silver solder would work as well.  Maybe some kind that I can just buy a half pound or 1 pound roll of so I don't need to spend $6 per 4 gram spool (or whatever gram weight is on each of them).   

I have repaired a few instruments with the ceramic strips (the two Tek 106's and some scope CRT circuits) and fortunately only had one incident where the silver strip partially came unglued, and that was because I hadn't allowed the solder to completely melt before pulling on the lead.

2. The Mycalex shaft - if you reverse it, would the reglued section end up somewhere under no stress, and also isn't in the RF field? There are obvious advantages to this.

The breaks happened outside of the oscillator can - at the 'bearing' surface fitting and at the dial plate.  In order to keep the glue out of the RF field, I am going to have to reinstall it oriented the same way which will leave the glued sections exposed to the same stresses as before.  Hopefully the glue formula and curing time will have allowed it to gain sufficient strength though, and I don't have any further issues.  It will have approx a week to fully cure before I reassemble.  If it re-breaks, I will buy some special purpose epoxy, soak the shaft in a solvent to remove the urethane & super glue residues, and attempt to epoxy it once more.  If again it fails I will find a suitable replacement shaft or buy a piece of new mycalex for nearly $100... or see if I can steal one out of an old genrad oscillator since that's likely the origin of the Tek one anyway.

3. Some before and after pics of the Deoxit cleaned silver tarnish would be nice. Might motivate me to buy some. I'm poor, don't like to buy stuff I don't know whether will really work or not. People here keep mentioning it, but seeing is believing.

The extent of the dirt/tarnish removal that I did on it is what I showed in the pictures previously. The only cleaning I did on the actual plates was just the layer of dirt and gunk on the outer movable plates.  I'll take a few pictures of the final product to show the before & after comparison though.   Deoxit is quite expensive... nearly $18 for a 5oz can of D5 is pretty ridiculous, but it's the only stuff I trust on the vintage equipment surfaces other than IPA.

[TerraHertz]

2. The Mycalex shaft - if you reverse it, would the reglued section end up somewhere under no stress, and also isn't in the RF field? There are obvious advantages to this.

The breaks happened outside of the oscillator can - at the 'bearing' surface fitting and at the dial plate.  In order to keep the glue out of the RF field, I am going to have to reinstall it oriented the same way which will leave the glued sections exposed to the same stresses as before.

Just to be clear, I said "isn't in the RF field", not "isn't in the oscillator can." Should have been more specific, and asked if the glued section would be all well inside metal sleeves. Because if it is, then it doesn't matter if that's inside the oscillator can.
It's only the exposed parts of the shaft, between metal objects with different RF potentials, that need to be low loss.

[TimFox]

I found Mycalex rods at McMaster Carr (if you can't find something there, you probably don't need it).
http://www.mcmaster.com/#mykroy/mycalex/=10gd462
It is somewhat pricey:  a 3/8" diameter by 6" long rod is $33.28.
It is machineable with normal carbide tools.