Topics

465 B sweep switch cam


Dave Peterson
 

Hi all,

I know this is a common problem, and have seen a nice description here:
https://forum.tek.com/viewtopic.php?f=568&;t=138253&sid=c827508d3401e2cd90eb52f42415517a

In his fix he replaced some of the inner guts of the switch cam. In my switch the shaft just spins in the cam. It doesn't come out, but just spins.

I found a listing for the part number, 105-0364-00, on eBay. It arrived Friday and I just tried to install it. To my disappointment it's not a 1-1 match with mine. I'll reach out to the seller to see if we can't figure out what's happened here, but when it comes to eBay I'm sure it's a sold as-is thing, and buyer assumes all risk.

In frustration I went back to the old cam and tried to see if the shaft would come apart, and with a little extra "encouragement" the shaft did come out leaving all the attached innards inside the cam. The only thing that came with the shaft was a ring-clip, which looks similar to the picture in the above tek forum post. What's interesting is that in my case there's just a lot of plastic powder filling the knurling where the shaft used to bond to the cam.

My question is: can I just JB Weld the knurled part of the shaft to the cam?

I'd clean the knurling of old decayed plastic, and make a bead of JB Weld at the beginning of the knurling so it would spread as the shaft is re-inserted to the cam.

Thing is, I have no idea what's going on inside the cam. There's obviously some kind of spring mechanism for the pull release of the B-delayed sweep time/div knob. Would the JB Weld just freeze all this up? I wouldn't go nuts with the JB Weld. I really love that stuff and have fixed a lot of hopeless cases with it. I think it might work in this case, but I'd prefer to take the cam apart to re-bond the shaft to the inner workings directly. But I have no idea how to disassemble the cam. Any ideas? I haven't found anything here or elsewhere with a how-to for that part of the job.

And finally, is there any sharing of part numbers across models? Could this "new" 105-0364-00 belong to something like a 475? I got the part number from the 465 Service manual I have. I don't think my A7 board is any different than other 465s. It's a high serial number 310XXX. I think it has to be a different switch cam that got the wrong tag on it somehow (nefarious or otherwise). It's an original looking Tektronix tag - old paper, Tek logo, etc.

Thanks for any help or pointers to other threads that deal with this.
Dave


 

On Tue, Dec 1, 2020 at 03:48 AM, Dave Peterson wrote:


I know this is a common problem, and have seen a nice description here:
https://forum.tek.com/viewtopic.php?f=568&;t=138253&sid=c827508d3401e2cd90eb52f42415517a
Just had a quick look at your post, Dave, but no time to read thoroughly: It's almost 4 AM where I live (Netherlands, GMT+1).
You seem to ask if you can just glue the aluminum shaft to the drum. If so, the answer is "yes". I did that for a friend of mine about 5 years ago and it's been posted somewhere in this group, because someone else asked. I used superglue, the water-like varitey, which just flows into the space between shaft and drum, being very careful to avoid glueing everything together. ISTR I covered part of a shaft with silicon grease to avoid stiction there but can't remember at the moment.
With care, it proved a lot easier than thought.

Raymond


Dave Peterson
 

Related:
The grey B time/div knob is supposed to be bonded to the metal part of the switch, right?
Mine is loose and only the "tails" of the setscrews in the holes are holding the plastic in position.
I ask because I'm all ready to JB Weld this thing together, but don't want to ruin an otherwise good knob - if it's supposed be this way. Or supposed to be able to come apart. Once I glue it it's never coming apart again!

This scope is physically in otherwise really good condition. What the heck are people doing to these switches!? This whole B sweep switch/knob has obviously been physically ripped apart.

Dave


 

How similar is the 465's sec/div switch cam to the 475's, I wonder. I've got 3 "parts" 475s and could probably spare one of the switch cam assemblies. If you had a full drum and shaft assembly would you be able to disassemble it and replace the drum?

I haven't spent any time studying the sec/div knob in either the service manual or the physical units, but I'm going to be transplanting the front panel from one of the parts machines onto another one at some point, and I could harvest the drum and shaft assembly for you, if you would like.

-- Jeff Dutky


Dave Peterson
 

I was showing my wife what happened and went through the 465B and 475 parts manuals from the Tek Wiki. To show her how similar the scope faces are, but also to look up the part numbers in the service manuals. They're all different. I think it's the 475 that has a similar part number, 105-0362-01 I think? Where the 465 is 105-0364-00.

After getting the shaft out (there's a joke there somewhere), I can pretty much see how this thing is put together. I'm going to JB Weld it and see how it goes. I really have nothing to loose at this point.

I also sent a note to the seller on eBay. We'll see where that goes!

I'm mostly curious about the knob attachment  to the metal body. I'm not convinced/ready to glue it yet. I would like to know if it should be removable.

Dave


stevenhorii
 

Just a suggestion for gluing plastic to metal. I have found the slow-cure
epoxies to be generally stronger than the quick-cure ones. I bought some
"industrial" epoxy from Loctite (Hysol 1C - not cheap, cost me about $17
for 4oz). I used it to glue the hand loop of a pair of scissors back
together. The full-strength cure time was specified as 24 hours, but it was
reasonably hard in about three hours. However, I waited for 24 hours before
using the scissors. It was a pretty small contact area, but it has held
despite my using those scissors to cut through cardboard and the like. I
did not think it would hold through that kind of stress. My other use for
it is not for bonding stuff. It's for printing durable letters onto
surfaces. This epoxy is white.

The knurling on the shaft ought to provide a nice surface area for bonding
in your gluing task.

Steve H.

On Mon, Nov 30, 2020 at 9:49 PM Dave Peterson via groups.io <davidpinsf=
yahoo.com@groups.io> wrote:

Hi all,

I know this is a common problem, and have seen a nice description here:

https://forum.tek.com/viewtopic.php?f=568&;t=138253&sid=c827508d3401e2cd90eb52f42415517a

In his fix he replaced some of the inner guts of the switch cam. In my
switch the shaft just spins in the cam. It doesn't come out, but just spins.

I found a listing for the part number, 105-0364-00, on eBay. It arrived
Friday and I just tried to install it. To my disappointment it's not a 1-1
match with mine. I'll reach out to the seller to see if we can't figure out
what's happened here, but when it comes to eBay I'm sure it's a sold as-is
thing, and buyer assumes all risk.

In frustration I went back to the old cam and tried to see if the shaft
would come apart, and with a little extra "encouragement" the shaft did
come out leaving all the attached innards inside the cam. The only thing
that came with the shaft was a ring-clip, which looks similar to the
picture in the above tek forum post. What's interesting is that in my case
there's just a lot of plastic powder filling the knurling where the shaft
used to bond to the cam.

My question is: can I just JB Weld the knurled part of the shaft to the
cam?

I'd clean the knurling of old decayed plastic, and make a bead of JB Weld
at the beginning of the knurling so it would spread as the shaft is
re-inserted to the cam.

Thing is, I have no idea what's going on inside the cam. There's obviously
some kind of spring mechanism for the pull release of the B-delayed sweep
time/div knob. Would the JB Weld just freeze all this up? I wouldn't go
nuts with the JB Weld. I really love that stuff and have fixed a lot of
hopeless cases with it. I think it might work in this case, but I'd prefer
to take the cam apart to re-bond the shaft to the inner workings directly.
But I have no idea how to disassemble the cam. Any ideas? I haven't found
anything here or elsewhere with a how-to for that part of the job.

And finally, is there any sharing of part numbers across models? Could
this "new" 105-0364-00 belong to something like a 475? I got the part
number from the 465 Service manual I have. I don't think my A7 board is any
different than other 465s. It's a high serial number 310XXX. I think it has
to be a different switch cam that got the wrong tag on it somehow
(nefarious or otherwise). It's an original looking Tektronix tag - old
paper, Tek logo, etc.

Thanks for any help or pointers to other threads that deal with this.
Dave






Dave Peterson
 

I think JB Weld is a good solution for the B switch cam/shaft joint. It's slow curing, and yeah, the knurling will make a great bonding surface. And I can see where I need to be super careful about getting it into the spring portion. But knowing what to avoid it should be no problem.

I just took the setscrews out of the B time/div knob, and remember now what my big concern is here: it's just loooose. But it doesn't come apart. I'm very afraid of cracking something forcing it apart. And it doesn't come apart enough to get any glue into it. If there's any apparent theme to my newbie questions here is that I don't know what I'm dealing with. Once apart I'll know what the issues are. I know that most of the time things turn out fine and aren't as big an issue as I fret. But I like to know what I'm getting into before I go breaking things. Kind of like taking the CRT out. Freeking scary as heck, but turns out more easy than I could have imagined. Still, a very good thing to be concerned and careful about.

So anyone know what a broken B time/div knob looks like? Will I break the plastic trying to get it off the metal internals? I've been going through the photos and haven't seen a "naked" one yet.

Dave


Dave Peterson
 

I'm going to post the picture(s) I took of the disassembled Time/Div switch assembly.
D.


Michael W. Lynch
 

On Tue, Dec 1, 2020 at 12:59 AM, Dave Peterson wrote:


I think JB Weld is a good solution for the B switch cam/shaft joint. It's slow
curing, and yeah, the knurling will make a great bonding surface. And I can
see where I need to be super careful about getting it into the spring portion.
But knowing what to avoid it should be no problem.
I have repaired a 465 (not "B") in this manner. Actually "reassembled" that little plastic part on the shaft from the pieces recovered from inside the drum. Tedious job, but JB Weld did the job. One thing that I will mention is that there are several designs of this mechanism within the 4X5 series. The 465 uses a couple of different versions, depending on serial number, I don't think that there will be interchangeability between the 465B and the 475, but I could be wrong.

--
Michael Lynch
Dardanelle, AR


Dave Peterson
 

I have updated the Photo Album: https://groups.io/g/TekScopes/album?id=257342

This is hopefully helpful to someone in the future. What I've found online is helpful, but these pictures should contribute a little more to the description of this switches parts and how it works.

One picture is a close-up of the insides of the B DELAY TIME cam - the rearward section of the TIME/DIV switch assembly attached to the 465 board A7.

In this picture can be seen the black plastic cylinder that the switch shaft should be attached to. This plastic cylinder slides back-to-front along the length of the cam barrel. A spring on the other side of this cylinder provides the spring action of pulling the B DELAY TIME knob away from the A portion of the TIME/DIV knob. Note the broken piece of this cylinder. It cannot be directly glued back in place as it would likely adhere to the cam body which the cylinder slides within. I will glue it to the shaft and ring clip first. Then glue the shaft into the cylinder.

Part of my original question (at least for myself) was can the shaft be glued back in without freezing the B DELAY TIME pulling action? I think the answer is yes, but it also must be done with care as it is just the innermost black portion of that cylinder that slides within the cam body. The cam body is that portion of grey that can be seen with a notch in it. I don't know what the purpose of that notch is. Perhaps part of the black cylinder is in it and that's what anchors it to the cam body? I have not been able to determine that.

In the annotated picture you can see the round spring clip that is attached to the shaft on the rearward side of the knurling. This clip is what pulls against the black plastic cylinder within the cam body. While gluing the shaft back into the cylinder care must be taken to not allow any glue (epoxy) to extend beyond the clip circumference. This would then interfere with the cam body preventing the shaft from being pulled in the direction of the arrow, allowing the B DELAY TIME knob to pull away from the A TIME/DIV ring.

I'm currently waiting for the small broken piece of cylinder to set on the shaft. Once set I'll epoxy the shaft and ring clip back into the cam. Wish me luck!

Finally, I included a picture of the B DELAY TIME knob separated from its aluminum body. The plastic of the knob was separated from the metal, and would have made for a sloppy B DELAY switch. But it was still a devil to remove. The remaining glue was holding the body in the plastic, tho the plastic was spinning around the body. I use a long 1/4 socket extension to use as a drift to drive the body out. I held the plastic and whacked the socket against the work bench, taking care to check and ensure the body was staying straight as it was driven out. It took about 20 minutes and fairly firm hits to get it to move. I felt this was easier on the plastic (held in my hand), rather than using a hammer on a drift. I had a much better feel for how much force I was imparting this way.

The glue cleaned off the body easily with some acetone. It did a good job of dissolving the glue. I used a q-tip with acetone to clean the thick portion of the glue from the plastic. It did appear to want to attack the plastic, so I wasn't too vigorous with it. I used an Exacto knife to scrape the remainder. Sandpaper would work too. I didn't care too much about making it pretty - it's internal and after cleaning and scraping it was rather loose on the body. This was good because it gave some room for the JB Weld I used to smear across the body as I slid it back in place. It will sit 24 hours to cure before I mess with it. I used a little of the leftover JB Weld to attach the broken piece of cam cylinder to the shaft/clip.

Like I say, hopefully this is more reference to someone affecting this repair in the future. The sorts of details I'd like to know going into a fix like this.

On to C1419 install!
Dave


 

On Tue, Dec 1, 2020 at 03:48 AM, Dave Peterson wrote:


And finally, is there any sharing of part numbers across models?
No, not for these parts.

Could this "new" 105-0364-00 belong to something like a 475? I got the part number from
the 465 Service manual I have. I don't think my A7 board is any different than
other 465s. It's a high serial number 310XXX. I think it has to be a different
switch cam that got the wrong tag on it somehow (nefarious or otherwise). It's
an original looking Tektronix tag - old paper, Tek logo, etc
105-0364-00 is for 465 below B250000
465 B250000 and up used: 105-0614-00.

/Håkan


Michael W. Lynch
 

On Wed, Dec 2, 2020 at 04:39 AM, zenith5106 wrote:


Could this "new" 105-0364-00 belong to something like a 475?
No, the 475 parts are a beast unto themselves. Strangely, there was no standardization of that mechanism, even thought the scopes are very similar. Come to think of it, The 475 never seems to fail and the 465 (at least the late s/N models) are prone to failure.

--
Michael Lynch
Dardanelle, AR


Dave Peterson
 

Thanks Håkan,

Is the 105-0614-00 shorter than 105-0364-00? My SN is 310XXX.

Dave

On Wednesday, December 2, 2020, 02:40:12 AM PST, zenith5106 <hahi@telia.com> wrote:

105-0364-00 is for 465 below B250000
465 B250000 and up used: 105-0614-00.

/Håkan


 

On Wed, Dec 2, 2020 at 04:38 PM, Dave Peterson wrote:


Is the 105-0614-00 shorter than 105-0364-00?
I have no info on the length but if you check the board layout of A7 if the manual for B250000-up you
can see that the B-sweep switch has 11 contacts which would match the shorter one on your pic.

There were also 105-0614-01 and -02 but they don't seem to be a direct replacement since for repair
the -00 was replaced by a complete switch assy, 263-1086-00, for S/N B250000 - B315029.
The -02 was a direct replacement for the -01.

/Håkan


Dave Peterson
 

Now all I need is the board layout for 250000 & above. I'll have to study the TekWiki - it's probably there. The manual I have is obviously for lower SNs. It does have changes that include the A5 Vertical Out, but even that doesn't match the component numbers on mine. So I should be able to count cams and switches for both low and high SNs. I'll post what I find.

I think I'm learning a $12 lesson a particular evolution of this scope. That's cool. That's a reasonable education cost.

Thanks so much for these particulars Håkan. This is why I'm enjoying focusing on the nitty-gritty details of this rebuild. I'm learning not just the function of the scope, but the physical particulars, the options, and its evolution over time.

Dave


Dave Peterson
 

My glue job on the B-delay switch cam was doing really well. I reassembled the switch assembly, attached the A and B knobs (B knob now solid as a rock after re-gluing the plastic and body), and figured out how to align it all. It was working like a charm.

Over the last several days I've gotten my blown C1419 replaced, reassembled the vertical input assembly and so on. Today I was trying to get the A7 board back in and it was giving me a devil of a time, but I got it in. Only lost a little blood. Reattached the A Time/Div knobs, and while attaching the B knob things started going bad. I don't know what did it - I wasn't being harsh with it all. But I realized it had failed again, so I had to take the A7 out again for the 3rd time. Disassembled the Time/Div switch cams and sure enough: the B cam was gone.

All my glue work held fine. It was the rest of the plastic cylinder that crumbled. The good thing is that it's all fallen out of the cam now, including the spring. So I can now see how it's put together. I'll have to build something. I'm not really sure where to begin, but I'll sleep on it. I'll document what I do for posterity.

I haven't had a chance to review the part numbers and variations with serial number. I did find another difference between the manual I have and this scope. It's quite apparent there were a lot of changes. If I want to know this model well there's a lot of history I'm going to have to learn. I would like to learn the part number variations for this cam. It seems a common failure, so it'd be good to know what to look for. I'll keep the "wrong" one I got. The seller is willing to take it as a return, but I have to pay shipping. Might as well keep it. Maybe I'll sell it myself down the road, if I don't end up using it some day.

Dave


robeughaas@...
 

The vintageTEK Museum has a complete 465B timing board assembly, part number 670-6001-01. We are asking $40 postpaid. Please contact me off-board if you are interested.

--
Bob Haas


Dave Peterson
 

Hi Bob,
Thanks for the offer, but I think my topic title was misleading, and I can't change it now. It should say 465 "B-sweep" switch cam. Meaning the B Time/Div switch on a 465 scope.
I'm new to the who universe of vintage Tek restoration. I'm certainly familiar with these portables from my Army and engineering career as a user, but that's a far cry from knowing them from an restoration perspective. So pardon my large ignorance for everything from history to terminology. I don't know the proper term to use for this component that's clear to everyone. I have a lot to learn.
I'm going through the Vintage Tek Museum right now. It's good to know you guys are a potential source for parts. Looks like I have a lot to review in your eBay store too.
Looking at the map I see you're about a mile away from where I used to live in Beaverton! Wow. Certainly worth a visit in the future. Once we have this whole COVID thing behind us.
Thanks again for the offer. Hope to talk to you more in the future.Dave

On Saturday, December 5, 2020, 09:07:16 AM PST, robeughaas@gmail.com <robeughaas@gmail.com> wrote:

The vintageTEK Museum has a complete 465B timing board assembly, part number 670-6001-01. We are asking $40 postpaid. Please contact me off-board if you are interested.

--
Bob Haas


 

Dave,

Have you seen this Tek document http://www.hakanh.com/dl/docs/kitinstructions/050-1627-00.pdf ?

It looks like it might answer some questions about differences in 465 time base switches.

-- Jeff Dutky


Dave Peterson
 

Hi Jeff,

No, I haven't seen that before/yet. It is yet another interesting piece of the puzzle. I feel a spreadsheet coming on? Maybe someday? Or is evolution of this model too complicated for any one person to understand? This bulletin is for a change having to do with the B-sweep lockout mechanism at the back of the switch. It prevents the decoupling of the A and B knobs in the 0.1 and 0.05 us positions. I think. Both of my scopes have this lockout and they're both later than SN 250000. Maybe I'm wrong about what the lockout is.

After absorbing the disappointment of the switch cam failing again, and frustrated that the local hardware store didn't have any brass stock (I'll have to go to Home Depot and buy too much of something?), I realized that I could probably glue/epoxy the remaining broken bits to the shaft with the rest of the connector already glued to the shaft.

I'll post pictures. Now that I've had a chance to study the guts of this thing I understand a lot more about how it's put together and some of the why's and what-for's. I spent an hour or so this morning with some small files I have for scale modeling, cleaning the excess epoxy and refitting the shaft and connector to the cam. It's not the same result as a new proper cam assembly, and I'll have to get into that in a more descriptive post. But I did finally get the whole A7 Timing Board reinstalled with the B-sweep switch working pretty good. It's a little sticky as my rework is a little on the tight side. But it's holding and everything's working as it should.

Dave