OK.... after literally a year doing nothing on this scope... I have finally managed to finish its restoration, or almost, 99 % ! A few pics below as always
As of this evening, It's all back together again, working like a champ and all clean, almost as good as new, quite happy with the result, I am in love with this thing, really am !
Last year I did the trouble shooting to fix the many issues it had. And after a year at idle, with the thing completely in bits all over the lab... it became urgent to put it all back together because... well I will be moving house in a month or two, so there was no way I was going to move this scope in a million bit, surely it some vital little part would get lost in the process... Anyway, it motivated me to move my butt and finish this restoration so I can put it all back together again and transport it easily and safely.
So, after spending some time inspecting the scope to make the list of all the nut and bolt sizes I would have to remove, measuring them best I could with calipers, and trying to figure out what imperial size that might correspond to, then ordering 2 times the scope worth, in countless spanners and bits, some short, some long, and Allen keys... I was ready to tackle the job.
WASHING THE INSIDESo a weeks ago I finally washed its guts, following advice I read on Martin's topic. I was reluctant to wash this old thing, thinking it could corrode all over the place and I would just ruin it for good... but since Martin did it so many times before with success... and since I read on Tektronix OWN literature of back in the day, how they themselves washed every customer scope that came for any servicing work, in a dedicate booth, detailing how one should do it.... well I why not go for it !
Tek even said they they didn't even REMOVED the tubes from their sockets, they washed the scope with all the tubes still in place !
So, I removed all the easily removable sub assemblies from the scope : CRT tube assembly ( which I too disassembled to give it a good clean), fan motor, shields on the CRT HV section and also the one on the HV "shelve" that sits underneath the CRT. Removed all the tubes, and placed in a polystyrene foam with the same layout they had in the scope, so that I don't mix tubes and I can put them back in place easily.
Then washed it with hot water and some detergent, but in an effort to spare the scope, I did not flood the scope with the mixture Rather, I plunged q-tips and small tiny paint brushes into the stuff, then used that to clean the scope. This way I could use the stuff sparingly and more easily avoid or baby the "sensitive" areas, like pots and the HV transformer. Then I rinsed with distilled water to keep the scope from corroding, and immediately took the hot air gun to removed the water as fast as possible, taking care not too over heat it, of course.
Then I let it dry in the lab, a warm and dry room, for 3 weeks, watching for any corrosion that might arise... and crossing fingers that I had not just killed my scope !
REFURBISHING3 weeks later, still not a sign of corrosion, feeling somewhat better... and me thought it must be dry by now... so I put it back on the bench, and proceeded to refurbish the thing, so I could then put it back together, at long last.
To be done :
- Replace the 3 neon bulbs indicators on the front panel ('"UNCAL" Vertical and Horizontal, and "X5 MAG" indicator), which are absolutely impossible to get to, because the old ones looked a bit dim to my taste, though wasn't sure how they should look to begin with, I must admit ! ...
- Replace 3 paper caps, the 3 last ones, which I had not done previously because the scope was working/fixed, and they were simply impossible to get to, mostly !
- Replace the 3 UHF coax connectors, which were so crusty.. and one of them was even missing its dielectric piece !
UHF connectorsI decided to start by replacing the UHF connectors... thinking it would be the easiest of the 3 jobs. NOT ! Actually in order to replace those connectors... guess what ? you have to remove the FACE PLATE ?! Seriously, Tektronix ?!
Removing the face plate meant dismantling 50% of the scope...
Had to remove the 3 black 4mm binding posts, even though they were just fine. These were impossible to remove because the nuts at their backs were seized and the post was just spinning round and round... eventually manage to find a way to remove them with damaging them... about a second and a half before I was ready to commit suicide, that was close ! LOL
Then removed every pot and control.
Then had to remove power switch, easy. However removing the pilot light was a PITA ! I did have the correct size spanner to nudo the nut at the back... but the chassis/metal work around the pilot light would not allow for any movement of the spanner, ! I could get the spanner on tot the nut, but that's about it, no way to rotate the spanner after that !
The face plate would then eventually come off...
Sourcing UHF connectors was not as straight forward a one would think. Tek uses connectors which have only 2 lugs, because that's required in order for them to clear the chassis. These are rare, 99.9% have 4 lugs, a square base. But, I eventually found some which had 2 lugs... but they were unbranded cheap stuff. When I received them, their body was blindingly shiny, almost like chromed, horrible, would would not " blend " with the scope, they would look out of place. Plus, the build quality of these connectors was... how to say... let's stay polite.... ATROCIOUS ! And even that, is an understatement... I don't even understand how people even bother selling such crap. Even for a toy scope I would not use them, so for a Tek scope, no way in hell !
So I looked at what I could get here, and found on Farnell some made by "Tyco ELectronics", aka "TE Connectivity". I was saved : build quality is fine, and the finish on the body is lees shiny... though still a bit too shiny to my taste. I think the Amphenol connectors look even less shiny, but sadly Farnell only carry them on the USA warehouse, and the import fee is outrageaous, they charge like 18 Euros per 2 Euros connector... so I made do with the Tyco instead...
Fitting these connectors requires.. patience and dexterity... and my tweezers were mandatory.. to put back these tiny 3/16" nuts in place. For each nut I had to put in place, I must have dropped/lost it in the chassis, 3 or 4 times... a nightmare.
Anyway, the Tyco (and Amphenol just the same anyway) connectors were 4 lugs, square base. So had to resort to trim/file down two of the lugs. Luckily it turned out not to be as painful and time consuming as I thought it would be...
Looking closely at the old connectors, it's clear that Tektronix just did that with their own connectors ! They did not even bother removing the burr from the trimmed edges, yikes ! At least I did that right, so the scope is now BETTER than new ! LOL
You have to be real careful when you fit the connectors in place, because if they are just slightly misaligned, the face place won't fit, or will look ugly... that happened to m the first tim, yikes.
Oh, and when you fit the connectors... make sure to orient them the correct way : I mean when you then want to solder the wire onto them, you must have the opened half of the terminal facing you, otherwise when you poor solder onto it just runs away instead of filling the terminal and covering the wire.
Spent 10 minutes fitting the connector on the external trigger input, and when finally done, went to solder the wire onto it and ... oh no, I put it upside down, bugger, must remove the connector and do it all over again! ARRRRRRRRRGH !!!!
Paper CapsThere were 3 paper caps still in there, 2 on the trigger switch assembly, and 2 on the sweep switch assembly. All of the m facing inward of the scope, so impossible to get to.
Started with the sweep switch. Removing it looked daunting...however, it looked like I could removed SOME of its wires, without too much drama, which would allow me to move the switch assembly enough so that it would stick out of the scope, and be able to rotate enough to reveal the two paper caps, which I then could replace easily. There is a nut holding the back of the switch to an angle bracket, then a grounding strap/braid soldered to the back of the assembly, then a wire that goes to the "uncal" neon indicator, then there are set of 4 wires that connect to a big blue "can" which contains 3 precision timing caps... but no need to desolder those wires, it's much easier to undo the two screws that hold the cap can to the chassis... and then the sweep switch can be made to stick out of the scope enough to let you replace those dreaded paper caps.
Then the third and last paper cap was located on the trigger switch assembly. This switch is impossible to get out or even move at all : its back is bumping against a ceramic strip ! So, you can't pull it backward at all... at all. Luckily, with the sweep switch and blue can out of the way, you can about access the cap in question, via an opening in the chassis. Using long tweezers I was just able to remove the old one and solder the new HV film cap, in situ.
Neons BulbsWith the sweep switch assembly and big blue cap can are out of the way, suddenly the 3 neons bulbs "kinda" look feasible... kinda. Again, impossible to get your hands in there, but using tweezers and some patience/calm... it is actually possible to replace them in situ. A pain in the butt, but doable.
The job was made more difficult by the fact that the replacement bulbs I had ordered, though they were "NE-2" bulbs like stated in the part manual... did NOT actually have the diameter and length as the old ones ! Oh no.... New ones were not as long.. which was not a problem because I could just push them farther into the plastic holder until they were sticking out on the face plate side. The terminal were very long so no problems, plenty of wire still sticking out the holder.
However the diameter was quite smaller than the old ones. The old ones fit snugly into the holder, they did not move. but the new ones were so loose that they would move all over the place in their holder, making soldering a bit of a pain, they just would not stay in place ! :-/
First time I replace/use neon bulbs... I guess something must have escaped me...
PUTTING IT ALL BACK TOGETHERBasically one job lead to dismantling yet more stuff... overall you can't do one job alone, you just end up dismantling a lot of stuff, replacing all that you need to replace, then put it all back together. This means that unless you have an exceptionally good memory... which is not my case, then you better do all these jobs at once, and put it back together as soon as you have finished replacing everything it was that you wanted to replace. Don't let anyone interrupt you, or you will forget where this wire goes, or what not... I let a phone call interrupt me, and yes too late, I forgot where some of the wires had to go on the sweep switch ! :-/
Luckily I had taken plenty of close-up photographs as usual, to help me with reassembly... saved me bacon !
Then I put back all the bits I had dismantled a year ago... somehow I still remembered how it all went together, and somehow, I had not lost a single not or screw, a miracle in its own right. The CRT assembly, chassis parts, all the tubes... laying them on a polystyrene foam was indeed a wonderful idea (which I "stole" from Martins thread ! ), refitting was a breeze, a no brainer !
Still worried about some possible corrosion, even minute, from the distilled water (which is never gonna be 100% pure of course...), I feared some corrosion might eventually develop on the tube socket terminals, over time, leading to problems... So, I sprayed that famous " Deoxit " stuff that's famous in the US (finding the stuff in Europe at a DECENT price, was not so easy, though... it usually retails at around 3 times the US price ! ), on every tube socket, and inserted/pulled each and every tube 3 or 4 times in its socket, to give it a good clean and lubrication.
TESTINGNow time to cross fingers and ... FIRE IT UP !!!
Honestly with the washing, I was expecting all kinds of weird and wonderful things to happen... and was worried about the dreaded CRT HV transformer having soaked humidity and going kaput....
So, took a deep breath, hoping for the best but expecting the worse as the saying goes...1....2.... 2 and half.......... FIRE !!!
Simply could not believe it... the thing worked first time ! And it even worked better than before, would you believe it ?!
There were just a couple minor problems I ahd to adress :
- The scale illumination was ineffective even at full throttle.... turned out I had mixed up the graticule and color filter. Putting the graticule closer to the CRT, thinking it was logical in order to reduce parallax error... but no, the color filter comes first, and the graticule is on the "outside". That fixed it.
- The signal trace was slightly rotated (like one small division). When I reassembled the CRT assembly, I aligned the CRT as best I could, by trying to center the anode/PDA electrode in the corresponding opening in the metallic shroud/jacket which houses the CRT. But it's not very accurate.
So... had no choice but power up the scope to display a flat line and rotate the CRT while the scope is power up ! Yes... a bit scary... but if you watch what you are doing, it's actually quite easy and fast. Power off, remove the CRT bezel, graticule and color filter. Unscrew the clip at the back of the CRT assembly, which holds the CRT neck. then "unstick" the CRT by pushing a bit against the connector at the back. Once the CRT is loosened, power up the scope. Put the graticule in place so you can check the trace alignment. Then it's a bit of trial and error. Push against the CRT connector at the back, using some non conductive "tool"... I used my big plastic desoldering pump.. just because it was there on the bench ! LOL Gently push the CRT to make it stick out half an inch or so, just enough so you can grab it with your fingers and rotate it a little bit... push it back into place, put the graticule back, check the alignment... repeat as necessary until you are satisfied with the result ! LOL
Played with it for an hour to make sure everything was OK, and that the HV was not dropping after a while.... but no, the scope works really beautifully and is rock solid !
That was my first in depth restoration of a tube equipment, I am glad it turned out quite well ! Scope looks lovely, a joy to look at and play with, really happy with the result !
Now of course since that was my first restoration, I learned as I went.. and some things I would do differently, or not at all, like :
- The blue painted cabinet panels looked dull/matte to me. I thought that was old age and that using some care paint polish I had laying around, would brighten it up... not only did it not have any effect on the matte finish... which I now think was original, but worse : once dried out the white powdery residue left by the polish, which on a car is easily removed.. did not go away on the scope, because of the "texture" of the crinkle paint, and the myriad of holes/venting.
Same problem when I tried to use metal polish to freshen up the grounding points on the face plate... left white residue all over, which would not go away with hot soapy water and a stiff brush. This white stuff is there forever... unless someone knows of some chemical able to efficiently dissolve the stuff...
- When removing the face plate... make an accurate "map" of what control uses what type of washer and nut, and where, on what side of the face plate... because upon reassembly, I was left with 3 "extra" large start washers..... ahem...
CONCLUSIONSo this scope is almost finished. I still need to sort out the cooling fan, which drives me nuts. Luckily with Martins input recently, there is some new hope that it might be fixable !
Also, the leather carry handle is very damaged, beyond repair... it looks a bit out of place now that the scope is otherwise really good looking. I see this type of handle on my other equipment of many manufacturers back in the day.. maybe Tek used an off the shelve unit (need to check the mechanical check part list...) that might still be sold these days, who knows. If not, I will look into getting another leather handle made, using the old one as a template.
Also, I would like to experiment some stuff to a better job with all the knobs : I would like to get some gear so I can use a little polish/budding wheel, to see just how shiny and "smooth" I can get those knobs. I would also like to try buffing the graticule of the CRT, to see how good I can make it look.
Also, I would like to experiment with redoing the white " dot ", because it looks a bit yellowed. I understand people manage to redo them just by applying a little dot of paint, and wiping the excess, and somehow it looks perfect afterwards... need to ask what type of paint is used exactly.
Also, I forgot about it when refitting all the knobs, but it would have good to put a tiny drop of fine machine oil on the set screws to lubricate them, as they tend to rust slightly, and become sometimes real stiff.
Oh, and I noticed that the scope is missing a part ! Nothing vital, but still ! It's about the tubes. 4 of them have a socket meant to receive a metallic "can"/"condom" that goes over the tube. Not sure what it's purpose is... can't be a heat shield I guess, maybe has to do with EMI, to keep a particular section of the scope "clean"...
There are 4 such tube sockets, and I am missing one of them. It's the one the goes on a tube in the CRT HV section, the oscillator tube I think. It is particularly tall/long, compared to all other tubes that use the same socket size/type.
Gear wise... I would also appreciate a new soldering iron with a longer tip and " thinner " hand piece, so that it's more " agile " when having to replace components in situ, in the inner parts of the scope... like these neon bulbs and paper caps in the trigger switch...
More and better tweezers would be good too, again to more reliably grab those hard to reach components when having to replace them in situ.
A little surprise in the pics below.... no your eyes or brain are not playing tricks on you : YES, I now have THREE of these 317 scopes !
A year after buying the one I just restored... I came across another one in France ! It was cheap at only 40 Euros, and the seller was OK to ship it to me... On the single pic the seller posted on his ad, the scope looked really very sad. Of course, completely untested, "as is", take it or leave it, no question asked etc etc... the seller hardly new what a scope was any way, he was just an antique furniture seller, he got the scope as part of a house clearing I guess... and thought he might get a few bucks for it, so picked it up.
At first I thought I would use it as a donor to help me restore and maintain my first one... but when I received it, it actually didn't look all that bad.. was complete, face plate and buttons were not damaged... so I am toying with the idea of trying to restore that one as well !
Then 3 months later, what were the odds... a THIRD one shows up ! Very similar story to the second one : seller is clueless, and picked up the scope the day before at a flea market ! Again, untested, no questions asked, as is etc etc... and again I was lucky the seller was ok to ship it to me. Got that one for even cheaper, only 35 Euros !
As you can see it looks real sorry : it covered with CEMENT all over the cabinet and face plate ! Still, upon reception... it actually does NOT look hopeless ! Again there is zero physical damage to the cabinet or fce plate or knobs... it's all there in good nick. Just need to remove all that cement in a soft way... without damaging the paint work or face plate finish. will see how that turns out...
so again, I can help but want to try to restore this one as well ! LOL
There is a big BUT though.... Both these scopes were packed really... really badly. There was simply no packing material what-so-ever !!! both sellers somehow found a box that just about fit the scope, and shoe horned into it ! Somehow the cabinet panels and face plate/knobs escaped intact... but that does not mean that the scopes were not dropped at least once in their journey to me... if so, then I guess it's possible that the CRTs suffered from internal damage to their electrodes.. if so, CRT is toast and so is the scope as a result !
So... until I get time to start working on these scopes, it's still too early to say if they will get restored or used a parts chassis...
OK that was a long post, but considering the restoration is finished and that it lasted over a year... if you average it over 12 months, it's actually not all that long !
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