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  1. #1

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    Working on a Tektronix C-53 oscilloscope camera

    Anyone ever worked on a Tektronix oscilloscope camera?

    Oscilloscope Camera with Polaroid back

    I got this thing off of eBay for $25+shipping, mostly just to get the polaroid back, but it seems like I ought to be able to do something with the actual camera itself. Seems like it's just fixed focus at around the front end of the box, and just uses what's essentially a focusing rail to move the whole camera forward and backward a small distance for focusing. So, limited usefulness unless I manage to modify the optics or something. (I guess I could put some lighting inside it and use it to copy flat images onto instant film for emusion transfers and stuff.)

    Anyway, that's not my main problem right now. Right now I just want to power it up and I can't find any information on what the power input should be. It would be easy to hook it up to this power supply I have but I'd rather not just start shooting current into the thing trial-and-error at various voltages until it either works or gets fried.

    Here's the control panel on the thing, for what that's worth:

    Click image for larger version. 

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    (The aperture/shutter speed controls are mechanically linked and seem like the whole mechanism really needs some oil. But I digress....)

    This would appear to be the power connector on the front:

    Click image for larger version. 

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    Looks like it just connects to something on the scope when you swing it into position. The black and red wires look pretty obvious but I have no idea what the white-and-black-striped wire would be. Maybe a ground or it could be a sync signal for the "single sweep" exposure mode?

    So it will be easy as dirt to connect up some power, if only I could figure out what the input is supposed to be.

    I guess I'll keep searching around on boat anchor manual sites, but any pointers or links would be greatly appreciated.

  2. #2

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    After a ridiculous amount of searching, I finally managed to figure this out. First I found this:

    http://www.schematicsunlimited.com/?z=tektronix

    And somehow managed to figure out that the Model 7384 oscilloscope was one of the ones that this camera was made to attach to. Of course the manual didn't say squat about cameras, so I had to read though a bunch of schematic diagrams until I found the one for the power supply that showed the leads connecting to the camera power connector. Finally.... +15V. And the black and white striped wire is some sort of sync line with the oscilliscope that syncs the camera up to take a photo of exactly one refresh ("sweep") of the screen. Not sure I care too much exactly how this works because the only thing I can figure it might be good for is flash sync, and there's already an X-sync connector on the side.

    I tend to keep the wall warts from old broken stuff for just this sort of occasion, and I just happened to have a power supply for a broken HP inkjet/scanner that had outputs for +16V and +32V. I tested it with a multimeter and it said 16.5V. Hoping that the camera would actually have a decent voltage regulator (that should be able to deal with an extra 1.5V out of 15V unless it's total crap), especially since this camera used to cost the insane equivalent of $4000 (adjusted for inflation between 1985 and 2012). For that much money I would hope it wouldn't have a total crap voltage regulator.

    Unfortunately there wasn't any indication of how much current the camera would try to draw, and this power supply would only output 500mA max, so I kept looking around. Then I found this catalog that actually had more info than the oscilliscope manual did:

    http://bama.edebris.com/manuals/tek/cat1985/

    This has some interesting stuff in it, but it still didn't say what the current draw was. I guess they didn't have regulations back then requiring that they print this stuff on the chassis somewhere or at least put it in the manual. Well, at least I have an idea of what other cameras they made that might be cheaper or easier to modify.

    One thing I did notice is that they used to sell a 15V battery pack that used 12 AA batteries. Given that 12 AA batteries would supply up to 18V if fully charged, that gave me some confidence in the thing's ability to deal with something over 15V. (You have to wonder how long that battery pack actually lasted with this thing.)

    Still no idea how much current this thing would try to draw, but I said what the hell and wired up the power supply anyway. I suppose the worst that could happen is that the power supply would blow a fuse, or the easily replaceable fuse in the camera would blow, but it appears to have worked. Either it doesn't draw more than 500mA or it does and the power supply can deal with it anyway. (Unfortunately my multimeter doesn't measure current.)

    From what I can gather, the mode settings mean the following:

    "NORM" - purely manual settings
    "BULB" - shutter is open only while holding the button down
    "TIME" - this seems to be a dumb way of saying "bulb mode where you click the shutter button once to open, then click it again to close" (instead of having to hold it down the whole time).
    "SINGLE SWEEP" - That's what uses that center pen, or that "gate" BNC connector, to open the shutter for exactly one refresh of the oscilloscope screen. I think the BNC connector is for use on scopes that don't have the 3 pin connector on the front. (The optional battery pack was also sold for the purpose of using the camera on scopes that lacked the power connector on the front.) Anyway, I can't really think of a terribly good use for this.

    Not sure what the difference between the "NO" and "NC", but I think they stand for "normally open" and "normally closed". (For example, the NO sync port is only "on" when the flash should fire. The NC is on all the time except when the flash should fire.)

    I'm guessing the "remote" port can just be wired to a simple pushbutton switch to operate the shutter as a remote shutter release.

    I never did find the actual manual for the C-53, aside from someone selling one on eBay.

    Now all I have to do is figure out how I might be able to modify the optics on this thing or otherwise find something useful to do with it.....

  3. #3
    Leigh B's Avatar
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    You'll find very few Tektronix manuals online for a couple of reasons:
    1) They're huge. My manual for the 7834 is about 2" thick. (I have a 7834. They never made a 7384.)
    2) The schematics are on fold-out pages, much larger than 8x10, and multi-colored. Monochrome copies are very hard to follow.

    The supply voltage (top pin) on my 7834 measures +15.145 volts, so it is regulated in the 'scope.
    The middle pin is the trigger to the camera, and appears to go to ground briefly (did not investigate fully).
    The bottom pin is ground (0 volts).

    The "single sweep" mode was used for recording transient events. These might be predictable, like the inrush current of a motor
    when you start it up, or unpredictable like a failure or fault condition. The camera would be triggered by the 'scope when the
    sweep was initiated, making the system totally automatic. One sweep could take up to 100 seconds.

    The NO and NC outputs would be used for starting external devices, like a chart recorder or similar. The oscilloscope could be used
    to initiate recording of data over a very long period of time, like hours or days or longer. No flash was used with these cameras.

    I expect the Remote input requires a contact closure, like a pushbutton, but I may be wrong. I never used that feature.

    I wouldn't be inclined to waste much time on 'scope camera optics. The lenses were not of high quality, and were optimized (if at all)
    for roughly 1:1 reproduction ratios.

    - Leigh
    Last edited by Leigh B; 07-06-2012 at 10:08 PM. Click to view previous post history.
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  4. #4

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    Quote Originally Posted by Leigh B View Post
    You'll find very few Tektronix manuals online for a couple of reasons:
    The supply voltage (top pin) on my 7834 measures +15.145 volts, so it is regulated in the 'scope.
    The middle pin is the trigger to the camera, and appears to go to ground briefly (did not investigate fully).
    The bottom pin is ground (0 volts).
    Sorry for the model number typo/dyslexia there.

    The reason I suspect that the camera itself contains a voltage regulator is that the optional battery pack uses 12 AA batteries. When fully charged 12 x 1.5 would mean 18V, and of course that would start to drop toward 15V as they get depleted. So it seems like, unless they battery pack has a regulator which it might, 15-18V input would be normal?

    The "single sweep" mode was used for recording transient events. These might be predictable, like the inrush current of a motor
    when you start it up, or unpredictable like a failure or fault condition. The camera would be triggered by the 'scope when the
    sweep was initiated, making the system totally automatic. One sweep could take up to 100 seconds.
    I think I get it after reading some Wikipedia. So you set up some trigger looking for some transient problem, go to sleep, some sort of spike or something sets off the trigger, the oscilloscope starts a sweep, and once the screen is "full" the camera automatically takes a photo. You then get up in the morning and see some blinking light or something, and pull out the polaroid to see what happened. That certainly makes such a camera seem much more useful.

    The NO and NC outputs would be used for starting external devices, like a chart recorder or similar. The oscilloscope could be used
    to initiate recording of data over a very long period of time, like hours or days or longer. No flash was used with these cameras.
    Ok... I just saw something about X-sync in the catalog and to me that implied flash, but that's just because I'm thinking purely in camera terms. Hmm... actually I see something about a flash in the C-5C for lighting up non-illuminated graticules... Anyway...

    I wouldn't be inclined to waste much time on 'scope camera optics. The lenses were not of high quality, and were optimized (if at all)
    for roughly 1:1 reproduction ratios.
    I basically agree. The only real use I can think of for the thing as is (other than it's original intended purpose) is something like making copies of images for emulsion transfers or something, and that assumes you can put some sort of diffused "ringlight" or something inside the thing without causing halation.

    It looks like the 53mm Ilex Oscillo-Paragon lens in this thing might be worth a little bit to someone with a view camera (apparently it's not too terrible as a view camera "macro" lens), and the shutter may be worth a little more to someone. With that stuff stripped out it seems like the thing is probably only suitable as an unnecessarily heavy box to make a pinhole out of. Anyway, I guess I'll probably just strip this thing. The mounting adapter is gone, and not surprisingly the darkslide is missing from the polaroid back. (Someone probably took the thing out as soon as they got it, put it in some drawer somewhere, and never used it again.) Maybe I'll hang onto the lens to play with since I'm planning to get a view camera at some point.

    At least the polaroid back is useful.

  5. #5
    Leigh B's Avatar
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    I'm sure the electronics had a regulator, probably to 12 volts, but possibly to 5. I expect the raw supply was used for relays and
    solenoids, when present. The battery pack would deliver 14.4 volts from rechargeable ni-cad batteries.

    Your understanding of the single-sweep function is correct.

    The C-5 (and C-12) are older cameras, designed for the 500-series 'scopes, some of which did not have illuminated graticules.
    A flash could have been used for those, but it would be a very special one since the graticules required edge-lighting, not face-on.
    I've never seen such an accessory, but it's quite possible. All my 500-series 'scopes had illumination.

    The C-31 cameras were designed for the 7000-series 'scopes, much later vintage and all had graticule illumination.

    Have fun with the toy.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato



 

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