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  1. (*steve*)

    DPDT relay lifespan.

    The lifetime of relationship is typically specified by the number of cycles under certain conditions (typically voltage switched). This is because physical operation is limited by wear, and the ability to form (and break) a good connection is determined by the contacts (and they are...
  2. (*steve*)

    New project - 1967 oscilloscope restoration

    And another one... Luckily I've been able to find some suitable caps. And no, of course I didn't touch the capacitor with the soldering iron. Really. No, nothing to see there.
  3. (*steve*)

    New project - 1967 oscilloscope restoration

    One more cap replaced Where are those other capacitors...
  4. (*steve*)

    New project - 1967 oscilloscope restoration

    A slightly more complete schematic. It shows the connection to the switch at the rear. I'm not sure how much sense it makes, but, it might have something to do with triggering.
  5. (*steve*)

    New project - 1967 oscilloscope restoration

    I decided to try to figure out what the switch at the rear is doing. So I started tracing some of the circuit. Ok, so I haven't got far yet, but that resistor between the two cathodes of the 6DJ8 looks interesting. Especially interesting because it seems to be connected to a screwdriver...
  6. (*steve*)

    Negative voltage spikes on 12volt power to car coil and injectors, help pls.

    Note my first question. Set the scope for one shot trigger, and set the trigger voltage to about 8 volts. Then set the horizontal speed to maybe 100us/div and see what you capture. Play around with the horizontal timebase until the pulse is between 1 and 5 divisions wide. Then post a picture...
  7. (*steve*)

    New project - 1967 oscilloscope restoration

    Let's take a look at that capacitor on the input terminal. From the bottom And from the side And when removed... Like most of the others it reads about 50% above it's nominal value, so it's probably leaky. A shame I left the replacement at home...
  8. (*steve*)

    Negative voltage spikes on 12volt power to car coil and injectors, help pls.

    What's the duration of that pulse? I expect it's pretty short. I also suspect it's harmless, and possibly caused by inductive or capacitative effects.
  9. (*steve*)

    New project - 1967 oscilloscope restoration

    My next day deliveries are taking longer than usual. I wonder if they've been souvenired by some passer by? Anyway, the 10uF 150V cap is now replaced with a 10uF 450V cap. The original was an actual cap connected from somewhere to ground. The replacement radial capacitor is connected to...
  10. (*steve*)

    Frame Detector Functional Specifications

    Same assignment eh?
  11. (*steve*)

    New project - 1967 oscilloscope restoration

    There is a different model described on this page. It's hard to say whether this is an older or newer model. On the one hand it contains some solid state devices, and newer looking resistors, but it has an earlier (lower) model number and is estimated to be from c1959. On the same site there...
  12. (*steve*)

    New project - 1967 oscilloscope restoration

    As the new capacitors arrive one by one... 0.1uF 100V replaced with 0.1uF 400V. This one was probably good, but it got replaced anyway. And the 50uF 15V cap replaced with a 47uF 63V cap I had in my junkbox. That one measured 107uF out of circuit, so it's definitely leaky.
  13. (*steve*)

    New project - 1967 oscilloscope restoration

    Wow, 5Hz to 400kHz response (3db). No mention of that third control on the back on a quick reading of the manual... Thanks @bertus
  14. (*steve*)

    New project - 1967 oscilloscope restoration

    First replacements are the 20uF 350V and 20uF 450V. Both replaced with 22uF 450V. The negative side of the original caps was connected to the chassis. There middle lug of the tag strip was unused (and connected to the chassis) so I used that as a common point. I added a wire from the chassis...
  15. (*steve*)

    New project - 1967 oscilloscope restoration

    Seems to be a reasonable deduction. Certainly 11 pin. Heater on pins 1&11, 5&6, and 8&9 appear to be deflection plates. There seems to be a separate heater winding for the crt. I guess this is due to the cathode being highly negative compared to the other cathodes. The 2 lugs are the...
  16. (*steve*)

    Hard to find replacement part.

    A mobile phone should be good enough. Crop the image so it just shows the board, then use an image compression tool to save it at about 80% quality JPG. That should make it small enough to post.
  17. (*steve*)

    New project - 1967 oscilloscope restoration

    Yep, I suspect that's the case.
  18. (*steve*)

    Hard to find replacement part.

    Go here. The shots you've posted are blurry, and the stuff we want to see is just a part of the picture. In a good picture we should be able to read the markings on the chips clearly.
  19. (*steve*)

    Hard to find replacement part.

    Post some sharp, well lit photos and we can take a better look. There's a resource that describes how to take good photos.
  20. (*steve*)

    New project - 1967 oscilloscope restoration

    I'm not sure if that was to save space or to minimize noise. I kind of suspect the latter, but it seems a lot of effort for what isn't a particularly high end piece of equipment. Indeed, but quite cute in its own way.
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