In this Workbench Wednesdays video, I look at a couple of tools to help with the teardown of a device. The device I picked is a vintage Tektronix 465B oscilloscope. I picked it up several months ago with a note that said "as-is." That told me it probably has some issues. And as I found out, it does. I did not do a complete teardown. I realized about halfway through; I still needed to shoot some footage with the scope next to me. But I was afraid if I tore it completely down, I may not be able to re-assemble it enough before my video deadline!
The mechanical design is just as amazing as the electrical design. It amazes me when I look at a piece of art like this that it was designed entirely on paper. The chassis is simple but effective. Each circuit board is absolutely beautiful. As I pointed out in the video, there are a few things that really caught my eye.
Below are some extra pictures I took. Follow my e14 blog (or Workbench Wednesdays ) to see future progress on this repair. I'm still not sure what is wrong with it, but I need to finish a few other projects before I come back to this one.
Picture 1. The Tek 465B is sitting on my desk. From this view, The module on top of the scope is a DMM. At first, I thought this was just attached to the top of the scope's case. It looked like to me it was an orderable option. (And it may have been.) But you'll see in the next picture, I was wrong about how it was attached.
Picture 2. This is the back side of the scope. Here you can see the DMM module is attached to the chassis. The cover, shown in the video, has a cut out for the DMM. You can also get a view of the cathode ray tube in the middle of the device. Before taking it apart, I didn't plug it in. So I know the CRT and its capacitors had at least two months to discharge!
Picture 3. My favorite board. This photo is the same angle as picture two. Here you get a better close up of the vertical board. It contains two custom ICs with a gold lead-frame packaging. I believe those to be the amplifiers for channel 1 and channel 2. Near the back are some 7400-series logic chips. In the video, I made a point that I didn't expect to see them. While editing, I got to thinking, maybe these are for some trigger logic. That's about the only reason I could think the analog amplifier board would have simple logic ICs on it. Especially on an instrument from 1978.
Picture 4. Same side as picture 3 but now from the front. The knobs are satisfying to turn. Though I can tell, they have aged quite a bit. I'm hoping to one day clean them up and get better detent clicks out of them.
Picture 5. These ICs are on the DMM module. There I would fully expect to see digital logic being used. What caught my eye in this section is the wires. Do those look familiar to you? Let's get a better look.
Picture 6. These are wires and headers on the DMM module. I joke in the video that they are like looking at an Arduino project but in an expensive piece of test gear. At least expensive for 1978.
Side note. The ABS plastic trays featured in this episode can be seen in this picture. Turned out, I only needed 1 or 2 of the bowls. However, you'll see them come back, and in heavier use, in a few weeks.
Picture 7. This teardown step was the last I took before running out of time. I removed the DMM board which exposed the metal bracket holding it in place. The CRT is visible. The two small silver capacitors in the center of the screen are tantalum slugs. Over towards the right is some Kapton film. Below it is a bank of bulky tantalum capacitors. At this level of tear down, I did not find any blown caps. So the good news is that I can probably re-cap the boards quickly. The bad news is, the most apparent repair probably won't help return functionality.
Picture 8. Finally, close up of the front panel. Not intentional, but I really got a kick out of how my new R&S RTM3004 is framed in this picture. It is the case of the "young" and "old" in a single shot. While I love using my R&S scope, for obvious reasons, this vintage analog scope is gorgeous.