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Not to mention PSU headaches.

Those were the tricks of the old trade. Tek even had their own part number for after they were pre-aged.

CRT scopes hard to maintain? For production, yes, because calibration labs will eventually refuse to accept them. But (so far) I've always been able to repair mine. Most problems are age related electromechanical issues sich as wiper contacts, trim-cap shaft contacts, things that can be fixed. When a CRT goes lalaland that's another story but not always the end of the world:

I gave one analog scope to a local school so the kids learn hands-on what raw electrical signals really look like.

Here is a good writeup on the 2465B issues.

True but ... this old Tek stuff was built to last. I've never had one of their unobtanium parts go bad on me.

My opinion is 100% opposite. One of the best portable analog scopes ever made, if not "the" best. The only series that could rival it is from Iwatsu.

Unfortunatly also very bulky, heavy, unwieldy. A Tek 2465 can fit into carry-on luggage. A Tek 7000, not a chance.

The only thing I found to be a problem sometimes regardless of serial number was the flimsy plastic clutch for the delayed trigger. You get an old 2465 that hasn't been used in years, fire it up, every just woiks, pull delayed trigger ... ka-crunch. Luckily there are people who still have/make knobs for these instruments. At one client we ordered a set from Greece that cost around $100. To our surprise it contained literally all knobs and the scope looked almost like new. For hobby use one can just "McGyver" a wire concoction because the delay trigger is really only a slide switch hidden behind the front panel.

A guy I once knew suggested a fiver for cleaning contacts. The linen has just enough of an abrasive property to get the oxide layer, alcohol notwithstanding. (Note to self: save a few old bills as the new polymer ones won't be anything like as useful.)

Regards,

Uncle Steve

Didn't tell me anything I didn't already know, apart from the stuff about replacing the NVRAM. I can still get new DS1225s off the shelf from a distributor, at a price that wouldn't pay for the modification time.

The formulas the author quotes for making up attenuators aren't very good, either in voltage ratio, or impedance. Certainly not calibration accessory standard.

My experience with a bunch of 2465/2467 is different. I'll agree about Iwastu, however, I'm tempted.I wonder if there are any bulk deals...

My days of carrying instruments onto airplanes are long over. Strictly lab only, these days.

Surprisingly, I've had little or no mechanical problems like that. The main problem has been surface mount electrolytics leaking electrolyte over the control PCB. Horrible to find, let alone fix, the O/C tracks and vias. Those United Chemicon electrolytics are the pits. Modern Panasonic may occasionally dry up, but never leak goop.

I feel incredibly lucky, having been spared the worst of the capacitor plague. I've had the occasional one go dry on me or leak but never to the point where it ate up a circuit board. Except once in a camera but the flex board was restorable.

Seems with electrolytics it's like with a lot of software, older is better. The large can in our Hammond organ still works fine. Since 1961, despite the fact that some clever engineer placed it right next to the hot rectifier tube.

Helps when the application can tolerate 100 ohms of ESR. :)

I've seen failures here and there... had a computer PSU and mobo (non-consecutive) with aging/split caps. My TDS460 scope (`96 vintage) leaked from every single SMT radial -- replaced them all, fortunately no traces are eaten through (yet?).

I haven't seen a dead tantalum in years, which really doesn't make much sense.

Which reminds me, I was inspecting an old Ethernet card the other day -- IBM made, 1993 vintage, 16 bit ISA bus, SMT construction. I checked the edge connector, and they're only using +5V onboard, yet every single tantalum is a massive 25V. The usual rule of thumb is double the voltage as a matter of course, triple for useful reliability -- five times, what were they thinking? :)

Tim

Dunno. Rebadged? When I designed mainframe stuff at IBM the rule of thumb for tantalums was 2x, minimum, but try for 3x. More was not considered better because of worries about the tantalum forming properly.

Write a "bot" to do that every millisecond non-stop.

No, we didn't use any 555s.

...as long as the circuit uses a 555.

Check the resistors in the focus circuit. Quite often a resistor between the intensity & focus pot goes bad. I've replaced a lot of them to correct focus problems.

My current collection of Tek scopes:

Tektronix 323 305113 Portable scope Tektronix 324 302310 Portable scope Tektronix 324 302903 Portable scope Tektronix 453A Portable scope Tektronix 2465 B012226 Portable 300 MHz Scope Tektronix 2465 B012567 Portable 300 MHz Scope Tektronix 2465A CT B018494 Rackmounted 350 MHz Scope Tektronix 7603 Scope B340753 Oscilloscope With 7A18,7A26,7B70 Tektronix 7633 Scope B141848 Scope

The owners of Sphere are retiring, and liquidating parts, equipment and their boneyard.

There is a design online to build a replacement for the U800 IC.

Hey, we got a shitload of these 25 volt tants we were going to dump. You got any use for them?

Or something like that.