oscilloscope – AB4UG Radioblog

So much for the oscilloscope

My dead oscilloscope is still dead. After spending some time poking around the innards, I’m starting to think the issue is on the high voltage side that provides power to the CRT. I’ve checked the voltages at connectors where the PCB is labeled with voltages, and those match up. It seems like the rest of the scope is probably working except for the CRT side of things.

I think at the moment, the scope is beyond my ability to fix. Guess I’ll shelve it for now and maybe go back to it when I’ve gained a few more skill levels and higher level items.

Off to the next project!

Diving into the oscilloscope

With the power supply repaired, the next item to go on the bench is the dead oscilloscope.

Undoing four screws on the sides of the scope let me slide the top cover off to reveal the innards.

The top circuit board looks to be the power supply board, and probably a few other things. Undoing a bunch of screws holding the top board down and a bit of fiddling around (discovered the board is on a hinge) let me lift it up to reveal more of the scope’s innards.

Three screws hold the cover of the power supply section.

A few dust bunnies inside, but overall everything looked to be in fairly decent condition (aside from not working).

First look around the inside didn’t reveal anything obviously wrong. No blown caps or scorched areas. Whether this is something I’ll be able to repair or not is still up in the air. This scope is probably going to be spending a while on the bench.

A new oscilloscope

Saw someone at the TARC swap meet with one of these little Tektronix 222 DSOs for sale, so I bought it. Terrific timing since my Hitachi oscilloscope died a while back and I still haven’t gotten around to looking into it.

It’s little, and doesn’t have a lot of capabilities but I think it will do pretty much everything I need (at the moment). It comes with two scope probes that are permanently attached. It’s designed to be powered with an 8V SLA battery, but it looks like batteries with the right form factor and voltage aren’t readily available anymore. I did find a promising looking battery replacement project though. This one didn’t come with a battery, but a standard sized power jack lets you power it with wall power. It’s even got a RS-232 serial port!

The scope seems simple enough to figure out how to use without a manual, and I was even able to find a service manual online to download.

Here I’ve got one of the channels measuring the output from one of my Etherkit Si5351 breakout boards. I don’t remember what I have my RedBoard making the Si5351 do, but I seem to be getting a pretty good signal out of it.

Dead oscilloscope

My oscilloscope died the other day. <sad trombone />

I was using it to look at the output of one of my Etherkit Si5351 breakout boards when it made a high pitched “pffft”, the waveform disappeared and a bunch of indicator lights came on.

Haven’t opened it up yet to see if I can spot anything wrong. The scope still turns on, but there’s no display. The indicator lights behave like the scope is working, but there’s nothing on the CRT. That could be a good sign.

Will be a while before I have some time to poke around the innards of the scope.