Yesterday afternoon I returned to the local electronics recycler with intent to buy an inexpensive dusty old oscilloscope for a friend who had displayed interest in it. Behold:


An old RCA WO 91B, I don't think RCA really made a huge splash in the scope market, dominated as it was by Tektronix, HP and so forth; still this feels as if it has a bit more capability than an EICO or Heathkit of the same era.. but I realize that may just be the conclusion I draw after being hypnotized by the RCA meatball.

I love this logo.

Scanning of the guts revealed no erupting capacitors, though, if this thing works it'll be a good preventative maintenance maneuver to replace all those paper bound caps. I love it when stuff is easy to spot and access.


I did spot one hanging wire in the horizontal refresh range that could have rendered this unit inoperable


It appears to have been connected to this lug:


So I'll solder it there prior to the application of electricity, what's the worst that could happen?

The lug itself slightly puzzles me, it looks like a section of solder has reflowed and has what could be an arc crater at the right edge. This could be visual artifacts from the photography, I'll give it a closer look when I'm in there. My current theory is that a resistive joint may have been heating up and the thermal cycling triggered a fatigue failure at the wire, which could have arced on its way out. Which, in my mind points to a tube failure, as that sort of current probably shouldn't be occurring at a ground reference for an oscillator to begin with.