Working on a TDS784D. Decently bright display (sucks by modern day standards but for the series and the age not terrible...). All channels work. Off course, SPC doesn't. Not the first time I tangoed with these so I proceed with all haste to excavate the hybrids. Which are, I'm sure, marvels of black magic RF engineering but they also suck donkey balls to work on. Sure enough, one cracks while getting it out. Measuring relays yields at least one dud (4 ohm resistance) and a few doubtfulls.
Now the fun really starts. I have attempted to repair these in the past, with limited success. Long story short: some of the pins are not accesible by soldering iron. Using the hot air gun has, thus far, always resulted in the relay and its neighbours melting before I could make it "stick". The plan was to make an attempt with a hotplate and/or chipquick low temp solder. As I don't have a hotplate (yet): chipquick + hot air it is.
Removing the relay is not the issue (cut the legs). Cleaned the pads of old solder after that. Applied some of the special flux to the pads; applied the solder. Observation: it doens't flow nearly as nice as normal paste. Has a tendency to "tear". Wetted the relay as well for good measure, more flux applied.
First attempt: as the solder offers less visual clues versus normal, I pick up the board and the relay slides off the board. Not yet cured.
Second attempt: better. But the least accesible leg is up in the air.
Pressing the relay down a bit while applying hot air seems to have done the trick:
Pretty it ain't but it'll do...