I changed the tuner Electrolytic caps on both my SX-780 and the SX-1050, one at a time, I even wrote down the cap number on the old one in case they changed something for the worse, I could swap them back in place. Between each cap I listened to the FM and AM radio sections, playing with the tuner, grabbing weak and powerful stations after each cap, and noticed no sonic difference or difference on how the stereo lamp operated, dial indication etc.
I repaired and recapped my SX-1050 first. I recapped the Tuner board after recapping all the other boards making sure it was working well, figuring that I would get it aligned anyways. While I was replacing the Tuner board caps, I did all the grey CEA's at once, fired it up, and the AM/FM Tuner worked exactly the same as before. So I started to replace each Orange CEANL type cap one at a time, then starting it and checking the tuner afterwards. (Note: I wrote the cap number on each removed cap so that I could reinstall it if it adversely affected the Tuner) The only cap that made any perceptable difference in the way the tuner reacted was C51. Previously, when a station was tuned in for best stereo light and sound, the Tuner indicator would be off to the right, after the new cap was put in, it reads almost dead center! I measured the original cap at 1.32uF, spec is 1uF. After replacing all the electrolytic caps, the sweet spot for the stereo operation in FM mode seems to be a bit broader. AM seems unchanged. The FM dial indication reads about 2 ticks low compared to the actual station, (same as before the recap). AM is perfectly aligned. AM radio works very well, too, I have an external antenna for AM, i like to listen to far away stations at night while working in the garage.
After experiencing no real change in the radio operation in the SX-1050 tuner recap, I decided to redo the SX-780 tuner after recapping the main board. Also did it one at a time, marking each old cap for reinstallation if needed. Again absolutely no audable/visable change I could hear on the SX-780 as to stereo lamp operation, ability to tune weak stations, dial accuracy, AM operation, etc. If anything, I think I notice less hum on AM radio, but that could also be due to the recapping of the rest of the unit.
I know it's not recommended practice to change them, and I'm not recommending that anyone else changes theirs unless they plan on sending it out for alignment, just relating my experience with two of my Pioneers!
Maybe anderslober will get lucky with his SX-1980, too! :smlove:
Note: I still want to get the SX-1050 professionally aligned, just need to find a tech within 100 miles or so, I'd prefer to drop it off in person, not ship it. If anyone knows a good shop in SoCal, please PM me!