Racapped Obxa
2011-02-22 by FL_799
Just want to share a little restoration project. My obxa was getting really unstable after about 30 minutes of playing. Autotune would fail voice cards the whole thing was getting WAY out of whack. The cards were just not uniform sounding any longer no matter how much they were calibrated. Something had to be done. Over Friday night and Saturday morning, I recapped the PSU and the 7 electrolytic caps on all 8 voice cards with Nicholson capacitors exactly as listed in the schematics i.e. 15uf/25v caps on the voice cards. Also replaced the 2 100uf caps on each of motherboards and few 6.8/35v tantalum caps. I bought 16 100k trim pots for the oscillators but they are too small to work so the originals stay until I find better (suggestions?). After recalibrating the cards, I have a solid 3 days putting the obxa through its paces and have several hours of sheer pleasure without a hitch. It's running and sounding great. I actually screwed down the lid and have not had to get under the hood so I'd say this mission was a success. Maybe I'll do the control boards in a few weeks and go all the way. So everything is just about done. Everything is functional, board level, new bushings installed, and it sounds great. Life is indeed good. James