Cross-posted from the Rain City Audio Repair Blog:
Another Bose® 901 Series I Active Equalizer came through the ship, Serial #46453. It came in with a variety of issues, just not sounding like it used to, and the owner requested a set of new audiophile-grade film output capacitors as an upgrade as well.
Based on the different ages of capacitors, it looks like this one was serviced some time in the late ’70s or possibly early ’80s. Several of the black capacitors had failed and were causing quality issues.
This particular one received Vishay and Panasonic signal capacitors in the intermediate stages.
After repair, this equalizer sounds perfect and the upgraded capacitors really bring out a lot of clarity and detail in the mid-range and upper frequencies. Paired with the 901 speakers, it makes a fantastic, room-filling, life-like sound and will last for a long time.