For the first couple components, I was trying to desolder and remove the whole component. Although, I used a wick for clean up in a couple places. I used a solder sucker as it seemed to be faster than a wick. Having a rework station would have made things much, much easier, but I wasn’t going to invest in one just for this project. But, once I got the hang of it, things moved along quite quickly. When I first popped the cover off this EQ, I was a little concerned about the number of components I would need to desolder. I also labeled each of the wires attached to the board before removing them. Before doing so, I took several pictures. The board needed to be removed from the enclosure. The Repair: Before getting started, I double checked the parts I had received against the parts list.I was able to source most of the parts from Digikey, but used Mouser for the parts that were out of stock. In those cases, I went with what was soldered to the board. There were a couple minor discrepancies between the schematic and the board. I took a similar tack with the capacitors in that I replaced with higher voltage ratings and lower tolerances in some cases. Per the KF7LZE post, I went with higher wattage resistors and in many cases, lower tolerances. There are a few ceramic capacitors, transistors and other parts that I didn’t bother to replace. Only the resistors and most of the capacitors. Note that I didn’t replace everything on the board. Ordering Parts: Using the schematic (PDF) and the actual board as a cross reference, I made a list (CSV) of all the components I would need to order.I was slightly concerned about by ability to execute, but I was reminded that the EQ didn’t work anyway–no matter what I did, it wasn’t going be any worse. Based on KF7LZE’s blog post, I was confident that, if executed properly, this repair would work. The before and after pictures appear below and there is a parts list in the resources section at the end. I’m happy to report that the repair was a success and, while I haven’t heard for myself yet, I’ve been told that it sounds “awesome” it sounds pretty awesome. He found this post on KF7LZE’s Blog about replacing the old resistors and capacitors to bring the old equalizer back to life and suggested that I give it a go. One of his EQs worked well, but the other, not so much. These speakers were designed to be used with an active equalizer without it, the sound quality is quite poor. BackgroundĪ friend got sort of a two-for-one deal on some vintage Bose 901 speakers. In this project, a non-functional Bose 901 Equalizer is repaired by replacing the old resistors and capacitors with modern parts. Over the years, vintage audio components can begin to fail due to the age of their electronics. I’m flattered, but I’m not an electronics pro, so I can’t repair other people’s gear. Update : Several people have contacted me asking if I could repair their equalizers or other equipment.

Bose 901 equalizer