Over the past few weeks, I've been setting up what's left of my old PA system in my music room so that I can use it for some live performance video recording. I was having a lot of problems with low output and distortion from one of the channels, so I had to figure out which part of the system was causing the problems. I ended up narrowing it down to one of the channels of the equalizer.
This is my 1980s vintage Peavey stereo 10 band graphic equalizer. We used this in the band PA system for a lot of years, and then when I had to quit playing, it sat for a lot of years.
All the input and output connections are on the back. This equalizer has both high impedance and low impedance connections for the inputs and outputs.
I had to take the cover off to get a look at the circuit boards. The first thing to do with something like this is to inspect all the solder connections. This unit has 2 circuit boards that are stacked one over the other and connected by plugs on one edge of the boards.
I had to separate the circuit boards to be able to inspect the solder connections.
The upper circuit board seemed to be in pretty good shape. I resoldered several connections on that board to make sure the connections were good. Then I went to the second board and inspected all the solder connections on it.
I found numerous cracked solder connections on the second board. The second board is the one with all the front controls mounted to it, and it seems that there just wasn't enough solder on the connections for them to hold up over time. This seems to be the most common problem with a lot of different equipment with circuit boards, either because of heat variations from the parts, or just not enough solder from the factory. A crack in the solder connection will cause connection problems that show up over time, and a lot of the time it will start with the problem coming and going intermittently. To fix the solder cracks, you just resolder the connection and add a bit more solder to the connection for better reliability.
I tested the equalizer today with my small monitor amplifiers, and it seems to be working properly now. I'm listening to music through it right now as I'm typing this post. Now all I have to do is set the PA system up again and see how it works with the big amplifier. I still have to finish putting together my little tweeter cabinets so that I have full frequency response with the PA system, but that's for another post.
That's it for this post, I hope you found it interesting!
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