This popular powered mixing board was made by Toronto’s Yorkville Sound, ca 1985. I was recently hired to service it and make it saleable.
There were no major issues, but being a very-often-used machine, much of the lettering was faded, and there were many scratches and scuffs on the cabinet. As well, most of the controls were quite noisy and had to be cleaned with contact cleaner. It’s a time-consuming job as every single knob must be removed first before the front panel can be separated from the printed circuit board assemblies.
As well, one channel output was intermittent (traced to a bad solder connection on the line output circuit board)
The “Main” sliding fader control had it’s shaft broken off. A new slider potentiometer was sourced and replaced. I used a knob I had in stock as the owner did not require an exact replacement.
Yorkville SP8 Powered 8 channel Mixer
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View of the board as received, before any work was started.
View of the board after work was completed
Comparison of the original dirt and grime on the front panel, and how it looked after being cleaned up. Much better!
Once completed and re-assembled, all functions (every single knob and switch) were tested. The power amplifier was connected to a 4 ohm load and the power output before clipping was seen visually on the scope, and calculated from the voltage measurement across the load. Both channels reached their rated 100 watts without any issue.
Printed board containing channels 1 to 4. Every one of these pots was cleaned with De-Ox-It spray. The slider pots were cleaned with the same spray, but with an added lubricant to keep them gliding nicely.