SPL4120

[Debbi]

I've got a couple of these EQs and they don't work. Both are doing the same thing, a distorted signal comes through, like bad impedance matching or an insufficent power supply. The EQ section will cut the bands at low levels; anything above zero gain is fuzz effect. I am taking signal from a SPL2216 sub 1 and 2, and going into an SA21. Signal is clear when eq section is out. Is the 4559 chip suspect, or how can I tell? Where would I get service manuals for this and the digital crossover (they are pretty flaky also)? If you haven't struck out yet, then where would I find a replacement flourescent display for a SA11? Help!

[Don T.]

Hello:
 Except for the IO section distortion would be frequency dependent. The in/out switches were a little problematic. Besides that there was a ground problem in the 4120 / 4320 units. The ground was dependent on a good connection at the jack to chassis mount which was only pop riveted. We would run ground wire from pin 1 to the chassis ground where the green wire hooks up. This would quite the unit down and all gear down circuit.
Don T.