Hi, I have an vintage API 550A (2x 2520) module here with an big problem. The module oscillates and makes a kind of distorted sine wave noise
like an Moog Synth without any signal on the input. The frequency changes the sound by moving the switches and it does not matter
which band. The noise disappears by pushing the left button L|F (Low pass ??). No input signal going trough . I replaced both 2520, I recapped the unit . Now I was
going to check the Transistors . Does somebody out there has an Idea .??
The version I have has no component numbers printed on the board. Can somebody post an picture from inside. Thanks.
Any suggestions highly appreciated
Thanks in advance.
like an Moog Synth without any signal on the input. The frequency changes the sound by moving the switches and it does not matter
which band. The noise disappears by pushing the left button L|F (Low pass ??). No input signal going trough . I replaced both 2520, I recapped the unit . Now I was
going to check the Transistors . Does somebody out there has an Idea .??
The version I have has no component numbers printed on the board. Can somebody post an picture from inside. Thanks.
Any suggestions highly appreciated
Thanks in advance.