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RCF ART 315A - Oscillating distortion on output
Hi Folks,
Thank you for your time. I was wondering if anyone here can help me. I am trying to repair a RCF ART 315A amplified two way speaker; the speaker seems to be outputting an oscillating distortion (especially on the HF end) with nothing plugged into it. As soon as you put it on, once the startup sequence is complete, the unit starts emitting short HF burst of sound every 4-5 seconds.
I have tested for DC in the output but there is none. I opened up the amp and visually inspected the unit, having seen some suspicious welds, I re-soldered most of the contacts that I though were bad. When I retested the unit, it seemed to be better but the problem persists. I measured around 98mVAC on the output during each oscillation. Before I start replacing all of the output transistors, has anyone ever heard of this problem? BTW, when I do plug an audio source, the audio plays but at around 4 to 6khHz the highs start to distort. I tested booth the speaker and the HF driver, they are not short and i get around 7 ohms so that rules out the speakers.
Kind regards,
Frank
Thank you for your time. I was wondering if anyone here can help me. I am trying to repair a RCF ART 315A amplified two way speaker; the speaker seems to be outputting an oscillating distortion (especially on the HF end) with nothing plugged into it. As soon as you put it on, once the startup sequence is complete, the unit starts emitting short HF burst of sound every 4-5 seconds.
I have tested for DC in the output but there is none. I opened up the amp and visually inspected the unit, having seen some suspicious welds, I re-soldered most of the contacts that I though were bad. When I retested the unit, it seemed to be better but the problem persists. I measured around 98mVAC on the output during each oscillation. Before I start replacing all of the output transistors, has anyone ever heard of this problem? BTW, when I do plug an audio source, the audio plays but at around 4 to 6khHz the highs start to distort. I tested booth the speaker and the HF driver, they are not short and i get around 7 ohms so that rules out the speakers.
Kind regards,
Frank