Hello, I’m a newbie on this forum, and would like to know if there is anybody out there still using the Hill Audio Chameleon 1400S/ 2200 or Dynaudio A-1. Or has done some time ago.
Having come into a pair of 1400Ses that have been used for more than a decade in a video editing suite and reading they have generally been used as reference amps and have even carried the awesome Dynaudio brand (A-1), I was quite surprised mine produse an awfull amount of broadband hum (50cps+ harmonics).
My pair has been branded unreliable because of frequent thermal breakdowns, but they have served in extremely densely packed and badly ventilated racks, often 24/24.
Suspecting either component failure (which would seem odd because I have 2 of them with an identical complaint) or design flaw, I hooked up an oscilloscope onto the +/- 24V supply line to find that there was an enormous 2V ripple on the + side.
I’ve been told that healthy opamps will not mind, but still am suspicious.
Remains to be said that mine are the revision with a healthy 15000 microfarad smoothing on the +/- 85V supply line, but only a meagre capacitance on the +/- 24V line. Unlike some other revisions I’ve seen, carriying enormous Elcos on the 24V rails as well.
I’d like very much to restore the pair to their former glory, so: any suggestions? Anyone?
P.S.: I've already downloaded some schematics from this forum, thanks Jez.
Having come into a pair of 1400Ses that have been used for more than a decade in a video editing suite and reading they have generally been used as reference amps and have even carried the awesome Dynaudio brand (A-1), I was quite surprised mine produse an awfull amount of broadband hum (50cps+ harmonics).
My pair has been branded unreliable because of frequent thermal breakdowns, but they have served in extremely densely packed and badly ventilated racks, often 24/24.
Suspecting either component failure (which would seem odd because I have 2 of them with an identical complaint) or design flaw, I hooked up an oscilloscope onto the +/- 24V supply line to find that there was an enormous 2V ripple on the + side.
I’ve been told that healthy opamps will not mind, but still am suspicious.
Remains to be said that mine are the revision with a healthy 15000 microfarad smoothing on the +/- 85V supply line, but only a meagre capacitance on the +/- 24V line. Unlike some other revisions I’ve seen, carriying enormous Elcos on the 24V rails as well.
I’d like very much to restore the pair to their former glory, so: any suggestions? Anyone?
P.S.: I've already downloaded some schematics from this forum, thanks Jez.