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'LIVEWIRE?' · 14th Mar 2019, 10:56 pm

Given my recent experience with an A3i, I'd second David's remarks re reconstructing transistor amplifiers. In that case I found one pre-driver transistor completely o/c, plus dry joints & bad printed track connections to the tone amplifier I.C. leaving no negative supply to the op-amp in question. This resulted in a DC voltage which varied with it's setting, on the volume control and the function switches. These faults in turn caused the speaker protection relay to trip in and out, which puzzled me for a while, and I've been working with transistor & valve circuits for almost 50 years!

14th Mar 2019, 10:56 pm	#16
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Cambridge Audio A500 Given my recent experience with an A3i, I'd second David's remarks re reconstructing transistor amplifiers. In that case I found one pre-driver transistor completely o/c, plus dry joints & bad printed track connections to the tone amplifier I.C. leaving no negative supply to the op-amp in question. This resulted in a DC voltage which varied with it's setting, on the volume control and the function switches. These faults in turn caused the speaker protection relay to trip in and out, which puzzled me for a while, and I've been working with transistor & valve circuits for almost 50 years!