Re: Mains interference on power amp



Gareth Magennis wrote:

I think I know what the problem is now. The 3 relays that do the soft start
and the protect switching are on the same PCB as the protection circuitry.
I removed all 3 and the PCB underneath was not too clean. Since the relays
switch mains voltages, it is not beyond the realms of possibility that mains
voltage and any hash will make its way over to the circuitry via the dirty
PCB. The main protect line runs along all 3 relays, only 5mm from the relay
coils. I have also established beyond doubt that the protect circuitry is
actually being pulsed on briefly via this protect line.

I'm going to fit 3 new relays tomorrow and clean it all up, and hopefully
the nightmare will be over. I might even re-route that protect line.

Did I ever mention you chat with Bruce at Shuttlesound ? He's very helpful. Nice
bloke.

Graham

.

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