Re: Mains interference on power amp


"Eeyore" <rabbitsfriendsandrelations@xxxxxxxxxxx> wrote in message
news:486BCED5.5FB3C5BA@xxxxxxxxxxxxxx


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


Yes I have spoken to Bruce about this a few times, he did give me some good
tips generally, but didn't seem to have come across this before.


Cheers,


Gareth.


.

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