Sequential circuits samplers

Anyone experience a constant buzz from the transformer of their
Prophet 2002?  Mine does this and I was wondering if it is a sign of
impending doom, bad power, or normal operation.

In response to the "constant buzz" question. Yes my Prophet 2000 does 
hum a little, as long as it's turned on. Once the music is playing, 
though, in headphones or moniters, I can't notice it. I also have a 
Roland JX-8P, which is just as old, and it hums as well. I've had two 
Juno-106's, and they both hummed. They all work just fine. I just 
tightened every screw on the chassis, to make sure there wasn't any 
extra noise makers. Maybe analog circuitry is more hummy than the 
purely digital innards. Hope this helps.  ESW





 In prophet2000@yahoogroups.com, "plus_321" <plus_321@...> wrote:

>
> Anyone experience a constant buzz from the transformer of their
> Prophet 2002?  Mine does this and I was wondering if it is a sign of
> impending doom, bad power, or normal operation.
>

To: prophet2000@yahoogroups.com
From: eric_swhite@...
Date: Thu, 8 Nov 2007 19:19:30 +0000
Subject: [prophet2000] Re: Power transformer buzz

In response to the "constant buzz" question. Yes my Prophet 2000 does
hum a little, as long as it's turned on. Once the music is playing,
though, in headphones or moniters, I can't notice it. I also have a
Roland JX-8P, which is just as old, and it hums as well. I've had two
Juno-106's, and they both hummed. They all work just fine. I just
tightened every screw on the chassis, to make sure there wasn't any
extra noise makers. Maybe analog circuitry is more hummy than the
purely digital innards. Hope this helps. ESW

In prophet2000@yahoogroups.com, "plus_321" .> wrote:
>
> Anyone experience a constant buzz from the transformer of their
> Prophet 2002? Mine does this and I was wondering if it is a sign of
> impending doom, bad power, or normal operation.
>;

I have both a p2k & a 2k2, & they both run hot & hum noticeably. this
is especially the case because I'm in the UK & the mains transformers
in the instruments are designed for 110V or 220V operation; here
they're getting closer to 240V.
the transformers are old-school iron-core jobs, not toroidals,
although if the noise is a nuisance, it would be easy enough to swap
them out. I did this on someone else's machine ages ago to quieten it
down for studio use. 
my biggest worry was always the extra heat disspiation from the
slightly harder-worked series regulators in the low-voltage part of
the power supply, though I only had to replace one ever, & that was
many years ago. other folks (quite recently) have had fairly standard
linear power supply problems, like leaky electrolytics & bridge
rectifier failures leading to shorts & blown fuses, but they're
reasonably simple faults. 

the rest of the machine (touch wood) seems pretty reliable, with only
the disc drive being a problem from time to time. I replaced both of
mine with TDK types a long time ago, & had to "bulk them out" with, of
all things, compact cassette cases to fill up the gaps in the
metalwork left by the slimmer drives. 

my 2000, though, has a dead keyboard controller IC which I can't
replace, so I am looking for a 2000 that's beyond repair in some other
way to scavenge parts from. I'm sort of hoping that one won't turn up,
because I'd rather folks kept their prophets working!

duncan.