----- Original Message -----
From: "Joe Loverti" <[email protected]>
To: <[email protected]>
Sent: Saturday, November 13, 2010 4:32 PM
Subject: [Drakelist] My AC-4 is humming just a little.
Hi guys:
I've rebuilt my AC-4 using the Heathkit Shop Kit recently
and all went well.
All the voltages read within range and I'm happy with the
rebuild and the
kit.
I have the AC-4 mounted inside the MS-4 cabinet and it
sits atop my MN2000
with brand new rubber feet, yet I can hear a very low AC
hum coming from the
cabinet. It's not coming from the speaker because I can
hear the same low
level AC hum with the speaker cable disconnected. It's not
enough to really
bother me and I only hear it when the room is quiet and
the audio from the
rig is turned down. I'm just wondering if this is normal
or do I have an
issue that I need to take care of.
Any ideas certainly most welcome. Thanks.
Joe
WW8X
Miamisburg
Ohio
That kind of hum is often from the transformer. Try
tightening the bolts that hold the laminations together,
that may eliminate it. Otherwise you may have to mount the
supply on isolators of some sort like soft rubber grommets
between the transformer and speaker case. There should be
gromets or at least thick washers on the bottom too so that
the screws do not make direct contact. Vibration isolation
can be difficult.
--
Richard Knoppow
Los Angeles
WB6KBL
[email protected]
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