X-77 Mods

[John Bittner <jbitt@primenet.com>]

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From:   OrganFxr@aol.com[SMTP:OrganFxr@aol.com]
Sent:   Sunday, March 02, 1997 10:28 AM
>I think the best thing you could do to an X-77, which I have done, is go to a
>tube-driven preamp.  I built mine from an L-100 Schematic and it cleared up
>ALL the X's inherent hum and buzz problems.

One reason for the X-77's hum and buzz problems is the lack of shielding on 
some circuit boards
and can be remedied without the use of a tube preamp.

For some reason Hammond choose not to shield the vibrato, non-vibrato,
bass, and percussion output amps, the bass preamp(!!), percussion preamp, and 
reverb preamp.
They did shield the vibrato and non-vibrato preamp and some of the gated 
amplifiers.

Enclose the unshielded circuit boards in grounded metal chassis boxes and the 
hum will drop dramatically.
I would also recommend replacing the push-on connectors which interconnect 
these boards
with a soldered connection.

John Bittner
X-77 Owner