Archive of the former Yahoo!Groups mailing list: Mellotronists

Ooops as of Saturday my work email server is labeling list emails as "JUNK".
Sorry didn't catch that sooner...

The story of the microphonic M400 - same machine as Baja Prog back in March
03, the one that nobody wanted to use because it had a "funny hum"
sometimes. Same machine at Claremont '91 that had a pretty big feedback
problem. Got brought over to my place a couple weeks ago. As I was messing
with it I finally noticed something strange. When the headblock was all the
way over to C, all the way, there was a motor whine in the output. Not as
loud as the program material, but if I cranked up the volume on the PA, I
could see why it was a problem at Baja (I was never around during the
soundchecks when it got sidelined). Also, if you knocked on the lid with
your knuckles, you could hear it in the speakers.

I discovered that when the head channel was cranked over to C track, it was
shorted to the frame. Move it to B or A, short gone. I traced it down to one
of the spring clips. There was an intermittant short where the clip was held
with the insulating washer. Took it apart, reassembled, short gone,
microphonicity gone.

Another thing for the maintenece checklist!

- Gene