Prophet 5 Power Supply Question

gstopp at gstopp at
Tue Oct 8 23:23:57 CEST 1996

     I don't have a P5 personally but one could suppose based on the 
     information provided that you may have a loose lamination in the power 
     transformer in the power supply, which is vibrating mechanically at 
     the line frequency. Elimination of the problem may require things like 
     screwing it down harder or the application of some epoxy, or in the 
     worst case replacement of the transformer itself.
     - Gene
     gstopp at

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Subject: Prophet 5 Power Supply Question
Author:  Sean Costello <costello at> at ccrelayout
Date:    10/8/96 2:12 PM

Hi DIYers,
I have a question for all of you knowledgeable types out there.  I recently 
purchased a Sequential Circuits Prophet 5 (rev. 3.3); upon playing it in a 
quiet situation (away from the sounds of the music store and band practice), 
I noticed it was emitting a hum.  The hum comes from the machine itself, and 
can be felt as a slight vibration in the music stand.  The output seems to 
be free of this hum, so it is not a simple ground loop problem (the hum can 
be heard without an amplifier).
Is this normal?  Any idea what could be causing this hum?  I presume it is 
something in the power supply, but I don't know what it would be.  Is this 
something that I should have serviced?  Will it cause damage to my Prophet? 
Does this sound too much like a letter to Dear Abby?
Sign me...
(Sean Costello)

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