KBG Luxford wrote:
at constant volume. Was there a change to the AF gain control circuitry
between the Rev A RF board and the post S/N 3000 B boards? Will the
change to the AF circuitry that I have yet to make fix this problem?
I'm surprised you haven't had an official reply.
Looking at the circuit diagrams, assuming that the rework fully produces
the new design, there was a significant change. The original just had a
variable resistance across the inverting and non-inverting inputs; I'm
not sure what forms the top of the potential divider. The result is
fully balanced. The current revision has the one input of the amplifier
connected to the counter-clockwise end of the control, but the other
connected to the slider. An extra pin (#3), on P1, carries that signal.
The current version is slightly more conventional, but only balanced
at full volume.
If the front panel changes were made without any corresponding
motherboard ones, you would get constant volume, because the control
slider would no longer be connected to the clockwise end.
--
David Woolley
Emails are not formal business letters, whatever businesses may want.
RFC1855 says there should be an address here, but, in a world of spam,
that is no longer good advice, as archive address hiding may not work.
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