al <alki...@gmail.com>: Sep 20 03:55PM -0700
Well, it turns out that an oscilloscope is an extremely useful tool for the
controller. With Howie's schematics you can trace what bit is non
functional: in my case the variable frequency generator on board 3. I
replaced the IC but that didn't work. So checked the power in and the -10v
rail was off. It comes through a resistor, which had failed. Replacing that
made everything work!
I also thought everyone might be interested in seeing the wow and flutter
trace and the corresponding voltage fluctuation in the drive to the motor,
which is surprisingly big (given that 33.3 is coded by 1.2v and 45 by 1.5v:
the variation is up to 0.1v!). The optical feedback loop is working hard
and I think the motor would be pretty ropey without it... The flutter is
typical of a direct drive: what is interesting is the biggest variation x1
per revolution, seen in both the wow/flutter graph and the voltage trace.
Can't make it go away however much I clean the disc: must be something
mechanical. Figures still excellent though...
On Monday, 24 August 2020 20:48:22 UTC+1, al wrote:
al <alki...@gmail.com>: Sep 20 03:56PM -0700
Well, it turns out that an oscilloscope is an extremely useful tool for the
controller. With Howie's schematics you can trace what bit is non
functional: in my case the variable frequency generator on board 3. I
replaced the IC but that didn't work. So checked the power in and the -10v
rail was off. It comes through a resistor, which had failed. Replacing that
made everything work!
I also thought everyone might be interested in seeing the wow and flutter
trace and the corresponding voltage fluctuation in the drive to the motor,
which is surprisingly big (given that 33.3 is coded by 1.2v and 45 by 1.5v:
the variation is up to 0.3v!). The optical feedback loop is working hard
and I think the motor would be pretty ropey without it... The flutter is
typical of a direct drive: what is interesting is the biggest variation x1
per revolution, seen in both the wow/flutter graph and the voltage trace.
Can't make it go away however much I clean the disc: must be something
mechanical. Figures still excellent though...
On Monday, 24 August 2020 20:48:22 UTC+1, al wrote:
al <alki...@gmail.com>: Sep 20 04:15PM -0700
.... and I just realised: the schematics are from Markus, not Howie. They
are what got me out of the hole. Thanks Markus!
On Monday, 24 August 2020 at 20:48:22 UTC+1 al wrote:
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Seems like a nice set. I’m sure they’ll need some attention. Perhaps buy some stands from Dave.
At the end of the day I a wonderful set of speakers for life.
From: gale-...@googlegroups.com <gale-...@googlegroups.com> On Behalf Of Jack Ward
Sent: Saturday, October 17, 2020 7:39 AM
To: gale-...@googlegroups.com
Subject: 401 set on ebay
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