[sdiy] MFB SEQ-02 question

[David Ingebretsen]

I'm working with MFB on this, too. However, I've come to respect the "brain
trust" on this list and will ask here. MFB is being very helpful, but very
slow due to time differences.

I have a new'ish pair of MFB SEQ-02's and a new'ish quantizer.

I wanted to see how the quantizer worked with the SEQ-02 and hooked it up.
The audio was a horrible buzz, and not right.

Short version:

The outputs of both my SEQ-02's suffer from:
1.	2 V peak to peak ripple on the output of the SEQ02, variable
frequency with output level, approximately 400 kHz
2.	The output level drops significantly when the output is fed into
more than one device: eg. VCO and an oscilloscope or volt meter.
3.	This ripple is present on both my SEQ02's and is essentially
identical
4.	The ripple is not filtered out by running this through a "buffer"
(MFB asked me to try)
5.	The ripple does not modulate my VCO and so I would never have caught
it had I not tried it through the quantizer.

It happens on both SEQ-02's and they are in completely separate racks. I
have tried isolating the SEQ-02 and adding extra grounding wires. I tried
different power supplies, etc. As stated above, the frequency of the ripple
varies with the voltage output over about 100 kHz or more.

Does anyone else have an SEQ-02? If so, would you put a scope on the output
and see if you see any high level (about 2 volts peak-to-peak) and high
frequency ripple?

If not, do you simply have any ideas as to what is happening? Is it
something I'm doing? I have some captures from my scope that are here:



http://www.xmission.com/~dingebre/page9.html



My SEQ-02's are in completely different racks, different power supplies,
etc. and they both do the same dang thing.

Thanks
David