Quad 44 Oscillation

[reddish75]

I've followed the DaDa mods to this Quad 44 pre amp but have Oscillation on the output and am needing some hand holding as to narrowing this down to a particular circuit board at first.

As it Oscillates on all inputs I though that I'd pop the old opamps back onto the Radio input card but still oscillation so input cards clear with that logic I think?

This then leads me to the Mother board, where would I probe the signal? I was thinking along the lines of on attached pic,

Points 3 inputs to the CD4066BE from the input cards

Points F and A on IC403 for the output of this board

Which points are the outputs of the IC Switches
Attached Thumbnails

[wasedadoc]

The points with a circled 3 are the sources' right inputs and points with a circled 5 are the sources' left inputs.  The line with circled 2s is the right bus and is finally switched by the right most 4066 to the empty circle labelled 'OUTPUT-RIGHT'.  Similarly for left bus circled 6s and 'OUTPUT-LEFT'.

4066s are passive switches.  No gain in them.  They cannot oscillate.

[MarkT]

I've followed the DaDa mods to this Quad 44 pre amp but have Oscillation on the output and am needing some hand holding as to narrowing this down to a particular circuit board at first.

As it Oscillates on all inputs I though that I'd pop the old opamps back onto the Radio input card but still oscillation so input cards clear with that logic I think?

Well the suggested replacements require proper decoupling, TL071/072 are very tolerant of lax decoupling, so that might be a reason for oscillation - but what frequency is this oscillation?

[floobydust]

OP tell us more about the mods you did. The DaDa site seems a bit off- the discontinued OPA604 replaced by OP07D? That seems wrong.
There is mention of adding decoupling caps on the rails if things oscillate. That would show up in both channels.
Quad 44 Service Manual or QUAD Manuals+diagrams 44