[sdiy] Super Psycho LFO question

[David Cornutt]

I'm completing the assembly of a Super Psycho LFO that I purchased
in a partially completed state.  (The board itself was complete, but 
there was
no panel and none of panel wiring had been done.)  I finally powered it
up for the first time yesterday.  It's got several problems that I'm 
working
through.  Most of this probably just has to do with my soldering (I 
lifted
a couple of pads while I was soldering all of the wiring for the 
individual
oscillator controls), but one thing that puzzled me was that the 
triangle
waveforms (from the two oscillators that have triangle shapers) kept
coming and going while I was probing and debugging the board.

After looking at the schematic, I noticed something.  Now I know you
old-timers have seen this before, but I can't seem to find the right
combination of keywords to make it come out of an archive search.
So: It seems to me that if you put the speed range switch of one of
the triangle-capable oscillators in the OFF position, the non-inverting
input of the TL072 is driven to the negative rail.  Won't that cause the
TL072 to latch up, or is this part latchup-resistant?  Can this be
prevented just by turning the speed pot to max before switching
the oscillator off?

Anyway, it's been a pretty good weekend.  I finally have a scope that
works; a deal with a more reliable vendor on Ebay yielded a pretty
clean Tek 464.  The SP LFO is mostly working; I have one oscillator
that always runs at high speed (probably a problem with the soldering
on the common for the range switch), two that have their rate pots
cross-wired, one oscillator that doesn't do anything (haven't figured
that one out yet) and one expensive white LED that I accidentally
fried by allowing a bare lead to come into contact with the vise.
But it basically works and it makes some really cool patterns
on the scope.  The second of my modular "function blocks" is
up and running (except for the +5V terminal strip, which I haven't
installed yet).  Now I need to finish some modules so I can fill it up!