Which LFO is it!!

[armdnrdy]

I'm working on deciphering a project : The Quadra Phaser.

For those of you not familiar with this phaser, it was a 14 stage CA3086 phaser design that was incorporated in an Arp synthesizer.
The synth project wiz, the late Jürgen Haible modified sections and worked it into a "stand alone" phaser.

So far I have found quite a few discrepancies between the schematic and the PCB layout. Since my internet provider doesn't allow me to email the "other side"  I can't email Mr. Haible for some clarification.

One of the discrepancies is in the LFO which Jürgen added.

Here's the original from his hand drawn schematic:
http://www.aronnelson.com/gallery/main.php/v/diyuser/LFO+2.jpg.html

Here's my re drawn rendition from the PCB file:
http://www.aronnelson.com/gallery/main.php/v/diyuser/LFO.jpg.html

Take a look at the 680K resistor that I designated R58. In the original it's connected from pin 6 of IC17B to the wiper of the Rate pot.
On the PCB layout it's connected from pin 6 of IC17B to pin 3 of IC17A.

I've taken a look at a slew of LFOs and I can't find anything to draw a conclusion on which version is correct.

HELP!  

[slacker]

In the first example the 680k doesn't seem to serve any useful purpose.
680k in parallel with 5k6 + 4k7 (10.3k) = 10.14k, in parallel with just the 5k6 = 5.55k. These changes are insignificant.
In the second example the 680k sets the minimum speed by allowing some current to flow even when the pot is turned all the way down, possibly also affects the pot taper. Without it when the rate pot is turned all the way down the LFO would stop.
The second one gets my vote.

[armdnrdy]

Thanks for the explanation Ian!

I actually understood and learned a bit from it! 

[slacker]

Cool glad it helped.
It's an interesting little snippet, normally when the speed pot is a voltage divider there's a resistor between lug 1 and ground to set the minimum speed, I've never seen this method before.