question on phase 90 500k pot mod

[donald stringer]

Does anyone know what function the 500k pot mod serves as it is listed here.http://aronnelson.com/gallery/albums/Schematics-etc/phase_90_board.sized.jpg I have done most of them and well pleased so far and was wondering if it is  worth the trouble.

[Alex C]

Was this posted on April Fool's Day or something?
"Replace R36 for a 500k pot."
I can't find R36 in that picture, after ten minutes of searching.

The labeling shows up a bit better in this one, but I still can't find it (click it to make it bigger).

In the link you posted, R36 to 500k is listed a an additional mod, and not part of the "script mods."


According to this schematic, the 470k pot is changed to a 500k pot.
This re-issue schematic ("block logo") shows R36 as being a 470k pot.
This "script" schematic shows a 500k pot for R36.


I don't know if the subbing a 500k for a 470k is going to make a lot of difference; what's the tolerance of a standard Alpha pot? 10%?  5%?
Maybe it's just about getting back to "script" values, rather than a big increase in available range of control of whatever it is this variable resistor is doing (I have no idea).
Perhaps someone more qualified than I or one who has performed these mods can offer his or her thoughts.   Nero1985?

-Alex

[donald stringer]

On mine you have to gently pull the pot back [thats attached to the board and you see an R36 below the opamp and inbetween two res. I am not sure what it controls but your correct its not on the picture.

[Eb7+9]

if you're referring to the speed pot - a higher value pot will make the mininum slow speed go even slower ... seems at first glance the circuit might work with a 1meg, 2Meg or even 3Meg pot and give you maximum slow sweeps roughly 2 to 6 times the length - with most pots this will compress the high-speed range a little ... a log pot wired backwards will stretch out the high-speed realm if that becomes a problem - just means the speed control will work backwards ...

[donald stringer]

Thanks for your reply, I think I will stick with two pots. The depth mods works like a charm along with the other mods. I have an new enclosure ready so I think I will remount it before I kill it.