F3 Dynacomp board query

[Mark Hammer]

Trying to install a recovery-time mod to a buddy's F3 board Dynacomp (LM13700-based).  I can find the transistor pair and the 10uf cap, but I'll be damned if I can fidn the 150k resistor to V+ .

Any clues?

[Rob Strand]

Maybe the value is different.  Can you follow the PCB track on the collectors of the two transistors and the cap?
Whatever else is on that track will be the thing charging the cap.

[Mark Hammer]

That's what I thought I'd do, but these 5-stripe metal film things are a royal pain to read.
The relevant transistor pair, and the 10uf cap, are visible in the upper left-hand corner.  Under the volume pot on the left are a pair of zero-ohm resistors connected to the cap.  My mission is to find something that measures 150k between that junction and V+.

[Rob Strand]

Hi Mark,  I've been poking around for a while and this what I can work out.  Maybe it's enough that you can run with it.

After looking at the bottom of the PCB from this pic:
http://i925.photobucket.com/albums/ad95/paulisme/f2ed6ce7d7b4f811353c97be6954c9e3.jpg~original

I could be wrong but this is what I can work out:
It appears the at least one of the 0R resistors connects the attack/release cap to the control pin (pin 1) of the OTA and to the sensitivity pot.

So it looks like the transistor on the original dynacomp,  which goes between the attack/release cap and the sensitivity pot, is not present on the F unit.  So it seems the attack/release resistor and the sensitivity pot are one and the same.

Roughly,
- sensitivity pot goes directly to the attack/release cap  (other side of pot to a +ve rail???),
  then to OTA control pin, pin 1
- there is no 150k attack resistor

Maybe you can buzz this through yourself on the board.

You aren't going crazy!
===================
[Edit]
What I've still isn't the whole story a it is missing a path to +V. 
Perhaps the why the sensitivity pot is wired is the key.
Maybe the +V is picked up *through* the sensitivity pot.

[Mark Hammer]

I ended up contacting Jeorge Tripps, who said he would try and locate the schematic for me.  Hopefully, that will resolve my challenge.
Behind those ever-present shades is a prince of a man. 

[Rob Strand]

Probably a lot easier to work out that way.

[Mark Hammer]

Being the prince he is, Jeorge came through.  I did the mod and it sounds great.  If folks google around for images of the Dynacomp board and the board for the Supercomp, you'll find that there are very few, if any, differences between the two boards.  The Supercomp adds an Attack control.  I have no idea where they found the space for the 3rd pot, but it would appear to be the exact same circuit, simply replacing a variable resistance for the 150k fixed resistance we've seen since the 70's.

I guess the takehome message is that, if you like the Dynacomp, the Supercomp delivers the same goods, but already does the mod for you.