Cgs synth

Hello, I'm new to this forum. I started building the VCO and I just have a few more little parts to get and solder in. I'm not a super-experienced builder so there's one thing I'm a bit confused and insecure about. In the instructions he gives Modifications to the different versions of the PC board. I have version 0.4 of the PC board. The first mod in the REV. 0.4 is this:

["Cut the track between Pin 5 of the TL072 in the bottom right corner and the 47uF capacitor. Make the cut near the capacitor."]

I can't find anywhere that pin 5 of the TL072 is connected to the 47uF capacitor. Pin 5 seems to be connected to a pad that is supposed to be a jumper wire. And that's another thing, in the Modifications for version 0.2 it says to remove the jumper between pin 5 and the WS Trim. Should I still not put in the jumper or should I go ahead and do it since this is a later version.

["Jumper pin 5 to the Saw AC output terminal via a 100k. This will set PWM control to 50% at 0 volts."]

So, disregard the jumper that's marked on the PC board and just solder in a 100K resistor between the hole at pin5 and the hole at Saw AC output?

["It is possible to place the resistor in place of the link on the PCB though the track modification is still required."]

I'm not sure what "link" means here.

["Replace the 330k resistor near the SYNC pad with a 220k resistor. This should stop clipping."]

I couldn't find any 330k resistor in this area.

One more thing. He give a schematic for "Power rail decoupling for the VCO". I have no idea what decoupling means. I have a Blacet power supply with -15, 0, +15. Does that mean I don't have to do any modifications to the PC board?

Sorry if these are really dumb questions, any help would be greatly appreciated.Thank you for your patience!
steve

Hi Ken and all

I have had something fail on a working CGS48 VCO on my BOG panel build.

It was working just fine ; when powered up the other day the output sounded no signal at all for about 12 seconds and then nothing but very high pitched output.

Way above the range that it's supposed to be putting out.

The Freq pot changes this pitch.

All inputs like 1V/Oct , FM etc seem ok.

I have swapped all the IC's with the VCO next to it except the LM394 (as it has a Tempco over it). No difference.

[Non-text portions of this message have been removed]

It was the LM394. ;)


________________________________

I´ve got all my CGS pcb:s working, but no panels. How about that?
I hope no drunk trip or another cold will stop my sound!

Anders, Sweden
http://rubidium.dyndns.org/cag/


________________________________
Från: Stephen Richards <okayjustalittle@...>
Till: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Skickat: lördag, 1 december 2012 1:45
Ämne: [cgs_synth] CGS48 VCO question



Hi Ken and all

I have had something fail on a working CGS48 VCO on my BOG panel build.

It was working just fine ; when powered up the other day the output sounded no signal at all for about 12 seconds and then nothing but very high pitched output.

Way above the range that it's supposed to be putting out.

The Freq pot changes this pitch.

All inputs like 1V/Oct , FM etc seem ok.

I have swapped all the IC's with the VCO next to it except the LM394 (as it has a Tempco over it). No difference.

[Non-text portions of this message have been removed]




[Non-text portions of this message have been removed]