[sdiy] ARP 2600 VCA - 4019 module

[rob]

Hi
I have cloned the ARP 4019 using the original ARP blueprints - which match
the Arptech ones.
I am finishing off the testing today, so will let you know..

http://www.emulatorarchive.com/Amplifiers/AM8019/am8019.html


Regards
Rob
www.emulatorarchive.com

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Dave Leith
Sent: 26 June 2009 05:44
To: SDIY
Subject: [sdiy] ARP 2600 VCA - 4019 module


Has anyone built this circuit from the ARP schematics from
http://www.arptech.synth.net/modmain.htm ?

I can't get the signal out to match the signal in (unless I change some
resistor values.) It's about half the level out compared to the input. I
have double checked resistor values, transistor orientation/polarity and
have used the circuit layout from the schematic package, and messed with the
trim pots. I've also measured voltages and they seem about right except the
current swing is too small....

Oakley makes a similar module as do some of the boutique repair shops so it
should work correctly unless I'm missing something really obvious (quite
possible especially after the number of hours staring at it :-) or I wonder
if the parts values are correct as shown.

Any suggestions?

Thanks Dave
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