Vintage Synth Repair

Thank's to paintingwith sound and thirteentech! Sounds like excellent leads
to follow..will do!

 

Mike Hunter

mike.hunter@...

Web Sites:

http://www.brainstatik.com

http://www.ombient.com

http://www.mayakara.net

 

 

 

  _____  

From: vintagesynthrepair@yahoogroups.com
[mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of paintingwithsound
Sent: Tuesday, July 15, 2008 6:59 PM
To: vintagesynthrepair@yahoogroups.com
Subject: [vintagesynthrepair] Re: Arp Axxe - CV Memory problem - De-Bounce
Keyboard?

 

I have posted the service manual on my downloads page at
http://www.painting <http://www.paintingwithsound.co.nz/downloads.htm.>
withsound.co.nz/downloads.htm. Look for the section
"Keyboard Control Voltage Memory". Because the note is climbing I
would look at Q6 first as it is probably leaking current into the
sampling cap c13. Regards

--- In vintagesynthrepair@ <mailto:vintagesynthrepair%40yahoogroups.com>
yahoogroups.com, "thirteentech"
<thirteentech@...> wrote:
>
> --- In vintagesynthrepair@ <mailto:vintagesynthrepair%40yahoogroups.com>
yahoogroups.com, "thainmlh" <mike.hunter@>
wrote:
> >
> > Hi, new to the list. I have two questions pertaining to an ARP Axxe
> > 
> > 1) It seems to me that the CV Memory needs alignment or repair. If a
> > note is depressed and released, the pitch slowly climbs. If the key is
> > depressed and held, the pitch remains constant.
> > 
> You can try cleaning the circuit board top and bottom around the CV
memory circuit, from 
> memory it is a very high impedence circuit with a single FET and a
dual FET and discharge 
> capacitor, so if ther is contamination on the board, particularly in
humid weather, there could 
> be leakage. As this is a sample and hold circuit it needs to be leak
free. 
> 
> Otherwise you would be looking at (depending on which version Axxe
you have) C13, Q5 or 
> Q6.
>