electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Articles  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links  |  Store
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
CGS VCO-no output. where should i start checking?
Post new topic   Reply to topic Moderators: Scott Stites
Page 2 of 2 [32 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Goto page: Previous 1, 2
Author Message
Adam-V



Joined: Jan 29, 2007
Posts: 300
Location: Australia
Audio files: 1

PostPosted: Tue Feb 03, 2009 2:23 pm    Post subject: Reply with quote  Mark this post and the followings unread

How are you going with this rj?

Cheers,
Adam-V

_________________
Digitalis Effect | Fractured Symmetry (www.spiralsect.com)
Back to top
View user's profile Send private message Visit poster's website
rjd2



Joined: Sep 02, 2007
Posts: 235
Location: philly

PostPosted: Tue Feb 10, 2009 3:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

hey adam, thanks for the check-in! no progress here. i had to slide out to EU for some gigs, got back yesterday.

alas, i think i need a break from "intensive troubleshooting type DIY" for some "instantly gratifying module works type DIY". gotta recharge my batteries. hopefully will pick this up at some point soon.....its alot harder to bail on a module once the front panel is made, though.....
Back to top
View user's profile Send private message
Adam-V



Joined: Jan 29, 2007
Posts: 300
Location: Australia
Audio files: 1

PostPosted: Wed Feb 11, 2009 2:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

OK. Let us know how you go with it when you do get back to looking at it.

Cheers,
Adam-V

_________________
Digitalis Effect | Fractured Symmetry (www.spiralsect.com)
Back to top
View user's profile Send private message Visit poster's website
macumbista



Joined: Sep 12, 2007
Posts: 360
Location: berlin
Audio files: 3

PostPosted: Mon Jul 16, 2012 1:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

Looking at a dead VCO myself. Have another, working one just next to it for comparison, but damned if I can find the difference. I've swapped out ICs, checked for shorts, polarity of diodes, everything. Wondering if I have to consider replacing the FET or (hopefully not!) the matched transistors.

How could I check if the FET or any of the transistors are bad before ripping them out?

_________________
Esoteric drones and nonlinear distortion
Custom/handmade experimental instruments
macumbista.net
Back to top
View user's profile Send private message
andrewF



Joined: Dec 29, 2006
Posts: 1174
Location: australia
Audio files: 4

PostPosted: Mon Jul 16, 2012 6:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

Assuming no shorts, all chips are getting +/-V correctly and assuming it is not oscillating, check around the core. Don't bother swapping out chips or other parts until you have exhausted all other possibilities.

With the power off, use a multimeter to check every component is connected to the places it should be. Do this on the component side not the solder side. If you actually probe the legs of the components and the pins of the chips, rather than the solder or pads, you can be sure they are connected.

The VCO core is circled in red, check all these parts, don't worry about the waveshaping stuff for now.

Equally important what FET are you using? There is a great variety in FET pinouts and this is a common source of 'nothing happening' in VCOs


cgs vco core.jpg
 Description:
 Filesize:  45.57 KB
 Viewed:  2434 Time(s)

cgs vco core.jpg


Back to top
View user's profile Send private message Visit poster's website
macumbista



Joined: Sep 12, 2007
Posts: 360
Location: berlin
Audio files: 3

PostPosted: Tue Jul 17, 2012 4:57 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks, Andrew. The FET is 2N4391 in both boards. Orientation is the same, one works and one doesn't. So that's not the issue.

I'm wondering if the FET or the transistors are bad somehow. A student did the soldering so I don't know if they got overheated, or static damaged in the case of the 3140 as all the ICs are socketed. Is the FET also static sensitive?

I'm about at the stage where everything else has been checked. But good advice to check from component side. Will report back.

_________________
Esoteric drones and nonlinear distortion
Custom/handmade experimental instruments
macumbista.net
Back to top
View user's profile Send private message
macumbista



Joined: Sep 12, 2007
Posts: 360
Location: berlin
Audio files: 3

PostPosted: Wed Jul 18, 2012 3:42 am    Post subject: Reply with quote  Mark this post and the followings unread

At a certain point, it was easier just to touch each solder joint with the iron to make sure it was good. In the process I found a bad connection to the TL072 at the lowest right hand side of the PCB. All good now. Thanks for your thoughts!
_________________
Esoteric drones and nonlinear distortion
Custom/handmade experimental instruments
macumbista.net
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: Scott Stites
Page 2 of 2 [32 Posts]
View unread posts
View new posts in the last week
Goto page: Previous 1, 2
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
e-m mkii

Please support our site. If you click through and buy from
our affiliate partners, we earn a small commission.


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use