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 
Live streaming at radio.electro-music.com

  host / artist show at your time
  EdisonRex Edison's Electronic Review
  Twyndyllyngs Special Monday edition of Chez Mosc
Please visit the chat
 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
Smoke testing the CGS VCO
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 1 [13 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Wed Sep 07, 2011 7:14 am    Post subject: Smoke testing the CGS VCO
Subject description: A narrow escape....
Reply with quote  Mark this post and the followings unread

Well, a few weeks ago I did something monumentally stupid.

I was doing a little bench work, and wanted to have my CGS VCO laying flat on the bench to do a little probing around. My power cable wouldn't reach, so I elected to use some jumper clips.

I looked at the board's power connector, and saw the little silk screen by the power connector that says +15V, and assumed that that was the 15V pin. Well, its not. It's the -15V pin. Oops!

There was no smoke or anything, but the power supply was clearly not happy (I have little leds for each power rail, and one of them went out). So I swapped leads, and found the VCO dead.

The chips on that board weren't socketed (stupid Mongo!) and after looking at the vast tangle of wires leading to the board, I decided that there were several things I needed to do that didn't involve that VCO.

And so it's been sitting on a shelf for weeks.

Last night I decided to gather my courage and fix it. I plugged it back in, and found that it actually did kinda sorta work a little bit. There was one narrow range on the coarse tuning knob that resulted in oscillation. It wasn't the kind of oscillation you'd normally like to hear - sort of the sound a baby calf makes when its looking for it's momma. But at least it was something.

After a little poking around with the scope, I determined that a good bit of the board was actually working pretty well, and nothing really obvious jumped out. So I did the hard part - I started clipping chips out and replacing them. The cheapest were the TL072s, so I did those first - no cigar.

The only chips left that could be responsible were the CA3140, the LM311 and of course the supermatched transistors. Of those, the only chip I had in stock was the 3140 (actually mouser sold me an NTE replacement for those) so I tried it. And you'd never guess - it worked like a charm.

So the little sick calf is now a mighty bull once again.

I guess the points of this post are

1) Never be lazy or impatient - wait for the sockets
2) Don't assume anything.
3) Ken Stone designs some pretty solid stuff - thanks Ken!

Gary

Last edited by Mongo1 on Wed Sep 07, 2011 9:51 am; edited 1 time in total
Back to top
View user's profile Send private message Send e-mail
andrewF



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

PostPosted: Wed Sep 07, 2011 9:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Well, i'm pretty curious, where does the 3080 go? Shocked
My CGS VCOs don't have any 3080s....do you mean the 3140?
Back to top
View user's profile Send private message Visit poster's website
Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Wed Sep 07, 2011 9:45 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
My CGS VCOs don't have any 3080s....do you mean the 3140?


D'oh!

Yep - I was just reading another thread about 3080s, and had a senior moment.

What the heck, I was only 60 off....

Thanks for catching that....

Gary
Back to top
View user's profile Send private message Send e-mail
djg



Joined: Nov 10, 2010
Posts: 12
Location: New York

PostPosted: Thu Sep 08, 2011 8:58 am    Post subject: Reply with quote  Mark this post and the followings unread

Yeah, the only time I've pulled a reversal was on my first CGS VCO a few weeks after I built it doing some calibration with the bench supply. Smoke and all. I remember a few of the outputs still working. I had spares of all ICs except the LM311 and LM3900, which I was able to get at my local electronics store for cheap. I replaced all the electrolytics just to be safe too. Gave me hope for any future disasters.
Back to top
View user's profile Send private message
djg



Joined: Nov 10, 2010
Posts: 12
Location: New York

PostPosted: Sat Sep 10, 2011 10:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

Well this is ironic. Did the same goddamn thing on a different CGS vco just now after a long day of general maintenance. Long story short-- too many beers, too late at night, and that same +15v pad that must've thrown me below the normal header's -V. Oh well, live and learn (and forget and relearn).
Back to top
View user's profile Send private message
Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Sun Sep 11, 2011 6:26 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
Well this is ironic. Did the same goddamn thing on a different CGS vco just now after a long day of general maintenance. Long story short-- too many beers, too late at night, and that same +15v pad that must've thrown me below the normal header's -V. Oh well, live and learn (and forget and relearn).


Well, thanks for making me feel better! Maybe we oughta ask Ken to change that damned silkscreen! Laughing

Gary
Back to top
View user's profile Send private message Send e-mail
macumbista



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

PostPosted: Tue Jul 17, 2012 10:58 am    Post subject: Reply with quote  Mark this post and the followings unread

I *almost* did this yesterday. I didn't have any ferrite beads when I was building, so I used 10 Ohm resistors. The benefit was, when I plugged the power backwards, the resistors burned and not the ICs!!! I've never noticed any noise difference with or without ferrite beads, but I did just discover a good reason to use a resistor instead of a link. A small tip, I suppose...
_________________
Esoteric drones and nonlinear distortion
Custom/handmade experimental instruments
macumbista.net
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1476
Location: Chicago
Audio files: 14

PostPosted: Tue Jul 17, 2012 11:37 am    Post subject: Reply with quote  Mark this post and the followings unread

I reversed a TL071 on a breadboard a couple weeks ago and got shrapnel Smile

Luckily nothing was damaged other than the chip.


pop-amp.jpg
 Description:
 Filesize:  41.02 KB
 Viewed:  3223 Time(s)

pop-amp.jpg


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



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

PostPosted: Tue Jul 17, 2012 11:47 am    Post subject: Reply with quote  Mark this post and the followings unread

Well, this happened in my professionally designed Doepfer without me having to do anything except plug a minijack cable in halfway:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Give me bananas every time!

_________________
Esoteric drones and nonlinear distortion
Custom/handmade experimental instruments
macumbista.net
Back to top
View user's profile Send private message
Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Tue Jul 17, 2012 9:01 pm    Post subject: Reply with quote  Mark this post and the followings unread

Holy merd!

That's pretty amazing. Did you let doepfer know about that? I can't imagine any engineer worth a damn not wanting to fix that problem.

What kind of chip was that when it was still, you know, NOT glass?

Gary
Back to top
View user's profile Send private message Send e-mail
elmegil



Joined: Mar 20, 2012
Posts: 1476
Location: Chicago
Audio files: 14

PostPosted: Tue Jul 17, 2012 9:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Looks like an LM324....
Back to top
View user's profile Send private message
JingleJoe



Joined: Nov 10, 2011
Posts: 878
Location: Lancashire, England
Audio files: 14

PostPosted: Wed Jul 18, 2012 1:59 pm    Post subject: Reply with quote  Mark this post and the followings unread

I burnt out an LM324 recently aswell, but nothing that spectacular happened, it just got very very hot and gave me another burn to go along with all the other soldering iron burns Laughing

I keep a stock of 16pin DIL sockets which I cut down to size when needed for 8 or 14 pin applications. A bit ramshackle but it saved me a lot buying in bulk Wink

_________________
As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"


Green Dungeon Alchemist Laboratories
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 2:06 pm    Post subject: Reply with quote  Mark this post and the followings unread

macumbista wrote:
I *almost* did this yesterday. I didn't have any ferrite beads when I was building, so I used 10 Ohm resistors. The benefit was, when I plugged the power backwards, the resistors burned and not the ICs!!! I've never noticed any noise difference with or without ferrite beads, but I did just discover a good reason to use a resistor instead of a link. A small tip, I suppose...


Veering back on topic... I just discovered the downside to using 10 Ohm resistors instead of links or ferrites. CV applied to the VC Shape affects the Square and Saw outputs as well. Ken helped me work that one out, going back to ferrites now.

_________________
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 1 of 1 [13 Posts]
View unread posts
View new posts in the last week
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