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 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
CGS114 DUSG Debugging
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mouldi101



Joined: Oct 29, 2009
Posts: 8
Location: Norwich

PostPosted: Mon Feb 25, 2013 8:16 am    Post subject: CGS114 DUSG Debugging Reply with quote  Mark this post and the followings unread

Hi!

I've so far had quite a lot of success with my CGS boards: My two VCOs worked at once, my VCAs have worked, and my ring mod has too...

...sadly my CG114 Dual Slopes hasn't been quite so successful, and this is my first real dubugging of anything like here, and I'm not sure where to start.

Both sides output the original signal when there is one fed to the input.

Neither cycles when the trigger in and out are linked (according to the CGS site, it should)

The rise pot does what it should on one side, not on the other. Neither of the fall pots are working

The LEDs work on both channels!

Any ideas on where to start? I populated the board a long time ago, but I definitely checked the transistor pin-outs with a multimeter before I soldered them in. It's my first time debugging a board, and I'm not really too sure where to start!

Thanks in advance,

Andrew
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johncronan



Joined: Feb 24, 2013
Posts: 42
Location: Chicago

PostPosted: Fri Mar 15, 2013 5:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

The asymmetry of the symptoms between the rise and fall controls suggests to me that you should check the quad-transistor core for bad transistors (I'll believe you that they're oriented correctly!). Or perhaps the collectors of those two that are supposed to be grounded ended up floating somehow? Also double check the 1.5k resistor coming off those two bases. Looking for differences in the base-emitter drop of these 4 transistors could also be helpful. They're operating in the active region, so that voltage difference should be less than about 0.6 volts, but should vary with the pot settings. -John
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tony d



Joined: Aug 31, 2009
Posts: 15
Location: boulder, colorado

PostPosted: Mon Apr 08, 2013 9:09 pm    Post subject: Reply with quote  Mark this post and the followings unread

I found that when i used the 2n5089 with the 2n3906 i had similar problems so i switched the 2n5089's out for 2n3904 and they work good now.
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