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 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
Everything Works Except Oscillator 1
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ianbargle



Joined: Sep 20, 2006
Posts: 8
Location: california

PostPosted: Thu Sep 21, 2006 1:46 pm    Post subject: Everything Works Except Oscillator 1
Subject description: Debugging Question for Oscillator 1 on the Sound Lab
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Hello everyone. I'm new to this forum, but it looks like you all give good advice so I thought I'd ask for some help. I finished my sound lab and everything works fine except for Oscillator 1. I'm getting no sound out of oscillator 1 at all. I did a continuity check with my multimeter and all the connections listed in the schematic are connected. The LF444 (IC5) is getting the proper power (it didn't melt on power up) and is outputting the following (dc) voltages:
pin1: 7.88
pin7: 0.10
pin8: 7.90
pin14:-5.47

All the capacitors and resistors are the correct value. This thing should be oscillating! (maybe it is...I don't have an o-scope to check it with) Could it be the JFET? Or maybe it's one of the 2N3904s? If anyone has any ideas I would really appreciate the help (or maybe I should leave well enough alone). Great forum! Thanks.
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Pehr



Joined: Aug 14, 2005
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PostPosted: Fri Sep 22, 2006 2:16 am    Post subject: Reply with quote  Mark this post and the followings unread

Check the pcb for cut traces? Confused I had that problem once with OSC2 pulse...
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Uncle Krunkus
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PostPosted: Fri Sep 22, 2006 4:10 am    Post subject: Reply with quote  Mark this post and the followings unread

Is it getting to the mixer pot?
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ianbargle



Joined: Sep 20, 2006
Posts: 8
Location: california

PostPosted: Fri Sep 22, 2006 1:50 pm    Post subject: Is it getting to the pot? Reply with quote  Mark this post and the followings unread

Hey Uncle Krunkus and Pehr. Thanks for taking the time to respond to my post. To answer your question, the signal is getting to the pot because the -5.47 volts from pin 14 (of IC5) makes it to R30 (which goes into the filter input--pin 3 of IC4) when the OSC1 volume on the mixer is turned all the way up. I'm beginning to suspect the JFET is bad (I had a similar JFET problem with one of the oscillators on my Theremin). I'll try replacing it and I'll let you guys know. In the meantime, if any more ideas come to mind, please let me know. I really appreciate it guys. Thanks!
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ianbargle



Joined: Sep 20, 2006
Posts: 8
Location: california

PostPosted: Sun Sep 24, 2006 6:04 pm    Post subject: Alright...I got it working Reply with quote  Mark this post and the followings unread

Hey guys. First, let me thank everyone who replied once again. I am pleased to announce that EVERYTHING now works on my Sound Lab. I got oscillator 1 to work by building it on a breadboard. From there I realized that the 2N3904s were not biased correctly on my PCB. The reason for this is I did a sloppy job etching my PCB (that's right...I decided to go it alone). I fixed the short circuit by removing the copper traces (they broke off after de-soldering) and by bridging the correct connections with hookup wire. I hope this post may help people in the future. Thanks again!
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Blue Hell
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Joined: Apr 03, 2004
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PostPosted: Sun Sep 24, 2006 6:20 pm    Post subject: Re: Alright...I got it working Reply with quote  Mark this post and the followings unread

ianbargle wrote:
The reason for this is I did a sloppy job etching my PCB (that's right...I decided to go it alone).


Does happen even with professionally made PCB\s, just bad luck, and when it's a one only product such a fault just has to be found and fixed, even when you're in it for the money, can be a real headache thing to solve, good you did !

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Uncle Krunkus
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PostPosted: Sun Sep 24, 2006 9:42 pm    Post subject: Reply with quote  Mark this post and the followings unread

Etched your own PCB,
filled it with components,
wired it to the controllers,
and de-bugged it!
Now that's gotta feel satisfying! Very Happy

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ianbargle



Joined: Sep 20, 2006
Posts: 8
Location: california

PostPosted: Sun Sep 24, 2006 10:13 pm    Post subject: Must feel great... Reply with quote  Mark this post and the followings unread

Oh yes Uncle Krunkus...it feels grand! I'll post some pics (and maybe some mp3s) soon.
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Joel



Joined: Sep 12, 2006
Posts: 97
Location: London, UK

PostPosted: Mon Sep 25, 2006 2:47 am    Post subject: Reply with quote  Mark this post and the followings unread

congrats Ian, you must be grinning from ear to ear Laughing
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