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 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
sound lab mini synth : AR generator & noise gen not working
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warpboy



Joined: Jun 09, 2010
Posts: 18
Location: paris

PostPosted: Tue Sep 11, 2012 7:06 am    Post subject: sound lab mini synth : AR generator & noise gen not working Reply with quote  Mark this post and the followings unread

hello,
i'm currently building my mini synth, and I have some problem with :

1. AR generator : for the first test, I don't use external gate.
In trigged mode with repeat OFF, I can read :
. S1 (push switch)=open, I read 4,3v on IC1 pin 1 and I see A square wave on IC1 pin2 !!!!!
.S1 closed= IC1 pin1=4,3v and IC1 pin2=9v dc (no square wave)

Normally when you push S1, IC1 pin 2 should go high and down when you release it, but It doesn't work.
I've looked at the wiring, I didn't find any mistake...... Question

2. noise generator : I have -1,23v on Q7 emitter, IC7 pin8=-7,51v and pin 14 of IC7=-7,51V (as Pin 8 of IC7) and no noise ....

I have triple checked panel wiring , IC positive and negative voltages ( no IC is hot) but the two regulators on the psu are hot and I don't know why....certainly there is something wrong in my work....but I don't know where/why

thank you for your help
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warpboy



Joined: Jun 09, 2010
Posts: 18
Location: paris

PostPosted: Tue Sep 11, 2012 9:22 am    Post subject: Reply with quote  Mark this post and the followings unread

Part II :

I've checked all ICs on the board,if I unplugged IC5 and IC6 the regulators (lm337/317) on the psu are really less hot...but IC5 and IC6 aren't hot when I put them in there sockets.
for info, I have taken the option to use CA3046 instead of a pair of 2N3904.

at this time oscillators don't work ( before they were working ....) but when I increased the level of one oscillators in the mixer, the level of the other decreased.....

H e l p
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warpboy



Joined: Jun 09, 2010
Posts: 18
Location: paris

PostPosted: Wed Sep 12, 2012 5:12 am    Post subject: Reply with quote  Mark this post and the followings unread

Part III : AR generator works in repeat mode only, but if repeat mode is off and second switch in gate mode I don't read 8/9v between pin 1 of C2 and ground but only 0,56v ???

I changed IC1 Q8, D8 (zener 9,1v)......

for the noise generator, I'll see later.
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warpboy



Joined: Jun 09, 2010
Posts: 18
Location: paris

PostPosted: Wed Sep 12, 2012 11:10 am    Post subject: Reply with quote  Mark this post and the followings unread

I reply to myself Cool :
I've cleaned as much as soldered points on the pcb and the two vcos are back....certainly there was a short between two points...or there is a cold solder that works not all the time....I've to look at all the cables maybe not correctly soldered.
the noise works better : I changed the value of a resistor (R100 : 4,7M) for a smaller one, and now I can hear the white noise !

I still have a problem with the AR generator that works only in repeat mode.

when I send directly the gate signal to pin 1 of IC1 it works... I don't understand why , I've changed Q8, the zener diode....
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warpboy



Joined: Jun 09, 2010
Posts: 18
Location: paris

PostPosted: Fri Oct 05, 2012 9:14 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello,
I'm working on the AR generator.
I can use the manual gate/trig only if the 2n3904 (QCool isn't soldered on the pcb (of course, that means I can't use an external gate in)

I've changed all the parts before the cd40106 pin1, I've tried 3 or 4 2n3904 (QCool and each time it's the same, if I put a new one the voltage between C2 pin1 and ground is too small : Ray Wilson says that normally the voltage at C2 should be around 8V, I have only approximatively 3v.!!!!

does all brands of 2n3904 have the same pinouts ?
Someone knows how Q8 works ?

thank you for your help...
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cds56



Joined: Jan 13, 2011
Posts: 18
Location: Canada

PostPosted: Sat Oct 20, 2012 10:29 am    Post subject: Reply Reply with quote  Mark this post and the followings unread

For your information, all brands of 2n3904 should have the same pinout, if they use the standard packet.

On my soundlab, I spent ages just thinking about how I was going to wire it so everything worked well.

make sure you read the pinouts properly and you're not soldering them backwards

maybe the caps are bad?

just follow the signal path, checking a lot.

I'm useless but my synth worked first try so good luck Smile
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