TM3030 sequential note tuning shift by semitone

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ark1971
Learning to Wiggle
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Joined: Sat Feb 04, 2012 12:28 pm

TM3030 sequential note tuning shift by semitone

Post by ark1971 » Tue Jun 19, 2012 10:45 am

Hi all,
I'm currently testing my TM3030. I have a strange problem. If I have a sequence of notes at the same pitch, every second note is a semitone higher out of tune. The voltage output from the DAC appears fine while I did notice a shifting DC level at the output of the op-amp U7. Has anyone come across this problem before?
thanks,
joe

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Synthbuilder
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Post by Synthbuilder » Fri Jun 22, 2012 9:32 am

Not heard about this one before. But I wonder whether it's related to the other problem that you were having.

Having a shifting output at pin 7, U7 would suggest a problem with the way the glide circuit is working. Does the problem go away if the notes are played with a gap in between them?

Tony

ark1971
Learning to Wiggle
Posts: 6
Joined: Sat Feb 04, 2012 12:28 pm

Post by ark1971 » Fri Jun 22, 2012 12:16 pm

Tony,
Thanks for the reply. Just a few minutes ago I replaced the 4066 to be a MCI4066BCPG and made sure that the 4050 ICs were from the same manufacturer. This has fixed it.,
joe

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