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 Forum index » DIY Hardware and Software » Klee sequencer
CV output B problem
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lexvortex



Joined: May 14, 2008
Posts: 155
Location: Toronto

PostPosted: Mon Sep 07, 2009 8:07 pm    Post subject:  CV output B problem
Subject description: doesn't respond to pot changes
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Hi,

I just finished my Klee and everything works great on it except out CV B only outputs a constant low voltage and does not respond to pot changes. I've checked the wiring and it's OK. I was able to calibrate and do all the tests without a problem. I'm not sure where to start looking for errors. Any help would be appreciated. What does work sounds awesome!!!!

Thanks,
Dave
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Scott Stites
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PostPosted: Mon Sep 07, 2009 9:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey Dave,

All righty, let's try a quick test to help zero in on where the problem might be coming from.

1. Remove the clock signal from the Klee so that it's not shifting the LEDs around.

2. Set only pattern bit 9 on by setting *only* pattern switch 9 on (set the rest of them off) and pressing the load button; after you've done this, make sure all other pattern LEDs are off and only LED 9 is on.

3. Now that only pattern bit 9's LED is lit, turn all of your glide pots to the lowest setting.

4. Set the range switch for a high range setting (2 volts or better will make this test easier).

5. Now, hook the A+B output up to a DMM or a VCO (so you can tell if it will put out any voltage).

6. Turn all the step pots down to zero.

9. Adjust the stage 9 pot up and down. Look to see if the A+B output is responding to the change in the pot setting.

This is what we are checking: The A+B output will output any voltage on the A shift register (stages 1 through 8 ) and any output on the B shift register (stages 9 through 16). Since the B stages feed this output, the A+B output should change just as much as the B output should when you move the stage 9 pot up and down.

If the A+B output does not change either, we'll know to look before the mixing section on the analog board. If the A+B output does change while the B output does not change, we will know the problem lies somewhere in the final mix circuit, which is also on the analog board.

Let me know what you find!

Take care,
Scott

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lexvortex



Joined: May 14, 2008
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Location: Toronto

PostPosted: Mon Sep 07, 2009 10:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Scott,

Thanks for the quick reply Very Happy Very Happy I just did what you suggested and the A+B output changes when I move pot 9 but out B does not. Actually when i unplug my VCO from A+B or out A, the pitch does not alter when the pot is fully CCW but as soon as I plug in output B the pitch goes down a bit...

Thanks for the help, I'm looking forward to resolving this issue and getting this fully functional!Q Very Happy Very Happy Very Happy

Edit: I tried changing U9 too, but that did nothing.
Edit 2: as I was playing around with it more extensively, i found that the optional CV B out works Very Happy but the glide output doesn't, so it must be a bad connection somewhere, I'll quadruple check the wiring harness's again from that area.

Dave
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Scott Stites
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PostPosted: Tue Sep 08, 2009 6:32 am    Post subject: Reply with quote  Mark this post and the followings unread

Hey Dave,

Good work!

Looks like the connection going from the analog board to output B's Glide pot may be the culprit, or somewhere thereabouts...

Cheerio,
Scott

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PostPosted: Tue Sep 08, 2009 7:13 am    Post subject: Reply with quote  Mark this post and the followings unread

Hey Dave,

I've gathered some info to help you out.

As you can see on the analog board schematic, the non-glide output B signal is tapped before the signal is sent to the glide pot. Down the line, the same signal passes through the glide circuit - the output at pin 8 of U9 is sent through R51 to the glide pot and is returned from the glide pot to pin 12 of U9.

The signal from R51 is sent from J12 pin 2 and returned on J12 pin 1.

I've marked pin 8 of U9 in red, and also R51 is outlined in red, as well as pin 2 of J12. These red points mark the areas you can measure output B before it goes to the glide pot. Pin 12 and J12 pin 1 are marked in blue - these are the points you should see the same voltage being returned from the glide B pot.

Hope this helps! Let me know what you find...

Take care,
Scott


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lexvortex



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PostPosted: Tue Sep 08, 2009 5:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Scott,

I decided to tear the Klee apart a bit to see if the signal was getting through to the actual PCB from the glide pot and it turned out that even though the signal was going fine from the the pot to the connector on the end it wasn't making it to the PCB Shocked Shocked so I looked into the header to see what was going on and it seems that the connector had been squashed and was not making a connection to the PCB Mad . I took it apart and fixed it and now it works great!!! Very Happy Very Happy Very Happy Very Happy Very Happy

I can't wait to get this thing into my next song!! Cool

Thanks again for all the help,
Dave
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PostPosted: Tue Sep 08, 2009 5:34 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hoo-ray! Break out the bubbly!

What sort of panel design did you use?

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lexvortex



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PostPosted: Tue Sep 08, 2009 5:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

I used Scott Deyo's from Bridechamber, it's a very nice looking panel Cool Cool . I am very happy with it Very Happy . I would post a pic of it but I don't have a camera right now.

The build documentation was exceptional and made what could have been a messy confusing build very simple, thanks for all the hard work you put into it Very Happy Very Happy

Cheers,
Dave
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State Machine
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PostPosted: Wed Sep 16, 2009 1:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Great work, nice thread guys ... Cool

Bill
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