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 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
MFOS 10-Step Sequencer Issues
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Chartreuse-J



Joined: Jan 21, 2014
Posts: 4
Location: Dixie

PostPosted: Tue Jan 21, 2014 5:40 pm    Post subject: MFOS 10-Step Sequencer Issues
Subject description: Sequencer and Wall Wart supply issues
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Greetings,

First post, I have to be abrupt with my first post (of many more) but here goes.....



First the Wall Wart Issue....

Got everything together, hooked up the (Jameco 120v AC 9w, Output 12Vac 500Ma to the populated PCB, No dice, found out I misoriented the small yellow caps (C10, C9, C5, C4 Respectively) No big deal just unsolder and reorient. Great, still no dice, check volt meter on wall wart leads, dead supply.

Ok so now time to try a different wall wart, this time it is one from an old Boston speaker system. Here are the specs (12vac 1500mA output) Ok great worked great for like 10 seconds and the led lit up on the 10-Step. But oh no, I see smoke coming from component CR1 (1N4004 General Purpose Rectifier) No good, disconnected and gave up on that for now. Is the Rectifier fried? Suggestions?

OK, now on to the MFOS 10- Sequencer Issues....

Scroll down for unabridged version

So now I've decided to test the Sequencer. I now have 2 banks of 8 double AA batteries for a total hooked together to produce a +12v and -12v and ground to the 10 step PCB. Hooked everything up, all the leds light and only one problem nothing cycles, I can step through the leds with the step button and I get CV voltage and Gate voltage and the thing resets, but it will not cycle through the gates or adjust said Gates when I move each pot for each channel. The switch for the Gates work, but it just does not cycle. Not sure what to do.


Here is a synopsys of the problems...

THIS IS PROPERLY FUNCTIONING

Gate- Yes - Gets Voltage
L0-L9 - Yes - Leds Light up through Step button press
CV1,CV2,CV3 - Yes I am getting voltage here
PB1,PB2 - Yes both Reset and Step buttons work
LCOM - I assume this works
GCOM - I assume the Gate works due to the switches working gates off/on


THIS IS NOT FUNCTIONING PROPERLY

PB2 - No Start or Stop function
RNG - CV/HI/LOW switch does not work
GL2 -GL1 - The Portamento pot does not work
X0-X9 - 12 Pot Switch does nothing ( Pretty sure this is wired correctly)
CR2,CR3,CR1 - The Clock Rate pot does nothing
V0-V9 - These wires to the the Gate pots are not functioning

So you can see I have quite a mess here and no clue as to what is wrong, my first thought was it might be the CD4016BE (CMOS Hex Schmitt Trigger) chip in U4, but I regress.


I have an Arduino, if anyone knows of programs that would possibly test these CMOS chips or whatever someone might recommend. Question
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elmegil



Joined: Mar 20, 2012
Posts: 1341
Location: Chicago
Audio files: 14

PostPosted: Tue Jan 21, 2014 9:08 pm    Post subject: Re: MFOS 10-Step Sequencer Issues
Subject description: Sequencer and Wall Wart supply issues
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Chartreuse-J wrote:
First the Wall Wart Issue....

Got everything together, hooked up the (Jameco 120v AC 9w, Output 12Vac 500Ma to the populated PCB, No dice, found out I misoriented the small yellow caps (C10, C9, C5, C4 Respectively) No big deal just unsolder and reorient. Great, still no dice, check volt meter on wall wart leads, dead supply.

Ok so now time to try a different wall wart, this time it is one from an old Boston speaker system. Here are the specs (12vac 1500mA output) Ok great worked great for like 10 seconds and the led lit up on the 10-Step. But oh no, I see smoke coming from component CR1 (1N4004 General Purpose Rectifier) No good, disconnected and gave up on that for now. Is the Rectifier fried? Suggestions?


Uh yeah, magic smoke means dead components Smile Triple check whether you have any shorts on the PCB before you hook it up again. And replace the diode, and check again that all the diodes are oriented correctly.

If you used Tantalum caps and had them reversed, you need to just replace them, now. They do not necessarily fail immediately upon being reversed, but even after it's been corrected, they will still likely blow at some point in the future, and you DON'T want that. A guy I know has an amusing story about the purple burns on one of the EE Lab benches that involves re-using tantys that had been reversed. Amusing in that the only thing damaged was the bench, thankfully.

Personally, I would just use 1uF electrolytic caps.


Chartreuse-J wrote:

OK, now on to the MFOS 10- Sequencer Issues....

Scroll down for unabridged version

So now I've decided to test the Sequencer. I now have 2 banks of 8 double AA batteries for a total hooked together to produce a +12v and -12v and ground to the 10 step PCB. Hooked everything up, all the leds light and only one problem nothing cycles, I can step through the leds with the step button and I get CV voltage and Gate voltage and the thing resets, but it will not cycle through the gates or adjust said Gates when I move each pot for each channel. The switch for the Gates work, but it just does not cycle. Not sure what to do.


The internal clock isn't working Very Happy (I have a gift for the obvious).

You need to check what's going on with the clock oscillator, U3 and associated bits.

Are you seeing anything at U3 pin 7? pin 1? Check for shorts, check the TL072 to be sure its OK, check the FET that resets the timing cap to be sure its OK....



Chartreuse-J wrote:

I have an Arduino, if anyone knows of programs that would possibly test these CMOS chips or whatever someone might recommend. Question


You're over thinking it Smile You need to 1) use a meter and 2) use a scope. If you go around robin hood's barn, there are ways to hook an arduino up to a computer and kinda sort use it as a scope, but I wouldn't recommend that.
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Chartreuse-J



Joined: Jan 21, 2014
Posts: 4
Location: Dixie

PostPosted: Wed Jan 22, 2014 6:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the reply....


Ok checked U3 Pin outs.

I do not have an Oscilloscope, just a volt meter, so bear with me. Embarassed

Anyway Pin 7 on U3 reads 9 volts and Pin 1 reads 9 volts for both TL072 Dual Op Amps. So these are getting power.

The 2N5457 JFET is getting power as follows...

D-Leg 7.85 Volts
S-Leg 9.83 Volts
G-Leg .24 Volts

These voltages are steady on the JFET.
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elmegil



Joined: Mar 20, 2012
Posts: 1341
Location: Chicago
Audio files: 14

PostPosted: Wed Jan 22, 2014 7:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

Have you checked AC readings? 1) you should have some kind of AC voltage if you're getting clock pulses and 2) you should be able to measure duty cycle or Hz as well.
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Chartreuse-J



Joined: Jan 21, 2014
Posts: 4
Location: Dixie

PostPosted: Wed Jan 22, 2014 7:37 pm    Post subject: Reply with quote  Mark this post and the followings unread

Alright pictures speak a thousand words I hope this will help....

Will post AC results ASAP..


But here are some pictures I hope will help trouble shoot this.

I also have a parts requisition list from Jameco and Mouser.


IMG_0241.JPG
 Description:
This is what I am working with as far as tools go.....
 Filesize:  1.44 MB
 Viewed:  19 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG_0241.JPG



IMG_0243.JPG
 Description:
Wall Wart Dead at the moment..
 Filesize:  1.35 MB
 Viewed:  20 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG_0243.JPG



IMG_0244.JPG
 Description:
What I'm using to power it currently
 Filesize:  1.57 MB
 Viewed:  17 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG_0244.JPG



IMG_0245.JPG
 Description:
The board in question
 Filesize:  1.94 MB
 Viewed:  21 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG_0245.JPG



IMG_0246.JPG
 Description:
Another of the board
 Filesize:  1.98 MB
 Viewed:  19 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG_0246.JPG


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Chartreuse-J



Joined: Jan 21, 2014
Posts: 4
Location: Dixie

PostPosted: Wed Jan 22, 2014 7:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

The start stop feature to cycle through the gates is now intermittently working. Sometimes the unit just stays on the 1st gate and will not move to another gate, I think there might be a loose wire as I used solid core wire instead of stranded. Oh well..


Will post those AC results soon, as I might put this off until tomorrow.
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elmegil



Joined: Mar 20, 2012
Posts: 1341
Location: Chicago
Audio files: 14

PostPosted: Wed Jan 22, 2014 8:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yeah, that sounds like grounding issues....
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