electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Articles  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links  |  Store
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
Live streaming at radio.electro-music.com

  host / artist show at your time
  Rob Adventures in Sound
Please visit the chat
 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
MFOS 10 Step Sequencer not sequencing
Post new topic   Reply to topic Moderators: dnny, Uncle Krunkus, v-un-v
Page 2 of 3 [69 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Goto page: Previous 1, 2, 3 Next
Author Message
elmegil



Joined: Mar 20, 2012
Posts: 1449
Location: Chicago
Audio files: 14

PostPosted: Fri Jun 20, 2014 3:52 pm    Post subject: Reply with quote  Mark this post and the followings unread

I can't say for sure since I don't know the voltage divisions, but going through a diode should cause a voltage drop, so I don't know if the last two are a problem or not. What is the voltage? A normal 4148 drop is about .65V.

If the drop is much higher, is it feasible to disconnect the cathode of D19 and see if you get the same waveform? Or possibly unsocket (assuming you've socketed) the 4017? Verify your diodes are pointing in the right direction while we're at it, just to be sure Smile.

You should verify that the junction of D19, D18 & R39 isn't being dragged to ground for some reason too.
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Sat Jun 21, 2014 12:06 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi I am still confused Confused , surely it should be sequencing automatically. The scope images support this, U3b is outputting a signal confirming that the clock is working. I don't get why the signal is weaker at the cathode of D18.
I had the clock rate set at 9 when I took the above scope images.

Should have used the scope earlier though.
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Sat Jun 21, 2014 12:21 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for explaining voltage drop, I have used IN914 diodes as specified in the schematics and they are all orientated correctly. Yes I have used IC sockets, thankfully. I will consider and investigate your advice further Thanks for reply. Smile
To recap the step, reset and start/stop functions are all working, as well as the stop reset and 10 step switch. Its just a lack of automatic sequencing.
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1449
Location: Chicago
Audio files: 14

PostPosted: Sat Jun 21, 2014 7:29 am    Post subject: Reply with quote  Mark this post and the followings unread

Is it possible that the pulses are too narrow to trigger the 4017?

I'd also maybe try running a wire directly from the output of the VCO to the 4017 clock in and see if that causes sequencing.

I agree, this ought to be going at this point unless the pulses are too narrow (unlikely) or too low a voltage.
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Sun Jun 22, 2014 5:11 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi I have checked out some of your suggestions.
I Have ran a wire direct from U3a pin 1 to 4017 Pin 14 and automatic sequencing works!! at any clock rate setting. Very Happy
D18 anode side shows 30 to 40 millivolts, fluctuating, at the cathode side I can't seem to get a consistent reading - possibly 5mv. When placing the probe tip on the cathode side it sometimes either steps the gates or partially sequences them, I guess this is the small amount of power coming from the multimeter. For some reason there doesn't seem to be enough power to trigger the clock on the 4017.
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Sun Jun 22, 2014 5:30 am    Post subject: Reply with quote  Mark this post and the followings unread

I have Just put the probes either side of C2 10pf to measure it, I know this is a questionable practice when a cap is in circuit. I got automatic sequencing. Again power from the meter?
C2 the ceramic disc cap I have in the board is marked simply 10, no other markings. I am wondering if I have the right cap in use ? am googling it for more info, remembering that I am in the UK.
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Sun Jun 22, 2014 6:27 am    Post subject: Reply with quote  Mark this post and the followings unread

Have placed uninsulated tweezers, on each of R23, C2, R29 and pin 5 U3b, ends where these all meet on circuit. (guessing I am acting as ground) on each of the four locations I have automatic sequencing.
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1449
Location: Chicago
Audio files: 14

PostPosted: Sun Jun 22, 2014 8:18 am    Post subject: Reply with quote  Mark this post and the followings unread

Cato wrote:
I have Just put the probes either side of C2 10pf to measure it, I know this is a questionable practice when a cap is in circuit. I got automatic sequencing. Again power from the meter?
C2 the ceramic disc cap I have in the board is marked simply 10, no other markings. I am wondering if I have the right cap in use ? am googling it for more info, remembering that I am in the UK.


"just 10" is a 10pf cap, so that's right. That should only be there for stability of that op amp stage.

Cato wrote:
D18 anode side shows 30 to 40 millivolts, fluctuating, at the cathode side I can't seem to get a consistent reading - possibly 5mv.


I'm assuming the 30/40mv is the peak of the pulse that you're seeing, correct?

If I'm correct about that, then whatever the cause, this is your problem. 30mV is not NEARLY enough to get through the forward voltage of the diode, so your VCO output is not making it through.

What is confusing though is that the same problem ought to be affecting the diode that routes the reset pulse that resets the VCO -- so you shouldn't even be getting oscillation!.

I would 1) verify continuity from U3 pin 7 to the anodes of D16 and D18, 2) measure the pulse at the anode and cathode of D16, 3) look for shorts or cold solders anywhere around D18 or the traces that run to it from U3, or from the cathode of D18 to the other components on the clock side.

Also measure the pulse at the output of U3 pin 7 and compare to the anode of D18 -- this should be IDENTICAL, but from what you're saying, it's enough with a direct wire to drive the clock, so it sounds to me like it is NOT identical. If that is indeed the case, then the p roblem is why is it not identical, which goes back to what I was suggesting about cold solders etc.

Cato wrote:
Have placed uninsulated tweezers, on each of R23, C2, R29 and pin 5 U3b, ends where these all meet on circuit. (guessing I am acting as ground) on each of the four locations I have automatic sequencing.


This completely baffles me Smile

So basically when you touch those areas, suddenly the pulses are getting through? Is the ground side of R39 showing good continuity to ground? Maybe a cold solder there...??

Last edited by elmegil on Sun Jun 22, 2014 8:25 am; edited 1 time in total
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1449
Location: Chicago
Audio files: 14

PostPosted: Sun Jun 22, 2014 8:23 am    Post subject: Reply with quote  Mark this post and the followings unread

One other idea: what's the voltage output peak at U3 pin 1? Have you checked the values for R23 & R29? R28 & R32? Diode orientation of D14? Voltage at pin 6 of U3 should be 8V, this is the comparator threshold. Is the peak at U3 going up to near 12V?
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Sun Jun 22, 2014 2:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

Reply to your last posts,

Peak voltage at U31 is 6v.
R23, R29, R28 and R32 are all correct.
Pin 6 U3 reads 8.14 volts.
Peak at U3, is this pin 7 ? It is -12 volts.
D14 is the correct way round.
The pulse on U3 Pin 7 to cathode D16 is stronger than the pulse at anode of D18.

Have rechecked voltage on D18 anode, its now 65mv. The cathode is 2.5mv.
As i am a 'noob' not sure if I have done above measurements quite right. measured the anode with the meters common (bipolar power side) connected to -12v. The cathode (as the 4017 is not bipolar) common to ground. Embarassed

U3 pin 7 has good continuity to D16 and D18.
So far I have checked, replaced and resoldered R39, D17, D18 and D19.

Continuing to check solder joints.
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1449
Location: Chicago
Audio files: 14

PostPosted: Sun Jun 22, 2014 2:52 pm    Post subject: Reply with quote  Mark this post and the followings unread

meter common should always go to ground, not -12V.

Please try that and let me know.
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Mon Jun 23, 2014 2:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

Have remeasured D18 voltage correctly,didn't think my logic was right... I have made no more changes to pcb since last post. The last component I swapped was D17.

So Voltage on D18 anode (with common to ground!) is -12 volts and is the same on U3 pin 7. Reading schemo notes I see this is what it should be doing but is stuck because U3b's output is supposed to shoot from -12v to +12v. Which it isn't doing. Yet.

Am I going in the right direction?
D16 could be at fault as it is the link from pin 7 to U5 pin 2 and the data pin , having already swapped out D17. Will check next.
D16 also goes to Q11 via R35.
Measured Q11 the Gate is -2.43 v and started auto sequencing due to probe tip, (isn't the gate supposed to be showing -12v meaning Q11 is off).
The source reads 5.14v and the Drain measures 0v. Rolling Eyes

Will carry on checking solder joints though
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1449
Location: Chicago
Audio files: 14

PostPosted: Mon Jun 23, 2014 3:28 pm    Post subject: Reply with quote  Mark this post and the followings unread

How are you measuring? A meter will not see the very short pulse. Look at it in the scope and find the peak.
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Mon Jun 23, 2014 11:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

Using scope the gate Q11 is showing short strong pulse, D18 cathode is showing same pulse but weaker or not as bright.

The source of Q11 shows the same waveform as U3 pin 1. D18 anode shows the same pulse as U3 pin7. The clock in of U1, pin 14, shows no pulse or voltage.
Back to top
View user's profile Send private message
prgdeltablues



Joined: Sep 25, 2006
Posts: 171
Location: UK
Audio files: 10

PostPosted: Tue Jun 24, 2014 4:41 am    Post subject: Reply with quote  Mark this post and the followings unread

If I've followed this correctly, your clock (U3 etc) is working to the extent that you are getting a sequence of short pulses (spikes) out of U3B pin 7. The 4017 is clearly working too, if you can manually step it.

It is not clear from your scope image what positive voltage these pulses are reaching - it needs to be close to +12V to trigger the 4017. Could you measure the peaks of those pulses on the scope?

Have you tried wiring U3B pin 7 directly to the 4017 Pin 14 - that should clock the sequencer.

If it does, and if you've got close to 12V on the pulses, then the problem sounds as if it is around D18, R39, and the trace to 4017 Pin 14. The strange thing there is that the manual step goes through the same part of the circuit, and you report that works fine. But it may be something is just on the edge - the manual step provides a fairly long +12V pulse.

Something else that might be worth trying is increasing the value of C5 - it is possible the U3B Pin 7 pulse is not long enough to clock the 4017 (though unlikely).

Peter
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1449
Location: Chicago
Audio files: 14

PostPosted: Tue Jun 24, 2014 4:47 am    Post subject: Reply with quote  Mark this post and the followings unread

What about the anode of D16? That should be the same as the anode of D18.

If cathode of D18 is showing the same as U3 pin 7, then the problem is either D18 or something unique to the other side of D18. My guess would be a cold solder there, have you hit those joints with your iron?

Have you checked the PCB to see if perhaps there is a trace problem between D18's anode and the other things that seem to properly trigger the clock?
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Tue Jun 24, 2014 1:19 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for replies Smile Have checked some things as follows.

D16 and D18 anodes are identical, used scope.

Pin 7 U3 direct to pin 14 of 4017 does not auto sequence, however pin 1 U3 direct to pin 14 of 4017 does auto sequence.

Can see no damage to tracks on pcb.

I direct wired D18/D19 cathodes and R39, no auto sequencing plus I have already swapped out and re-soldered these parts.

I will carry on checking and work on your ideas thanks
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Tue Jun 24, 2014 2:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

btw I have still got -12v on pin 7 U3 not + 12 volts.

So its stuck stuck, but I need +12v to trigger pin 14 of 4017 into sequencing. Right? The question is why I am not getting +12v. Right?

Ray Wilson quote "the clock only generates pulses when the sequencer is in the 'running' state. U5a pin1 Q output high."
U5 pin 1 is +12v, high? Pin 2 is 0v. Does this confirm U5 is ok as the clock is working? That I can ignore U5 area and D17 which leads to Q11 which is part of U3. Trying to understand how the whole thing works.
Back to top
View user's profile Send private message
prgdeltablues



Joined: Sep 25, 2006
Posts: 171
Location: UK
Audio files: 10

PostPosted: Wed Jun 25, 2014 5:34 am    Post subject: Reply with quote  Mark this post and the followings unread

Starting to sound to me like the problem is around U3b. You will need to use a scope - the pulse output from pin 7 - going from -12 to +12V is too short to show up on a meter. You don't necessarily need 12V to clock the 4017, but they do need a decent voltage relative to the power supply, so if or some reason you were only getting say less than 4V out of U3b, it wouldn't trigger.

Your earlier scope shots suggest there is a pulse coming out of U3b, but without knowing the scale it's difficult to say more. IF the images of scope shots of U3b and D18 cathode are to the same scale, then it looks as if you might only be getting 1v or so, which after the diode drop won't be nearly enough to trigger the 4017. It will though be enough to pull the gate of Q11 up, allowing the clock oscillator to work, which is what you report.

I'd suggest checking component values around U3b, and scope shots of the voltages on pins 5, 6 and 7.

Peter
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Fri Jun 27, 2014 1:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

I'm working on it
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Sun Jun 29, 2014 6:45 am    Post subject: Reply with quote  Mark this post and the followings unread

I have some scope images, still new to using the scope!
I have set the horizontal to centre line by using scopes ground setting then I switched to scopes DC setting. The volts/Div was set at 0.5. The probe was set at 1x10. My bench power supply is set at 12v drawing 0.004 amps when I press start on sequencer, the clock rate was set to 10. I then took the images.


V-DIV.jpg
 Description:
 Filesize:  1.83 MB
 Viewed:  4 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

V-DIV.jpg



U3A pin 1.jpg
 Description:
 Filesize:  2.64 MB
 Viewed:  5 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

U3A pin 1.jpg



U3B pin 7.jpg
 Description:
 Filesize:  2.64 MB
 Viewed:  4 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

U3B pin 7.jpg



U4F pin 12.jpg
 Description:
 Filesize:  2.73 MB
 Viewed:  5 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

U4F pin 12.jpg



U5AQ pin 1.jpg
 Description:
 Filesize:  2.78 MB
 Viewed:  4 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

U5AQ pin 1.jpg


Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1449
Location: Chicago
Audio files: 14

PostPosted: Sun Jun 29, 2014 8:31 am    Post subject: Reply with quote  Mark this post and the followings unread

The probe will have a 1x or a 10x setting. I'm not sure which you used, but I'm guessing 10x? 1x10 doesn't really clarify that Smile

If you're using 10x then your volts/div are multiplied by 10, so .5V x 10 = 5V, and those spikes coming out of U3B are strange in that they don't appear to be going -12V to +12V per Ray's description, more like -5 to 2.5. It's also strange that the integrator is only going 0 to +5V.


if I didn't know any better I'd say this looks like you are using a 5V supply not a 12V supply. Are you sure you have 12V / -12V at the power pins of U3?
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Sun Jun 29, 2014 10:13 am    Post subject: Reply with quote  Mark this post and the followings unread

Scope is 10x setting.
Measured, using scope, pin 4 0f U3 showing -5.5v and pin 8 +6.5v.
However using meter I got -12v on pin 4 and +12v on pin 8.

Used meter to check output of bench supply and confirmed +/-12v.
used meter on power supply inputs on pcb and confirmed same result.
Used meter on all power pins for all ic's again got correct readings for all.

Using scope for the above I get -5.5v/+6.5v readings??? Confused I was expecting the same results as the meter.


scopeset.jpg
 Description:
 Filesize:  1.85 MB
 Viewed:  7 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

scopeset.jpg



power.jpg
 Description:
 Filesize:  1.8 MB
 Viewed:  4 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

power.jpg



pcb.jpg
 Description:
 Filesize:  2.15 MB
 Viewed:  5 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

pcb.jpg


Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1449
Location: Chicago
Audio files: 14

PostPosted: Sun Jun 29, 2014 10:33 am    Post subject: Reply with quote  Mark this post and the followings unread

Sounds to me like there is some problem with the scope set up. Smile

Unfortunately I'm far from an expert there, so I have no good advice.
Back to top
View user's profile Send private message
Cato



Joined: May 29, 2014
Posts: 42
Location: uk

PostPosted: Sun Jun 29, 2014 11:25 am    Post subject: Reply with quote  Mark this post and the followings unread

Just checked scope manual I had the volt/div fine tune red, inner dial, set wrong, so it is now all the way clockwise. Now getting correct scope readings, so readings in previous scope image set should be doubled. I am going to recheck all of them.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: dnny, Uncle Krunkus, v-un-v
Page 2 of 3 [69 Posts]
View unread posts
View new posts in the last week
Goto page: Previous 1, 2, 3 Next
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
e-m mkii

Please support our site. If you click through and buy from
our affiliate partners, we earn a small commission.


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use