electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links
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 
 Forum index » DIY Hardware and Software » fonik's place
X4046 weird problem.
Post new topic   Reply to topic Moderators: fonik
Page 1 of 1 [9 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
bubzy



Joined: Oct 27, 2010
Posts: 594
Location: United Kingdom
Audio files: 64

PostPosted: Thu Jul 26, 2012 1:56 am    Post subject: X4046 weird problem. Reply with quote  Mark this post and the followings unread

Hey,
Ive been using 2 4046's for a while with no problems, the other day after deciding that the sine wave wasnt *quite* round enough, i unplugged all the power connections from one oscillator, and when i plugged it back in its not working.

the 4046 chip gets VERY hot, have tried more than one chip in this position, the tl074 also warms up but not as much,
there doesnt seem to be any shorting with power, as i can simultaneously plug the other oscillator in and it runs no problem.

the other weird thing that happens is that when I power down the circuit, i get a 3 or 4 second delay and then an oscillaton from very high going down to very low as the capacitors in my psu run out of power.

any suggestions? (ive replaced all the chips and resoldered a few iffy looking resistors)

many thanks

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



Joined: Mar 20, 2012
Posts: 2177
Location: Chicago
Audio files: 16

PostPosted: Thu Jul 26, 2012 5:34 am    Post subject: Reply with quote  Mark this post and the followings unread

Probably not much of a suggestion, but...that sounds like it's running, just at a ridiculously high frequency. When you cut power, the frequency drops off.

1) do you have a scope to look at the output (I suspect you do from other conversations...) and confirm that nothing is coming out, or high frequency is coming out?

2) what is static sensitive in the frequency control section? Anything there that if it was shorted could cause the frequency range to jump ridiculously?

I'm not very experienced with expo converters, but looking at my X4046 schematic, I'd be looking at IC2 ofr whatever you're using for the Q1/Q2 pair. (edit: duh, should read it all...you replaced all the chips, so I'd be looking at the transistors then) I suppose it's also possible for the hard sync to be misbehaving, but it seems less likely.

Disclaimer: I have not been doing this a long time, so I reserve the right to be completely off in the weeds Very Happy
Back to top
View user's profile Send private message
bubzy



Joined: Oct 27, 2010
Posts: 594
Location: United Kingdom
Audio files: 64

PostPosted: Thu Jul 26, 2012 6:35 am    Post subject: Reply with quote  Mark this post and the followings unread

i get a sort of ac looking wave when i plug scope into it, doesnt change at all.

funny you shuold mention hard sync as i was messing about with that on it a couple of days ago.
where shuold i be looking if thats the trouble?

_________________
_Richard_ Smile
Back to top
View user's profile Send private message
fonik



Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23

PostPosted: Thu Jul 26, 2012 12:30 pm    Post subject: Re: X4046 weird problem. Reply with quote  Mark this post and the followings unread

bubzy wrote:
Ive been using 2 4046's for a while with no problems, the other day after deciding that the sine wave wasnt *quite* round enough, i unplugged all the power connections from one oscillator, and when i plugged it back in its not working.

what did you do between unplug/plug back in? could it be that you created a short or solderbridge somewhere?

_________________
Posted Image, might have been reduced in size. Click Image to view fullscreen.
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
Back to top
View user's profile Send private message Send e-mail Visit poster's website
bubzy



Joined: Oct 27, 2010
Posts: 594
Location: United Kingdom
Audio files: 64

PostPosted: Thu Jul 26, 2012 12:33 pm    Post subject: Reply with quote  Mark this post and the followings unread

pretty sure i didnt do anything.
its unlikelytheres a solder bridge, however, with me, anything is possible. im going to have another look in a bit to make sure that i havent missed anything important. (i even moved the HF and scale pots :/) time to recalibrate.

will post results back later

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



Joined: Mar 20, 2012
Posts: 2177
Location: Chicago
Audio files: 16

PostPosted: Thu Jul 26, 2012 8:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

What's the frequency of your wave?

the only thing that seems likely to be a problem for the Hard Sync (as far as handling causing it to zort) would be Q3, NPN transistor. I'd see if I could measure the current going in on pin 11 of the 4046 and verify all its voltages too.

I'd also back up; when your'e adjusting the coarse/fine pots, do you see voltage differences at pin 2 of IC2? What about at the base of Q1? What's voltage at the collector of Q1 (connected directly to pin 6 of IC2)? It ought to be held to ground by the op amp if I have it right....as before with my disclaimers, I can't say I'm terribly confident about expo converters' behavior...

I haven't re-read the build notes/troubleshooting notes at Scott's site, but I'd think there might be some clues there too.
Back to top
View user's profile Send private message
bubzy



Joined: Oct 27, 2010
Posts: 594
Location: United Kingdom
Audio files: 64

PostPosted: Thu Jul 26, 2012 10:59 pm    Post subject: Reply with quote  Mark this post and the followings unread

seems i didnt change ic2 Very Happy

now working. thanks for your efforts

_________________
_Richard_ Smile
Back to top
View user's profile Send private message
fonik



Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23

PostPosted: Fri Jul 27, 2012 2:46 am    Post subject: Reply with quote  Mark this post and the followings unread

Very Happy
_________________
Posted Image, might have been reduced in size. Click Image to view fullscreen.
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
Back to top
View user's profile Send private message Send e-mail Visit poster's website
elmegil



Joined: Mar 20, 2012
Posts: 2177
Location: Chicago
Audio files: 16

PostPosted: Fri Jul 27, 2012 5:37 am    Post subject: Reply with quote  Mark this post and the followings unread

Cool, glad it's working Smile
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: fonik
Page 1 of 1 [9 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » fonik's place
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


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