electro-music.org   Dedicated to experimental electro-acoustic
and electronic music
 
 Front Page  |  Radio  |  Forum  |  Media  |  Playlists  |  Wiki
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 » Thomas Henry designs
trouble shooting xrvco/lfo
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 1 [4 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
scriptstyle



Joined: Jan 22, 2008
Posts: 250
Location: nj

PostPosted: Thu Apr 16, 2009 9:57 pm    Post subject: trouble shooting xrvco/lfo Reply with quote  Mark this post and the followings unread

so i stuffed 2 xrvco/lfo pcbs acouple months[these are the bug-brand layouts]. this was before i knew that the resistors i bought off ebay where fake resistors from sure electronics. to make matter worse i used single turn trims all the way around except for one that called for a single turn. i just kinda through them together with stuff i had laying around hoping more then anything that they would make 2 nice vclfo's.

so i finished wiring up the first one. initial testing gave me nothing.. then i noticed i totally forgot the .22uf mylar between the jack and pot, and also found a solder bridge on the pcb Embarassed

so after i caught those 2 mistakes i hooked everything back up and now i have a high frequency osc(i think) out of the tri/sine out. nothing out of pulse yet. i only had a minute to check it. only the shape pot seems to be doing anything to the signal. at this point im thinking i fried some ic's. Should i swap?or does someone have any suggestions? thanks
Back to top
View user's profile Send private message
scriptstyle



Joined: Jan 22, 2008
Posts: 250
Location: nj

PostPosted: Sun Apr 19, 2009 10:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

updated had a little time today swapped the tl074 and did a better first run.

i now have a square, and tri/sine.

my exact problems are,

1. my shape pot works but once it gets to about 60% the oscillator goes very high in freq/pitch? im not really sure what its doing there im yet to hook up to the scope.

2. my fine and coarse controls do not do anything...

3. when i moved the Linear fm pot the oscillator changed in sound. nothing was connected to the input??

im really wondering if the shitty components are causing some of the weirdness im experiencing. like i said in my first post i did sub in single turn trims [i haven't even had the time to give the trims adjustments], and used the junky ebay resistors from sure electronics. Crying or Very sad

4. what resistor values are the ones that need to be closer to ideal? maybe i could switch out a couple of the more important ones?

next up on the list for me is changing the lf442 since this was the ic closest to the solder bridge. then hookup the scope and do some trimming.

the fact that my fine and coarse pots are not working really has me bummed.

thanks to anyone who can shed some light to a guy who needs to pull some time out of his pocket!
Back to top
View user's profile Send private message
scriptstyle



Joined: Jan 22, 2008
Posts: 250
Location: nj

PostPosted: Wed Apr 22, 2009 1:58 am    Post subject: Reply with quote  Mark this post and the followings unread

I'm super puzzled I had ten spare minutes today poped in a new lf442 and now all I got is a short oscillation followed by a pop, then another short oscillation pop ... All ic's are getting the correct voltages. Hopefully I can get some more time and go poking around with the scope. Maybe I'm having a stray capacitence problem. I clean my boards well, but some may have seeped through the holes and be hiding on top?
Back to top
View user's profile Send private message
scriptstyle



Joined: Jan 22, 2008
Posts: 250
Location: nj

PostPosted: Sun Apr 26, 2009 7:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

i worked it out today. and made a real dumb mistake when replacing an ic Embarassed

now i just need to tune it up. i may need change values some where.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 1 [4 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 » Thomas Henry designs
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
Log in
Username:     Password:      Log me on automatically each visit    


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2026 by electro-music.org