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 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
Subcommander problems, please help!
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jay66



Joined: Dec 31, 2011
Posts: 21
Location: Minnesota

PostPosted: Sun Jan 15, 2012 9:07 am    Post subject: Subcommander problems, please help! Reply with quote  Mark this post and the followings unread

I am having troubles with my Subcommander build. I get some clean sound with the master and clean to master cranked way up. If I hit a string hard enough I get a crackly sound like a badly biased transistor. None of the other controls work.

I tested all pots before I started as well as all transistors.

I have gone over all my wiring to pots checked for solder bridges and cold joints with a magnifing glass. The only substitutions I made is th 2K resistors R40, R74, R98, couldn't find a 2K and subbed 2.2K as well as socketing a few resistors for possible mods later on.

I am posting a couple pictures in hopes that some of the pros around here can spot anything obvious I missed or screwed up. I've built a lot of pedals but nothing this involved so I'm not really sure where to start looking. Any Idea's would be greatly apreciated.

Posted Image, might have been reduced in size. Click Image to view fullscreen.
By jcm66 at 2012-01-15

Posted Image, might have been reduced in size. Click Image to view fullscreen.
By jcm66 at 2012-01-15
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Thu Jan 19, 2012 8:37 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi - I don't have one of these, but I noticed R37 and R38 don't seem to be stuffed in the pictures. Is that intentional?

Gary
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Thu Jan 19, 2012 8:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

Oh - one question. Do you have an oscilloscope and voltmeter?

Typically when I have a module that doesn't work right I take the following steps

1) Check the voltage on the power and ground of each of the chips.

2) Check the behavior of the pots. Example, if one of the pots is a voltage control point, check to make sure the voltage varies properly when you turn the pot.

3) Pick some noticeable aspect of the problem, and ignore everything else. Just start following that circuitry and see what you find. Quite often there is only one or two real problems, and they cause a bunch of different symptoms.


If you can do step 1, that would be a good start. Then we can go from there.

Gary
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jay66



Joined: Dec 31, 2011
Posts: 21
Location: Minnesota

PostPosted: Fri Jan 20, 2012 7:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yes R37 and R38 are omitted on the layout and the lower spot on R38 gets connected to R43 and R45 the clean and level pots.

I don't have an oscilloscope but I do have a multi meter to check voltages.

I did something stupid while messing with it the other day and grabbed one of the cords from my power supply hooked it to the 18V instead of the 9V and cooked the CD4013 so I ordered another. It should be here next week.

Thanks for the tips I'll post once that gets here and I can check voltages.
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jay66



Joined: Dec 31, 2011
Posts: 21
Location: Minnesota

PostPosted: Sun Jan 22, 2012 6:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

OK I grabbed a CD4013 in a MXR Blue Box clone I built so here are the voltages of the chips.

U1 11.39V+ 0V- TL074
U2 11.38V+ 0V- TL074
U3 11.36V+ 0V- CD4013
U4 11.33V+ 0V- TL072
U5 11.26V+ 0V- LMC 555
U6 11.23V+ 0V- TL072
U7 11.28V+ 0V- CD4013
U8 11.29V+ 0V- TL072
U9 11.25V+ 0V- TL072
U10 11.23V+ 0V- TL072
U11 11.23V+ 0V- LM13700
U12 10.56V+ 0V- TL072
U13 11.31V+ 0V- LM13700
U14 11.29V+ 0V- TL072
U15 11.29V+ 0V- TL072
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Tue Jan 24, 2012 3:00 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Jay -

One thing jumps out at me here. Do you have a negative supply?

Gary
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jay66



Joined: Dec 31, 2011
Posts: 21
Location: Minnesota

PostPosted: Tue Jan 24, 2012 4:25 pm    Post subject: Reply with quote  Mark this post and the followings unread

I wired it up like a standard stompbox with true bypass. I'm using a 12- center wall wart then tried my T-rex fuel tank also negitave center. Should this be ground positive?
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Tue Jan 24, 2012 5:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
I wired it up like a standard stompbox with true bypass. I'm using a 12- center wall wart then tried my T-rex fuel tank also negitave center. Should this be ground positive?


I'm not sure I understand. This project absolutely requires +12V AND -12V, so most simple wall warts won't do the job. Did you use Ray's wall wart supply or an equivalent?

Gary
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jay66



Joined: Dec 31, 2011
Posts: 21
Location: Minnesota

PostPosted: Tue Jan 24, 2012 6:00 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ok the power supply has to be my problem. It's just a 9V 800mA wall wart for a standard a Boss guitar pedal.

Yeah I didn't understand what you meant either, I was thinking you meant positive ground like the old Fuzz face and Tone benders.
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Tue Jan 24, 2012 6:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ok - that sounds like the problem.

I'd advise you to get one the wall-wart supplies Ray sells - that will give you the +/- supplies you need. Be very careful about trying to put a connector on this. If you have a metal case you definitely DON'T want either of the conductors on the power supply going to the case.

Gary
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jay66



Joined: Dec 31, 2011
Posts: 21
Location: Minnesota

PostPosted: Tue Jan 24, 2012 7:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yeah that looks like what I need. The case is part Walnut and part metal So I can mount it to the wood bottom.

Just have to see if I can find an AC wall wart.
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jay66



Joined: Dec 31, 2011
Posts: 21
Location: Minnesota

PostPosted: Fri Jan 27, 2012 4:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

I have everything ordered for a power supply and after some reading I know how to hook it up correctly.

I did get it up and running today on two 9V batterys so that was most of the problem.

I'm not sure the LFO on the VCA is working, the controls don't seem to change anything. Kind of wondering if I could have cooked something else when I hooked it up wrong...
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Fri Jan 27, 2012 5:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

That's great news. I'm really surprised it survived. Chalk that up to good design.

Troubleshooting the LFO should be relatively simple I think.
The first question is does it do anything at all. or is it just that you can't change the frequency?

It looks like U14 is the chip that is used in the LFO, so if you used sockets it would simple to replace that, or swap it with U15.

Gary
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jay66



Joined: Dec 31, 2011
Posts: 21
Location: Minnesota

PostPosted: Fri Jan 27, 2012 6:38 pm    Post subject: Reply with quote  Mark this post and the followings unread

It is it is very subtle as is turning anything on the VCA.

Should there be a radical change in sound from turning any of these? It's possible that it's working as it should because it changes some. Plus it's too late to really pour the coals to my amp.

Add tired ears and I'm just now this week starting to feel a little better from a nasty round of carbon monoxide poisoning I got hit with in late Oct. I'm surprised it works at all and I didn't solder my fingers together... Smile

Tried swapping out U14 and no change.
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Mongo1



Joined: Aug 11, 2011
Posts: 411
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PostPosted: Fri Jan 27, 2012 10:20 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
starting to feel a little better from a nasty round of carbon monoxide poisoning I got hit with in late Oct.


Holy Crap! That's some serious stuff. I'm glad to hear you're feeling better.

Quote:
Should there be a radical change in sound from turning any of these? It's possible that it's working as it should because it changes some. Plus it's too late to really pour the coals to my amp.


Well, I don't have one of these gadgets, but I suspect the effect should be pretty noticeable. I suspect that the LM13700 may have gotten damaged. They're pretty delicate. If you have a spare one, you might try replacing U13

Gary
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jay66



Joined: Dec 31, 2011
Posts: 21
Location: Minnesota

PostPosted: Sat Jan 28, 2012 2:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

That must have been it, I had a couple here and swapped it out and now you can tell it's changing the sound. I'm such a synth newb this is going to take a while just to figure out what everything does.

Also I had socketed some resistors and did a couple of Rays recomended resistor changes plus tweaked the trim pot a little and that made things even more pronounced.

Now with a little luck those caps for the power supply are not too tall and I will have room in the case for it.

Thanks for all the help Gary. This has been a real learning experience.

Jay
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Sat Jan 28, 2012 3:27 pm    Post subject: Reply with quote  Mark this post and the followings unread

Great! I'm glad I could help.
Gary
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jay66



Joined: Dec 31, 2011
Posts: 21
Location: Minnesota

PostPosted: Mon Jan 30, 2012 7:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

The power supply arrived today. It's built and installed and I'm happy to report it sounds awesome. It sounds even better with a good power supply than with batterys, more punch and more defined sounding. Very Happy

A couple pics...
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By jcm66 at 2012-01-30
Posted Image, might have been reduced in size. Click Image to view fullscreen.
By jcm66 at 2012-01-30
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Mongo1



Joined: Aug 11, 2011
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Location: Raleigh NC

PostPosted: Tue Jan 31, 2012 7:16 am    Post subject: Reply with quote  Mark this post and the followings unread

Congratulations! It always feels good to get something like that accomplished. Hope you have a great time with it!

Gary
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