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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Mon Jan 14, 2008 2:46 am Post subject:
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I just spent a couple hours going through and triple-checking all the resistor, pot, and capacitor values, as well as resoldering any iffy joints on the top and bottom of the board -- but the problem persists. How frustrating. Maybe there is a bad capacitor? I tested the resistance values with a multimeter. I guess the next step is to study the schematics -- please let me know if any of you have additional ideas on what could be causing my problem.
Thanks,
Lars |
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bugbrand
Joined: Nov 27, 2005 Posts: 846 Location: Bristol, UK
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G2 patch files: 1
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Posted: Mon Jan 14, 2008 10:59 am Post subject:
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Hmm, sounds like the envelope is working (you can get the bweeeee synth drum sounds) but maybe the VCA isn't working - sounds like it is fixed open. Had a quick look at the schem ---- maybe you've used a 2n3904 instead of a 2n3906?? That's a guess... 3904 is NPN (as used for Q1 and Q2) whereas Q3 needs to be a 3906..
Could be a 3080 problem otherwise maybe??? That's the area I'd be looking anyway... _________________ http://www.bugbrand.co.uk
http://www.bugbrand.blogspot.com |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Mon Jan 14, 2008 11:14 am Post subject:
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That's a good tip... thanks! I did double check all my transistors and everything's where it should be, but maybe there's a bad one... I'll try that first thing, checking all the pins from the 3080 and replacing potentially bad parts.
I've tried the LM3080 sent with the board kit, and a CA3080 from Small Bear (as well as an LM566 and NE566) and results are identical.
Is the pitch range supposed to be that high? I understand the VCA affecting the constant tone problem, but why would the VCA be affecting the pitch like that? During the sound clip I rotate "initial pitch" from 0 to 100%, and I'm making sure the CV range and sweep knobs area all the way down...
Assuming I can get this working without shooting myself first, it will at least be a good learning experience... |
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bugbrand
Joined: Nov 27, 2005 Posts: 846 Location: Bristol, UK
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Posted: Mon Jan 14, 2008 12:30 pm Post subject:
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Yeah, I actually changed the 566's rate cap (C8) to something bigger - I found the pitches generally too high with the stock 22n - I was looking for low drum tones and found you'd only have a tiny range of lows at the bottom of the pot travel. Actually, I kind of don't like the tuning response so much - its hard to tune things in the low regions... _________________ http://www.bugbrand.co.uk
http://www.bugbrand.blogspot.com |
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State Machine
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Joined: Apr 17, 2006 Posts: 2809 Location: New York
Audio files: 24
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Posted: Mon Jan 14, 2008 5:21 pm Post subject:
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Sounds like a couple of things going on here. The decay is very very long and the decay capacitor, C12, seems like it's not discharging completely leaving the VCA "open". Several seconds after you trigger the UD-1, there should be about zero volts across C12 decay capacitor. If not, turn the power off, turn the decay pot, R32, to minimum decay (Minimum resistance" and and measure the resistance across C12. It should be less than or equal to 1K. If not, check your connections.
As for the high frequency, without any pedal connected, the voltage across R35 should be 0V. If not, check that Q4 is not shorted from collector to emitter. Also make sure your INIT range into summing resistor R29 is from 15V down to a approximately 0.18 V. Also, check R8 and R19 values ....
OK, I will wait for your response ..........
Bill |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Mon Jan 14, 2008 6:09 pm Post subject:
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Badass! Thanks so much. Got this info just as I'm sitting down to work on this thing. I'll get back with my results in a few hours. |
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State Machine
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Joined: Apr 17, 2006 Posts: 2809 Location: New York
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Posted: Mon Jan 14, 2008 6:58 pm Post subject:
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Quote: | Badass! Thanks so much. Got this info just as I'm sitting down to work on this thing. I'll get back with my results in a few hours. |
OK, cool. We should get this up and running for you in short order I hope. I got your e-mail also. OK, let me (us) know man !
I will take a peek at this thread in a bit to see how you are doing. the measurements should go quick
I can always break out my UD-1 if need be, power it up and make comparative observations ......
OK, good luck, Bill ........ |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Mon Jan 14, 2008 7:13 pm Post subject:
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Quote: | Several seconds after you trigger the UD-1, there should be about zero volts across C12 decay capacitor. |
It's hovering at about 1.2v (when decay pot is turned to max resistance) or 1.8v (when decay pot is turned to min resistance.)
Quote: | If not, turn the power off, turn the decay pot, R32, to minimum decay (Minimum resistance" and and measure the resistance across C12. It should be less than or equal to 1K. |
Ack! It's measuring about 55-60k.
Quote: | If not, check your connections. |
I've triple checked all the applicable solder joints (top and bottom) i can think of, and used the meter to verify connections all around this part of the circuit... everything seems to be good. Given this new information, does the evidence point to a specific connection...?
Quote: | the voltage across R35 should be 0V. |
Check. Reading 0v across R35
Quote: | make sure your INIT range into summing resistor R29 is from 15V down to a approximately 0.18 V. |
Yes, I'm measuring a range of 14.85v to 0.1v
Quote: | Also, check R8 and R19 values |
Resistance across R8 (supposed to be 3.9K) is ~about 3.3K, and Resistance across R19 (supposed to be 27K) is ~about 15k. I've got the right value resistors in, though -- not sure what they're supposed to read, measuring across, when in the circuit... don't think there's any way they could be bad? I'm measuring about 0.5v-2.1v (or -2.1v?) across them both.
I'm going to continue checking, just thought I'd post these results first. Let me know if you think of anything else.
Also, I noticed the parts list calls for "N.O. jacks" are these just normal jacks? I wasn't sure if there was a difference. I have a big bag of surplus panel-mount stereo 1/4" jacks I bought at the local electronics store, I think they are just standard jacks.
[/quote] |
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State Machine
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Joined: Apr 17, 2006 Posts: 2809 Location: New York
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Posted: Mon Jan 14, 2008 7:33 pm Post subject:
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Quote: | Quote:
If not, turn the power off, turn the decay pot, R32, to minimum decay (Minimum resistance" and and measure the resistance across C12. It should be less than or equal to 1K.
Ack! It's measuring about 55-60k. |
That 1.8 V is probably enough to feed current into the CA3080 and keep it "open" ........ Not good .......
OK, lets fix that first before we do anything else as attacking everything at once will not help us . The decay pot when minimum resistance should be close to zero ohms so the only things left going to ground from C12(+) is R2, a 1K resistor. First check R2. Is it 1K ? If so, check to see the the decay pot really goes close to zero ohms by measuring with your ohm meter from the junction of R2 and R32 to ground when set to minimum. This should be close to zero ohms. If not, make sure that junction IS connected and also make sure R32 measures about zero ohms to your power supply ground .......
Bill |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Mon Jan 14, 2008 8:31 pm Post subject:
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You guys should personally come down here to Denton, Texas and kick my worthless ass!
I never connected the pot/panel/jack ground to the board ground anywhere.
Guess I saw the headers and thought I was done.... Once I connected the two grounds to each other (ground lug on output jack to ground pin on header 1) it started working perfectly.
Your last instructions totally led me to this, though. Thanks for all your time. And, now... my first synth module is working! Time to wire up that populated Clangora, now... |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Mon Jan 14, 2008 11:17 pm Post subject:
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Okay, I made sure everything was securely connected and mounted it up after making a couple of the mods Bugbrand suggested in an earlier thread (added another .022 cap on top of the current one to allow for lower frequency range, and swapped the decay pot for a log 1M -- definitely like the mods.)
I'll post some sound clips/videos when I get a few more voices added. |
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bugbrand
Joined: Nov 27, 2005 Posts: 846 Location: Bristol, UK
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State Machine
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Joined: Apr 17, 2006 Posts: 2809 Location: New York
Audio files: 24
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Posted: Tue Jan 15, 2008 6:00 am Post subject:
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Quote: | You guys should personally come down here to Denton, Texas and kick my worthless ass! |
Oh, don't ever say that man !! I have learned the most when having to troubleshoot the mistakes i've made. Nothing beats practical hands on training with good theoretical background. I am so glad you got your first module working. Congrats and good troubleshooting with you !!!!!
I had started to think the ground was missing just by the sound of the sample you gave. The sound was meandering all over the place. The sample you posted really led to the analysis so good job !!!
I think for now on, when folks have an issue with a module, rather than describe the sound, just sample and upload it for all to hear. It really clears up lots of uncertainty and leads to the most accurate analysis. Words just lead to the wrong interpretation of a problem. "A sound is worth a 1000 words" .......
Quote: | Time to wire up that populated Clangora, now... |
That circuit is a blast !!!!!! Good luck
Bill |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Tue Jan 15, 2008 9:03 am Post subject:
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Thanks for the encouragement! This is a big milestone for me. I've been planning and constructing the Midibox Sequencer and case/PSU/modules for the drum modular for about 3 months now, working on it every night -- everything hand constructed, painted, silkscreened, etc. And this is the first "finished" piece. So it's a euphoric experience... I was beginning to think I'd never have this thing done. My band is on hiatus from performing and writing until I get our new rig, ready... so the tension was killing me. I'm going to hold off on a second UD1 until I finish constructing the rest of the modules I already have parts and panels for, but I think I will probably want two (or I may hold out for MPS boards instead.)
Quick question, if you don't mind -- is there a way to wire a normal stereo jack as an NC jack, so that I can do the send/return Clank/Clatter sections on the Clangora without buying new jacks? Little confused on this. |
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State Machine
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Joined: Apr 17, 2006 Posts: 2809 Location: New York
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Wed Jan 16, 2008 11:54 am Post subject:
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Awesome, thanks for clearing that up.
After digging around, I found some surplus stereo jacks I bought which have 5 lugs... so I can wire them with the NC option. Using a single jack wasn't an option, because I'd already finished drilling, painting and silkscreening the panel a few weeks ago.
I got my 808 bass drum clone module firing last night, too. Figured out I have to send in a pulse at the Accent and Trigger inputs simultaneously. I used the NC jack option for this, too... so that when there is nothing in the Accent jack, it sends the Trigger signal to both.
I might add the TH Trigger Conditioner circuit to the 808BD input(s) to smooth things out... Slowly starting to get a much clearer mental picture on how all this shit works now. For the 808 module I need to try to figure out how to convert a constant CV at the Accent input into a 1ms pulse, triggered by a 1ms pulse at the Trigger input, prior to things going into the circuit... that way I can modulate velocity with an LFO or whatever.
Thanks again for the help. I'm really looking forward to increasing my knowledge and being able to offer help and information back to the community as soon as possible. |
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State Machine
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Joined: Apr 17, 2006 Posts: 2809 Location: New York
Audio files: 24
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Posted: Wed Jan 16, 2008 2:20 pm Post subject:
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Quote: | I need to try to figure out how to convert a constant CV at the Accent input into a 1ms pulse, triggered by a 1ms pulse at the Trigger input, prior to things going into the circuit... that way I can modulate velocity with an LFO or whatever. |
Not sure I understand completely. Do you want to have a pulse ride on top of the DC going to the accent input? Like a voltage summer would do? Is my understanding off here? If you diagram it for us, maybe we can help.
Bill |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Wed Jan 16, 2008 3:27 pm Post subject:
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I'm just thinking out loud here, I guess. When I have more specific questions I will definitely come babbling at you guys again. I think what you've mentioned is what I am talking about, though.
I'll have pics and soundclips of the working modules by this weekend, I hope! |
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State Machine
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Joined: Apr 17, 2006 Posts: 2809 Location: New York
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Posted: Wed Jan 16, 2008 4:14 pm Post subject:
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Quote: | When I have more specific questions I will definitely come babbling at you guys again. |
OK, standing by
Bill |
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