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WIGGLING 'LITE' IN GUEST MODE

J.Haible's Living VCO for Eurorack [Build Thread]
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3 ... 23, 24, 25 [all]
Author J.Haible's Living VCO for Eurorack [Build Thread]
shiftr
hihi w00t
thanks! SlayerBadger!
shiftr
I found an error.
I put a 620k resistor in the vibrato circuit where there was supposed to be 510k. I found a whole collection of 620k resistors wrongly marked as 510k in my drawers.
I took out the 620k and the circuit works fine without it. I tried putting in a 510k resistor but i liked it better without. The vibrato runs slower without.
Now i've got a problem with one of the sine shapers. One om the generates a clipped sine.
This project seems more work then building a TTSH smile
cleaninglady
Because I am quite busy and lazy too, could any kind Wiggler point me to a wiring diagram for the the Living VCO's.
I have completed Barcode edition V1.3 pcbs sitting here that I finished about 5 years ago. I'm planning to just ratshack it all into one box so I won't need a panel. Actually as the pots are all PCB mounted and the outputs are obvious, all I really want to know is :

1. How do the Driver pads on each OSC pcbs connect to the Driver PCB ?

2. The switch wiring. (I'm going to look at the Option 3 Diagram on Jurgen Haible's legacy site).

EDIT : Problems above solved. Option 3 diagram was great ! SlayerBadger! SlayerBadger! SlayerBadger!
cleaninglady
More questions...

So, (first question), I was just checking over the BOM on page 1 of this thread, i'm sure that i never matched R1,R2 and R3.

Is there a high res image of the unstuffed PCB around ? (I have the
Logicgate 2014 Barcode Edition v1.3 PCB)

I can find R1 and R2 from making the first image above bigger but i can't find R3 anywhere. Dead Banana

Also, (second question) i have a very badly misshapen TRI wave on one of the OSC PCB's. It actually wen't from being just a Triangle with a spike to a bad TRI / SAW combination with a spike after i changed C7 and C8 to BP electrolytic.

Is a clean TRI wave heavily dependent on R1,R2 and R3 being matched ?
oscarthesquirrel
Not sure if anyone can help with this but here goes...


Finished building my Living VCO today, but I've got a problem. No output from any VCO...

OK - so I already have a LVCO (built by someone else) and I've used that as a reference during my build.. so I started by measuring a few voltages


The power header for the VCO section is reading -10.66V and 11.17V

I've also checked all 3 IC1's and IC7's (I'm using OPA2134s here for better tracking) and all 3 IC1s show 10.7V at pin 3 , with IC7's showing 12.48V at pin 3. The values from the working LVCO ICs are 11.9V and 12.2V respectively.

Voltage at the driver pin header seem fine at -11.95V and 12V

So I've checked for solder bridges, cold joints, IC orientation, transistor orientation, diode orientation and also cross referenced against the working LVCO.

I'm stumped as to where to start looking...I'm no electronics engineer.

Any immediate suggestions as to a potential culprit ??? The fact that all 3 VCO circuits have the same issue leads me to think I've installed the same thing incorrectly in all 3 circuits....but I can't figure out what that would be.
oscarthesquirrel
After a week of checking I'm no further forward.

Have literally checked every single component for value and placement, I've reflowed all the joints, i've checked IC sockets to make sure they're all seated OK..but still I have a non-functioning module.

Any kind-hearted soul out there able to help ?

Dead Banana very frustrating
Muff McMuff
I have noticed many times on muffs people posting photos and somebody points out potential issues straight away. I would post some good images.
elmegil
After you post photos, start with a single VCO.

Sounds like you've verified the voltages and components. Have you verified your panel wiring?

Are you sure the driver voltages are reasonable and not pushing you up into ridiculous inaudible rates or down into near-DC? If you can detach them you probably should.

When you adjust the frequency knob(s) do you get voltage changes at the output of the summing amp? I don't recall Barcode's designators and whether they match Juergen's original schematics, but talking about the output of U1A from the original.

Are you seeing any oscillation on the output of U1B? I hope you have a scope of some sort....
oscarthesquirrel
Attached is a pic of the board. Not the prettiest I know... if a higher res is needed, I can dig out my Nikkor 105 macro and send a monster file...

1. Yes, I have a scope
2. I have a working LVCO to compare voltages, components etc and that helped me spot 2 ceramics that were wrongly positioned in the driver section - that's now fixed..driver section works (I fed in quantised voltages from an A-155/156 combo and the signal through 1V/O seems fine)
3. Voltage at the pin header is weird +11.2V / -10.6V What might cause this voltage imbalance ?
4. Saw output steady +7.6V,across all 3 outputs (ie flat line)
5. Pulse output was 4.66V when I measured it, then I noticed it was slowly dropping..almost as if it was cycling very slowly..same across all 3 outputs+0.0008, +0.0041)
6. Sine outs -1.01, -0.4056, -0.2267 (flat line)
7.R33B is on the other side of the board - long story, but the solder simply wouldn't flow out when replacing R33B, so I ended up placing it on the other side. >,<
8. No panel wiring - am using the R*S bard set, so its a simple jacks, pots 'n' switches solder job and no complicated wiring.

Now the saw is the feed for the other waveforms via wave shaping, so I guess I need to start at IC1A/B/C. I've checked the transistors - correctly positioned, correct components

So where to go next ?

oscarthesquirrel
High res shot front of the board. Back to follow - for some reason can't upload - maybe file is too big.

Picture file
oscarthesquirrel
And the (ugly) back as an attachment
oscarthesquirrel
Latest update:

I pulled all of the ICs from the VCO section and measured the pin header voltage...perfect +12 V / -12V

So i started re-introducing the ICs one at a time and measuring...

All the OPAs - fine. Voltage is good at the header +/- 12V

The problem seems to be with the 311P chips I have - I suspect they're a fake batch from China. With each one I added in, the negative voltage dropped by 0.2-0.3V, and the positive voltage dropped too. I'd ordered them locally in Malaysia, so its a possibility they're duff...I've tried several from the batch in various locations and they all give the same (or worse) results.


The TL074CN ICs I've used also seem to be pulling down the voltage, although with them in place (and no 311Ps) the voltages are + 12v and -11.3V at the header.

So there are still issues, but hope this helps someone more knowledgeable than me to point in me a suitable direction

thanks !
elmegil
Quote:
4. Saw output steady +7.6V,across all 3 outputs (ie flat line)


This means you're right, the comparator section isn't working. The cap charges up, but never gets reset. I would suggest you find an alternate source of 311 chips.....
sduck
By the way, this isn't the build thread for the R*S version, this one is for a different flavor of LVCOs. The actual R*S thread is at - https://www.muffwiggler.com/forum/viewtopic.php?t=150988 - but it seems this one is working for you.
oscarthesquirrel
sduck wrote:
By the way, this isn't the build thread for the R*S version, this one is for a different flavor of LVCOs. The actual R*S thread is at - https://www.muffwiggler.com/forum/viewtopic.php?t=150988 - but it seems this one is working for you.


Yeah - sorry... I went for the thread that has [BUILD] in the title !

If you need to move this bit of thread across that's cool with me. thumbs up
oscarthesquirrel
elmegil wrote:
Quote:
4. Saw output steady +7.6V,across all 3 outputs (ie flat line)


This means you're right, the comparator section isn't working. The cap charges up, but never gets reset. I would suggest you find an alternate source of 311 chips.....


This makes sense...at least to a novice like me...thanks for the explanation.

New 311 chips already on order from Farnell.
elmegil
Sounds good. We can pick it up in the other thread if if continues to be an issue... smile
sduck
oscarthesquirrel wrote:
[

If you need to move this bit of thread across that's cool with me. thumbs up


Doesn't matter to me. Seems like it's doing fine here. And with this ancient software you can't really move sections of threads around anyway. Carry on!
oscarthesquirrel
Update..

All sorted...the new 311 ICs did the job. I must have picked up a bad batch (ie fakes)...let that be a lesson for anyone thinking of buying from eBay if they can't find the chips on Tayda, Mouser or Farnell.
elmegil
I buy nothing on ebay any more unless I can find absolutely no other source, and if it's something that ought to be expensive, not even then.

311's are not expensive, but like original SSM/CEM chips and such, would not touch ebay for the world. Not to mention a lot of those are getting re-manufactured again....
oscarthesquirrel
elmegil wrote:
I buy nothing on ebay any more unless I can find absolutely no other source, and if it's something that ought to be expensive, not even then.

311's are not expensive, but like original SSM/CEM chips and such, would not touch ebay for the world. Not to mention a lot of those are getting re-manufactured again....


I agree 100%.... I'd only ventured to Ebay because Farnell didn't have any stock locally, nor did Tayda and Mouser wanted to charge me a gazillion dollars to chip 3 chips to Malaysia ....anyway lesson learned. Dead Banana
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