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WIGGLING 'LITE' IN GUEST MODE

a legend is back...System-700 in eurorack
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3, 4  Next [all]
Author a legend is back...System-700 in eurorack
Modulart_JP
No, the numbering is not the same as the original schematics.

As mentioned before, the 1st thing you want to check on the filter is a CV variation at pin6 of IC7.
Set both trimmers half way, no audio signal nor CV in then check that you get a voltage variation when turning the freq pot.

Regarding the 711, where did you get the 324C chips from ?
Are you sure they are OK ?
They can be replaced with TL064 (or even TL074).
If you have a couple around, you may want to put them in place of the 324C to see if it makes a difference.
Again, calibrating is important because at some setting of the trimmer, you will not get any phasing.

I'll upload layouts on my website later today.
I'll let you know once done.

A couple of news...
713 Gate Delay will be available by the end of this week.
723 Analog Switch and 715 Multimode Filters modules coming soon...
nanners
LektroiD
Modulart_JP wrote:
No, the numbering is not the same as the original schematics.

As mentioned before, the 1st thing you want to check on the filter is a CV variation at pin6 of IC7.
Set both trimmers half way, no audio signal nor CV in then check that you get a voltage variation when turning the freq pot.


I'm getting a fixed 11.8V at pin6 of IC7 (741), turning the frequency pot makes no difference to the result. I also changed the 741 and the results are the same.

Quote:
Regarding the 711, where did you get the 324C chips from ?
Are you sure they are OK ?
They can be replaced with TL064 (or even TL074).
If you have a couple around, you may want to put them in place of the 324C to see if it makes a difference.
Again, calibrating is important because at some setting of the trimmer, you will not get any phasing.


The µPC324C chips were from Little Diode in the UK, I also had some NOS 324's. Both yielded the same results - ie. no phasing.

With TL064s, at a certain trim setting I'm hearing the LFO sweep a high frequency oscillation over a lot of distorted noise (not phasing, just a high pitched oscillation). The distortion can be tamed a little, but when I change the resonance, the distorted noise is back.

**UPDATE**
The 711 phaser is now working. I went through a few µPC324C's and it came alive. Seems these chips are hit and miss, shame these are not available from any of the major outlets.

Just a personal taste thing, but which timing cap regulates the speed of the LFO? I would like to slow it down a little.

Quote:
I'll upload layouts on my website later today.

Much appreciated smile
ringroad1
Yeah sorry, I should've realised the numbering would be different given that this version of the 711 doesn't include the spring reverb or the tuning oscillator.

LektroiD wrote:

I went through a few µPC324C's and it came alive. Seems these chips are hit and miss, shame these are not available from any of the major outlets.


FWIW I used an LM324 which I presumed to be the same - worked ok off the bat.

LektroiD wrote:

Just a personal taste thing, but which timing cap regulates the speed of the LFO? I would like to slow it down a little.


On the phaser, http://www.florian-anwander.de/roland_system700/711_a3.jpg is as clear as it gets from the original schematics, reckon it's the 0.22uF cap marked C33 in the schematic here.

Yves Usson posted his schematic for the 12db VCF here: http://yusynth.net/gear/ROLAND/R700-schematics/703B-C-VCF.pdf

+1 for schematics with DIY boards and part numbers on the board rather than values, we play these guessing games otherwise.
Modulart_JP
Uploaded the layouts for all SYS-700 PCB's.
They are available for download on the PCB pages in the shop.
LektroiD
Modulart_JP wrote:
Uploaded the layouts for all SYS-700 PCB's.
They are available for download on the PCB pages in the shop.


That's briliant! Thank you!

I have now repaired the fault. Thank you for taking the time to help out.
wendallsan
So far it sounds like I'm having more luck than others! My noise module is making noise as advertised!

Rockin' Banana!

Of course I'm starting with the simplest modules and working my way up. Will be building a couple of the VCA's next, and hoping to have full "block 1" worth of modules built by end of September.
Modulart_JP
thumbs up

If you take your time, you don't hurry, chances are the builds will go smoothly.
Good luck !
SlayerBadger!
wendallsan
Progress continues! I've gotten my 2 VCA's together and then the Amp/Env Follower/Integrator. Haven't plugged them in to do final testing/calibration yet so can't say that they actually work yet. Will be building the 703C filter next and then a couple of the LFO's.

I have one correction for your Mouser cart for the LFO-- the BOM has 2x 24k resistors, but the Mouser cart only includes one.

Other than that, it has been smooth sailing on this work here, fingers crossed that the momentum keeps up!

Pics!

The Faceplate spread


Multi



Bring the Noise!



The VCA Twins



The Amp/Envelope Follower/Integrator

wendallsan
I've got a question about the 703C filter.

In the BOM, there is a 1u electro cap and a 1u NON-POLARIZED (NP) electro cap (that I had no idea such a thing existed). There isn't anything on the board to identify which is which. I assumed that the NP cap is the one identified as C15 on the board, and that C10 is the regular 1u electro cap. Is this correct?

A follow-up question about NP electro caps-- can I assume that if an electro cap doesn't have a 'negative' stripe on it or some other obvious indicator, is it safe to assume it is NON-POLARIZED? I do have several of these that showed up from the Mouser cart orders, and was wondering about that, as I had never seen a 'non-striped' electro cap before.

Many thanks! I look forward to plugging this in and calibrating it once I know I've got my caps in the right place. Work on the LFO boards has begun.
Modulart_JP
Quote:
In the BOM, there is a 1u electro cap and a 1u NON-POLARIZED (NP) electro cap (that I had no idea such a thing existed). There isn't anything on the board to identify which is which. I assumed that the NP cap is the one identified as C15 on the board, and that C10 is the regular 1u electro cap. Is this correct?


The NP 1u cap is C10 and there is "NP" written on the board beside it.

NP caps have no negative stripe and usually there is BP written on them as well.
Non-Polarized electrolytic caps are also called Bi-Polarized.
BadPixel
These look delicious hyper As a total 700 newb, which modules would be the optimal to begin with?
wendallsan
BadPixel wrote:
These look delicious hyper As a total 700 newb, which modules would be the optimal to begin with?


I am a total noob to this as well, and started with the simplest ones I could find in the series (aka the patch bay and the mixer). I've then been working my way up the food chain of complexity and haven't had any major issues other than my own ignorance of electronics, which I'm slowly overcoming. It's taking me at a guess 3-4 hours to build the 'complex' ones like the VCO's and LFO's, but it speeds things up to do 3 VCO's at once, etc, for what that's worth.

I've always wanted a System 700 and this is the 1st feasible opportunity I've been given, so I'm jumpin' on it! I'll have some more pics of the the latest modules soon.
BadPixel
Ah, sorry. Building is not the issue. I was more thinking in the lines which modules to choose for a basic 700 setup. A couple of VCO’s, a VCF, ADSR and an envelope?
wendallsan
About half of my VCO's are populated. I have a question about the 1k and 100k resistors. There are two types: the 0.1% "matched" ones and the regular 1% ones. Which ones go where on the boards?

And thanks for letting me know about the "NP" indicator on the filter board. I had totally missed that and yes, I did get my caps in the wrong place, so some desoldering is called for, but not too much at least and I'm glad I asked before I turned it on and smelled smoke!
Dead Banana
wendallsan
BadPixel wrote:
Ah, sorry. Building is not the issue. I was more thinking in the lines which modules to choose for a basic 700 setup. A couple of VCO’s, a VCF, ADSR and an envelope?


3 VCOs, 2 LFOs, 2 VCAs and 1 of everything else will get you a close approximation of a "block 1"
hyper
BadPixel
Awesome thumbs up and yeah don’t let the magic smoke out wink
Modulart_JP
Quote:
About half of my VCO's are populated. I have a question about the 1k and 100k resistors. There are two types: the 0.1% "matched" ones and the regular 1% ones. Which ones go where on the boards?


The info is in the build notes PDF.

Quote:
Ah, sorry. Building is not the issue. I was more thinking in the lines which modules to choose for a basic 700 setup. A couple of VCO’s, a VCF, ADSR and an envelope?


A good start would be the Laboratory System config.

BadPixel
Modulart_JP wrote:
A good start would be the Laboratory System config.



Just what I was looking for, thank you thumbs up
wendallsan
Modulart_JP wrote:
Quote:
About half of my VCO's are populated. I have a question about the 1k and 100k resistors. There are two types: the 0.1% "matched" ones and the regular 1% ones. Which ones go where on the boards?


The info is in the build notes PDF.


D'oh! I didn't realize there was more than 1 page to that build notes PDF and hadn't noticed. Thanks for pointing that out.

I have a question about the rotary switch for the LFO now. I see in the Build doc how to wire it, but wanted to check if there is a 'right side' up to that switch or not. In other words, if you flipped it upside down from the photo in the build notes, would that matter at all? I don't see any indication on the switches as to what pin is "pin 1" and am concerned that I might wire it 'upside down' if such a thing exists.

EDIT: I see that there are 3 lugs on the inside ring of lugs on the switch and that those can be used to orient the switch to match what is shown in your illustration. Sorry for having missed that, no response is needed on this question.
d'oh!
wendallsan
I have finished building all the boards I've ordered to the best of my ability, and have arrived at the VCA's after finding several problems with my noise/ring mod module that I need to fix before testing further. I'm trying to calibrate it according to the build doc, but am confused by the instructions. It says:

Quote:

Linear adjustment:
The 1st step is the adjustment of the DC balance.
Set the switch to LIN, all pots to 0 and feed one of the modulation input with 10V.
Probe the VCA output with an oscilloscope (use high gain) and adjust the DC BAL trimmer so changing the CV amount produces minimum change


I have a David Jones O'Tool acting as voltage meter and a 2hp MIDI acting as CV source, which only seems to be able to output +5V. I have taken the following steps:

- set the switch to LIN
- set all the pots to '0'
- connected the 2hp module feeding a +5V source to the 1st modulation input
- turned up the 1st modulation input's pot to '10'/full

My expectation is that I can adjust the DC BAL trimmer so that it matches the voltage provided at the 1st modulation input (+5V). As I adjust the trimmer, the level comes to this value, but appears a little 'jittery' and seems like a very fine tune to arrive at it-- I'm not sure if this is typical or an indication of a problem. Once the output range is within view of the level meter (showing 0-6V DC), the slightest nudge on the trim pot seems to adjust it pretty widely, making it difficult to adjust in increments less than about 1-2 volts.

Once I have this set so that it is at the +5V level to match the provided modulation input, I figure a simple experiment would be to provide a changing voltage level to the modulation input to see if output is 'following' the input, which again is my best guess as to what should be happening. To my surprise, I see that the output slightly increasing as the input voltage drops. As the input voltage comes in at +5V, the output voltage is also at +5V, and then as the input voltage drops to 0 over the course of about 4 seconds, the output voltage raises to +6V. Likewise, adjusting the modulation input's pot down from full to 0 increases the output voltage from +5V to +6V.

Here's what I've done to troubleshoot so far:

- checked all solder joints
- checked resistance values and placement
- checked cap values, placement, and orientation
- checked diode placement and orientation
- checked transistor placement and orientation
- checked IC placement and orientation
- checked pot and trim values

All I can think to ask (and I shudder to do so, as I've done this on all the modules I've built) is that all my trims are on 'upside down' according to the silkscreen artwork, which allows them to match the positioning of the trim screw shown in the silkscreen art. All my trim pots have a screw at the left side of it, if I am looking at it from the 'front' (screw is facing me). In your artwork all the trims have their screw at the right side. My limited knowledge of electronics suggests the pot orientation doesn't much matter, as it's just adjusting between two points-- but you are welcome to tell me I'm wrong if this is possibly the issue.

Otherwise, I am open to suggestions on how I can begin testing this beyond the simple steps I've taken so far. The 'good' news is that I have built two VCA's, and they are both displaying this same issue, so if I can fix one, I should be able to fix the other with the same effort!
Modulart_JP
Your VCA is probably OK but your calibration is not.

The calibration procedure in the build notes is a copy of the one in the System-700 service manual and the 1st step is, in other words, the feed through adjustment.
In a perfect world, the CV's should not go through the VCA path.
In real life, it's different, there's a feed through and you get a very very small amount of the CV in the VCA path.
The goal is to minimize that.
With no signal in the inputs and a full CV (10V, not 5V) in 1 of the modulation inputs, you adjust the DC BAL trimmer so you get the smallest amount of CV at the VCA output.
Another way to do it is by ear.
With no signals in the VCA inputs, feed one CV input (amount fully CW) with an audio source (a VCO output, for example) and listen to the VCA output on your monitor system (headphone, speaker) with the volume very high so you can hear the very low level feed through signal.
Then adjust the trimmer so the level of that signal is at its minimum.
wendallsan
Modulart_JP wrote:
Your VCA is probably OK but your calibration is not.


I will take this as great news that my VCA's are PROBABLY working applause

I will take another pass at calibrating by ear, as my 2hp MIDI module appears to have no means to output more than +5V.

Thanks for the additional instruction on calibration, this is my 1st forray into eurorack and diy synths, so calibration is new to me.

NEXT QUESTION: would the C&K tactile switch available from Thonk work for the pushbutton on the ADSR? Alternately, would any parts from Mouser work for this? I realize I didn't wind up with a button and am putting together another order for parts, and would love to get all the remaining bits needed from Mouser if possible.
Modulart_JP
wendallsan wrote:
NEXT QUESTION: would the C&K tactile switch available from Thonk work for the pushbutton on the ADSR? Alternately, would any parts from Mouser work for this? I realize I didn't wind up with a button and am putting together another order for parts, and would love to get all the remaining bits needed from Mouser if possible.

The PCB is designed for that kind of switch.
Thonk carry them but you should be able to find them (or equivalent) locally.
wendallsan
As always, thanks for the answers. Soon I will run out of questions, because everything will be built and working!

Could I use the Amp portion of the Amp/Envelope Follower (EF)/Integrator to boost the +5V from my 2hp MIDI module up to +10V?

If so, I can focus on troubleshooting that module and then use it to test and calibrate the other modules properly. I've done some initial tests of this module and it appears that the amp portion is not working, although the integrator portion is working great. I have not tested the EF portion as the calibration instructions call for a 1khz sine wave at 10Vp-p, and that will take a little work for me to produce currently.

In my testing of the Amp portion of the module, feeding a CV or an audio signal into the Amp's input results in nothing being output from the amp out, regardless of position of the pot and switch involved in the amp. Additionally, the EF's green LED lights as soon as power is supplied to the module, probably also an indicator of something wrong.

I've taken the usual steps to troubleshoot this that I currently know to take, including checking solder joints, resistor values and placement, checked cap values, placement, and orientation, checked diode placement and orientation, checked transistor placement and orientation, checked IC placement and orientation, and checked pot and trim values. All components seemed to be properly placed and oriented.

Are you able to provide any suggestions on how to troubleshoot this, or alternately provide schematics for me to ATTEMPT to use to troubleshoot this on my own? Fortunately this is one of the more simple modules, so I'm hoping it'll be an easy fix.
Modulart_JP
You can contact me privately via my website.
I'm sure we'll figure out what's wrong.
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