CGS Serge VCF '73 filters input leaks
2018-10-13 by 81ed0892d158dae1c4002fd7e00f9f17
CGS Serge VCF '73 filters input leaks through the bandpass and high pass outputs. The low pass sounds normal. Any idea what this can be? thanks! Floris
Messages
Browse messages
Page 1 of 114 · 5656 messages matched
Re: LPG
2018-10-12 by Mike Burnham
Thanks guys It turns out that the problem was a bad thru connection at the Molex connector itself There are traces on both sides of the board and the thru plating was not working or stopped working! I need a right angled header to make sure both sides are adequately soldered to t
Re: LPG
2018-10-11 by Richard Brewster
If I were building this board, I would draw my own schematic from it. I wouldn't publish a schematic that isn't publicly available, but if you bought the board I feel it's within your rights to understand it. I see this board is currently available from Modular Addict. CGS / EAR
Re: LPG
2018-10-11 by Ken Stone
No. Peter G didn't release it. On Thu, Oct 11, 2018 at 3:54 AM Mike Burnham mikejburnham@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: Is it possible to get a schematic for the full LPG BOARD I am building 2 on one chassis piggy backing the power from one to the other. It wo
LPG
2018-10-10 by Mike Burnham
Is it possible to get a schematic for the full LPG BOARD I am building 2 on one chassis piggy backing the power from one to the other. It worked fine for 10 minutes then dropped the +15v rail. without the traces or schematic it's hard to troubleshoot Sent from my iPhone
Re: VCS
2018-10-05 by Ken Stone
Yes, without those caps changed, it will only oscillate at low frequencies. There is a resistor change there too. 150k to 100k from memory, On Fri, Oct 5, 2018 at 11:10 PM Mike Burnham mikejburnham@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: Trying to compete a Voltage con
VCS
2018-10-05 by Mike Burnham
Trying to compete a Voltage controlled slope I have rev 1.0 boards I can't get it to oscillate/cycle. Is it important to change the 10nf caps on the trigger inputs to 1nf? I overlooked this when I was stuffing the boards Thanks
CGS Serge VCF '73 filters input leak
2018-09-30 by Floris V.
Dear, my CGS Serge VCF '73 filters input leaks through the bandpass and high pass outputs. The low pass sounds normal. Any idea what this can be?
Re: SERGE NOISE
2018-08-11 by Ken Stone
Scope or ears. On Sat, Aug 11, 2018 at 1:32 AM, Mike Burnham mikejburnham@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: Is there any way to test the noise circuit without a true RMS multimeter? -- Ken Stone otherunicorn@...
CGS88 - one channel not working
2018-08-10 by richs19
I'm troubleshooting 2 CGS88s I've built that both seem to be doing the same thing. I've built them up as Triple Bi-Directional Routers. I've added the 3 position switches and I'm taking +15 off the positive Bead. The channels connected to U3 and U4 work fine. They flip the inputs
SERGE NOISE
2018-08-10 by Mike Burnham
Is there any way to test the noise circuit without a true RMS multimeter?
Re: Digest Number 1980
2018-08-04 by Dmitri SFC
if its not the first rev of the board you can use bi polar LEDs its pretty cool lookin! google "richard brewster pugix cgs ssg" On Sat, Aug 4, 2018 at 3:37 AM, cgs_synth@yahoogroups.com > wrote: CGS synthesizer support group Group 3 Messages Digest #1980 1a LEDs on SSG by "Mike B
Re: LEDs on SSG
2018-08-04 by Mike Burnham
Gotcha thanks Sent from my iPhone On 4 Aug 2018, at 16:29, charles kerr thebadproducer@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: The Original SSG may not have had any LEDs, or if it did, just LEDs for SMOOTH and STEPPED outputs. Ken has added an LED for the COUPLER outpu
Re: LEDs on SSG
2018-08-04 by charles kerr
The Original SSG may not have had any LEDs, or if it did, just LEDs for SMOOTH and STEPPED outputs. Ken has added an LED for the COUPLER output too - it's all shown on the schematic. You don't have to fit any or all LEDs to your panel. http://loudestwarning.tumblr.com/ On Saturda
Re: LEDs on SSG
2018-08-04 by Mike Burnham
I can only see 2 LEDs on the front panel From: cgs_synth@yahoogroups.com on behalf of Ken Stone otherunicorn@... [cgs_synth] Sent: 03 August 2018 23:33:37 To: cgs_synth@yahoogroups.com Subject: Re: [cgs_synth] LEDs on SSG Just a BOM error, 3 are used. On Sat, Aug 4, 2018 at 7:39
Re: LEDs on SSG
2018-08-03 by Ken Stone
Just a BOM error, 3 are used. On Sat, Aug 4, 2018 at 7:39 AM, Paul Bower paul@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: What does the schematic say ? Could be a typo in the BOM On 3 Aug 2018, at 21:11, Mike Burnham mikejburnham@... [cgs_synth] cgs_synth@yahoogroups.com >
Re: LEDs on SSG
2018-08-03 by Paul Bower
What does the schematic say ? Could be a typo in the BOM On 3 Aug 2018, at 21:11, Mike Burnham mikejburnham@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: A bit confused why there are 3 RLed on the pcb but only 2 on the BOM Sent from my iPhone This email has been scanned by N
LEDs on SSG
2018-08-03 by Mike Burnham
A bit confused why there are 3 RLed on the pcb but only 2 on the BOM Sent from my iPhone
Re: A couple of parts questions
2018-07-08 by Ken Stone
Agreed. When I was shipping transistors with my PCBs, it was not the loudest that I chose, but rather the one that put the signal level where I wanted it. On Sun, Jul 8, 2018 at 3:01 PM, Andre Majorel aym-htnys@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: On 2018-07-06 11:0
Re: A couple of parts questions
2018-07-08 by Andre Majorel
On 2018-07-06 11:04 +0000, mikejburnham@... wrote: > For the Serge Noise circuit it specifies the noise transistor > as 2n/PN4250 but these are stupidly expensive nowadays > > Is it possible to use BC557? Are they noisy enough? BC557C > probably best? Not a month ago, Tony Allgoo
Re: A couple of parts questions
2018-07-06 by Mike Burnham
Thanks for the heads up on AS394 Are these known to be good? Sent from my iPhone On 6 Jul 2018, at 13:32, JAMIE logan jammie.emma@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: using matched pair . 1/ there matched for you. 2/ because they are on same die the first thermal er
Re: A couple of parts questions
2018-07-06 by Mike Burnham
Can any small signal PNP be used? Sent from my iPhone On 6 Jul 2018, at 12:54, Ken Stone otherunicorn@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: You may have to try a lot of different transistors to get one that is noisy enough. I selected the 4250 because they were all n
Re: A couple of parts questions
2018-07-06 by JAMIE logan
using matched pair . 1/ there matched for you. 2/ because they are on same die the first thermal error is cancelled. which is perfect for vca. 3 / Erica synths sell the https://www.ericasynths.lv/shop/diy/diy-accessories/as394-matched-transistors/ for cheap. time is money and mat
Re: A couple of parts questions
2018-07-06 by Boris Klompus
I'm not sure about the latter question - I assume the 2 matched transistors would be fine - but mouser stocks PN4250A. it's nearly identical according to the datasheet, just has higher capacity for collector-base voltage, and collector emitter voltage. The price is $0.41/ea: http
Re: A couple of parts questions
2018-07-06 by Ken Stone
You may have to try a lot of different transistors to get one that is noisy enough. I selected the 4250 because they were all noisy to the point of some of them being too noisy. For transistors, the better the matching, the better they work - less bleed through. Try them and see
A couple of parts questions
2018-07-06 by Mike Burnham
Hi there For the Serge Noise circuit it specifies the noise transistor as 2n/PN4250 but these are stupidly expensive nowadays Is it possible to use BC557? Are they noisy enough? BC557C probably best? The VCA specifies a matched transistor package Would matched 2N3904 be OK? Or do
Re: touch pads with old programmer problem
2018-06-07 by Ken Stone
Not sure why that would happen. The old programmer is essentially the same circuit as the later ones I did. Try adding a capacitor between the output of the the touch pad and the input of the programmer, along with a pull down resistor at the programmer side. On Fri, Jun 8, 2018
touch pads with old programmer problem
2018-06-07 by babyd_lhp
trying to use the touch pads with the old programmer, the programmer wont step via a clock though i tested programmer without the touch pads & confirmed as working. Any idea why ? Am connecting the gate outputs of the pads to the PB connection on programmer.
Re: Random switch transistors
2018-05-25 by Ken Stone
"generic NPN" so, yes, other types will work. Ken On Fri, May 25, 2018 at 7:44 PM, Mike Burnham mikejburnham@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: Hi there The transistors in the output buffers are specified BC547. I don't have any in stock and I wanted to finish thi
Random switch transistors
2018-05-25 by Mike Burnham
Hi there The transistors in the output buffers are specified BC547. I don't have any in stock and I wanted to finish this Can I use BC550? Or if not 2n3904? Thanks
Re: CGS85 Bottom Channel Problem
2018-05-17 by richs19
Thanks for the suggestions Ken. I removed the wire coming from the input jack, the potentiometer and the wire going from the pot to the PCB (pad A). This was the problem zone. After testing and determining this I replaced both wires and the pot, wired them in (and added the Groun
Re: CGS85 Bottom Channel Problem
2018-05-17 by Ken Stone
The only thing that could make sense is that you either have the wrong value for the output 330R resistor, or there is a fault in the wire to the jack, or in the jack itself. Ken On Thu, May 17, 2018 at 5:17 AM, richs19@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: Thanks fo
Re: CGS85 Bottom Channel Problem
2018-05-16 by richs19
Thanks for your reply Ken. I’ve triple checked the orientation of the diodes against the PCB and against the working module. Ditto for the other components. I swapped the LM3900 with the same results. I can’t see any obvious error although it’s obvious I’ve made one. I took some
Re: CGS85 Bottom Channel Problem
2018-05-15 by Ken Stone
Check for diodes that are in backwards would be my first guess. If your chips are in sockets, swap the "bad" one to the working unit and see if it works correctly. Check your other component values. If it is none of those, have a very close look at the PCB itself, to see if there
CGS85 Bottom Channel Problem
2018-05-15 by richs19
I'm troubleshooting a CGS85. I was going through the calibration procedure and the first two channels worked fine. I was using an input of 4.2V and was able to calibrate the outputs to match the inputs. When I got to the third (the bottom on the wiring diagram - furthest from the
Re: CGS90 Phaser
2018-04-12 by andrew buscher
Good Morning. Pin 6 varies between 0 and .475V with the phase pot (LEDs brighter). Pin 9 stays at .467 Thank You -Hans Buscher 310-776-0143 text On Apr 12, 2018, at 12:25 AM, Ken Stone otherunicorn@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: Also, what is the voltage at pi
Re: CGS90 Phaser
2018-04-12 by Ken Stone
Also, what is the voltage at pins 6 and 9? Does it run cooler when the voltage at pin 6 is higher? On Thu, Apr 12, 2018 at 5:22 PM, Ken Stone otherunicorn@... > wrote: A genuine Vactrol has a LED voltage drop of 1.6 V per LED. I am betting you are using LEDs with 2V or more drop.
Re: CGS90 Phaser
2018-04-12 by Ken Stone
A genuine Vactrol has a LED voltage drop of 1.6 V per LED. I am betting you are using LEDs with 2V or more drop. Put some 1N4148 or a LED or two in series in the other leg of the circuit to drop the voltage across the overheating transistors. On Thu, Apr 12, 2018 at 4:28 PM, andr
Re: CGS90 Phaser
2018-04-12 by andrew buscher
Hi John. I'm using the Excelitas Technologies VTL5C3/2. When the circuit started getting hot I swapped them with plain orange LEDs In case a transistor shorted. For now I'm ignoring the phasing part until I can get the led driver part working. Other than the heat and high current
Re: CGS90 Phaser
2018-04-12 by john slee
Hi, You could feasibly have a different max resistance across the CdS cell in your DIY vactrol**, vs. the max resistance across the cells in the VTL vactrols? You'll need to do some measuring ** I assume by "plain 3mm LEDs" you actually meant "CdS cell + 3mm LED inside a bit of b
Re: CGS90 Phaser
2018-04-12 by andrew buscher
Thanks for the replies guys. The vactrols are Excelitas Tech. I'm using plain 3mm LEDs to avoid blowing the VTLs till I figure this one out. Maybe hot is just how it's supposed to be. :) Thank You -Hans Buscher 310-776-0143 text On Apr 11, 2018, at 5:39 PM, JAMIE logan jammie.emm
Re: CGS90 Phaser
2018-04-11 by JAMIE logan
if your using xvive vactrols your need 2 trimmers to get them to act right and its better to use 2 singles than the dual types. as the variation is so large. first trimmer is for current limiting the xvive use brighter leds so on the 208 redesign we did we added current limit tri
Re: CGS90 Phaser
2018-04-11 by Ken Stone
I wonder if the voltage drop of whatever you are using as Vactrols is different to genuine vactrols. Are you using genuine or the recent "clones"? On Thu, Apr 12, 2018 at 10:15 AM, andrew buscher hansbuscher@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: Hello again. I checke
Re: CGS90 Phaser
2018-04-11 by andrew buscher
Hello again. I checked the board, resistance values and it follows the schematic. I went ahead and breadboarded the same circuit and get the same result. The 3 240R resistors and the paired transistors get hot. Circuit still draws 33ma. Head Scratcher... Thank You -Hans Buscher 3
Re: CGS90 Phaser
2018-04-11 by Ken Stone
Check the values of the other resistors, and look for shorts etc. Something is turning on the transistors way harder than they should be. On Wed, Apr 11, 2018 at 5:29 AM, andrew buscher hansbuscher@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: Hello. Recently built this phas
CGS90 Phaser
2018-04-10 by andrew buscher
Hello. Recently built this phaser. It works but the 3046 and 220Rs get quite hot. I swapped the 3046 with BC550s in 4 positions and the 123 transistor is boiling. When manipulating the Phase control I get a +2.2v to +4v swing at pin 8. With only the 3046 and vtl5c3/2s in, the cir
Re: CGS116 Serge Extended ADSR transistors
2018-04-08 by Ken Stone
I expect they will work just fine. Ken On Sun, Apr 8, 2018 at 6:25 PM, mauro.tondini@... [cgs_synth] cgs_synth@yahoogroups.com > wrote: Hi, i'm building CGS116, and have some 2n3904-3906 matched transistors, can i use them instead PN3565-PN4250? Thanks Mauro -- Ken Stone otheruni
CGS116 Serge Extended ADSR transistors
2018-04-08 by mauro.tondini
Hi, i'm building CGS116, and have some 2n3904-3906 matched transistors, can i use them instead PN3565-PN4250? Thanks Mauro
Re: ASR alignment
2018-03-12 by Ken Stone
It may well be better to just use LF356, as those are meant to have much smaller offsets. Some 3140 I have since received were so bad I could not trim their offsets at all. On Tue, Mar 13, 2018 at 1:21 AM, Mike Burnham mikejburnham@... [cgs_synth] cgs_synth@yahoogroups.com > wrot
ASR alignment
2018-03-12 by Mike Burnham
Connect a constant voltage to the input. Connect one output to a VCO and the Clock input to an LFO or clock running at a few hertz. You should get a constant tone. If there is a stepped warble, one of your ICs has a different offset to the others. You can work out which chip it i