VCS3 Card for 208 and Easel build thread

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papz
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VCS3 Card for 208 and Easel build thread

Post by papz » Wed Feb 27, 2019 2:02 pm

Last edited by papz on Thu Aug 22, 2019 3:25 pm, edited 5 times in total.
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I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
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jonny_w
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Post by jonny_w » Wed Feb 27, 2019 2:32 pm

Awesome! Any plans on offering a black version to match my Toolbox, BOB, and Easel set? Blue is fine of course, but I had to ask :mrgreen:

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Post by papz » Wed Feb 27, 2019 2:54 pm

Thanks
No plan on a black version, sorry.
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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pathein
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Post by pathein » Thu Feb 28, 2019 7:34 am

have just ordered the pcb and looking around for the non tayda parts,

for the metal can NPN supermatched pair(2N2916 or MAT02 or LM394 or KC811)

most are hard to get from where i am and worried bout fake old parts of sort. Then i saw cabintech has the as194H/394H (194H)

Hi papz, was wondering for this part, will it be critical together with the 1k tempco, as in using the 194H instead of 394H.

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Post by papz » Thu Feb 28, 2019 11:14 am

Thanks for your order, I posted it today.

I haven't tested this 194H but it should work, in fact any metal can NPN supermatched pair should be ok, or even 2 matched NPN transistors glued together, as it was in the early Synthi A and VCS3 (but this may reduce tracking accuracy and stability).

I just tested cheap MAT02EH purchased on ebay (seller adeleparts2010), probably are fakes because the labeling is different and their hFE is much lower than real ones that I have (the Chinese one is 171, the real one 662) but the pinout is ok, the pair is properly matched and I could get a perfect tracking over 5 octaves.
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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heapish
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Post by heapish » Thu Feb 28, 2019 9:56 pm

Jaw on the floor :hail:

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Post by pathein » Mon Mar 04, 2019 9:30 am

Thanks Papz, for the pcb and info on the transistors!

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Post by papz » Mon Mar 04, 2019 10:11 am

You're welcome, happy building !

I just modified the card edge connector of Jerome's 208r rev1 to fit in the VCS3 Card and it works perfect.
I'll post the modification details on my website soon.
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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Post by papz » Tue Mar 05, 2019 8:37 am

I updated the build notes with
208r rev1 program card slot modification
CO dedicated output modification (the CO is a great master for the VCS3 Card oscillator sync input)
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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Post by papz » Thu Mar 21, 2019 7:21 am

I updated the build notes with some helpful info.
Happy building.
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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Post by papz » Tue Apr 09, 2019 10:29 am

Still no questions despite 15 DIY PCB sets were sold ?
Hopefully this means no builder had problems. :tu:

In a batch of KC811 with code A50 and A40, many cause small jumps in the oscillator pitch, mostly noticeable in high frequencies, and others are ok.
These supermatched pairs are cheap and good working when ok but need selection on test, it may be better to buy another type if you plan to buy only one.

I ordered some AS394 from https://www.ericasynths.lv/shop/diy/diy ... ansistors/ and will test in a few days.
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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jonny_w
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Post by jonny_w » Sat Jun 08, 2019 5:50 pm

Guess I'll be the first :mrgreen:

I'm getting no output on anything, no LED indication from the card. Here are some findings:

LM7812 output: +12.2V
LM7909 output: -9V

All TL072 cards are showing a Vcc of +14.3V/-14.4V

Pictures:
Image
Image
Image
Image

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Post by papz » Sun Jun 09, 2019 12:27 am

The measured voltages are ok. The TL072s are powered separately.
No noise or random output is normal as long as the SOT 2N5172 is not in place.

Check all solder joints for bad solder or bridges (I seem to see one between the top lead of the BC214L located between the 2 shape resistors and the 330pF cap located above it) and clean the flux.

Check all transistors are the right type and there's no 2N5172 in place of a BC214L or vice versa.

Are you sure of the LM394 provenance, is not a fake ? Did you test it ?
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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jonny_w
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Post by jonny_w » Sun Jun 09, 2019 1:33 pm

Good eye! It *was* a solder bridge at the BC214L. Fixed it and now it's come to life. Thanks! :tu:

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Post by papz » Sun Jun 09, 2019 3:59 pm

:sb:
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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jonny_w
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Post by jonny_w » Mon Jun 10, 2019 12:44 am

After calibrating, it seems everything works except for my random.

The mini slide switch is toggled down, and I'm not getting random CV output. Any suggestions on what to check?

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Post by papz » Mon Jun 10, 2019 12:47 am

Do you clock the random via the 208's inverter "to prog" socket ?
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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jonny_w
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Post by jonny_w » Mon Jun 10, 2019 7:25 pm

papz wrote:Do you clock the random via the 208's inverter "to prog" socket ?
I was plugged into the "from prog" socket :doh:

All good now! I love this thing. Such a great compliment to the Toolbox & 208 :tu:

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Post by papz » Wed Jun 12, 2019 2:33 am

So do I :party:
Thanks for the feedback !
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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Post by papz » Sat Jul 06, 2019 8:23 am

papz wrote:I ordered some AS394 from https://www.ericasynths.lv/shop/diy/diy ... ansistors/ and will test in a few days.
I finally tested one, sorry for the delay. :oops:
It works very good, I'll recommend it in the BOM. :tu:
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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Question about Oscillator Freq and tracking calibration

Post by eveready9v » Thu Aug 01, 2019 9:13 pm

So in the calibration manual it says:
"Allow about 10 minutes warm up for better stability.
With the "frequency" and "fine" panel pots at mid-course, adjust the "frequency" trimpot to get about 100Hz."
Do I do this with the switch set to Hi or Low? I'd imagine its Low but I just wanted to double check.
Thanks
Barry

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Post by papz » Fri Aug 02, 2019 6:46 am

The tracking should be calibrated with the switch set to hi position.
Thanks for pointing this, I added this info to the calibration procedure.
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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davebr
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Post by davebr » Tue Aug 20, 2019 12:20 am

I just built one of these for a client. I posted photos and scope images on my Portabellabz VCS3 Card page.

Dave

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Post by papz » Tue Aug 20, 2019 10:44 am

Thank you Dave :tu:
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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Post by papz » Wed Dec 04, 2019 10:38 am

The random voltage and noise amplitudes on the white banana jack are set by the resistors next to the TL072 in the top right corner. Some may want to increase it.

The 120k and 240k resistors to the left set the random amplitude :
Image

The 120k and 330k resistors to the right set the noise amplitude :
Image

Image
The 240k and 330k resistors are R1.
The 120k resistors are R2.

Reducing R2 will increase the amplitude. This is the easiest solution if the VCS3 Card is already built : add a resistor (select value on test) in parallel to the rear of the PCB. This ay no need to take the card apart.
The brave ones may prefer to unsolder the resistor and put a new one in place.

The other way is to increase R1's value.

In an unfinished build, you can test various values for R1 or R2 to find the gain that best suits your needs prior to soldering.

Beware that increasing the noise amplitude will also increase the random one and you don't want to overdrive the circuit.

To increase the random amplitude only keeping the noise one as is, don't touch the noise resistors but change the random ones only.



The noise is routed to the mixer separately, to increase its amplitude sent to the mixer you can reduce the value of the 120k resistor in series with the noise level pot wiper, soldering a resistor in parallel to the rear of the PCB :
Image

Beware that if the noise is too loud, it might happen to bleed into the mixer even with its level pot set to 0.
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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