The VCS3 Card : Every 208 / Easel needs a SYNTHI !

Discussing some incredible modules that don't quite fit into the other forum categories.

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papz
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Post by papz » Mon Mar 25, 2019 11:55 am

Yes, the cause is the Easel's own +/-15V power rails derivated from the external block's +12V, the internal PSU is too weak. A powered Hub is a good solution and doesn't need any intervention to the Easel.

A local friend has an early BEMI Easel and has been using a VCS3 Card prototype together with a ToolBox and a BOB expander on an unpowered Hub for a long time. He didn't report any problem but I'll ask him to confirm and let you know.
Because of the PSU this Easel's outputs were noisy and weak (PSU and 1/4" jack outputs are on the same PCB), I could fix it by disconnecting the 1/4" jack sockets from the PCB and connecting them in parallel with the 208's tinijax outputs with shielded cable. When I serviced it I noticed that the tuning of the complex and modulation oscillators was also slightly affected when the ToolBox only was inserted, but I can't remember if this was before or after working on the PSU.

My guess is the behaviour depends on each unit and I'm afraid there's no other alternative than test the ToolBox and VCS3 Card together and see what happens.
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Post by bcomnes » Mon Mar 25, 2019 12:25 pm

Papz...Thanks for your comments, we shall see what happens when my vcs3 card gets here....
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Post by papz » Mon Mar 25, 2019 12:31 pm

If you plug your ToolBox while the Easel is on, does it affect the pitch ?
It's safe doing it as long as the ToolBox is inserted vertically, not at an angle, to avoid the risk of shorting 2 contacts.
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Post by bcomnes » Mon Mar 25, 2019 12:46 pm


If you plug your ToolBox while the Easel is on, does it affect the pitch ?
It's safe doing it as long as the ToolBox is inserted vertically, not at an angle, to avoid the risk of shorting 2 contacts.


Well I'll try that later when the caffeine is worn off so I don't get hand shake,

:hihi:


If the pitch changes what does that mean?

My BEMI Easel is very early edition, it was one of three demo units that went to NAMM on their first release.
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Post by papz » Mon Mar 25, 2019 2:19 pm

If the pitch changes means the PSU likely has some difficulties with the extra load and using both the ToolBox and VCS3 Card together may cause issues like Umcorps reported.

My friend said he also experienced an envelope looper issue at some point but it fixed "on its own", he'll check again. I'll give it a look next time we meet.
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Post by Minimoog56 » Wed Mar 27, 2019 7:39 pm

My tool box and synths cards play fine together with my 208r2. Loving this dual card setup. Frees up the mod Osc to do just that. Great design on this Osc - intuitive interface and integrated timbre with easel Osc. Papz, what is the size of the bolts for the standoffs?
Last edited by Minimoog56 on Thu Mar 28, 2019 3:08 am, edited 1 time in total.
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Post by Minimoog56 » Wed Mar 27, 2019 7:40 pm

:yay:
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Post by papz » Wed Mar 27, 2019 8:06 pm

Thanks !
The bolts are M3, 4mm long.
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Post by Minimoog56 » Sun Mar 31, 2019 8:05 am

:bang:
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Post by papz » Sun Mar 31, 2019 12:04 pm

Thanks for confirming.

Only the early BEMI Easel PSU seems too weak, the later ones and clones using Mean Well PD2515 or 211r are ok.

I measured the VCS3 Card's consumption, it's 55mA on +15V and 50mA on -15V.
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Post by darmklacht@gmail.com » Sun Mar 31, 2019 2:38 pm

FWIW I have a rev 2 powersupply in my BEMI Easel and it powers the card without a problem.

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Post by slam » Mon Apr 01, 2019 2:44 am

papz wrote:Thanks for confirming.

Only the early BEMI Easel PSU seems too weak, the later ones and clones using Mean Well PD2515 or 211r are ok.

I measured the VCS3 Card's consumption, it's 55mA on +15V and 50mA on -15V.
How do you tell the difference?

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Post by papz » Mon Apr 01, 2019 3:17 am

The VCS3 Card on its own works on any Easel, even early BEMI with a weak PSU.
The weak PSU problem occurs when a second card is connected together with the VCS3 Card only, using the rear edge connector, passive Hub or card doubler.

The simple test I explained above is a good indicator : if plugging in a card causes a pitch change, the PSU is weak and problems may occur if the VCS3 Card is connected together with another card.

Anyway, the problem can be bypassed easily thanks to a powered Hub with own PSU to avoid extra load on the Easel's one.

More technical details on the BEMI Easel revisions :
Drillionaire wrote:There have been different revs of almost every part of the easel, and they were all updated at different points, so you won't find an easel with a single applicable revision.

208:
Several cards have been updated.
• The 1B Sequencer card got a resistor change to make the 3-step length more reliable (R4 was changed from 100k to 120k)
• The 6B and 7B cards have had multiple revisions. Initially there was a socket for NOS ua726 transistor pairs.
• When those were replaced with SSM2212 transistor pairs, initially there were adapter boards made, and an extra trimmer was added to the middle of the board.
• Another revision was made and the trimmer was added to the edge of the PCB like the other trimmers on the 208 daughter cards.
• The most recent revision (as far as I know) is the removal of the socket, and the placement of the SSM2212 directly on the PCB. For this revision, a tempco resistor replaced one resistor each on the 6B and 7B cards. This resistor is a green 0804 package compared to the 1206 black resistors used everywhere else. These resistors make it so the drift over the warm up period of the easel is less than a quarter semitone. These resistors can be added to any 6B and 7B cards that don't have a real ua726 in them, and combined with the improved linearity of the SSM2212 compared to the ua726 provide the best tracking for the oscillators in the easel.
• The 208 motherboard was updated to add some extra grounding around the mod oscillator traces to reduce bleed into the reverb return path. The resistors to reduce the level of the headphone output were also relocated from the jack to the PCB.

218:
There has been one revision of the 218e to add sustain pedal and MIDI out functionality. The sustain pedal functionality is achieved with a pull-up resistor and newer firmware that can be added to an earlier revision 218. The MIDI out functionality is achieved through a level shifter to get the MIDI serial data to a 5v level compliant with the MIDI standard. The newer revision is discernible by it saying "Model 218e" instead of "Model 218" on the top of the panel.

Easel Case Power:
There have been a number of revisions of this board as well.
• The earliest board uses monolithic switching power supply ICs and the -15v rail had ~500mV of 'noise' in the form of a triangle wave. Some of these had a resistor and capacitor removed that fixed the fluctuation of the negative rail, but still had switching noise issues that were audible in the output.
• The next revision had a single DC-to-DC regulator brick that generated the ±15v rails, and a linear regulator for the 5v rail. These power supplies and all subsequent revisions do not have noise issues. The linear regulator for the 5v rail is not capable of producing enough current for a 223e in the lower boat (and probably other combinations of 200e modules as well) and needs to be updated to a switching regulator rated for higher current in order to use an easel case with this power supply for an Easel-K or a LEM208 type of setup.
• The next revision had the same DC-to-DC converter brick and added a second linear regulator for the 3.3v rail necessary for the h-series. Additionally an h-Series power connector was added. Due to a silkscreen error on the PCB, a capacitor and resistor were swapped, and the 3.3v rail was actually 10v. If you have an example of this power supply before the mistake was caught and the 3.3v regulator and h-series power header removed, DO NOT use it with h-series modules, as it will destroy their CPUs. The linear regulator 5v rail issue of the above revision applies to this one as well.
• The most recent revision of the power supply has the DC-to-DC converter brick for the ±15v rails, and switching regulators for both the 5v and 3.3v rails, with sufficient current for an Easel-K or LEM208 setup. These PCBs are marked "EASEL POWER SUPPLY REV3". They also have a replaceable fuse, a header to get MIDI from the DIN jack on the side to a 225e/h, and a jumper to select functionality of one of the 1/4" jacks to be a sustain pedal input for the 218e, or a second audio output, as on the earlier easel case/power revisions. There is also a slot for the USB firmware/MIDI/memory card like on the 200e cases and LEM218.
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Post by papz » Mon Apr 08, 2019 11:53 am

Today a customer reported power issues using the VCS3 Card on its own with an early BEMI Easel :
The envelope doesn’t cycle anymore in self mode
When I use it in triggered mode to control the LPG there always remains some voltage that keeps the LPG a bit open and a low level constant sound plays
The whole easel sounds overall a little bit different (maybe the oscillators change their tune a little bit)
One could ask Buchla USA for a more recent upgraded PSU board but it may take long and be expensive, so I updated the build notes with info to add a dedicated PSU inside the Easel leaving the original one untouched for those who are not interested in a powered Hub, which is a bit overkill if no other card is used.
This upgrade should be performed only by those experienced in electronics who know what they're doing.
http://www.portabellabz.be/images/vcs3/ ... _notes.pdf

Sorry about these issues, BEMI didn't do the best job with their Easel. :zombie:
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Post by weinglas » Sun Apr 14, 2019 5:48 am

This really is a must have especially for owners of a Sputnik 208 rev1
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Post by papz » Sun Apr 14, 2019 6:12 am

Thanks for the pic and kind words :chug:
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Post by Minimoog56 » Sun Apr 14, 2019 4:14 pm

How a bout a Synthi Trapazoidal AD card with Filter?
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Post by captnapalm » Sun Apr 14, 2019 4:44 pm

I finished mine this week; great item as usual Papz!

The only problem I had that I think I should mention for others is that I used a star washer under the nut to secure the edge connector as shown below. The +15 trace is right next to the ground plane, and my star washer shorted them together. Once I removed it and used a small split washer everything was fine :cloud:

Image

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Post by papz » Sun Apr 14, 2019 5:16 pm

Thanks for the feedback.

Yes I noticed it too and updated the build notes about 2 weeks ago to recommend the use of a nylon washer or no washer. I had a short with a flat washer because the solder mask was scratched, it is not enough for proper insulation.

In the next batch there will be no ground plane in this area and the +15V trace will be moved.

Image
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Post by captnapalm » Sun Apr 14, 2019 5:56 pm

papz wrote:Thanks for the feedback.

Yes I noticed it too and updated the build notes about 2 weeks ago to recommend the use of a nylon washer or no washer. I had a short with a flat washer because the solder mask was scratched, it is not enough for proper insulation.

In the next batch there will be no ground plane in this area and the +15V trace will be moved.
Ah nice, I didn't see that in the build notes but I was probably using an older revision I had downloaded earlier. I figured it was my own fault for not being more careful, but thanks for being on top of it!

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Post by bcomnes » Sun Apr 14, 2019 6:38 pm

Do have a picture of that PSU mod in the build notes,

i'm getting a powered hub, but would love to see what the mod looks like
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Post by papz » Sun Apr 14, 2019 7:39 pm

No pic sorry, I didn't do this upgrade in a BEMI Easel yet (why the mounting instructions are not detailed). It's a solution that I imagined to help the aforementioned customer but I might do it some day in an Easel, then I'll take pics.
It's basic and easy : a small brick like the one used on the Hub, 2 wires to the DC socket, 2 wires to the edge connector, 1 wire to 0V.
The small brick is installed inside the Easel rather than on the Hub and could even be simply glued to the bottom of the 218 boat, but this is not the sexiest way.

Image

No modification to the original circuitry except desoldering 2 pads of the edge connector, which is a very minor modification. It's more an addition than a modification. 100% reversible.
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Post by papz » Sun Apr 14, 2019 8:08 pm

Minimoog56 wrote:How a bout a Synthi Trapazoidal AD card with Filter?
I've been thinking about it for a while ;)
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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.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

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Post by bcomnes » Sun Apr 14, 2019 9:35 pm

Thanks for that additional info, I just get nervous about farting around with a $5000 synth,
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Post by papz » Mon Apr 15, 2019 5:00 am

I understand.
All is relative though :mrgreen:
I regularly service and modify synths that may sell for 15k or even more and find it relaxing to work on a 5k "only" one. :lol:

I'll do the PSU upgrade in a BEMI Easel on Friday and I'll post pics.
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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