Build a buchla 208 rev2

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boops
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Build a buchla 208 rev2

Post by boops » Mon Dec 08, 2014 9:40 am

I start this topic to concentrate the infos of this built
Thanks to xewin ,Alka Who share their experience .
Mine is finished,i ve worked deeply on this,and hope help everybody Who need..

MOD .There are several calibrations,by example the threshold of the step seq...mine in position 3 gave me a 2 steps ,than with the decade resistor i found the resistor to have the 3 steps..270k ..then with a little switch and the first resistor,200k ,i have now the following :step/2/3/4/5 Great...

MOD Complex Osc bleed in reverb. replace the return from the reverb to the input of the IC of the last board 12 by a shielded cable and cuted the original PCB trace. Now the reverb is quiet


TIPS
Build your mother board...
With the original schematic built the 13,5 V only on the board 3 ,then build your board 4 ,the pulser,then board 1 seq ,then board 2 random ,interface keyboard...finish board 3 ....test all these logic boards

Build your board 12 output dont solder the lm 380 use only the audio output with the 4136 to check

Then build board 6 mod osc,and LPG 2 board 11 test with audio out tinyjacks

Then your board 5

Then all the complex osc boards 7/8/9
And board 10 LPG 2
Finished your board 12 assembled ....done



BECAREFUL FOR' THE UA 726 THE SQUARE ON THE PCB IS THE pin 1,ON THE UA726 THE NOTCH IS THE 10 ,V- IS THE 5 , V + the 8,triple check
Dont use spacers for seq leds....

Cut the switch solder pin under the board 11 ( can touch the transistor case)


MOD there are two missing traces:

1- from the Enable A of Board 3 (pin 15 on the motherboard) to the Enable A of Board 4 (pin 10 on the motherboard). Because my front panel was already mounted and we did not want to disconnect all the soldered banana jacks, etc., we connected a small thin teflon wire between the two pins on the exposed side that sits just underneath the daughter board connects when mounted. As the teflon hook up wire is so thin it does not interfere with the mounting of the daughter boards. I'll try to take a photo of this ASAP but until then you figure out the pin numbers by counting down the connector pins on the rear of the unit from the top.

2-

I ve worked to the second issue,miss a trace between key pulse out of board 2 to switch pulser pin Down right,same as Env switch ,you can find the key pulse here,easier to solder a wire between the two switches not tested i ve to debug my 208 before ,if some one can comfirm this before validation...

Now the control switch works as it should.


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BECAREFUL,IN MY BOARD 5 PIC ,THE VERTICAL ICS ARE BACKWARD !!!


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Do you use Jamma 56 edge connectors (Bom)cause there are not flats !!
then i cut them with a metal saw.

Put a small washer under...


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Last edited by boops on Wed Feb 04, 2015 7:46 pm, edited 6 times in total.
FS :custom buchla 203 style càbinet ,skiff new design,boat ,hardware for diy cabinet ,easel case ,new 1u to 10u to 56u and more. / New 208 buchla card 12 /
HQ small case buchla psu PCB
https://www.muffwiggler.com/forum/viewt ... 93#3118393
https://www.muffwiggler.com/forum/viewt ... highlight=

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fiocz
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Post by fiocz » Tue Dec 09, 2014 12:15 am

Many many thanks for this !!!! :hail:

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aethyr
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Post by aethyr » Tue Dec 09, 2014 3:31 pm

How does it sound?

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boops
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Post by boops » Tue Dec 09, 2014 3:45 pm

Really deep sound ....an audio demo very soon.... :bananaguitar:

I hope to upgrade the circuit around the rev ...or someone else perhaps...

new card 12 pcbs are available,forget to note here.

viewtopic.php?t=211862
Last edited by boops on Wed Apr 15, 2020 1:54 am, edited 1 time in total.
FS :custom buchla 203 style càbinet ,skiff new design,boat ,hardware for diy cabinet ,easel case ,new 1u to 10u to 56u and more. / New 208 buchla card 12 /
HQ small case buchla psu PCB
https://www.muffwiggler.com/forum/viewt ... 93#3118393
https://www.muffwiggler.com/forum/viewt ... highlight=

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lamouette/rck
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Post by lamouette/rck » Tue Dec 09, 2014 3:57 pm

waiting my pcb, ordered for the black friday. and start the beast !
Setup is never done.

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Post by Miso » Tue Dec 09, 2014 4:58 pm

Waiting my pcb too - can't wait!

Thank you so much for this topic boops!

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Post by fracinfrucer » Tue Dec 09, 2014 6:39 pm

Yes, thanks Boops! :tu:

Looking at the BOM, for the motherboard, it states that the 15uF caps should be regular electrolytics, but the link is for tantalum (mouser # 74-173D25V15). Does anyone know which would be better? Since I've heard tantalum are prone to fail, I might rather use the electrolytics if the sound wouldn't be impacted. Any thoughts?

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Post by boops » Tue Dec 09, 2014 6:57 pm

fracinfrucer wrote:Yes, thanks Boops! :tu:

Looking at the BOM, for the motherboard, it states that the 15uF caps should be regular electrolytics, but the link is for tantalum (mouser # 74-173D25V15). Does anyone know which would be better? Since I've heard tantalum are prone to fail, I might rather use the electrolytics if the sound wouldn't be impacted. Any thoughts?
Use the MOuser ones...
FS :custom buchla 203 style càbinet ,skiff new design,boat ,hardware for diy cabinet ,easel case ,new 1u to 10u to 56u and more. / New 208 buchla card 12 /
HQ small case buchla psu PCB
https://www.muffwiggler.com/forum/viewt ... 93#3118393
https://www.muffwiggler.com/forum/viewt ... highlight=

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Post by fracinfrucer » Wed Dec 10, 2014 7:20 am

boops wrote:
fracinfrucer wrote:Yes, thanks Boops! :tu:

Looking at the BOM, for the motherboard, it states that the 15uF caps should be regular electrolytics, but the link is for tantalum (mouser # 74-173D25V15). Does anyone know which would be better? Since I've heard tantalum are prone to fail, I might rather use the electrolytics if the sound wouldn't be impacted. Any thoughts?
Use the MOuser ones...
OK, thanks!

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Post by alka » Thu Dec 11, 2014 12:41 pm

Very helpful as always, boops. Looking forward to what you might come up with up regarding modifications to the reverb circuit.
the Colour of Terrible Crystal out on Vince Clarke's VeryRecords
http://veryrecords.com/portfolio-item/a ... e-crystal/

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Post by boops » Tue Dec 16, 2014 5:52 pm

alka wrote:Very helpful as always, boops. Looking forward to what you might come up with up regarding modifications to the reverb circuit.
Thanks

From xewin mod: MO Audio Range"

Like on the new 208 from BEMI. Use the 50k trimer to calibrate the range shift as you like. I have done this mod on my 208 rev2 and it work nice!! I added one switch in the MO section on the front panel.

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Mod vco pics of xewin mod, in my 208 ,dont do this if you dont know what you are doing ,check short etc ...Please

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Red for 13,5 v enable of the logic ic,black ground Q,Green CV freq of MO
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I ve choosen a multiturn tŕimmer for exact octave change...

BOOPS step 2 seq MOD ...fun and funky feeling garanted :)
This simple MOD adds a step 2 in the 208 seq

My step 3 works with 270 k ,my step 2 with 200 k

just add (one resistor 120K/200 k) test to have the 2 steps with original toogle on step3 ),to the 200k already installed R1 ,choose one or the other with another miniature toogle switch

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The Green wire to the right of resistors is the middle of the toogle switch ,go to pin 1 of the board 1 Seq ...
FS :custom buchla 203 style càbinet ,skiff new design,boat ,hardware for diy cabinet ,easel case ,new 1u to 10u to 56u and more. / New 208 buchla card 12 /
HQ small case buchla psu PCB
https://www.muffwiggler.com/forum/viewt ... 93#3118393
https://www.muffwiggler.com/forum/viewt ... highlight=

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Post by boops » Mon Dec 22, 2014 5:07 am

Hello
I have calibrated my 208 rev2 ,with infos here and There ....i have taken a few notes:

First ones

208 1v/oct
R5 on PCB6 is responsible for Mod Osc scale

Changed by 68 k 1%


R14 on PCB7 is responsible for Complex Osc scale

Changed by 59,5 k 1% ,i ve taken 56k+4,7 k


On the mod MO audio range ,i càn have exactly 2octaves
Trim. tr1 ,tr2 trimmers under the panel for a fine octave
Last edited by boops on Fri Jan 23, 2015 6:05 pm, edited 1 time in total.
FS :custom buchla 203 style càbinet ,skiff new design,boat ,hardware for diy cabinet ,easel case ,new 1u to 10u to 56u and more. / New 208 buchla card 12 /
HQ small case buchla psu PCB
https://www.muffwiggler.com/forum/viewt ... 93#3118393
https://www.muffwiggler.com/forum/viewt ... highlight=

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Post by fracinfrucer » Tue Dec 30, 2014 3:59 pm

So, is there any reason to use the C&K switches instead of NKK (replace C&K part# 7101SYCQE with NKK part# M2012SS1W03, for example)? The only difference I can see is the bat on the NKK are 0.420" long instead of 0.413". That doesn't seem like it should make that much of a difference. But I did order the colored caps for the switches, so I wanted to make sure.

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Post by boops » Tue Dec 30, 2014 6:25 pm

I ve used small bear ones,really cheaper,only one NNK for pulser one shot
you have to choose pin pc option ,to match pcb holes
the caps work for all these brands
FS :custom buchla 203 style càbinet ,skiff new design,boat ,hardware for diy cabinet ,easel case ,new 1u to 10u to 56u and more. / New 208 buchla card 12 /
HQ small case buchla psu PCB
https://www.muffwiggler.com/forum/viewt ... 93#3118393
https://www.muffwiggler.com/forum/viewt ... highlight=

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Post by fracinfrucer » Tue Dec 30, 2014 9:52 pm

Awesome thanks! :tu:

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Post by boops » Fri Jan 02, 2015 2:15 pm

Good new,i ve résolved the reverb problem,yesterday ....with one LRC filter ,infos soon
The résult is really magic....like a real fx send
You càn make this mod to the rev 1...too.(as the rev1 and rev2 have the same schematic output)
FS :custom buchla 203 style càbinet ,skiff new design,boat ,hardware for diy cabinet ,easel case ,new 1u to 10u to 56u and more. / New 208 buchla card 12 /
HQ small case buchla psu PCB
https://www.muffwiggler.com/forum/viewt ... 93#3118393
https://www.muffwiggler.com/forum/viewt ... highlight=

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Post by boops » Fri Jan 30, 2015 4:50 am

Up for the builders ....
FS :custom buchla 203 style càbinet ,skiff new design,boat ,hardware for diy cabinet ,easel case ,new 1u to 10u to 56u and more. / New 208 buchla card 12 /
HQ small case buchla psu PCB
https://www.muffwiggler.com/forum/viewt ... 93#3118393
https://www.muffwiggler.com/forum/viewt ... highlight=

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Post by Ginko » Fri Jan 30, 2015 2:58 pm

Just wondering if I am being an idiot, is there a fast way to import the BOM from Roman's store page to Mouser, or is there a complete BOM somewhere else? if not I am slowly building up a "Project" which I will share when I am done

The mouser site doesn't even like me copying and pasting the project codes from his documents, I have to manually type them in :(
Last edited by Ginko on Tue Feb 03, 2015 3:35 pm, edited 1 time in total.

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Post by captnapalm » Sat Jan 31, 2015 10:46 am

Ginko wrote:Just wondering if I am being an idiot, is there a fast way to import the BOM from Roland's store page to Mouser, or is there a complete BOM somewhere else? if not I am slowly building up a "Project" which I will share when I am done

The mouser site doesn't even like me copying and pasting the project codes from his documents, I have to manually type them in :(
There's a link to a BOM from the other 208r thread here:
https://cloud.mail.ru/public/c1c387c3f129/208-BOM.xls

You should be able to upload that using the Mouser BOM tool:
http://www.mouser.com/bomtool/

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Post by Ginko » Sat Jan 31, 2015 10:55 am

Great thanks! Yes I tried using the BOM tool with the documents on Electric Music Store but they aren't in .xls format!!

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Post by Ginko » Sat Jan 31, 2015 3:30 pm

Nearly at the end of ordering!

In the BOM there is a capacitor labeled as a 56µf Tantalum - but the code links to a 47µf Tantalum rated at 10V - the 47µf cap was on 'back order' and not due until April - I had a look for a 56µf, but can only find them rated at 6V (or very expensive!!)

Which is the right capacitor to use?

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Post by captnapalm » Sat Jan 31, 2015 3:44 pm

Ginko wrote:Nearly at the end of ordering!

In the BOM there is a capacitor labeled as a 56µf Tantalum - but the code links to a 47µf Tantalum rated at 10V - the 47µf cap was on 'back order' and not due until April - I had a look for a 56µf, but can only find them rated at 6V (or very expensive!!)

Which is the right capacitor to use?
47uf will work fine. You can use this one:
http://www.mouser.com/ProductDetail/Vis ... dLKmHvA%3d

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Post by boops » Sat Jan 31, 2015 5:57 pm

captnapalm wrote:
Ginko wrote:Nearly at the end of ordering!

In the BOM there is a capacitor labeled as a 56µf Tantalum - but the code links to a 47µf Tantalum rated at 10V - the 47µf cap was on 'back order' and not due until April - I had a look for a 56µf, but can only find them rated at 6V (or very expensive!!)

Which is the right capacitor to use?
47uf will work fine. You can use this one:
http://www.mouser.com/ProductDetail/Vis ... dLKmHvA%3d
These are the good ones...sure
FS :custom buchla 203 style càbinet ,skiff new design,boat ,hardware for diy cabinet ,easel case ,new 1u to 10u to 56u and more. / New 208 buchla card 12 /
HQ small case buchla psu PCB
https://www.muffwiggler.com/forum/viewt ... 93#3118393
https://www.muffwiggler.com/forum/viewt ... highlight=

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Post by Ginko » Sat Jan 31, 2015 6:06 pm

Great thanks :tu:

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Post by aethyr » Mon Feb 02, 2015 11:19 pm

How far is everyone along in their builds of the rev2 208?

Mine is almost done but we are having some calibration issues...what is the general range of the complex osc it hertz and does the modulation osc track with the keyboard and do the corresponding switches do anything?

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