208p build thread (papz's PCBs)

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Kent, luketeaford, Joe.

Post Reply
friedemann
Learning to Wiggle
Posts: 7
Joined: Wed Apr 01, 2020 11:32 pm

Re: 208p build thread (papz's PCBs)

Post by friedemann » Sat Jan 09, 2021 1:19 pm

Sometimes only sequence LED 1 lits but same behavior.

User avatar
papz
Super Deluxe Wiggler
Posts: 3654
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: 208p build thread (papz's PCBs)

Post by papz » Sat Jan 09, 2021 2:04 pm

There's most likely a same build error on both cards, double check all.
Just in case, there is no 4016/4066 on card 1.
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.

User avatar
sendepause
Wiggling with Experience
Posts: 252
Joined: Mon Jan 20, 2014 3:54 am
Location: Amsterdam

Re: 208p build thread (papz's PCBs)

Post by sendepause » Sun Jan 10, 2021 5:55 pm

sendepause wrote:
Sun Dec 13, 2020 1:14 pm
Question:
I have build a 208 ( not Papz) and there is a lot of knowhow in this thread I put the question here.
So how noisy is your 208? I have a new card 12 installed and without any cards, except the 12, there is some serious noise on the output. Headphone out is a total no go.
I’m doing a open heart surgery atm and check everything on the motherboard and can’t find any weird things.
So: is your 208 noisy as well? How noisy? Headphone out noisy?
Well...
I contacted the great Dave Brown about my problems. After some emails back and forth, we managed to localize the problem around the headphone output. When I desoldered the electrolytic caps, the noise was almost gone. So we even narrowed it a bit more, specifically to the 12v rail. And after some more measurements and emails, we couldn't find the problem. I did have a very noisy Cincon power supply and my last try, before giving up and send the 208 to the doctor, was buying a new power supply.

Guess what... Problem solved! When I plugged it in and there was no noise, I could almost cry with happiness hahaha

Albeit not a papz 208, there is another working easel on the planet!

thecivildefense
Common Wiggler
Posts: 81
Joined: Sun Aug 11, 2019 11:48 am
Location: Brooklyn, NY

Re: 208p build thread (papz's PCBs)

Post by thecivildefense » Mon Jan 11, 2021 6:02 pm

Can someone help me understand the Tinijax wiring for the Switchcraft 42a for the preamp in on the panel? So I get tip is supposed to go to card 10. Ring to ground wherever. But what about the switched connection?

Also I know tinijax and 3.5mm cables are different sizes, but also that 3.5mm should work here. BUT I'm noticing if I use a 3.5mm cable here (don't have tinijax yet) it seems to NOT break the switched connection. If the function is to short to ground w/ no cable plugged in I'm assuming this won't work then w/ 3.5mm if it's not switching.

Don T
Super Deluxe Wiggler
Posts: 1366
Joined: Sun Feb 02, 2014 3:11 pm

Re: 208p build thread (papz's PCBs)

Post by Don T » Mon Jan 11, 2021 9:27 pm

thecivildefense wrote:
Mon Jan 11, 2021 6:02 pm
Can someone help me understand the Tinijax wiring for the Switchcraft 42a for the preamp in on the panel? So I get tip is supposed to go to card 10. Ring to ground wherever. But what about the switched connection?

Also I know tinijax and 3.5mm cables are different sizes, but also that 3.5mm should work here. BUT I'm noticing if I use a 3.5mm cable here (don't have tinijax yet) it seems to NOT break the switched connection. If the function is to short to ground w/ no cable plugged in I'm assuming this won't work then w/ 3.5mm if it's not switching.
Wire the switch to ground. I.e., the tip contact should be grounded when not in use.

User avatar
papz
Super Deluxe Wiggler
Posts: 3654
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: 208p build thread (papz's PCBs)

Post by papz » Tue Jan 12, 2021 6:56 am

Here's a pic.
The green cable is signal, soldered to the tip.
The shielding is ground, connected to both other tabs via a piece of component lead.

IMG_1671.JPG

Some minijack plugs work in tinijax sockets, others don't.
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.

thecivildefense
Common Wiggler
Posts: 81
Joined: Sun Aug 11, 2019 11:48 am
Location: Brooklyn, NY

Re: 208p build thread (papz's PCBs)

Post by thecivildefense » Tue Jan 12, 2021 12:56 pm

papz wrote:
Tue Jan 12, 2021 6:56 am
Here's a pic.
The green cable is signal, soldered to the tip.
The shielding is ground, connected to both other tabs via a piece of component lead.


IMG_1671.JPG


Some minijack plugs work in tinijax sockets, others don't.
Perfect. Thanks all. I'll have to remember to use a proper tested cable when I finish the build so I make sure the cable breaks the normal.

thecivildefense
Common Wiggler
Posts: 81
Joined: Sun Aug 11, 2019 11:48 am
Location: Brooklyn, NY

Re: 208p build thread (papz's PCBs)

Post by thecivildefense » Mon Jan 25, 2021 2:50 pm

Another question. I know vactrols are discussed in various places and I've seen info on testing them, but building gear using them is fairly new to me. If I have a handful of the older vactrols and a bunch of the Xvives, I get that the gates are the critical position, but is there anywhere else they should be more closely matched? Like the pairs in the balanced modulator?

Don T
Super Deluxe Wiggler
Posts: 1366
Joined: Sun Feb 02, 2014 3:11 pm

Re: 208p build thread (papz's PCBs)

Post by Don T » Mon Jan 25, 2021 3:12 pm

thecivildefense wrote:
Mon Jan 25, 2021 2:50 pm
Like the pairs in the balanced modulator?
Yes

User avatar
papz
Super Deluxe Wiggler
Posts: 3654
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: 208p build thread (papz's PCBs)

Post by papz » Mon Jan 25, 2021 4:25 pm

The best way to select vactrols is selection on test in the actual circuit, VT 1 2 3 4 on card 5 are the trickiest, it's good to start with those.
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.

User avatar
papz
Super Deluxe Wiggler
Posts: 3654
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: 208p build thread (papz's PCBs)

Post by papz » Tue Jan 26, 2021 12:03 pm

I updated the FAQ with some info regarding expensive obsolete rare parts and modern equivalents.
http://www.portabellabz.be/208pcbfaq.html#parts
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.

kennylovrin
Learning to Wiggle
Posts: 2
Joined: Mon Aug 31, 2020 3:53 am

Re: 208p build thread (papz's PCBs)

Post by kennylovrin » Wed Feb 03, 2021 3:47 am

papz wrote:
Mon Jan 25, 2021 4:25 pm
The best way to select vactrols is selection on test in the actual circuit, VT 1 2 3 4 on card 5 are the trickiest, it's good to start with those.
Actually, I was thinking about this the other day.. What does this actually mean in practice? That I solder them to the board then power up and test and desolder if it's no good? Or there is a more "temporary" trick to do it in the actual circuit?

And re. the vactrols, what is the primary thing I am after? The highest possible resistance when deactivated? Or just that they are matched to each other etc?

Even asking these questions perhaps means that I shouldn't even be doing this, but what the hell.. ;)

User avatar
papz
Super Deluxe Wiggler
Posts: 3654
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: 208p build thread (papz's PCBs)

Post by papz » Wed Feb 03, 2021 7:08 am

Unfortunately the temporary trick to simply insert the vactrols into the holes doesn't work very well.
So I solder them in place with very few solder, test, desolder to replace if needed and do a strong soldering when it's ok. Having a good desoldering tool (thank you so much Hakko ;)) helps a lot and prevents damage to the PCB trace due to multiple soldering-desoldering.
What you're after is proper AM waveform and a smooth progressive slider course with the max effect when it's all the way up as explained in the build notes.
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.

kennylovrin
Learning to Wiggle
Posts: 2
Joined: Mon Aug 31, 2020 3:53 am

Re: 208p build thread (papz's PCBs)

Post by kennylovrin » Wed Feb 03, 2021 7:38 am

papz wrote:
Wed Feb 03, 2021 7:08 am
Unfortunately the temporary trick to simply insert the vactrols into the holes doesn't work very well.
So I solder them in place with very few solder, test, desolder to replace if needed and do a strong soldering when it's ok. Having a good desoldering tool (thank you so much Hakko ;)) helps a lot and prevents damage to the PCB trace due to multiple soldering-desoldering.
What you're after is proper AM waveform and a smooth progressive slider course with the max effect when it's all the way up as explained in the build notes.
Ok cool thanks, so there is no point in activating them on a breadboard and match them up with each other or something like that, in your opinion?

User avatar
papz
Super Deluxe Wiggler
Posts: 3654
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: 208p build thread (papz's PCBs)

Post by papz » Wed Feb 03, 2021 8:01 am

This may help, I don't know, I'm used to test them on the board and I'm happy doing so.
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.

IStankov
1-Post Wiggler
Posts: 1
Joined: Thu Jan 28, 2021 12:03 pm

Re: 208p build thread (papz's PCBs)

Post by IStankov » Fri Feb 05, 2021 3:22 am

Hi there. I’ve got few minor questions before I start my build. I am absolutely new to buchla world so please don't judge me too much)

So, first, panel. I know that Papz has his source, which I have nothing against, but a friend of mine has one unused. It seems to be an older clone panel, not LEM, not BEMI at all, but the one based around original 70s 208z should this fit? Or are there any minor differences between different runs of pcbs?

Second, how is midi?:) Synovatron went down permanently, and even converting things between formats is going to be an issue now. Has anyone found a suitable workaround? Maybe you have schematics/sources of kits etc?

Third, even older Easels had Line out jack, but from all materials I had access to there was no obvious way it was connected to the main out (tinijax) I would love to have one somewhere on the side of the case, but don't really know how I should do it. Any ideas?)

Thank you all!

User avatar
papz
Super Deluxe Wiggler
Posts: 3654
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: 208p build thread (papz's PCBs)

Post by papz » Fri Feb 05, 2021 6:02 am

1. All 208 panels are compatible except the BEMI.
2. Various small midi to CV/gate converters DIY solutions exist and can be installed in the case. I can't recommend any though, never used.
3. Connect the 1/4" jack sockets in parallel with the tinijax.

Many questions are answered on http://www.portabellabz.be/208pcbfaq.html
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.

User avatar
djangosfire
dimensionally transcendental
Posts: 3351
Joined: Sun Sep 06, 2009 11:13 pm

Re: 208p build thread (papz's PCBs)

Post by djangosfire » Sun Feb 07, 2021 9:58 pm

Here’s a new one for the hive mind:

I just finished building and calibrating a 208p - Its the second 208p that I have built (although I have built probably 20x 208 V2’s over the years). Sounds, tracks and works great - BUT.... I noticed something that seems odd:

The MO and (or) CO pitch will shift a “very slight amount” (.1 hz) as either LPG slider (in any mode) is opened past the 6 mark on up to 10. I had not noticed this in other builds, has anyone else?

I wasn’t really sure where to look for a solution. I did clean the cards, and they look great. I did not clean the Motherboard... but rather used no-clean solder.. and in my opinion the MB looks very clean.

After a recommendation from Dave Brown, I did verify that R43 on Card 10 (and card 11) was indeed correct at 100R, also verified the correct orientation of the zener.

As an easy test, I did try putting a 100k in series with the LED.. via card 10, between the molex and the 2n1711 (as per a Papz build note about LED’s affecting VCO pitch) - No change, so I removed the mod.

I am probably overthinking. Maybe this has always been part of the way a 208p (or 208 V2, or original 208). Let me know what you think - Thank you, Adam
Last edited by djangosfire on Mon Feb 08, 2021 10:20 am, edited 1 time in total.
Djangosfire - new Adam Scramstad Acoustic Finger-style Album:
https://adamscramstad.bandcamp.com/releases

User avatar
papz
Super Deluxe Wiggler
Posts: 3654
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: 208p build thread (papz's PCBs)

Post by papz » Mon Feb 08, 2021 7:03 am

Hi Adam
I tested on 2 208p and a 208r rev2, a similar very slight shift occurs too. Adding a resistor in series or fully disconnecting the LPG LED doesn't seem to alter it indeed.
Sounds like a small 208 quirk we have to live with thus, it never bothered me.
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.

User avatar
djangosfire
dimensionally transcendental
Posts: 3351
Joined: Sun Sep 06, 2009 11:13 pm

Re: 208p build thread (papz's PCBs)

Post by djangosfire » Mon Feb 08, 2021 10:22 am

papz wrote:
Mon Feb 08, 2021 7:03 am
Hi Adam
I tested on 2 208p and a 208r rev2, a similar very slight shift occurs too. Adding a resistor in series or fully disconnecting the LPG LED doesn't seem to alter it indeed.
Sounds like a small 208 quirk we have to live with thus, it never bothered me.
Thanks Papz, I appreciate the feedback... I figured it was just me overthinking :) Onward!

BTW, thank you for these amazing sets - Truly are a joy to play and build! Excellent work

Cheers, Adam
Djangosfire - new Adam Scramstad Acoustic Finger-style Album:
https://adamscramstad.bandcamp.com/releases

User avatar
papz
Super Deluxe Wiggler
Posts: 3654
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: 208p build thread (papz's PCBs)

Post by papz » Mon Feb 08, 2021 11:53 am

Your feedback is always very valuable and appreciated.
Cheers !
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.

thecivildefense
Common Wiggler
Posts: 81
Joined: Sun Aug 11, 2019 11:48 am
Location: Brooklyn, NY

Re: 208p build thread (papz's PCBs)

Post by thecivildefense » Mon Feb 08, 2021 3:16 pm

Is it possible to use VTL5c3/2 on card 5 in either the VT3/4 or VT 1/2 positions? At first I thought maybe yes but from what I can tell in the docs it seems like they may need separate vactrols. Sorry for the newbie question...just very new to vactrol operation.

User avatar
papz
Super Deluxe Wiggler
Posts: 3654
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: 208p build thread (papz's PCBs)

Post by papz » Mon Feb 08, 2021 3:38 pm

I wish that was possible too, but unfortunately not.
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.

User avatar
papz
Super Deluxe Wiggler
Posts: 3654
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: 208p build thread (papz's PCBs)

Post by papz » Wed Feb 10, 2021 11:34 am

SAmodular will offer full kits and 208p + 218 bundles.
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.

weedywhizz
Super Deluxe Wiggler
Posts: 1013
Joined: Wed Oct 20, 2010 3:51 pm
Contact:

Re: 208p build thread (papz's PCBs)

Post by weedywhizz » Sat Feb 20, 2021 1:24 pm

papz wrote:
Wed Feb 10, 2021 11:34 am
SAmodular will offer full kits and 208p + 218 bundles.
Yes, working on it. New BOM is done already with high quality parts and additional NOS parts were sourced.
The BOM everybody knows is OLD. I changed the resistors for example so you'll be able to order single pieces again.

Full kits should be ready in approx. 2 weeks :party:
Buchla format cases & parts - Buchla 200s series clone PCBs & panels - www.samodular.com

Post Reply

Return to “Music Tech DIY”