Buchla 208r V2.1 (Blue) Build Thread

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Don T
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Post by Don T » Tue Jan 31, 2017 2:14 pm

thermionicjunky wrote:
Don T wrote:...The 208's balanced modulator sounds a lot more like what I expect from a ring modulator with VTL5C1 installed. Perhaps if I get time soon, I'll make and post a couple of comparison videos...
Please record any type of comparison. I've been considering this mod for years but I never have any spare vactrols.
I will do my best. I need something better to record with than my iPhone though.

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Post by Don T » Tue Jan 31, 2017 2:20 pm

Just added another edit to the original post, to the general troubleshooting tips:

"2A. If you put your chips in sockets, make sure none of the pins got folded under and are not making contact."

I found a chip that had done that on my Balanced Modulator card a couple months ago, forgot to mention it.

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Post by Don T » Wed Feb 01, 2017 4:54 am

Just added another edit and attachment to the original post: A very good image of the 208 Mother Board schematic. You'll probably need a piece of poster paper to print it out large enough, because it combines both halves of the motherboard schematic into one continuous image. I've found it very useful for debugging.

I cannot remember where online I found the image, so if anyone knows who should get credit, please let me know!

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Post by davebr » Wed Feb 01, 2017 12:12 pm

Don T wrote:Just added another edit and attachment to the original post: A very good image of the 208 Mother Board schematic. You'll probably need a piece of poster paper to print it out large enough, because it combines both halves of the motherboard schematic into one continuous image. I've found it very useful for debugging.

I cannot remember where online I found the image, so if anyone knows who should get credit, please let me know!
I photoshopped the two halves together, cleaned it up, and posted a PDF on my Buchla 208 V2 Stored Program Sound Source Module page. I also combined the later version motherboard schematic. While this looks nearly the same, it has been slightly straightened so someone either did the same work or did some post processing on mine. I can't claim it as it isn't truly identical.

Dave

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Post by Don T » Wed Feb 01, 2017 1:59 pm

davebr wrote:
Don T wrote:Just added another edit and attachment to the original post: A very good image of the 208 Mother Board schematic. You'll probably need a piece of poster paper to print it out large enough, because it combines both halves of the motherboard schematic into one continuous image. I've found it very useful for debugging.

I cannot remember where online I found the image, so if anyone knows who should get credit, please let me know!
I photoshopped the two halves together, cleaned it up, and posted a PDF on my Buchla 208 V2 Stored Program Sound Source Module page. I also combined the later version motherboard schematic. While this looks nearly the same, it has been slightly straightened so someone either did the same work or did some post processing on mine. I can't claim it as it isn't truly identical.

Dave
Dave,

You are correct, the image is yours. When I went to your page a second ago, it showed me that I had indeed clicked on that link. I hadn't seen the later version yet, that will make an interesting study later. Thanks for all you do, and all the info you share on these projects! You are the "go-to" source!

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Post by Don T » Sun Feb 12, 2017 1:23 pm

For today, Card 9, and a small note on constructing the motherboard:

Card 9 builds up as expected. There are a lot of diodes on this one, so double-check their direction.

Image

When I first tested this particular Card 9, I got a little wavefolding action, but nothing but clicks when it was being fed the Sine wave generated on Card 8. After running through part of the troubleshooting checklist, the culprit was found, a not-too-easy-to-spot solder bridge:

Image

For comparison, the correct version:

Image

After clearing the bridge, the card worked just fine, and the wavefolding was even better. davebr has photos of all the V2 cards up on his website if you want a quick reference to check your cards against. If you want a higher-res closeup of a certain card, please feel free to send me a PM and I'll try to get a decent photo of what you need. Remember the troubleshooting checklist folks! It just may save you money on hair replacement treatments...

On to a note on the motherboard:

I noticed this awhile back, but forgot to point it out earlier. On the new, blue V2.1 motherboard, there is now an octagonal pad to designate the cathode (-) lead of every LED, even the ones not visible in the photo. On almost every LED I have ever seen, the cathode lead is the shorter of the two, even if the LED doesn't have a flat spot to designate the cathode. This may not seem like much, but if you have built one of the previous version before that had nothing but identical round pads for all the LEDs, this is a most welcome addition. It is REALLY easy to get lost on that giant motherboard, and to even lose track of which way is up if you're looking at it too closely. By the way, the octagonal pad appears on both sides of the board:

Image

Another update soon, I hope.

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Post by Don T » Sun Feb 12, 2017 2:36 pm

OH yeah, I haven't mentioned this yet, but: When you are done, wash the board to get rid of the solder flux residue!! I don't care if it is the "no-clean" kind! The only way to truly know something isn't going to damage the board over time is to get rid of it! I've made many a dollar (in huge multiples) repairing gear that the factory and/or builder didn't bother washing the board when it was finished. Trying to find all the places on a piece of equipment where the solder pads have become separated from their traces due to corrosion is frustrating, time consuming, and if someone else is doing it for you, expensive!

Image

See, nice and clean. If you are troubleshooting a faulty board, sometimes washing it helps to find a bad solder joint, missing solder joint, or a solder bridge.

I won't go into "how" right here, since the method varies with the type of rosin in the solder used. That said, I do not recommend using those spray cans of flux remover at home. If you don't know why, just trust me. If you do know why, no explanation is needed.

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Post by Peake » Sun Feb 12, 2017 11:09 pm

Don T wrote:That said, I do not recommend using those spray cans of flux remover at home. If you don't know why, just trust me. If you do know why, no explanation is needed.
Oh yes, learned that one... Thanks for the insight into Card 9. I've checked all component values, tested in-circuit for all resistors, caps, and diodes, confirmed diode orientation, checked against Dave Br's images for solder bridges, tested continuity on all of the bottom traces point to end point, swapped out all ICs, confirmed power to at least the 4136. Not a peep. Some of my caps are different than what I see on your build; I'll take it the three green film caps are ones you had in stock, etc.
I just can't help imagining that this would be better with vactrols

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Post by MrRoper » Mon Feb 13, 2017 7:18 am

Thanks so much for this thread Don T.

I havent built one of these yet as I was quite intimidated by all of the fixes needed on the old board but this new thread as well as Davebr's page has been a god send!

Currently saving to get in on this!

Also, sorry to go off track, but why are the aerosol flux removers a bad idea? Can you recommend something else?

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Post by Don T » Mon Feb 13, 2017 11:19 am

Peake wrote: I'll take it the three green film caps are ones you had in stock, etc.
Yes, most of the film/ceramic caps on my builds are recycled. The green ones in that photo came from a dead Roland JX-3P. If you see old-style ceramic disc caps in the photos, they came from either a dead Korg Poly-61 or a Polysix. Any part I recycle is tested to be in spec before it is soldered in.
MrRoper wrote: Also, sorry to go off track, but why are the aerosol flux removers a bad idea? Can you recommend something else?
As I mentioned earlier, the method will vary with the type core of your solder, but for starters I recommend scrubbing with an old toothbrush and at least 90% isopropyl alcohol, followed by scrubbing with detergent and water. That should take care of most things. As for the aerosol stuff, since I see you are in London, I imagine it isn't even legal there! Let's just say that most of them are a mixture of all the most dangerous substances studied in an organic chemistry class.

Card 8 should be ready to go this afternoon!

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Post by muncky » Mon Feb 13, 2017 11:22 am

Any tips for the over enthusiastic who have added the sliders, switches and trimmers but not cleaned their motherboard yet? :hmm:

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Post by Don T » Mon Feb 13, 2017 11:27 am

muncky wrote:Any tips for the over enthusiastic who have added the sliders, switches and trimmers but not cleaned their motherboard yet? :hmm:
Either leave it, or just clean the side away from the sliders. The switches and trimmers on the BOM are all sealed, therefore waterproof, as well as being safe from most other chemicals. Plain water shouldn't hurt the sliders once it is allowed to evaporate, but I wouldn't let anything else get inside them.

[EDIT]: When all is said and done, cleaning every solder point on the motherboard will be quite difficult. In fact, I never cleaned the solder joints from my LEDs and banana jacks, as the panel was already in place. I figured on gambling on the "No-clean" type of rosin. If it had been the old type of brown sticky rosin found in old 60/40 solder, I would've found a way to clean it off.

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Post by Don T » Mon Feb 13, 2017 7:49 pm

As promised earlier, Card 8:

Image

A few, not-quite-Earth-shattering notes on construction:

First, as noted earlier on the other cards that there was a small pad added to indicate the + lead of the LED for any vertically-mounted Vactrols, Card 8 does not have this feature. Instead is has a big honkin' giant pad on the + lead (Simply because there is a trace on top that connects there. This is the only vertically-mounted Vactrol like this):

Image

Next thing of note, this card is the one where your selected 2N4339 goes. This one had an Idss of .733, and even before trimming it has a nice sounding Sine wave. Please refer back to the original post for a diagram showing which resistors and diodes should be matched in the Sine shaper circuit:

Image

Ok, stay with me here, this next part is spread out over a few photos. There are only 2 errors on the motherboard, both small, and both easily corrected. This is where you correct one of them, and requires no modification to the motherboard. It is a simple and elegant mod, courtesy of davebr's website. On Card 8, you need to bridge Pin 11 and Pin 12 on the edge connector. Here's my method:

When you tack-solder the connectors in as suggested earlier in this thread, make sure you leave Pins 11 and 12 unsoldered. The pins are counted from Left-to-Right looking at the back of the card, with Pin 1 on the Left:

Image

Then take a resistor leg and make one of these:

Image

Then insert it into the grooves on top of the connectors of Pin 11 and Pin 12:

Image

Then finish soldering the connectors onto the card. For future reference when tracing signals and/or bugs, on all the cards the pin numbers are counted from Left-to-Right, looking at the back of the card, with Pin 1 on the Left. Seems counter-intuitive to me, but it is what it is, and this is the way they are numbered on the schematics:

Image

And yes, I washed the board after testing it! 8-)

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Post by Don T » Tue Feb 14, 2017 3:38 am

It appears there is an error on the motherboard schematics. This was discovered when helping someone diagnose a troublesome bug. The connections crossed out in the photo below between Card 8 and Card 9 do not exist:

Image

Not only do these connections not exist on the motherboard, but Pins 10 & 11 on Card 8 and Pins 4 and 7 on Card 9 are not connected to anything on the cards themselves.

This error appears on all versions of the motherboard schematic that I have seen.

Carry on!

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Post by davebr » Tue Feb 14, 2017 12:06 pm

Don T wrote:It appears there is an error on the motherboard schematics. This was discovered when helping someone diagnose a troublesome bug. The connections crossed out in the photo below between Card 8 and Card 9 do not exist:

Image

Not only do these connections not exist on the motherboard, but Pins 10 & 11 on Card 8 and Pins 4 and 7 on Card 9 are not connected to anything on the cards themselves.

This error appears on all versions of the motherboard schematic that I have seen.

Carry on!
I have noted that there are discrepancies between the early schematics and the 208. I don't specifically remember if it was these pins or something else but I always view the motherboard schematic as being close, not exact.

Dave

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Post by lucid » Tue Feb 14, 2017 12:37 pm

davebr wrote:
Don T wrote:It appears there is an error on the motherboard schematics. This was discovered when helping someone diagnose a troublesome bug. The connections crossed out in the photo below between Card 8 and Card 9 do not exist:

Image

Not only do these connections not exist on the motherboard, but Pins 10 & 11 on Card 8 and Pins 4 and 7 on Card 9 are not connected to anything on the cards themselves.

This error appears on all versions of the motherboard schematic that I have seen.

Carry on!
I have noted that there are discrepancies between the early schematics and the 208. I don't specifically remember if it was these pins or something else but I always view the motherboard schematic as being close, not exact.

Dave
well on schematics I used for debugging it is like this:
board 8
Image
and board 9
Image
so from this point of view makes sense to not have the traces there[/img]

what makes me more crazy was that on schematics for board 3 there is part which does not exist in reality on board:
Image
but maybe it is just wrong set of schematics I used. everything else was fitting to BOM and real layout on boards.

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Post by Don T » Tue Feb 14, 2017 1:06 pm

davebr wrote: I have noted that there are discrepancies between the early schematics and the 208. I don't specifically remember if it was these pins or something else
Dave
If you remember that it was something else, please let us know!

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Post by Peake » Tue Feb 14, 2017 9:17 pm

This just gets better and better. Thankfully the clone works as-is.
I just can't help imagining that this would be better with vactrols

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Post by tarandfeathers » Wed Feb 15, 2017 4:03 am

Don T wrote:For future reference when tracing signals and/or bugs, on all the cards the pin numbers are counted from Left-to-Right, looking at the back of the card, with Pin 1 on the Left. Seems counter-intuitive to me, but it is what it is, and this is the way they are numbered on the schematics
They're that way round so that, when mounted on the motherboard, pin 1 is at the top and the highest numbered pin is at the bottom. There was probably no thought that cards would be tested separately from the motherboard so it makes sense to have the numbering that way round.

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Post by Don T » Thu Feb 16, 2017 3:58 pm

Just curious, has anyone else finished their Blue V2.1? My panel and sliders have yet to come in, so I've been checking all my cards built so far in my completed V2 208. Trying to help a fellow wiggler debug something, and I want to make sure there isn't an issue with the V2 vs. V2.1 motherboards, specifically if anyone has a working Timbre section or not.

Also, anyone else that would like to contribute to this thread, please do! Until my panel and sliders arrive, I'm rapidly running out of stuff to build! (especially since I'm going to be out of town all of next week, and possibly the week after as well).

I've almost finished Cards 6, 10, 11, and 12, so hopefully I'll have those up before the weekend.

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Post by Don T » Thu Feb 16, 2017 4:02 pm

tarandfeathers wrote:
Don T wrote:For future reference when tracing signals and/or bugs, on all the cards the pin numbers are counted from Left-to-Right, looking at the back of the card, with Pin 1 on the Left. Seems counter-intuitive to me, but it is what it is, and this is the way they are numbered on the schematics
They're that way round so that, when mounted on the motherboard, pin 1 is at the top and the highest numbered pin is at the bottom. There was probably no thought that cards would be tested separately from the motherboard so it makes sense to have the numbering that way round.
Fair enough. That doesn't change the fact that I'm easily confused, though :dizzy:

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Post by Peake » Thu Feb 16, 2017 5:09 pm

Shout-out to Don for the enormous amount of help and contribution to the community!
I just can't help imagining that this would be better with vactrols

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Post by muncky » Thu Feb 16, 2017 5:18 pm

:nana:

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Post by bsilverberg » Thu Feb 16, 2017 6:22 pm

Peake wrote:Shout-out to Don for the enormous amount of help and contribution to the community!
Couldn't agree more!!!

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Post by Don T » Thu Feb 16, 2017 9:35 pm

Thanks for the kind words, guys!

Anyhow, meant to post Card 12 tonight, but wound up just one part short of completion, a 470uf axial cap. Luckily, a quick Radio Shack run tomorrow morning should take care of that issue.

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