Geek Peek: Roland A-80

Keyboards, Synths, Samplers and Groove Boxes.

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Geek Peek: Roland A-80

Postby Plink Floyd » Mon Jan 09, 2012 4:39 am

Let's join the effluent and mildly disturbing Dr. Plinkenstein, as he delves into the innards of his latest aquisition: "Come on, down the stairs and into the lab... Eh? Oh, don't be such a faintlady. That's nowhere near the biggest spider I've seen down here. What? Yes, it is kind of dark. Just hold still while I throw this big knife WHAT??!! Don't shriek like that, my dear fellow, you didn't let me finish! Just let me throw this big knife switch! How else am I to turn on the lights?"

Image

"There, don't you feel silly? Now, make yourself comfortable, over there out of the way,
and I'll begin vivisecting... heh, I mean, disassembling our subject."
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Re: Geek Peek: Roland A-80

Postby Plink Floyd » Mon Jan 09, 2012 5:04 am

I trust my friends will kindly overlook the poor quality of some of my images.
I find it difficult to regularly achieve photographic acuity whilst shooting with arc light.

Image

Those of you at home who faithfully follow my follies will recall that I was recently fortunate enough to 'dig up' a Roland A-80,
for very few bones. As a matter of fact, Your Humble Dr. paid nothing at all for the instrument, as is was damaged in transit
by a clumsy henchman... er, hunchman? Let's just say deliveryman, shall we?

Image

Now here we have the expansive view of the controller, with a few of the keys already extracted. This was necessary to diagnose
and remedy an uncooperative G1 key. It was the only key that didn't work, so Your Doctor didn't suspect any more than some local
cause, perhaps a dirty key contact, faulty matrix diode, or most likely, the mucilaginous residue of a clumsily misplaced potation.

Image

The cause of the trouble, however, remains a mystery. After attaching the oscilloscope probes to the appropriate points on the
matrix board, and pressing on the rubber dome switches with my finger, I found the missing note to have returned! Nothing could I
do to render it defective again, I re-soldered all the associated joints and chalked it up to "oh well, I've seen weirder shit".
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Re: Geek Peek: Roland A-80

Postby Plink Floyd » Mon Jan 09, 2012 5:43 am

Ho hum, you say? Ah, but now, my friends, we come to the spine-tingling goose-bumpy part (come closer...closer...)
The Modification! (What? You think I should do what? Oh, very well... bwa ha ha. Sheesh, that's sooo cliche.)

As you may know, the A-80 is distinguished by being one of the elite instruments that can boast of polyphonic aftertouch.
You may also know that, in it's native state, this fabled feature may only be activated by the most laboriously applied pressure.
Scientifically speaking: you really have to stand on it like a sumbich. Your thumb can barely tickle it, so the pinky is pretty much
out of luck. According to certain denizens of the internets, however, this condition can be greatly improved by changing the
value of a particular resistor in the associated aftertouch circuitry (R43, 5.6K).
Let's locate him, shall we?

Image


Hmm. Too many dinguses. We must Go Deeper.


Image

Ah, there he is, R43, between IC14 and IC15. Cute little fellow, eh? Too bad he must pay for some incompetent engineer's mistake.

Now, Your Humble Dr. has found several posts on the webbz that suggest that we substitute the 5.6K value with 10K.
But, a few radicals ridicule this conventional thinking and say "WTF no wai man UR WRONG IT SHLD B 50K NOOB!!"
Always willing to be forward-thinking and consider all sides of an issue, The Dr. has cleverly implemented the following
experimental scenario thingy, to wit: I yanked out the fixed resistor and bunged in a 100K ten turn pot.

Image
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Re: Geek Peek: Roland A-80

Postby Plink Floyd » Mon Jan 09, 2012 6:25 am

So, after much scientific endevourage and highly empirical pounding, I discovered that, indeed, the radicals were right.
Setting the pot at 10K resulted in a barely noticeable improvement, whereas 40K or 50K seemed to be optimal.
Anything much higher was fruitless. So, I installed me an All American 1/4 Watt 51K resistor:

Image

I hope he acclimates well with his new diminutive Japanistic neighbors, and I hope they don't taunt him for being a
big fat amelican lardass.

But then, Oh Dear Reader, Your Humble Seeker after the Facts had an epiphany. He realized that he wished not merely to
putz about in his basement, but to furnish mankind with Useful Knowledge that Makes a Difference! His inquiring mind
reeled with questions like "Holy shit, how much does just the keybed in this thing weigh?" This rarefied state of awareness
(coupled with the comforting fact that Mrs. Doctor and the little experiments weren't due home for quite a while yet),
fueled a veritable frenzy of highly productive research. I weighed the keybed assembly on the bathroom scales: thirty nine
hefty, well constructed pounds that thing weighs. Mostly because of the metal weight in each key, I surmise. The whole
machine weighs 66 Lbs, which means almost two thirds of the total weight is keys alone.

Then I said to myself "this is a pretty lame way to measure aftertouch, just tweaking this pot and squashing the keys randomly.
By Heisenberg, I must devise a way to remove all this confounded uncertainty from my observations!"
So, ask me "how much actual force do you have to apply to a key to generate the maximum aftertouch output?"

Well, go on, ASK ME!

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Before the modification: over TWENTY POUNDS, by damn! No sweat, you say? Then try this at home,
Mr. Force Fingers: go press down on a bathroom scale with one finger until you register twenty pounds.
See? Not so tough now, are ya, dinkydigits?

And now, thrill at The Doctor's highly honed acumen with regard to building Doodads:
Behold the Highly Scientific Linear Force Applicator with Pretty Good Repeatability!

Image
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Re: Geek Peek: Roland A-80

Postby Plink Floyd » Mon Jan 09, 2012 6:35 am

Turns out, though, the barbell weight device was a waste of time. I got the sensitivity pretty low, so when you first applied the weight, the midi aftertouch value was around 05, but over the time period of 30 or 40 seconds, it slowly crept up to maximum. I think it's because the switch contacts are under the felt downstop strips. So, even when you apply a fixed weight every time, the felt slowly compresses and the conductivity increases.

But all in all, it was some fun geekery, and my controller is all nice and 100% fixed and cleaned up now.

What? TLDR, you say??!! Philistine!! But no, wait, forgive me, I mustn't react that way... In fact, by way of apology, follow me back further into the basement... I'm pretty sure I've a cask of Amontillado tucked away somewhere...
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Re: Geek Peek: Roland A-80

Postby ElectricPuppy » Mon Jan 09, 2012 6:42 pm

I am entertained. :thu: CONTINUE
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Re: Geek Peek: Roland A-80

Postby MetroSonus » Mon Jan 09, 2012 7:30 pm

Image
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Re: Geek Peek: Roland A-80

Postby topcat » Mon Jan 09, 2012 10:33 pm

aha Dr Plinkenstein. Vat you have done here iz quite zee project! vit zee pictures too!
Danke! :thu:
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Re: Geek Peek: Roland A-80

Postby Plink Floyd » Tue Jan 10, 2012 3:31 am

I thankee for all this here affirmation. I can't really continue, though, because there isn't anything else that needs done to this machine. If someone wants moar pics of the gutz, I could do that, I guess, but there are better pix than mine already out there.

I know that, in lieu of a better cam, I need better lights that position easily, and maybe some kind of gooseneck camera holder thing. I have good lights, diffusers, and tripods for normal photography & portraiture, but nothing for this gizmacro type stuff.

But soon, I hope to finish up my Hammond refurb job, and the Leslie conversion. I'll photo-document that geekery with great pleasure, if it so pleases.
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Re: Geek Peek: Roland A-80

Postby ElectricPuppy » Tue Jan 10, 2012 4:31 am

Oh definitely, I'd like to see pics of that. :thu:
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Re: Geek Peek: Roland A-80

Postby Plink Floyd » Tue Jan 10, 2012 7:30 am

Then it shall be so.

But don't hold your breath, for hobby time is scarce...

:cry:
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Re: Geek Peek: Roland A-80

Postby stickman393 » Sun Feb 09, 2014 8:09 am

Thank you, Plink, for your entertaining rant and excellent pictures of the resistor replacement process.
I followed your instructions and recommendations.

OK, I got my Roland A-80 about two years ago. Aftertouch was not useable, and required way too much force.
This weekend, I opened her up and checked resistor 43. It was 10k, factory installed I'd estimate.
I replaced R43 with a 51k 1/4 watt. The mod is pretty easy to do if you are handy with a soldering iron and solder braid or solder-sucker to remove the old component.

The aftertouch now works as expected. It's fairly firm, but totally usable. Some keys are more sensitive than others but I would expect this on a 'board this old, especially with individual key sensors.

I verified that it was transmitting poly-AT - you need to enable it on a per-zone basis from the front panel - and then played around with chords using Arturia CS80v. Poly AT is now working fine.

I highly recommend this mod. Replace R43 with a 56k resistor, and you're golden.

Thanks to the following online resources:
http://www.soundofmusic.se/new/archive/ ... 20A-80.pdf
for which screws to remove from base in order to lift up the panel.
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Re: Geek Peek: Roland A-80

Postby Plink Floyd » Mon Feb 10, 2014 6:23 am

:wave:

Glad you found it useful! I recommend this mod too.

But as you observed, it's not a project for the absolute beginner. For those folks, I suggest practicing on junk VCRs. They contain lots of soldering practice opportunities, from big easy joints to many legged niggly surface mount components. Us frugal types can even harvest a few doodads such as rectifier bridges, LEDs, IR recievers, PCB mount jax & such.
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Re: Geek Peek: Roland A-80

Postby MetroSonus » Tue Feb 11, 2014 2:46 pm

welcome aboard matey! arrghh.. Image
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Re: Geek Peek: Roland A-80

Postby etl17 » Mon Jul 28, 2014 5:26 pm

Thank you for going through the trouble of figuring this out!
My A-80 now feels like a bright new instrument (after 15 years of ownership).....

:-)
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Re: Geek Peek: Roland A-80

Postby MetroSonus » Mon Jul 28, 2014 7:25 pm

Plink, you should really pat yourself on the back. You've had two people sign up to tell you thanks! :wave:

And you two are welcome to stay and hang out as much as you like :wave:
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Re: Geek Peek: Roland A-80

Postby selfinflikted » Mon Jul 28, 2014 7:27 pm

MetroSonus wrote:And you two are welcome to stay and hang out as much as you like :wave:


There are cookies in the Hai Guyz thread.
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Re: Geek Peek: Roland A-80

Postby christianrock » Mon Jul 28, 2014 7:43 pm

yes

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Re: Geek Peek: Roland A-80

Postby Plink Floyd » Tue Jul 29, 2014 10:09 am

Well I just looked all through that dreadful HAI GUYZ! place and found nothing but a lot of silly.

:mad:

THE COOKIES ARE A LIE!
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Re: Geek Peek: Roland A-80

Postby selfinflikted » Tue Jul 29, 2014 11:30 am

Plink Floyd wrote: :mad:

THE COOKIES ARE A LIE!


Maybe just a little.
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