ChromaTalk Archives: March 2015
- Re: Looking for early ARP-labeled Chroma PSU assembly (3 messages)
- CPS availability? (3)
- chroma bender issue.. (5)
- Restarting issue. (5)
- Off topic: SSM chips (3)
- cps kit question for chris b.
- History (2)
- Original CPS (10)
- Eprom failures (10)
- Chroma poly aftertouch sensor has loosened (15)
- Controller, pitch bend/ vibrato (2)
Re: Looking for early ARP-labeled Chroma PSU assembly
Go to first message in thread, February 2015
Ron Joseph [21030042+] · Sun, 1 Mar 2015 21:26:52 -0500
Howie,
I might have mine; I'm not sure if I kept it. If so, you're welcome to it for whatever postage to you costs--Ron
Howie Shen [21030552] · Mon, 2 Mar 2015 03:55:36 +0000
Hi Ron,
Thank you for messaging me. Yes! If you could check and see that you still have it, I'd certainly like to buy it from you. Your offer to part with it just for postage costs is extremely generous, but I'm happy to give you a little extra for time & effort.
Best,
Howie
Rob Belcher [21030095+] · Mon, 02 Mar 2015 09:32:21 +0000
Hi Howie,
Just out of curiosity i was wondering why you particularly want an ARP badged power supply, are they different to the later Rhodes Chroma power supplies?
I have a Chroma power supply here you can have for £30, not sure if its a original Arp labelled unit or not, id have to double check.. the offers there anyway.
Regards,
Rob.
CPS availability?
Dylan Wahl [21030410] · Tue, 3 Mar 2015 01:15:16 -0500
Hello all,
I am restoring Chroma #21030410, and wanted to know if the Chroma Pressure Sensor kit was still available? I've installed CC+ and the SPSU already, and gotten the synthesizer running again (my original CPU actually is in very good shape, the batteries were removed at some point in its past).
Thanks!
--Dylan
David Hobson [21030506] · Tue, 3 Mar 2015 14:10:56 -0500
Hello, Dylan.
I ordered my CPS kits (plural) from Chris Borman [21030194+] many moons ago... I am still wondering why he never answered emails to his selection of email addresses.
The good news is that he finally got around to producing the batch of CPS kits...almost a year later.
If you have success reaching Chris Borman, please let the few of us who are tying know. Maybe a few of us could throw in for another build???
In any event, I have sent you a private email.
I am wondering when Chris Borman's contact info will be update at the Rhodes Chroma site? I guess we'll have to wait and see. This is one of those grey area topics.
Whatever you choose to do, I hope you find your CPS kit.
Regards,
~David Hobson.
P.S. I just purchased my second (not my last) CC+ from David Clarke [21030085++], and a second power supply from Luca Sasdelli. Good guys.
Dylan Wahl [21030410] · Wed, 4 Mar 2015 13:35:46 -0500
FSR sensors?
Hopefully Chris B. will see this, I was wondering if you still had CPS kits available for sale, if not do you have any of the sensor pads still? I could build the mux boards if I had to, but the FSR elements I assume were custom from Sensitronics?
Thanks,
Dylan
chroma bender issue..
Elan Benaroch · Tue, 3 Mar 2015 12:25:44 -0800
I have a chroma with CC+ when I boot it up it tunes fine.. where I use the bender the tuning drops one tone. I play an A and it becomes a G it doesn't go back to normal until I reboot.
is the bender pot bad?
is there a factory reset for the CC+ I could try?
David Clarke [21030085++] · Tue, 3 Mar 2015 21:36:58 -0400
There are no normal settings or configurations in the CC+ which would otherwise come into play in this area, so it would be recommended to focus on the actual behaviour of the bender/bender pot.
I'd suggest experimenting a bit to see what's actually happening. One approach would be to enable a MIDI monitor on the MIDI stream. Power up, and then move the bender to see what you do/don't see get sent from the bender on MIDI - and what you see get sent when the bender goes back to the middle position.
Part of this too will be to see whether you get both positive and negative changes for the bender - or if it only ever bends the note high/low.
To rule out outside influences (e.g., loop through external hardware which is performing a transpose) you can temporarily disconnect the MIDI IN to the Chroma while you do your evaluation.
David Clarke
Heinz Weierhorst [21010276] · Wed, 4 Mar 2015 17:59:39 +0100
Hi all.
Isn't it so that the actuell levererpostion(s) during power up is declared as zeroposition(s)?
Heinz
Elan Benaroch · Wed, 4 Mar 2015 11:54:13 -0800
David, good suggestions.. I will try disconnecting the midi in. Forgot to mention I've lost the negative range of motion on the pot.. can't bend up anymore (pitch down).
David Clarke [21030085++] · Sat, 7 Mar 2015 16:06:02 -0400
Isn't it so that the actuell levererpostion(s) during power up is declared as zeroposition(s)?
Yes, and no.
During startup the Chroma will read the initial position of the levers.
It has an internal allowable range for "center" - and as long as that inital position is within the 'allowable range' for center - then the Chroma will use whatever the actual initial position was as its new center.
If the initial position of the lever is too far off though (e.g., outside the allowable range) - then the Chroma won't use that value as a new center value - but instead it will impose a center value thats within the allowable range.
So - the Chroma will account for variation in the actual 'center' - but it won't arbitrarily let the center be redefined.
... where I use the bender the tuning drops one tone. I play an A and it becomes a G it doesnt go back to normal until I reboot."
There's two key Chroma behaviours which can help to explain this.
First (as described above) - if the bender pot is too far away from center, it is going to 'impose' a nominal value within the allowable range for center.
Second - a lever movement doesn't become 'active' until a change in the lever position is detected.
The swing of voltages from the lever is about 2V - with about 1V being the intended center. The voltage increases with a lever push.
For the sake of discussion, lets assume that the lever is quite a bit out of adjustment, so that the 'center' is already at 2V.
When the Chroma starts up it is going to detect that as being too far away from the center, and so it is going to internally impose a value that is about half-scale (as what it things the center 'should' be.)
So - just sitting there, the lever is mechanically at 2V (the max value). The configuration at starutp has seen this as too high for center and so it has imposed its own 'internal' version of center (for this argument, lets say it internally will think 1V is center).
The lever has not been moved - and so the Chroma is using its normal tuning.
Now - as soon as you move the lever, the Chroma will see a 'change'. Now it is going to evaluate the lever value based on what it thinks is the center. Since the imposed center value is quite a distance from the mechnical value, the Chroma will think there's been a very wide pitch bend made - and it will stay thinking that until the Chroma restarts.
I'd first suggest looking at the voltages seen on the pot associated with the lever. You should see 0V on one side, 12V on the other and then there's the wiper voltage which should go from about 0 -> 2V, with the center position nominally about 1V. Based on what you see/don't see it should give a really good idea of whats happening.
Let us know how you make out.
David Clarke
Restarting issue.
Michael McInnis [21030027] · Sat, 07 Mar 2015 17:43:53 -0500
My Chroma is starting to have an issue where if I power down, it will fail to boot unless I wait 15 or twenty minutes. I have both the new power supply & CC+ installed.
Sometimes the panel will have some lights lit and other times totally dark.
Anyone seen this behavior before?
Thanks!
Regards,
MM
Michael McInnis
David Clarke [21030085++] · Sat, 7 Mar 2015 19:58:50 -0400
My Chroma is starting to have an issue where if I power down, it will fail to boot unless I wait 15 or twenty minutes. I have both the new power supply & CC+ installed.
Sometimes the panel will have some lights lit and other times totally dark.
Michael - just on the basis of how the panel looks, the two items which would be recommended to be reviewed first would be what the 5V power and the 'reset' signal from the power supply to the CPU board looks like when the unit is failing to boot.
In parallel - looking back in older correspondence [see] - you had earlier spoke of S/N 0027 - and specifically commented that it had the earlier ARP circuit boards.
If that's the Chroma where the behaviour is currently being seen, then while I wouldn't expect necessarily to directly explain the 20 minute 'cooling off' period, this note (from a month or so on the Chroma list) is worthy to review. In summary - if you're still using the original ARP I/O board (which used to have a dedicated ground wire going to the ARP CPU board) then an additional ground connection may be needed to ensure expected operation with the newer CPU boards (both newer 'original' CPU boards as well as the CC+).
Michael McInnis [21030027] · Sat, 07 Mar 2015 19:09:36 -0500
Yes, this is on 0027 with Arp branded boards.
Just to make sure I understand. So, ground connection from Z2-10 on the CPU board to P9-2 on the I/O board? Is there a Z2-10 on the CC+?
Regards,
MM
Michael McInnis
David Clarke [21030085++] · Sat, 7 Mar 2015 20:51:05 -0400
Just to make sure I understand. So, ground connection from Z2-10 on the CPU board to P9-2 on the I/O board?
Put another way - on the original ARP setup they had:
---------
I/O Board: J9-1, J9-2, J9-3, J9-4 = Ground. All connected together
CPU Board: J9-1, J9-2, J9-3, J9-4 = Ground. All connected together
Separate Wire: ground from I/O board to an isolated ground pin on the 74LS245 on the CPU board, as a dedicated 'buffer digital ground.'
---------
In the 'production' Chroma setup they had:
---------
I/O Board: J9-1 = Buffer Digital Ground
J9-2, J9-3, J9-4 = Ground. All connected together
CPU Board: J9-1 = Buffer Digital Ground (which went to ground on the 74LS245)
J9-2, J9-3, J9-4 = Ground. All connected together
---------
In most cases, the new CPU will 'just work' - but ideally to mix and match an old I/O board with a 'new' CPU board, you'd want to split J9-1 from J9-2/3/4 so that it is its own connection - and to have the dedicated buffer ground connected there.
Is there a Z2-10 on the CC+?
The reference designator has changed - but the 74LS245 on the CC+ (U5) serves the same purpose as Z2 on the original CPU board.
Michael McInnis [21030027] · Sat, 07 Mar 2015 20:14:35 -0500
Very clear now to me. Thank you!
Regards,
MM
Michael McInnis
Off topic: SSM chips
Matt Thomas [21010021] · Sun, 08 Mar 2015 18:45:27 +0000
Off topic query, I hope Chris will forgive me but this is the only synth forum/discussion group I¹m part of & have a sense of the contributors' expertise regarding synth servicing issues -
I have a set of SSM chips carefully removed from a Siel DK-600 that had suffered water damage to its power supply in storage. None of the rust & water markings came close to the circuit boards which were clean & dry. In a nutshell my question is - how can I test them / get them tested? I have almost no electronics equipment or experience myself.
Again apologies for the off-topic question - if people would rather reply direct to keep the OT traffic to a minimum please do. I¹m just a touch flummoxed about how to resolve this problem.
Dave Bradley [16330135] · Sun, 8 Mar 2015 20:17:14 -0500
That's a hard question. I used to have a bunch of SSM Voice Demo boards that I built a synth around. One of those would work, if you had the right set of SSMs. You could use protoboard and hookup wire to apply power and test them that way.
Doug Terrebonne [21030114] · Mon, 9 Mar 2015 00:40:16 -0700
You could test the SSM2044s and SSM2056s in a Korg Polysix if you have access to one (the 2056s are also used in the Poly-61)...
cps kit question for chris b.
Dylan Wahl [21030410] · Tue, 10 Mar 2015 00:33:09 -0400
Hi all,
If one of you has contact with Chris Borman [21030194+], please forward that I could help with circuit boards or a re-design to add the metal bracket supports back, or try to help with assembly. I'd like to buy a set of the FSR strips, unless the first order is already sold out. (Or a kit, if one's available...)
Thanks,
Dylan Constan-Wahl
History
Eric W. Mattei [21030443+] · Wed, 11 Mar 2015 11:04:08 -0700
Greetings to All
What year was the CC+ first introduced? (2006?)
What year was the SPSU first introduced? (2008?)
What year was Mister Borman's Pressure kit first introduced?
I came across a lame Chroma article on Wikipedia and I'm fixing it up.
Thanks
Eric
Chris Ryan [21030691] · Wed, 11 Mar 2015 11:06:18 -0700
I could give you the exact dates but you should be able to determine them from the Site News page—e.g. June 2006 for the CC+.
Original CPS
Dylan Wahl [21030410] · Fri, 13 Mar 2015 14:04:33 -0400
Hello,
Does anyone have an original Chroma CPS, preferably broken? I was wondering if you could measure the molded rubber parts that contact the FSR's.
Thanks,
Dylan
David Clarke [21030085++] · Fri, 13 Mar 2015 17:07:06 -0300
Dylan - I don't have the physical measurements, but just for clarification, the original pressure sensor didn't so much use a 'force sensing resistor' as it just used a resistive material that was allowed to touch a conductor in varying amounts, based on how much of it was squeezed into it via a rubber cone: xref: Pressure Sensor & Interface: Technical
Dylan Wahl [21030410] · Fri, 13 Mar 2015 16:14:05 -0400
Yes, that cone would be nice to replicate. First try would be with a 3d printer. But it would be nice to match the original's durometer.
I don't think the FSR's are much different, maybe more linear, but it looks very similar to a shunt-mode FSR. It would be interesting to know how different it feels with the varying surface area effect.
Luca Sasdelli [21010226] · Fri, 13 Mar 2015 21:37:20 +0000
I knew that only two Chromas left the factory with the pressure sensor installed. Isnt't it?
Al Tutlys [21030645] · Fri, 13 Mar 2015 18:35:23 -0400
I used to frequently visit the woburn facility and spoke with bill thomas and a couple other people I knew that worked there. I was anxiously waiting for the pressure I was waiting for the pressure kit to be shipped and was told that it "failed the life test" and would not be shipping. I remember seeing a chroma by the loading dock set up with a device that would repeatedly press a key. Needless to say, I was kind of let down that I couldn't add that feature to my Chroma. I did get a fan kit and ended up modifying my Chroma to use 4 banks of 50 programs. (with help from Mark Smith) Although, I did go with a CC+, that original CPU still works fine.
Dylan Wahl [21030410] · Fri, 13 Mar 2015 18:55:24 -0400
I mean, the Prophet T8 pressure sensor system is similar, less elaborate though. It doesn't have the rubber cones (which I actually think was clever...) just circular FSRs shunting across a set of tracks on the board. These are covered with clear tape and then a thin, soft foam strip.
The key side is different, there's a small cylindrical piece under each key that contacts the foam above the FSR. They are threaded into the wood, and can be adjusted so that the key response of each key matches (the keys all dig into ~1/4" thick foam at the end of their travel, not felt).
David Clarke [21030085++] · Fri, 13 Mar 2015 20:53:31 -0300
Out of curiousity - how many list users happen to have a Chroma with an 'original' pressure sensor?
(I have one here, and had assumed that some other users did too).
Yes, that cone would be nice to replicate. First try would be with a 3d printer. But it would be nice to match the original's durometer.
It was close to 13 years ago that I took mine apart. I don't think I took any 'inside' pictures - but from what I recall, the sensor area itself was large-ish - say about 1/2 to 3/4 of the size of the space in question.
So - you could estimate the size of the sensor area from Figure 7 here: Pressure Sensor & Interface - Figure 7: Sensor - Key Interface Close-Up.
The max size is bound by the width of the red strip (which is slightly narrower than the width of the wooden mounting bar) - so you could estimate the max. diameter a circle could have - then use 1/2 or 3/4 of that. The shape of the taper is close to that in the drawing on the site - sort of a parabolic cone with the fatest part being the measurement above.
The 3d printers that I'm familiar with end up with a hard material so I'm not too sure if it would give you anything helpful as the original is rubber and will deform with pressure (so that it 'squishes' to cover more surface area).
Paul DeRocco [21030230] · Fri, 13 Mar 2015 16:51:28 -0700
From: Dylan Wahl
I mean, the Prophet T8 pressure sensor system is similar, less elaborate though. It doesn't have the rubber cones (which I actually think was clever...) just circular FSRs shunting across a set of tracks on the board. These are covered with clear tape and then a thin, soft foam strip.
The key side is different, there's a small cylindrical piece under each key that contacts the foam above the FSR. They are threaded into the wood, and can be adjusted so that the key response of each key matches (the keys all dig into ~1/4" thick foam at the end of their travel, not felt).
Did a software cal not occur to them? Or could they not spare 76 bytes of CMOS RAM?
I installed a CPS into my Digital Chroma, and it sounded really granular. When I hooked a scope up, I saw that the voltages from each sensor didn't vary smoothly, but instead produced distinct steps. I guess that's due to the resistive material making and breaking contact with individual fingers. It's probably more noticeable on the Digital Chroma since the scan rate is four times as fast, and there are no S&H caps to filter the changes. I should probably put per-note pressure filtering into it.
So my opinion is that there's still a lot of room for improvement in the sensor design. If I wanted to go off and build my own, I wouldn't just copy that design, I'd do a bunch more experimenting with different finger patterns.
Dylan Wahl [21030410] · Fri, 13 Mar 2015 20:31:03 -0400
I have a feeling Sequential was having a hard time with the new keyboard mechanism generally? It has hammers with optical flags, and other somewhat more elaborate mechanisms...
I agree, I should try building a sensor, it didn't occur to me that the finger digits would make the stepping nearly discrete. Maybe a test board is in order, with several different patterns.
David, I work at a university, and the engineering lab has a new-ish $180k 3d printer. It can print materials in a fairly wide range of durometer, and there are samples of membrane keys...
John Leimseider [21030434++] · Sat, 14 Mar 2015 00:44:47 +0000
I have the original Chroma pressure. I was told at the time that there were about a dozen kits made. I got mine from a customer who had me remove it from his, because he hated the feel. I found that the install is VERY critical. A sixteenth of an inch makes a lot of difference. Once it's installed and adjusted, it stays that way for a long time. I haven't adjusted mine in over twenty years. It works great. I tried two of the new CPS's and thought it was OK. It didn't seem as consistent. I spent a lot of time adjusting them, got it as good as I could and retested them. I like the original way better. I also have a CS80, a Mellotron M4000D, a Buchla 400 and have access to a T8 and the VAX at work. I have also extensively played on the Kurzweil Midiboard. Each keyboard has its own way of implementing pressure. Hall effect sensors have the advantage of not needing readjusting after they are initially set up. Any mechanical sensor will wear out or at least change over time.
There was also the GZ1000 which never worked. I had the displeasure of having to work on many of them...
Eprom failures
Brian McCully [21030361] · Fri, 13 Mar 2015 20:24:55 -0700
Hi Chroma group,
I've tried to get updated Eproms (or Eeproms?) installed and have had 5 out of 6 that I've received fail.
3 were from a friend who said that he could produce them, and when I installed them all of them failed. He said that, possibly given the specs on the site, that the ones he used may not have been fast enough. He did not offer any substitutes. He said that the Eeproms passed all of their verification tests at the end of the burn in. He also said that Eeproms are old technology and finding burners and Eeproms is becoming a more difficult situation.
I received 3 Eeproms from William Santana [21030244] and the first two failed. The lower panel LEDs would light up on power up, but not go through the flashing routine. The 3rd Eprom worked - yay. I swapped the last v217 working Eprom in and out between, and it worked, so I'm not sure what else to say.
I am absolutely positive that the Eeproms were well seated and no legs were bent etc. I have plenty of light and magnification at hand. Just wish the underside of the panel was an easier access. I'm getting to be quite experienced at this swap in and out exercise...
So I still need one more Eprom or Eeprom...I've emailed William a number of times to alert him to this situation and offer to send back the duds, but no response.
William?
Brian
Paul DeRocco [21030230] · Sat, 14 Mar 2015 09:27:52 -0700
It sounds to me like you may have a problem in some other component on the bus. EPROMs aren't normally that troublesome. And it's not true that it's getting hard to find burners and parts. You can buy good programmers on eBay (like the GQ-4X) for cheap all day long. And the old pulled EPROMs that are commonly sold are typically parts that were burned once and sat in a piece of equipment for 30 years, meaning that they can be erased and reprogrammed perfectly reliably.
Unfortunately, this may not be an easy problem to diagnose.
Brian McCully [21030361] · Thu, 19 Mar 2015 15:13:10 -0700
Hi Paul,
Well you inspired me to make some room, and open up the other Chroma, and swap in a 'dud' v218 Eprom I got from William Santana [21030244]. That Chroma also has a v217 in it and works fine. Making doubly sure so, I powered up the Chroma before opening it. I was going to open it up anyway, but having two open Chroma's is a space... consideration.
Installed it - same result. A few lower panel LEDs turn on solid. No flashing LEDs. So - It's dead in both Chroma's. I'm not going to bother with installing the other Eprom that doesn't work. I'm awaiting receipt of more Eproms from a reliable source. I'll let y'all know how that turns out.
My theory is that William received a mixed bag of Eproms and didn't test them all after the burn (in a Chroma). I've got a static discharge protection wristband on, and all I've done is pour them out of the container they were sent in, onto an inert surface. I'm handling the v217 Eproms in the same manner, and after re-installing them back in the Chroma, they are functioning properly.
It'd be awesome if you want to burn Eproms for the 'US group'. Or spec an Eprom 'system' (e.g. with PC and hookups) for someone who wants to get involved with that process. With ballpark prices, and maybe some reliable source suggestions for correctly spec'd Eproms, etc. Would be worth the ROI?
regards, -Brian
Eric Frampton [21030501] · Fri, 20 Mar 2015 02:03:38 -0400
FWIW, when I was getting my Chroma running I tried burning literally a half-dozen copies of the keyboard CPU firmware eprom based on the image posted on the Chroma site (double-checking that the EPROMS were blanked, trying different speeds/types, making sure they properly verified, etc.). Not one of them worked. The one that finally did work was a copy of a pulled eprom (with the same firmware rev.) from another Chroma. And, I burned it back on top of one of the other previously-failed chips I’d already tried (erased first, of course).
All this to say, if any of the other eprom files are like the one that’s posted for the keyboard scanner firmware, I could imagine there being problems. Is that possible?
Dan Wilson [21030052] · Fri, 20 Mar 2015 08:49:22 -0000
Hi Eric,
This is a little concerning - are you able share the binary you made of the key scanner EPROM? In the meantime would it be possible to email me a copy for my archives? At the very least we can verify it against the image on the site.
All the best,
Dan Wilson
David Hobson [21030506] · Fri, 20 Mar 2015 12:03:35 -0400
I purchased 3 EPROM's from William Santana that I have not yet tested. I will make time later today and try each one and provide my own feedback.
Paul DeRocco [21030230] · Sat, 21 Mar 2015 01:16:28 -0700
From: Eric Frampton
FWIW, when I was getting my Chroma running I tried burning literally a half-dozen copies of the keyboard CPU firmware eprom based on the image posted on the Chroma site (double-checking that the EPROMS were blanked, trying different speeds/types, making sure they properly verified, etc.). Not one of them worked. The one that finally did work was a copy of a pulled eprom (with the same firmware rev.) from another Chroma. And, I burned it back on top of one of the other previously-failed chips I'd already tried (erased first, of course).
If that's the case, then the binary file you read out of the pulled EPROM should have been different from what is on the site. It would be interesting to see what the difference is.
By the way, I believe what the site says is an unknown revision was rev 1, and that rev 2 was basically rev 3 with a tiny bug that never got shipped. Rev 1 didn't have an actual bug, but if the system got busy, and the main CPU made the scanner CPU wait, then the time-of-flight measurements in the scanner would get shorter than they should be. Revs 2 & 3 fixed this.
Since I didn't have the original source code, I hand disassembled both versions, and commented them to explain what's going on. I didn't find anything that looked like an error. I was unable to assemble them with the SourceForge ASM48 project--it barfed on the first instruction--but I did managed to assemble them using an old copy of Intel's ASM86 and a bunch of codemacros for 8048 instructions, and I got the same binary that I started with. I've attached both source files, in case anyone is interested. (I believe rev 2 would be the same as rev 3, but without the "orl" instruction at the TIMER label.) Feel free to put them on the site, Chris.
David Clarke [21030085++] · Sat, 21 Mar 2015 07:48:32 -0300
... Since I didn't have the original source code, I hand disassembled both versions, and commented them to explain what's going on... Feel free to put them on the site, Chris.
Paul - thank you for sharing.
I had earlier taken a poke at dissembling and commenting the code (the scan2.asm and scan3.asm files at the bottom of the EPROM Code page).
You'd likely know better than me the intent of the code, so I'll let you direct Chris in terms of whether there's any merit in any of notes I had in that code or note (note - while these are labelled as scan2 and scan3, based on your notes - this probably should have been scan1 and scan3).
Eric Frampton [21030501] · Sat, 21 Mar 2015 13:14:18 -0400
I’ll do some poking around and see if I can find the binary. Stand-by to stand-by.
Paul DeRocco [21030230] · Sun, 22 Mar 2015 08:13:41 -0700
From: David Clarke
You'd likely know better than me the intent of the code, so I'll let you direct Chris in terms of whether there's any merit in any of notes I had in that code or note (note - while these are labelled as scan2 and scan3, based on your notes - this probably should have been scan1 and scan3).
Oops, I wish I had noticed those. I wouldn't have bothered. ;-) Yours look fine.
Chroma poly aftertouch sensor has loosened
Magnus · Thu, 19 Mar 2015 15:18:35 +0100
Hi all!
I have a Rhodes Chroma with the Chroma poly aftertouch sensor installed. Unfortunately the "glue" in the sensor is vanishing (between the textile and the long sensor) and makes the whole construction fall down on the keys. The textile is still glued to the wood above the keys. I hope you understand my description. Is this common problem? I would appreciate a lot if someone can guide me how to solve this the best way. I'd don't want to make a mistake and destroy something (electronically) on the sensor.
Many thanks in advance.
Best regards,
Magnus
Stockholm, Sweden
Luca Sasdelli [21010226] · Thu, 19 Mar 2015 15:35:10 +0100
Hi,
yes, it has been noticed several times. A suggestion was to use a different glue type: please look in the mailing list archive to find out which one.
My personal opinion is that, because the center is already held by the encoder PCB, it should be enough to fix the assembly ends to the wood with a small screw, one per each end, with the screw external to the strip and holding it just by menas of the screw cap itself.
When I'll have some spare time (when...?), I'll try to apply this fixing to my Chroma and will post some photos if I'll find an easy way to do it.
Cheers
Luca
Jesper Ödemark [21010135] · Thu, 19 Mar 2015 16:00:39 +0100
Not uncommon. I flipped the wooden bar and glued it to the back with a glue gun... But do take care not to mess up the electronics.
We can take it in swedish offlist if you want more feedback or go into details. :)
Johnny Vintage [21010244] · Thu, 19 Mar 2015 16:04:14 +0100
I have two, they both fell off :)
David Hobson [21030506] · Thu, 19 Mar 2015 11:12:51 -0400
A repair shop set aside two for me; I'll build my own, or help fund someone who can build it better.
Dylan Wahl [21030410] · Thu, 19 Mar 2015 11:17:37 -0400
group CPS replacement project?
Hi all,
I would propose that we design an open CPS replacement board, which would address current issues. If Chris [21030194+] is available that would be great, otherwise we can do it separately.
As part of this, I would like to find other Chroma users interested in participating in group buys for the components. PCB's will not be a problem, as they are inexpensive even in small quantities. The main cost will be the force sensing resistor assemblies, as these have to be run in a relatively large batch.
If we group-buy we should distribute the batch among the buyers. I don't envision trying to make money modifying Rhodes Chromas.
Is anyone else interested?
--Dylan
Michael McInnis [21030027] · Thu, 19 Mar 2015 11:19:03 -0400
New England Analog just designed a poly aftertouch kit for the T8. They said they could make one for the Chroma, but it would only be cost effective if there was a substantial order up front.
Regards,
MM
Dylan Wahl [21030410] · Thu, 19 Mar 2015 11:25:48 -0400
The T8 kit uses standard FSR from Sensitronics. I think the custom FSR on the last Cps kits was a good idea.
It would be great to collect a set of known issues for the existing kit in order to design a new one.
Magnus · Thu, 19 Mar 2015 16:37:41 +0100
Hi!
Thanks for all the great input.
Best regards,
Magnus
Ian Hamilton [21010150] · Fri, 20 Mar 2015 07:06:57 +1100
Re: group CPS replacement project?
I'm interested. Following with great interest.
David Hobson [21030506] · Thu, 19 Mar 2015 16:39:25 -0400
Re: group CPS replacement project?
I'm interested.
Daniel Rickenbach [21010172] · Fri, 20 Mar 2015 03:04:31 +0100
Hi
I’ve heard from this problem before I have installed the CPS, so I was thinking about another solution. I have made „brackets“ to clamp up the whole CPS board under the wooden bar, the self adhesive stripe wasn’t used and I have removed it. All the things are described at my website: Chroma CPS Improvement.
there is also a description of a change in the aftertouch electronic to make the response smoother.
Best regards
Daniel
Doug Terrebonne [21030114] · Fri, 20 Mar 2015 04:15:14 +0000
My sensor has also fallen down on one side, what was the consensus for the type of glue to use to re-attach?
Thanks,
Doug
Paul DeRocco [21030230] · Fri, 20 Mar 2015 00:28:11 -0700
From: Daniel Rickenbach
I've heard from this problem before I have installed the CPS, so I was thinking about another solution. I have made "brackets" to clamp up the whole CPS board under the wooden bar, the self adhesive stripe wasn't used and I have removed it. All the things are described at my website
I haven't tried it, but it wouldn't surprise me if a couple carefully placed tie wraps would solve the problem.
Jesper Ödemark [21010135] · Fri, 20 Mar 2015 09:35:10 +0100
Doug Terrebonne skrev den 2015-03-20 05:15:
My sensor has also fallen down on one side, what was the consensus for the type of glue to use to re-attach?
There was no consensus I believe...
Controller, pitch bend/ vibrato
Buddy Casino [21010137] · Wed, 25 Mar 2015 13:04:59 +0100
Hi,
I'm using the Chroma to play various synth via Midi. Chroma doesn't send pitch bend commands and other controller's There is no Midi going out, just when I hit the keys, I can see Midi activity.......
Do you have any idea what to do?
Ciao, Buddy
David Clarke [21030085++] · Wed, 25 Mar 2015 09:56:45 -0300
... Chroma doesn't send pitch bend commands and other controller's There is no Midi going out, just when I hit the key's, I can see Midi activity.......
Controllers for the Chroma are not 'fixed' - but instead are 'programmble'.
For pitch bend (for instance), go into the configuration menu ([Set Split][36]) and select P9 (which is the "Lever 2 Select" option).
Review the data in the small LED window. If you want to use Lever 2 for pitch bend, then ensure the display shows "Ptch".
For generic controllers (such as just using the slider), ensure that "Allow Param Changes" is turned on.
[Set Split][36], P6, ensure setting is set to "on".