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ChromaTalk Archives: January 2013

Re: Fuzzy chips

Go to first message in thread, December 2012

Mike Todd [21010097] · Tue, 01 Jan 2013 10:06:06 +0000

Thanks for the fast response, Dee

I've checked the various lines - they all look okay on first sight, and consistent with a CPU that is running but has failed to boot (maybe not surprising if an EPROM isn't functioning). However, I haven't yet had time to analyse things a bit more systematically.

I'm disappointed to hear that the fuzzies are so conductive, as I'd checked them and they seemed non-conductive (at least > 500Mohm). But with CMOS, who knows.

I've also been round the boards with an otoscope and can see nothing untoward under/around any other chips (at least where I can see).

More investigations to come

Paul DeRocco [21030230] · Tue, 1 Jan 2013 10:04:15 -0800

From: Mr M Todd

I've checked the various lines - they all look okay on first sight, and consistent with a CPU that is running but has failed to boot (maybe not surprising if an EPROM isn't functioning). However, I haven't yet had time to analyse things a bit more systematically.

I'm disappointed to hear that the fuzzies are so conductive, as I'd checked them and they seemed non-conductive (at least > 500Mohm). But with CMOS, who knows.

I've also been round the boards with an otoscope and can see nothing untoward under/around any other chips (at least where I can see).

I'd try unplugging all the chips and just cleaning them off. The fuzz is certainly not anything from inside the chip package. It's from the battery leakage. It's likely that the chips are fine. If any are physically damaged, you can find them on eBay all day long, but you'll have to have access to a programmer and eraser. If the CPU still doesn't run, it may be a good idea to erase and reprogram the EPROMs anyway, because after 35 years, some bits may have faded.

Rob C, New England Analog · Tue, 01 Jan 2013 15:17:36 -0500

I have several spare CPU boards with EPROMs intact. Contact me privately if you are interested in one. This article about tin whiskers is really interesting: Basic Info on Tin Whiskers

I have a microscope in my shop that I often use to find faults on synthesizer pcbs. I have been able to find lots of issues with shorts and other types of faults using this. A lot of what I have found would have been undetected to the naked eye.

Mike Todd [21010097] · Tue, 01 Jan 2013 23:17:25 +0000

On 01/01/2013 18:04, Paul D. DeRocco wrote:

I'd try unplugging all the chips and just cleaning them off. The fuzz is certainly not anything from inside the chip package. It's from the battery leakage. It's likely that the chips are fine. If any are physically damaged, you can find them on eBay all day long, but you'll have to have access to a programmer and eraser. If the CPU still doesn't run, it may be a good idea to erase and reprogram the EPROMs anyway, because after 35 years, some bits may have faded.

Paul

Thanks. I agree that the EPROMs may have become corrupted after all this time, but I don't have access to an eraser/programmer any more.

I agree that the fuzzies may have been encouraged by acidic vapour from the leakage, but it certainly looks like they are coming from the chips.

fuzzies

Mike Todd [21010097] · Tue, 01 Jan 2013 23:28:05 +0000

Rob, many thanks.

The NASA article on tin whiskers is very interesting, and it's also interesting to note that they're still not fully understood.

I think my example is quite dramatic, so I may pass the details on to them.

I used an old small hand-held microscope (20x) I got from a dermatologist (a bit like a loupe), with a decent conventional bench microscope for stuff I can put on slides.

I've certainly heard of tin and zinc whiskers before, but this is my first encounter with them.

Paul DeRocco [21030230] · Tue, 1 Jan 2013 15:33:40 -0800

The fuzzies you photographed don't look like the same thing that is outlined in the article mentioned by Rob C, which are generally individual filaments that are barely visible. I'm curious what chips have them. The chip in your photo looks like the driver for the display on the I/O board, which is a high-current chip. I'm wondering if a short caused it to overheat, and the fuzz is from the epoxy used to glue the ceramic top onto the chip. But that's not the sort of thing that would happen on an EPROM, or other part that doesn't get hot.

Mike Todd [21010097] · Wed, 02 Jan 2013 00:17:37 +0000

Paul

Yes, it is the "driver" chip for the display.

I agree that my fuzzies don't look that similar, although they do have (or rather had) a distinctly filament appearance, with some individual filaments running 10-15mm from the chip.

The epoxy theory sounds much more plausible, as they do seem to originate from the interlayer, including at the ends of the chip, which would not be from any tin, and also they appear to be non-conductive.

Whether this was as a result of overheating or not is difficult to know, but I'm pretty certain that the last time I had the Chroma open there was no sign of them, and it hasn't been switched on since.

Could something in the epoxy in this and the EPROM chips be crystalising out in the slightly acidic atmosphere?

But I'm beginning to think that these are a red herring (albeit an interesting one).

Paul DeRocco [21030230] · Tue, 1 Jan 2013 18:23:52 -0800

So it's the 74S374 and the EPROMs doing it? Any others?

Mike Todd [21010097] · Wed, 02 Jan 2013 08:58:16 +0000

Paul - yes, it is only the 74S374 and the EPROMs. The keyboard-scan EPROM shows it a little worse than those on the CPU board, but no other chips are affected.

I sent the photo to the people who did the NASA pages. I was very surprised to get a reply from one of them. It was along the lines that it is clearly made up from crystaline filaments, but that tin whickers tend to be more grey than these.

They have offered to analyse a sample and send me the report. Unfortunately, once I photographed them I cleaned them off.

Technician Larry [21030198] · Wed, 2 Jan 2013 08:35:29 -0800

I'm disappointed to hear that the fuzzies are so conductive, as I'd checked them and they seemed non-conductive (at least> 500Mohm). But with CMOS, who knows.

Possibly not the fuzzies alone, but my past observations suggest maybe the crystalyn structures attract and absorb humidity that contributes to conduction. Perhaps the humidity contributes to the growth of the crystals in the first place. In my efforts to repair Poly 6 boards there was evidence that resulting conduction messed with proper operation of tri-state logic lines. >

Paul DeRocco [21030230] · Wed, 2 Jan 2013 13:27:31 -0800

From: Mr M Todd

Paul - yes, it is only the 74S374 and the EPROMs. The keyboard-scan EPROM shows it a little worse than those on the CPU board, but no other chips are affected.

I sent the photo to the people who did the NASA pages. I was very surprised to get a reply from one of them. It was along the lines that it is clearly made up from crystaline filaments, but that tin whickers tend to be more grey than these.

They have offered to analyse a sample and send me the report. Unfortunately, once I photographed them I cleaned them off.

Well, I think it would be a good idea to replace those chips, even if they appear to work. Someone said they had a set of EPROMs available. You can get 74S374 chips from Digikey.

Mike Todd [21010097] · Sun, 06 Jan 2013 20:26:45 +0000

Just following up this non-working Chroma and its fuzzy chips.

First of all, I've had some very helpful and authoritative input on the "fuzzies" (including from NASA).

They are actually simply salt crystals that have grown from the special adhesive used to bind the chips' central ceramic layer to the protective outer layers. And indeed it is only chips constructed this way that are affected.

They almost certainly arise because of the slightly acidic atmosphere caused by the leaking batteries, and the phenomenon is apparently

Being salts, they are easily removed with distilled water and are only conductive when in solution, so I'm told that they should have had no influence on the electronics. In any case, I've now thoroughly cleaned the circuit board.

On the EPROMs, it is apparently almost certain that the chips are corrupted after all this time. The recommendation is to replace them. Although I don't have enough 2716 chips, I can use the 2732 - I just need to see if I still have my eraser and buy/borrow a programmer.

One of the concerns I did have was that the keyboard scanner seems to be working initially, but then locks up. However, looking at the source code it seems that it gets into a software loop waiting for an acknowledgement from the CPU once it asserts the keyboard interrupt. With the CPU not running properly, the acknowledgement never comes.

So, next step is to source a programmer burn, verfiy, and then replace the EPROMs (and the 74S134) and see what happens. It's a pretty cheap option.

Paul DeRocco [21030230] · Sun, 6 Jan 2013 16:00:19 -0800

On the EPROMs, it is apparently almost certain that the chips are corrupted after all this time. The recommendation is to replace them. Although I don't have enough 2716 chips, I can use the 2732 - I just need to see if I still have my eraser and buy/borrow a programmer.

You can find blank 2716s on eBay. Or if you have some chips with data in them, but no eraser, you could leave them out in direct sunlight for a day, and that should erase them.

Mike Todd [21010097] · Mon, 07 Jan 2013 08:44:17 +0000

Thanks, Paul

Yes, there are 2716s on eBay, but I have plenty 2732s (which I know can be used) so it's a no-cost option.

As for direct sunlight ... there's not a lot of that at this time of year where I live :-)

Chroma expander case wanted to possible trade

Matt Hillier [21010094+] · Tue, 1 Jan 2013 15:13:31 +0000

Hi guys

due to a downsize i am looking to switch my chroma key version to an expander or maybe if i can find an expander case swap out things.If anyone has an expander case or wants a keyboard version in exchange of some kind then please mail me as i really don't want to lose Chroma sound in our studio but we literally dont have room for the keyboard version now.I will happily take an expander case that needs work or renovation also and i really dont know how rare these are so sorry if i am asking for a miracle :)

regards and happy 2013 to you all

Paul DeRocco [21030230] · Tue, 1 Jan 2013 10:05:22 -0800

Where are you located?

Switched PSU Retrofit on eBay

Chris Ryan [21030691] · Wed, 2 Jan 2013 20:31:41 -0800

Item #130828831721; USD$180.00. See Switching Power Supply Unit Replacement Kit on the site for details.

Re: Keyboard Triggering Problem

Go to first message in thread, December 2012

Eric W. Mattei [21030443+] · Thu, 03 Jan 2013 13:09:14 -0800

For the record: We cleaned all the key contacts a couple more times and that fixed the problem. Thanks to all.

Luca Sasdelli [21010226] · Fri, 04 Jan 2013 03:02:37 +0100

BTW: how did you clean contacts? My way to do it is to dismount the two contact PCBs and clean them one by one with a lint-free cloth and IPA.

Brian McCully [21030361] · Thu, 3 Jan 2013 19:45:49 -0800

In Seattle (at least), IPA = India Pale Ale. Hmmm. Nice thought. I've had other gear share malt beverages, but not beneficially. A pint of Guiness once engulfed my Traynor powered mixer during an encore performance (i.e. the dance floor was jumping and so did the full pint glass ;>). That took a lot of distilled water to ungunk, after the incident.

I'd stick to the lint free cloth, or even just a thin scrap of paper spiked with 'rubbing' alcohol, i.e. not the consuming variety (although ... a fine vodka might work...).

-Brian (cheers, and happy new year!)

Doug Terrebonne [21030114] · Thu, 3 Jan 2013 19:55:41 -0800

I would recommend denatured alcohol (doesn't leave any film behind) rather than IPA or rubbing alcohol...

Luca Sasdelli [21010226] · Fri, 04 Jan 2013 08:48:49 +0100

Well... IPA = Isopropyl alcohol :-)

AFAIK, for cleaning of laser light path, IPA does not leave any film behind, while denatured alcohol still has a greasy component, and not vice versa :-)

Anyway, contact cleaning with generic contact spray is definitely useless.

Andrew Dalebrook [21010180] · Fri, 4 Jan 2013 15:50:39 +0100

Alcohol types

Chemist here, just for the record:

  • IPA = rubbing alcohol = isopropanol or isopropyl alcohol.
  • Denatured alcohol = methylated spirits; mostly ethanol but containing methanol to put people off drinking it, also to escape liquor taxes. (Sometimes a pyridine is added to make it smell unpalatable, often with a dye as colourant.)

Assuming there are no other additives, IPA is less volatile, so it may seem to leave a film, but it probably is taking longer to evaporate or "flash off." In any case, you should wipe off any residue, as the solvent will only serve to dissolve the dirt. If you leave it to dry the dirt is right where you left it!

Philippe [21010227] · Sun, 6 Jan 2013 19:08:25 +0100

Re: Alcohol types

Thanks for the details but which one would be the cleanest ? Which one would leave no or the least grease ?

Luca Sasdelli [21010226] · Sun, 06 Jan 2013 19:11:40 +0100

Re: Alcohol types

Normally I use IPA and wipe each contact individually with a lint-free cloth. This requires to dismount both keycontact boards, but to do a good job I don't think there should be an alternative.

Eric W. Mattei [21030443+] · Thu, 31 Jan 2013 11:01:05 -0800

Hello folks

Finally got a hold of my guy. He doesn't use India Pale Ale... at least, not for cleaning contacts. He's cleaned thousands of contacts over the years and he uses a spray on, drip off, contact cleaner. I'm sure that doesn't sound ideal in many people's opinions (including my own), but he's trying to avoid dismounting those PCBs. Meanwhile, I don't think those contacts have been cleaned in all the time I've owned it (30 years). I haven't picked up the Chroma yet because we're waiting for parts for my mix board (the other project I gave him). He's going to test it again before I pick it up. I'm sure things will get worked out in the end.

Thanks for all the input.

squeeking oscillator

Claes von Heijne[16330008] · Mon, 7 Jan 2013 17:08:04 +0000

hello everybody

I have a chroma [21030290] and an expander [16330008], routed together through a bcr2000, all the updates, CC+, power and polytouch (works nice), but today something happened that worries me. In every 8-note patch, the first pair of oscillators squeek and shiver, not correct pitch. I guess something happened to one of the 8 cards; can anybody just through this simple description have an educated guess about the problem? Me, I have sen error in voice 1 on the display, but now there is no error on the display, but the sound. How come autotune does not silence the board, isn´t that supposed to happen?

I cannot repair this myself, but if I have a good theory I´m more likely to get help on this one.

Luca Sasdelli [21010226] · Mon, 07 Jan 2013 18:17:21 +0100

Hi Claes,

a voice board not silencing could be due either to a CMB logic failure or - more likely - to a failed CMOS switch. Moreover, if both tones in a voice board are failing, it's definitely an output bus failure (e.g. Z17 or its logic driver Z26).

Just try to identify the offending board, by using the SetSplit [37] command.

David Clarke [21030085++] · Tue, 8 Jan 2013 23:40:42 -0400

... How come autotune does not silence the board, isn´t that supposed to happen?...

The auto-tune will attempt to adjust certain parameters of the voice cards, under certain pre-set conditions. It is possible to have failures that occur which can't be directly detected by the auto-tune algorithm - and so it is possible for certain types of 'failures' to occur (and to not result in a disabling of the channel/voice).

Following up to Luca's suggestion - you can use the voice-watch (Set Split 37) functionality to determine which channels are impacted.

Assuming the problem consistently happens on the same channel, you can move the Channel Boards around on the Channel Mother Board and then retest - to determine if the issue follows a channel board or follows the channel mother board slot.

Assuming the problem follows a channel board you could then at least perform some subjective testing on just that one channel board to look to see what parameters allow the issue to occur (e.g., does the problem come from the filter, does it come from the oscillator, does it only occur at high frequences/low frequencies, is it only on the 'A' channel or the 'B' channel, etc.) Some of those tests may allow you to subjectively determine the nature of the issue.

Heinz Weierhorst [21010276] · Wed, 9 Jan 2013 15:24:14 +0100

Hello All.

May be the CD4016 switches (Z16,Z17) on CMB are defective. When the Chroma autotunes output summ 0 coming from the dual voice board is removed from the inverting input of Z18 (4558) and connected to the zero crossing detector input. The remaining summs 1-3 are also removed from their inverting inputs and switched to ground to prevent any crosstalk. This outputs are currents so it's no problem to short them to ground. Another fault is that the switches are controlled wrong by the autotune flip-flop CD4013 on CMB.

Claes von Heijne[16330008] · Wed, 9 Jan 2013 14:50:04 +0000

hello everybody

and thank you. Today a set split 50 followed by a set split 37 revealed that all oscillatorcards worked, 0 to 7. I collect all chromatalkmessages in its own folder, so now I know something at least. Thank you all for your input.

I guess the best way to keep this instruments working is to start them up every other day, and play them. I tour with nothing but Claviastuff these days, and have the chromas in my electronics-room.

all the best

Claes

Claes von Heijne[16330008] · Wed, 9 Jan 2013 14:59:40 +0000

hello again

there was one more issue, I remembered. The pressure-sensor is a nice addition, but after having it installed key 24 (Eb) is both different than the others and before; its heavier and needs more pressure than the rest. Is there som sort of divison or edge in the pressure-sensor-kit that would result in something like this? Has anybody had this reaction after installing the CPS?

Jesper Ödemark [21010135] · Wed, 09 Jan 2013 22:02:09 +0100

Hi Claes,

I had some similar issues on my first pressure sensor board. Not sure if your problem is the same. Mine was probably due to the fact that the fuxxing postal service had used the parcel as a baseball bat or something... :-/

Brian McCully [21030361] · Sat, 12 Jan 2013 09:41:28 -0800

there was one more issue, I remembered. The pressure-sensor is a nice addition, but after having it installed key 24 (Eb) is both different than the others and before; its heavier and needs more pressure than the rest. Is there som sort of divison or edge in the pressure-sensor-kit that would result in something like this? Has anybody had this reaction after installing the CPS?

Yes. I have one note (I think it's an Ab, in the upper part of the keyboard) that requires much more pressure, relative to the others. In an earlier kit it was a different note, or set of notes. I used a thin piece of sticky backed rubber pad to try to 'even' things out (i.e. add height to the key weight) on a few notes, but there is nothing I can do about that one note's pressure difference. It's not an alignment issue as far as I can tell. I just figured if it ever came down to dealing with a MIDI recording of it, that I'd hopefully be able to edit the poly pressure data in the sequencer.

I'm not sure what you mean by heavier (more resistance?) but the action is slightly different with the pressure sensor installed. Did you remove the front felts? There were a number of earlier threads on this topic.

Dave Manley [21030547] · Sat, 12 Jan 2013 14:06:24 -0800

I ran into the same issue - one note requires much more pressure. I measured the resistance of that one sensor pad and it was much higher than all the rest, and even sent it back to Chris and he said it was ok, but that one note doesn't really work properly due to the fact the resistance doesn't drop as low as all the rest. Since it seems to move around from sensor to sensor I think it is a manufacturing issue and there's nothing you can do to fix it.

I don't recall the exact measurements, but my recall is a good sensor measures down to <<10ohms with heavy pressure, but the defective position only gets down to ~1K? I'll have to dig through old emails to see if I have more specific measurements.

Dave Manley [21030547] · Sat, 12 Jan 2013 14:14:24 -0800

Dug through the old emails, sorry for the double post. My recall wasn't too accurate - here's the old info [see Re: re-glueing the CPS etc., September 2011]:

"...I checked the resistance at each FSR by clipping an ohm meter between the +5 common and each FSR return signal. On the left hand side when squeezing between thumb and index finger, the resistance drops down to about 5K, while on the right hand side it drops to about 1K. The 'B' below middle C on the other hand only drops to ~100Kohm. To make sure it wasn't a soldering problem (measurements were taken at the headers by the mux board), I probed at the via on the backside of the pcb nearest the FSR and saw the same ~100K.."

MOD DEPTH questions

Eric W. Mattei [21030443+] · Tue, 08 Jan 2013 21:31:05 -0800

Hello All

Chris Ryan [21030691] suggested I ask the list. I've got some questions about the MOD DEPTH parameters [28], [30], [32], [36], [41], [43] and [45].

The original manual says MOD DEPTH "Adjusts the gain..." and specifies the range as "–64 through +63"

The original parameter chart said: 63 Deep, -64 Shallow

The new parameter chart says: 63 Deep, 0 None, -64 -Deep

So if MOD DEPTH is 0, there's no modulation? That makes sense because the scratch patch sets the first 7 MOD DEPTH parameters (28 - 45) to zero.

So MOD DEPTH is polarized??? If so:

How does negative MOD DEPTH differ from positive? Do you get the "valleys" where the "peaks" were for repetitive control signals? For controllers, up acts like down and vice versa? Are envelopes applied upside down or inverted somehow?

Your answers could help us improve the parameter chart.

Paul DeRocco [21030230] · Tue, 8 Jan 2013 21:41:08 -0800

Yes. So for a sine wave sweep, the polarity isn't very important. But for a lever, or an envelope, it's night and day.

Luca Sasdelli [21010226] · Wed, 09 Jan 2013 09:20:27 +0100

Hi Eric,

Eric Mattei 09 gennaio 2013 06:31

"Adjusts the gain..." and specifies the range as "–64 through +63"

The VCO MOD range varies, as stated on mentioned pages: [28] steps are 1/16 semitone, [30] steps are 1/4 semitone, [32] steps are semitones. The VCF MOD is the same for all three values (semitones), with value of 32 for perfect pitch tracking.

The original parameter chart said: 63 Deep, -64 Shallow

The new parameter chart says: 63 Deep, 0 None, -64 -Deep

So if MOD DEPTH is 0, there's no modulation? That makes sense because the scratch patch sets the first 7 MOD DEPTH parameters (28 - 45) to zero.

So MOD DEPTH is polarized??? If so:

Yes: each MOD control at zero means no modulation.

That makes sense because the scratch patch sets the first 7 MOD DEPTH parameters (28 - 45) to zero.

So MOD DEPTH is polarized??? If so:

How does negative MOD DEPTH differ from positive? Do you get the "valleys" where the "peaks" were for repetitive control signals?

Correct. If talking about vibrato range, the polarity makes no difference (except by modulating another VCO with same LFO wave and inversed polarity, that will cause the algebraic sum of both MOD values); with very low LFO frequencies, synced with same usage of that LFO waveform in another module (VCF, VCA, pulse width), polarity will have a different effect.

Just to point out a relevant aspect of the Chroma structure: all MOD values are simulated within software and their algebraic sum is finally fed to the DAC, together with the involved control voltage (e.g. VCO): this assures that different MOD source combinations will be exactly related one to the others, and only the resulting summed value will be used. At those years, other synths e.g. Moog and Prophet (and ARP too) had analog voltages summed together, causing some drift and/or error(s) propagating from a given MOD source to another one, thus influencing the overall precision.

A matter of terminology on the parameter chart

Eric W. Mattei [21030443+] · Thu, 10 Jan 2013 12:08:38 -0800

Hello List

Chris Ryan [21030691] and I have been discussing improvements to the parameter chart and we wanted to get your opinions on some things.

This is regarding the descriptive text for values for parameters 2, 13, 20 and 50. Specifically:

Parameter 2 FSW MODE: values 6 and 7 say "-Note Gate"; should be "Note Gate (inverted)"?

Parameters 13 and 20 AMPL TOUCH: value 7 says "-Threshold" should be "Threshold (inverted)"?

Parameter 50 MOD 3 SELECT value 7 says "-Pedal 2" value 5 says "-Pedal 1" should be "Pedal 2 (inverted)" "Pedal 1 (inverted)"?

The theory is that it's nice to spell things out. Personally, I love it because "(inverted)" is easier to see than a minus sign and I'm half blind. Also, consistency is a virtue. For parameters 2, 13, 20 and 50, the manual refers to the selections with minus signs as "inverted". I think this is true for all parameter values that had minus signs on the original parameter chart. But the manual doesn't always get it right.

Squeezing "Threshold (inverted)" into table 13 would be tight, but it's doable. But is it right?

Does "Pedal 2 (inverted)" make as much sense as "-Pedal 2" for parameter 50?

On Parameter 20 value 7 -Threshold: is a threshold "inverted" or negative?

Any input will be greatly appreciated.

BTW, if you have any ideas to improve the parameter chart, this is a good time to talk about it.

Thanks.

Paul DeRocco [21030230] · Thu, 10 Jan 2013 12:17:26 -0800

Using a minus sign is just a space saver. If you've got room, you can write out the word.

Sometimes, "inverted" means the value is negated. Sometimes, it means its value is subtracted from the maximum, so the value goes from max down to zero instead of zero up to max. And sometimes (as in the case of the note gate or the velocity threshold) it means that the on/off response is complemented. But I don't think there's anything wrong with using the word "inverted" in all cases.

Some Chroma Troubles with CC+

Arun Majumdar [21030348] · Sun, 13 Jan 2013 00:28:29 -0500

Hi,

I have version 2.11 of the CC+ and I was trying to program it with an external interface.

I have tested everything that I could - P20, P6, you name it.

I have found that when I twiddle MIDI values externally, that the green LED does *not* light up to signal MIDI activity (unless notes are being played).

The Chroma works with MIDI notes but does not work with parameter editing remotely. I enter set-split 36 to get into the mode and nothing works.

So I am thinking that I have two options:

  1. Burn a New EPROM of the latest OS (it means I need to setup a PC again since I have an older burner that only works on windows XP)
  2. Debug the CC+ / Interface combo

Any thoughts about what I can do?

The external interface is a the Chroma Enabler and it can control a *test* softsynth just fine (I tested the Enabler fully, so it is definitely working and sending out MIDI and Randel [21030467] has been of *enormous* help - I *highly* recommend the Enabler - I used on another soft-synth as a controller and it works amazing! But I want my Chroma to work!).

Any thoughts about what I should do before I plunge into to full on hardware/software debug are welcome.

Thanks,

Arun

David Clarke [21030085++] · Sun, 13 Jan 2013 11:28:03 -0400

I have version 2.11 of the CC+ and I was trying to program it with an external interface.

I have tested everything that I could - P20, P6, you name it.

I have found that when I twiddle MIDI values externally, that the green LED does *not* light up to signal MIDI activity (unless notes are being played).

The Chroma works with MIDI notes but does not work with parameter editing remotely. I enter set-split 36 to get into the mode and nothing works.

In general, if the Chroma can successfully receive note on/note off information, it should also be able to successfully receive MIDI CC data from the enabler (each CC+ is tested and demonstrated to be able to receive MIDI CC's before being shipped).

That being the case, while Rev 211 of firmware is now a bit old - there should be no reason that you coudln't use it with the Enabler. The behaviour you're seeing should only be controlled by one of the CC+ settings.

Just to confirm - are you able to successfully see "EP" in the large 2-digit LED display when you press set split?

If so:

  1. Confirm that P1 is set to 0 (e.g., base channel of 1)
  2. Confirm that P2 is set to Normal.
  3. Confirm that P6 is set to On
  4. Confirm that P18 is set to "Cust"
  5. Select P20, and move the parameter slider.
  6. Confirm that P24 is set to "Inst"

Based on your notes, I'm presuming that P6 and P20 may have already been done - so P18 may be the key change in your case. The default shipping configuration is to support the MIDI continuous controller mapping for the Syntech MIDI interface - and so a change to the 'Custom' MIDI controller map would be needed for a controller that uses all of the Chroma parameters (such as the enabler) (Also, when selecting P20, it is important to move the parameter slider to tell the system to actually perform the 'initialization' of the custom mapping table.)

(#'s 1, 2 and 6 aren't strictly required - but they will help to simplify the configuration until you're successfully running.)

Let us know how you make out.

John Leimseider [21030434++] · Sun, 13 Jan 2013 08:40:58 -0700

I've been trying to get the iPad editor to work with the CC+... It doesn't send anything... Some of the editors I have are sending. I'm using an iRIG interface. Will this work? Thanks!

David Clarke [21030085++] · Sun, 13 Jan 2013 11:56:38 -0400

John - is this the 'iRIG' that you're referring to?

If so - can you clarify what is/isn't working (e.g., are you not seeing MIDI exit the iRig MIDI - or does it seem to be exiting the iRig but not being actioned by the Chroma/CC+?)

John Leimseider [21030434++] · Sun, 13 Jan 2013 09:20:07 -0700

It doesn't exit the iRIG... There are some templates from touchOSC that do send MIDI. Do I need something else in addition?

Matrix [21030220] · Sun, 13 Jan 2013 08:26:46 -0800

Which template are you using? There are two, one for The Missing Link and one for Core Midi. The one for The Missing Link is wireless but will not work with other Midi adapters.

John Leimseider [21030434++] · Sun, 13 Jan 2013 09:32:57 -0700

The Core one.

Go to next message in thread, February 2013

Screws

See previous thread Screws, January 2009

David Hobson [21030506] · Sun, 20 Jan 2013 03:38:53 -0500

Hello,

I am writing to share with you all where I got screws for the Chroma and how much they cost. As for my Chroma, it is running fine. I got the CC+ and it is a joy to work with. I will also, in the next few months, purchase a SPSU and then I will probably purchase the recap kit on eBay.

Anyway, these are the screws I purchased:

For the 4 control panel screws AND the for wooden strip above the control panel I used the same screws for Amazon.com($2.49 for 25): 6-32 x 1 Black Phillips Machine Screw (25 pieces)

To replace my worn clip nuts under the wooden strip($4.75 for 25 w. free shipping): 6 32 Tinnerman Style Clip Nuts 25 Pcs

And to replace the rear panel screws($3.02 for 40): 6-32 x 3/8 Black Phillips Machine Screw (40 pieces)

It was nice to have new screws. I hope this helps somebody.

Suspicious eBay offer

Paul DeRocco [21030230] · Mon, 21 Jan 2013 00:45:49 -0800

At the moment there is a Chroma supposedly on sale on eBay, with a current bid of $0.99 [a few days later listed again under a different seller as item #370745219344]. I've had this pop up in my watch list repeatedly lately, and each time I've checked it, it's been withdrawn. But this time I managed to grab a copy of it.

The owner's supposed eBay id is 123luv2quilt, with 99.9% positive feedback. The seller explains that he wants to be contacted at his work e-mail address about his terms of sale, and shipping arrangements. He provides a long description, and claims it is serial number 21030828, which the registry shows was sold back in November [see Chroma S/N 21030828 Sold on eBay], yet this user claims it's a one-owner Chroma. The text of the description matches the text of the November sale, although that one looks completely legit.

Text from the auction: "Refurbished & Fully Functioning Rhodes CHROMA! (with Original Anvil Flight Case) This refurbished Chroma works flawlessly. I?m the single original owner of this amazing Vintage Rhodes Chroma (Serial Number 21030828). It has a new, completely upgraded, power supply. All voices register and autotune properly. The original factory pre-set sounds have been loaded from the original cassette that comes with the keyboard as does the original Anvil Flight Case. You won't find a better Chroma than this one. This is one of only 1400 ever produced. It's still one of the purest and most unique sounding polyphonic synths ever made.This keyboard was carefully upgraded in 1986 at the CBS Fender Rhodes factory (the power supply and eproms were replaced) and again in 2009 by Steve "Doc" Hickerson, a factory authorized Chroma technician who's worked on Chroma's since they were introduced, whose reputation for experienced, excellent work has been trusted by A list performers, such as Eric Clapton. By today's standards it's still well specified. It?s an open architecture, multi-voiced, portable synth with a real weighted keyboard that allows for layering performances and sequencing. The additional ChromaFace by JD Cooper [sic] allows it to speak MIDI. As is common with the ATA flight cases that came with the keyboard, the inner lining of the case decomposed, staining the wood side boards. I cleaned it up in 2009 when it was refurbished (see pictures). The Chroma will be shipped to you, bagged and padded, in its original ATA Flight Case. There is no foot-pedal or volume pedal. A copy of the manual is included (they never gave me an original? just a copy!). The original cassette tape of voices from the factory is also included. Call with questions to 918.742.2600 Jeff I always believed the Chroma was an instrument of historical significance that would be worth keeping. It belongs with a high end studio or in the collection of someone who will use it often."

The list of this seller's eBay sales lists hundres of quilt patterns under Sewing and Fabric, followed by tons of scattered items in music, business & industrial, cameras & photo, etc., all of which have the same suspicious pattern of offering some multi-thousand-dollar item with an initial bit of $0.99, and insistence that one contact him at his work e-mail address.

I'd say this quilt lover's eBay account has been hacked, and the Chroma is as illusory as the 600mm Canon lens, the Stradivarius bass trombone, and the Taylor soft serve ice cream and milkshake machine.

NAMM anyone?

Paul DeRocco [21030230] · Fri, 25 Jan 2013 18:39:46 -0800

Is anyone at NAMM? I have my prototype Digital Chroma (a Chroma with the guts replaced with a 48-voice soft synth) over at the Hilton. If anyone is interested, contact me off-list, and I'll give you my cell number, and we can set up a meet.

Dave Bradley [16330135] · Fri, 25 Jan 2013 22:10:27 -0600

Pics!

Paul DeRocco [21030230] · Fri, 25 Jan 2013 20:13:03 -0800

It looks like a Chroma. ;-)

Brian McCully [21030361] · Fri, 25 Jan 2013 22:43:21 -0800

Great news, Paul. As far as any of the NAMM 2013 reports I've read (new Moog Phatty, Prophet 12, KorgKing, etc.), a release of a new Chroma would be way tops. Really looking forward to hearing more about it! I was hoping to see a polyphonic Phatty announced for guitar synth app's but a Chroma would totally suffice! What a surprise. Wish I was in LA only for this reason - otherwise the show looks pretty darn 'dudly' from my net perspective. yay!

Paul DeRocco [21030230] · Fri, 25 Jan 2013 23:53:03 -0800

From: Brian McCully

Great news, Paul. As far as any of the NAMM 2013 reports I've read (new Moog Phatty, Prophet 12, KorgKing, etc.), a release of a new Chroma would be way tops. Really looking forward to hearing more about it! I was hoping to see a polyphonic Phatty announced for guitar synth app's but a Chroma would totally suffice! What a surprise. Wish I was in LA only for this reason - otherwise the show looks pretty darn 'dudly' from my net perspective. yay!

I played the Prophets and the Phatty, and didn't like them very much. I couldn't get a decent touch response from the former, and both use bend and mod wheels which I think totally suck compared to the levers that the Chroma and Polaris used. They just didn't feel very musical, to this piano player. But to listen to all the other show-goers tinkering with them, they mostly like to get strange, raunchy sounds, not play music. I couldn't really judge the sounds, though, because even with headphones, the show environment is just too noisy.

Rob Witt · Sat, 26 Jan 2013 09:37:20 -0500

Paul-

I think it's wonderful that thirty years on you are doing a Dr. Frankenstein on a Chroma "body". Wish I could hear it.

Dave Bradley [16330135] · Sat, 26 Jan 2013 09:58:35 -0600

Can you talk about the soft synth piece of it? Is it something you are writing yourself? Does it replicate Chroma functionality?

Marais · Sat, 26 Jan 2013 12:40:56 -0500

the important question Paul is can it do the Chroma bagpipes patch ?

Paul DeRocco [21030230] · Sat, 26 Jan 2013 09:53:23 -0800

Yes. It does broken glass, too. There are still bugs in the converter, so some of the old patches don't sound right yet, but the new instrument is capable of making all those old sounds, if the parameters are set correctly.

Paul DeRocco [21030230] · Sat, 26 Jan 2013 10:12:45 -0800

From: Robb Witt

I think it's wonderful that thirty years on you are doing a Dr. Frankenstein on a Chroma "body". Wish I could hear it.

Thanks, Robb. At some point I'll do a web site for it, with lots of samples.

Paul DeRocco [21030230] · Sat, 26 Jan 2013 10:16:14 -0800

From: Dave Bradley

Can you talk about the soft synth piece of it? Is it something you are writing yourself? Does it replicate Chroma functionality?

Yes, I wrote it. It runs on an Intel dual core Atom processor, under Linux. All the old functionality is retained, but it adds lots of new features:

  • Stereo, with modulatable panning. Two-output patches can have each oscillator panned separately.
  • High-res, modulatable resonance.
  • 4-pole mode for the filters.
  • Tone controls are program parameters. They have adjustable frequency, and resonance for the middle control.
  • Detune scaling, for contant Hertz difference, constant pitch difference, or half way between.
  • Reverb (not finished yet), with choice of room size and reverb send.
  • Selective pitch bend, as in the Polaris. Actually, both levers and pedals have selective modes, in which they freeze when you take your finger off the key.
  • In addition to saws and pulse waves, there are single-operator FM sounds with various integer relationships between carrier and modulator frequence. The Width varies the modulation depth.
  • Independent noise generator per voice, so that playing two noise sounds together gives a proper 3db increase, instead of 6db.
  • Most modulations have quantization and sampling options.
  • Modulations that were fixed (e.g., Sweep Rate Mod or Decay Mod) now have adjustments.
  • A Strum keyboard algorithm, in which the top or bottom two keys are used to retrigger chords held over the rest of the keyboard.
  • Link Spread and Link Detune parameters, for introducing pan and tuning differences between main and link sounds.
  • Much higher control signal computation rate, allowing much shorter envelopes and faster sweeps.
  • Individual per-key velocity and pressure calibration.
  • Most parameters have extended parameters behind them, accessed with SET SPLIT in Param Select mode. Some also have global or calibration parameters behind them, accessible with SET SPLIT in Prog Select mode.
  • Nine banks of programs, which are stored as text files, and which can contain additional information added by an external editor. The program number display shows a 3-digit program number.
  • The parameter display shows two lines of text, including the parameter name, and a description of the value if it selects from a list.
  • Three different slider modes, including Jump (like the old Chroma), Capture, and Smooth.
  • Old-fashioned MIDI, plus a USB device port that can communicate MIDI to a PC or other host, plus a USB host port that can communicate MIDI with an external MIDI device. (No Chroma port.)
  • 1000base-T Ethernet, for accessing program files in the Chroma.
  • One stereo output (can drive headphones), plus 48KHz S/PDIF and TosLink outputs. Analog and S/PDIF are transformer isolated.

And a lot of other minor things.

Dave Bradley [16330135] · Sat, 26 Jan 2013 14:59:00 -0600

Wow!

Brian McCully [21030361] · Sat, 26 Jan 2013 13:52:26 -0800

Paul, that's awesome! # of voices? multi-timbral? mono midi mode for guitar synthesis (n, n+!, n+2 ... up to six channels)?

I don't miss NAMM's ambient noise floor. Especially crazy on the weekend. Maybe the only way to walk around listening to the new synth gear is with your own headphones.

Chris Smalt [21010280+] · Sun, 27 Jan 2013 02:28:25 +0100

  • Tone controls are program parameters. They have adjustable frequency, and resonance for the middle control.

[Cue Dr.Frankenstein laugh]

Paul DeRocco [21030230] · Sun, 27 Jan 2013 00:08:57 -0800

From: Brian McCully

Paul, that's awesome! # of voices? multi-timbral? mono midi mode for guitar synthesis (n, n+!, n+2 ... up to six channels)?

Right now I'm running 48 voices, but it'll do 64 once I have a clean Linux kernel without any unnecessary daemons sucking up CPU time.

It doesn't support the traditional mono MIDI mode, but it is certainly multi-timbral, so if you send the same program changes on six channels, you can play a six-channel guitar synth on it just fine.

I don't miss NAMM's ambient noise floor. Especially crazy on the weekend. Maybe the only way to walk around listening to the new synth gear is with your own headphones.

You'd need noise canceling headphones. Most booths with keyboards have headphones for you to use, but you can still hear the din of the hall through them.

Donald Tillman · Sun, 27 Jan 2013 00:16:28 -0800

On Jan 26, 2013, at 10:16 AM, Paul D. DeRocco wrote:

Yes, I wrote it. It runs on an Intel dual core Atom processor, under Linux. All the old functionality is retained, but it adds lots of new features:

And you can read your email on it!

Paul DeRocco [21030230] · Mon, 28 Jan 2013 00:04:49 -0800

From: Dave Bradley

Pics!

The only things that look different from the outside are the two displays and the rear panel, so I took pictures of them. Here they are. (I hope the list allows .jpg attachments.)

digitalchroma1thumb

digitalchroma2thumb

Jesper Ödemark [21010135] · Mon, 28 Jan 2013 11:05:55 +0100

Impressive work hardware-wise! :D

Brian McCully [21030361] · Mon, 28 Jan 2013 11:42:55 -0800

Anybody from the 'Rhodes Piano Corporation' like the concept? Last time I was at NAMM (2-3 years ago) I mentioned to them I had a Chroma and one of the guys there jumped on it, saying that they'd love to eventually (re-)release a new version.

Also I was trying to get them to demo the polyAT on their keyboards but it didn't happen - there was some sort of glitching or equipment mismatching. It is/was an optical design. Did you get a chance to check that out?

When Rhodes Piano Co. first announced they were opening shop again a half dozen NAMMS or more ago, the actions the demo units had were great - like butter. When I finally played their production releases, it was a lot heavier. The company guy who I was interfacing with remembered the initial action, and agreed that while the earlier version was better playing, said that it would have had too many manufacturing and repair issues.

Paul DeRocco [21030230] · Mon, 28 Jan 2013 12:45:03 -0800

From: Brian McCully

Anybody from the 'Rhodes Piano Corporation' like the concept? Last time I was at NAMM (2-3 years ago) I mentioned to them I had a Chroma and one of the guys there jumped on it, saying that they'd love to eventually (re-)release a new version.

I didn't see Joe this time at the show, but I spoke to him a few years ago about other things, and mentioned the idea in passing. From what I hear, I don't think he's in a position right now to take a big gamble on something like a new Chroma. In this economy, it's hard enough to sell electric pianos.

David Gowin [21030611] · Mon, 28 Jan 2013 13:02:58 -0800

Can see the point. But would be a good case builder to use comparative sales of the other retro synths being revamped and brought to market like the Moog and Sequential Circuits designs

Dave Manley [21030547] · Mon, 28 Jan 2013 13:09:01 -0800

Is RMC still in business?

Dave Bradley [16330135] · Mon, 28 Jan 2013 15:39:28 -0600

AFAIK Rhodes Piano Corp has folded.

Paul DeRocco [21030230] · Mon, 28 Jan 2013 14:38:23 -0800

I can't find anything on the web, other than rhodespiano.com, that looks like a zombie site. They weren't at NAMM.

It's too bad. Although I'd never buy one, I liked the fact that the Rhodes piano still existed. I guess everyone felt the same way as I did.

Brian McCully [21030361] · Mon, 28 Jan 2013 15:29:12 -0800

Oops ... I hadn't heard they'd folded (obviously). There was such a big hoopla when they first came back that I'd have thought they'd still be happening. It's hard to justify laying out $4k+ for a MIDI'd piano that weighed >100 lbs, when my Nord Stage doesn't break tines, weighs ~15lbs, sounds fine. I was quite disappointed that their production keyboard action was nowhere near as good as their prototypes. I wouldn't doubt if that was one of the reasons they didn't make it, but yes I'm sure there were lots and lots of other factors. Too bad.

Chris Ryan [21030691] · Mon, 28 Jan 2013 19:24:07 -0800

There is a long saga of Joseph Brandstetter and his relationship to the Rhodes name. In 2006-07 I had some email exchanges with James Garfield of the Rhodes Super Site about his struggles with the guy: see for example WIPO Domain Name Decision D2007-0628. At one time, James' site was renamed "FenderHordes.com" as a result. I think James has long since removed from his site the pages that described these hassles, but it was quite a battle: even Harold Rhodes' widow was involved. I don't remember the details. (But see for instance Keyboard Confidential: The Making of the New Rhodes, Keyboard, February 2010—I've just skimmed a small part of this, but I'm sure there's more to be found on the web.)

For a time, I expected I'd probably be next: although I can't easily find it now on the U.S. Patent and Trademark Office site, James informed me that Brandstetter had applied for the ARP and Chroma trademarks. I had heard directly from Brandstetter a few years earlier, in 2004 (the Chroma site started in 1999); he asked me questions that I thought betrayed a lack of understanding of the industry. For example, "I am the owner of the Rhodes Mark worldwide for musical instruments, can you render me your opinion were [sic] the industry stands today vs yesterday." Or, "What are you doing in your carrier [sic] path today?. What if any plans for Chroma do you have?" I advised him that it might be wiser to pursue a software plug-in than a reboot of the hardware keyboard. (Am I smart, or what?)

With respect to the Chroma brand, he opined that "Trademark probably would be considered abandoned, patrons [patents?] probably expired after 17-20 years." I'm not sure if this is true, and I don't know where it stands at this point. As far as I can recall, Roland acquired the Chroma brand along with its purchase of the remains of the project in 1987. See Roland "Rhodes" Models on James' site.

See also Rhodes bust? in the MusicPlayer forums. Again, I'm sure there's more to be found.

Jesper Ödemark [21010135] · Tue, 29 Jan 2013 15:43:25 +0100

Paul D. DeRocco skrev 2013-01-28 23:38:

I can't find anything on the web, other than rhodespiano.com, that looks like a zombie site. They weren't at NAMM.

It's too bad. Although I'd never buy one, I liked the fact that the Rhodes piano still existed. I guess everyone felt the same way as I did.

Judging from the amount of red gear behind the vocalists and guitarists on the average stage I bet Clavia has taken a huge chunk of that market. Being swedish I think that's kind of cool (despite the fact that they're digital). :)

See "Digital Chroma," January 2014.

Parallel Filters, Filter FM diagram flaw

Eric W. Mattei [21030443+] · Sun, 27 Jan 2013 20:56:46 -0800

Hello All

Working on some Programming Manual improvements. Check me on this, please.

I think there's a flaw in the flow diagram for Patch [1], Value = 8 Parallel Filters, Filter FM. Specifically, the vertical arrow that points down from OSC A to OSC B. I don't think it should be there.

I see that vertical arrow connecting the OSC's on the three SYNC patches: 6, 10 and 14.

1.8

I think the vertical arrow indicates the SYNC, but Patch [1], Value = 8 is not a SYNC patch. Right?

Thanks.

Paul DeRocco [21030230] · Sun, 27 Jan 2013 21:41:43 -0800

Right. That's an obvious typo. Or draw-o.

Chris Ryan [21030691] · Sun, 27 Jan 2013 22:02:23 -0800

Fixed.

Eric W. Mattei [21030443+] · Sun, 27 Jan 2013 22:07:59 -0800

What took you so long? :)

Chris Ryan [21030691] · Sun, 27 Jan 2013 22:16:38 -0800

I know. Twenty minutes, forty seconds. I'll try to do better next time.

Service Manuals on eBay

Chris Ryan [21030691] · Mon, 28 Jan 2013 12:26:32 -0800

Chroma Service Manual: item #370746866149, USD$20.00.

Polaris Service Manual: item #370746862840, USD$20.00.

Both originals, and appear to be in good condition.

servicemanualsonebay

Patch [1], Value = 9 Series Filter doc

Eric W. Mattei [21030443+] · Wed, 30 Jan 2013 12:17:24 -0800

Hello Folks

More manual labor. Below is a (hopefully) enhanced version of the Programming Manual section for Patch [1], Value = 9 Series Filter. The parts I added / changed are in bold. Assuming I got everything right, what are the apps for a high-pass four-pole filter response?

Also, attached is a preliminary revision of the illustration for this section. I added titles and a lot of labels to the frequency response diagram, so please check for accuracy.

Thanks in advance.

Patch [1], Value = 9 Series Filter

The two oscillators feed the A filter which in turn feeds the B filter. The B amplifier controls the output of oscillator B, the A amplifier controls the overall output volume. In this configuration, a four-pole or band-pass filter response can be established.

A four-pole filter response can be established by setting both filters to high-pass (LP/HP [37], value 1), or setting both filters to low-pass (LP/HP [37], value 0). A low-pass four-pole filter response is useful for brass or flute sounds. The higher harmonics are filtered more than in the single filtered configuration, producing better mellow sounds. The resonance settings of the A and B filters may be set to different values to increase the resonance range.

A band-pass filter response can be established by setting one of the filters to high-pass (LP/HP [37], value 1), and the other to low-pass (LP/HP [37], value 0). Start by setting the high-pass filter slightly higher than the setting of the low-pass filter.

Applications

  • Low-pass four-pole: Brass, flutes, "fat sounds," many orchestra sounds
  • Band-pass: solo violins, reeds
  • Band-pass: vocal sounds
  • High-pass four-pole: ??????????????????

1.9