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Conference napalm::commusic_v1

Title:* * Computer Music, MIDI, and Related Topics * *
Notice:Conference has been write-locked. Use new version.
Moderator:DYPSS1::SCHAFER
Created:Thu Feb 20 1986
Last Modified:Mon Aug 29 1994
Last Successful Update:Fri Jun 06 1997
Number of topics:2852
Total number of notes:33157

2209.0. "Roland RD200 Piano distorts at high volume setting" by NRPUR::DEATON () Wed Dec 20 1989 13:47

	I've had a problem with my RD200 ever since I bought it.  It's not a
serious problem, but I'm wondering if people in this file can help...

	Whenever I turn the volume slider up past the halfway mark it sends out
distortion.  It is even more noticable when the chorus is turned on.  If I leave
it down below the halfway mark it is fine, but I have to pick up the gain 
elsewhere.

	Does anyone have any suggestions for what to look for or does this sound
like something that should be given to a reputable repair ctr?  I bought it used
and have no warranty.

	Dan

T.RTitleUserPersonal
Name
DateLines
2209.1Dirty Slider??WEFXEM::COTECall *who* Ishmael???Wed Dec 20 1989 14:431
    
2209.2hmmm...NRPUR::DEATONWed Dec 20 1989 16:138
RE < Note 2209.1 by WEFXEM::COTE "Call *who* Ishmael???" >

>                              -< Dirty Slider?? >-

	But would it do that if the slider is not moving?

	Dan    

2209.3Worth a squirt of cleaner to find out...DCSVAX::COTECall *who* Ishmael???Wed Dec 20 1989 16:507
    It's been my experience that it would, or at least *can* cause the
    output signal to break up.
    
    I've seen it on my Mirage, and on one of the input trimmers on my
    board...
    
    Edd
2209.4NRPUR::DEATONWed Dec 20 1989 17:064
	What kind of cleaner?

	Dan

2209.5STROKR::DEHAHNWed Dec 20 1989 17:145
    
    Rat Shack ozone depleter followed by compressed air
    
    CdH
    
2209.6Methinks they doth protest too much....WEFXEM::COTECall *who* Ishmael???Wed Dec 20 1989 17:1510
    I've used Color TV tuner cleaner with totally acceptable results,
    however, I've heard that this maybe too 'abrasive' for pot use. (?)
    Again, I keep a can handy and use it freely.
    
    Rat Shack undoubtedly sells a switch cleaning fluid.
    
    If it clears it up, you may want to consider treating your pots and
    sliders with a 5% Cramolin solution...
    
    Edd
2209.7NRPUR::DEATONWed Dec 20 1989 17:301
	I'll pick up a can of cleaner tonight and see what happens.  Thanks all.
2209.8NRPUR::DEATONWed Dec 27 1989 12:214
	No improvement.  Any other suggestions?  

	Dan

2209.9SuggestionsDRUMS::FEHSKENSWed Dec 27 1989 13:0310
    Have you done the requisite experiments to confirm that the distortion
    is originating in the unit itself and not downstream?   If it is
    in fact within the unit, can you adjust some programmable gain
    parameter?  It's relatively easy to drive just about any synth into
    distortion with a suitable combination of parameters and the VCA
    gain topped out.  If the distortion seems to be patch specific,
    that could be an indication of this kind of problem.
    
    len.
    
2209.10NRPUR::DEATONWed Dec 27 1989 13:3818
RE < Note 2209.9 by DRUMS::FEHSKENS >

	Well, the RD200 is an entirely pre-set instrument.  The only controls
over patches I have is master volume, chorus (on/off) and tremelo (on/off/rate/
depth).  As I said earlier, the problem may be mostly in the chorus circuitry, 
as the distortion is magnified when it is turned on.  Or it could be that the 
chorus circuitry adds the kind of modulation that amplifies the distortion in 
the output stage.

	Oh, there is a three postion switch in the back (as in most Roland 
products) to control output level.  It appears that the distortion is happening 
before it reaches this attentuator, since it distorts at any setting.

	And yes, I have traced the distortion to the RD200 and not in other 
components (mixers/amps/etc.).

	Dan

2209.11Oh No, Roland Field Servcie RequiredDRUMS::FEHSKENSWed Dec 27 1989 15:206
    Well, that uses up my supply of standard answers.  Sounds like
    something's broke.  I suspect the chorus is just making it worse
    rather than being the source.
    
    len.
     
2209.12It's only half brokeNRPUR::DEATONWed Dec 27 1989 16:478
RE < Note 2209.11 by DRUMS::FEHSKENS >

	Well, I don't know how anxiously I will pursue sending it out.  As I 
said, it works o.k. if I leave the volume fader at "half mast".  I was just
hoping to find some "useful tips" here (which I did, but to no avail).

	Dan

2209.13Bad PSU???AYOV16::ABELSEYTue Jan 02 1990 12:1015
    I had a similar problem with a Yamaha sound module (EMT-10). The piano
    sounds had distortion when I hammered the keys during playing. I traced
    this to a bad power supply (it uses what you guys call a wall bug)
    which was not providing enough guts to drive the output stages cleanly
    when high volume was being output. This resulted in clip distortion.
    
     I know that the RD200 doesn't use wall bugs but you could check the
    PSU part of it if you were feeling brave. Perhaps there is a suspect
    smoothing capacitor, &c.
    
     Try putting a 'scope across the audio out and see if you can see any
    clipping of the output signal (probably require many hands to do
    this!).
    
    					Andy
2209.14... but I listen well...NRPUR::DEATONTue Jan 02 1990 12:2219
2209.15Power SupplyROYALT::TASSINARIBobThu Jan 04 1990 11:288
    
      I have a less-expensive keyboard that I use a wall bug with. I can run 
    on batteries which causes the keyboard sound to distort as the volume 
    increases.
    
      It does sound like a power supply.
    
       - Bob
2209.16Some improvement!MAIL::EATONDIn tentsWed Aug 29 1990 15:0416
    Just to put a closing note to this topic...
    
    	Shortly before I moved down to misery - er - Missouri, I brought the
    piano into Union Music to have them look at it.  It was there for quite
    a while and it seems that the tech there tried a lot of different
    angles.  It seems that this is not a common bug as he went through a
    number of ROM changes and such to uncover the difficulty.  He finally
    gave it back to me at no charge saying he did the best he could.
    
    	What is intersting about it all is that whatever he did actually
    *did* seem to help out.  There's still some distortion there if you
    turn it up really high, but it seems to be less than what was there
    before he worked on it.  I am please, and it cost me nothing.
    
    	Dan