Conference napalm::commusic_v1

    Could it be SATAN?????
    
    Edd_The_Church_lady

    I had a problem with my Juno 106 where one of the 6 VCF's was not
    working properly and caused the sound of the instrument to change every
    6th note .  It sounded very intermitant until the service tech and I
    walked up the keyboard one note at a time and discovered the pattern
    (every sixth note sounded different than the others).
    
    The repair was to replace the VCF chip.  Cost me about $80.
    
    		Derek

< Note 1053.0 by AKOV68::EATOND "He who toys with the most wins, dies." >
                       -< Juno goes beserk, film at 11. >-

	I was at someone's house last night playing a Juno 106 when I came 
across a curious phenomenon.  On certain patches (it seemed arbitrary) certain
keys would sound more than one voice or at other times would play what sounded 
like major LFO routing to the VCF.

	My first thought was that there may have been something in the key 
contacts that were messing something up, but things got curiouser and curiouser.
If I changed the patch and then called the offending patch back, the key that
produced the bad sound would be O.K., but another key would take up the burden!

	Does anyone have any idea what caused such a thing?


It definitely sounds like a hardware problem. The keyboard would not cause
such a problem. Think of the keys as simply an on/off switch. Velocity
sensing is usually accomplished by uP timing of the open/in flight/closed
transition state of the key switch. After-touch is created by a pressure
sensitive transducer which controls an analog voltage which is A/D converted
and interpreted by the uP to vary some parameter such as timbre, volume,
pitch, etc.

The problem you encountered would seem to be a power supply or memory
problem. The grounding could affect both. Does the Juno have
a 3 prong power cord? If so, try not using the extension cord and connecting
to a 3 prong grounded outlet. If the Juno has a 2 prong power
cord, try reversing the plug in the outlet. Observe polarity if one of the
prongs on the power cord is larger than the other. An intermittent connection
of the power cord would cause the Juno to turn on/off similar to flipping
the power switch on/off. Some electronic devices do not respond well to
being turned back on immediately after being turned off. Try turning the
unit off for about 30 seconds to allow the power supply filter capacitors
to discharge. Then turn it back on and see if the problem changes/goes away.
Try to make the power cord connect more securely to the Juno by bending the
prongs *SLIGHTLY*.

Good luck, E.U. Wurlitzer Boston has a repair facility in the same building.

I hope you don't have to send it to Roland. It could take months.

Dave

	Thanks to all for help (except Edd).  8^)

	Derek, I'll ask him to count the keys as he plays,like you said.  
Thanks.

	Dave,

	We were unable at that time to get a more reliable power source.  He
was going to check out another source today, with better grounding.

	It is a two-prong plug that is used.  It seems that every Roland
I've tried has the same two prong connection.  If I see it again, I'll try
bringing up my RD200 power cord.

	Do you think power supply or memory would account for the 'floating'
key problem as well?  If so, how?  (Or is that kind of thing too difficult to
put into words?).

	Dan

< Note 1053.4 by AKOV75::EATOND "He who toys with the most wins, dies." >
                           -< 2 outa 3 ain't bad... >-

>>	Do you think power supply or memory would account for the 'floating'
>> key problem as well?  If so, how?  (Or is that kind of thing too difficult to
>> put into words?).

The uP determines what key was pressed, and then must look up a number of
parameters in ROM and/or RAM. It must determine such things as:

1. pitch
2. timbre shift with velocity
3. which tone is assigned to that key
4. look up the patch parameters assigned to that key
5. turn on the sound generator(s) for that key at the right time
6. control the envelope
7. turn the sound off at the right time
   etc.

If any of this information is determined incorrectly due to memory problems,
the resulting operation of the keyboard can be pretty bizarre. I had an
ARP Pro DGX that went South and became a Frankenstein monster.

If the power supply is not putting out the +5vdc within a range of +- .25vdc,
all bets are off. The unit will operate randomly. Maximum entropy. Any custom
VLSI chips may require special voltages other than +5vdc.

You can think of a keyboard synthesizer as consisting of the following
subsystems:

1. Keyboard
2. Control Panel
3. CPU/Memory
4. Sound Engine
5. Audio Section
6. Back Panel
7. Power Supply

Try to isolate the problem to one of these sections. In this case, we seem
to be pointing at the CPU/Memory, Sound Engine, or Power Supply.

This kind of flakiness is somewhat unpredictable. When ICs sockets are used,
I generally find that the mechanical connections of the IC pins to the
socket have become oxidized (nee intermittent). Cold solder joints, mechanical
connections, PCB vias, IC sockets, temperature sensitive components, etc.
all can account for intermittent problems. It helps to know the history of
the particular unit that you are working on. I wrote the ROM based diagnostics
for the Kurzweil 250, and always kept track of the serial numbers of the
units, the selling dealer, the registered owner, the service history, the
manufacturing test history, etc. Here are some questions to ask the owner:

1. Did this unit function correctly when purchased?
2. Is this a recently developed problem?
3. Does this problem only occur when a questionable power source is used?
4. Is the unit under warranty? If so, exchange for a new one if possible.
   You should always keep the receipts, original packaging, shipping
   information, send in the owner warranty registration card, etc.
   Infant mortality is becoming quite a problem with the new "lower cost"
   equipment. Lower cost generally translates into "poor quality control".
5. Is the unit temperature sensitive? Does it work ok when first turned on
   but then "flake out" later on? Is it flaky when first turned on, but
   then ok after it warms up?
6. Is there any chance of operator malfunction? Is the user
   experienced enough with this equipment to be able to determine that it
   is not operating as programmed?

Dave

< Note 1053.5 by LEDS::ORIN "Raucous Roland Renegades" >

	Just to let you know, incidently, the Juno 106 is not velocity 
sensitive, either in it's internal sound module, or in its keyboard.

	I can answer some of these questions right now:

1. Did this unit function correctly when purchased?

	Yes

2. Is this a recently developed problem?

	Yes, this was the first time.

3. Does this problem only occur when a questionable power source is used?

	Will find that out soon.

4. Is the unit under warranty? If so, exchange for a new one if possible.

	No, and Juno 106's are no longer in production.

5. Is the unit temperature sensitive? Does it work ok when first turned on
   but then "flake out" later on? Is it flaky when first turned on, but
   then ok after it warms up?

	We didn't have it on longer than a half hour, was that enough time?

6. Is there any chance of operator malfunction? Is the user
   experienced enough with this equipment to be able to determine that it
   is not operating as programmed?

	Without saying I am an expert, I would say that I ahve a very good idea 
of what to expect from the synth.  Also, I had a Juno before, for about 6 
months, and it never happened on mine.

	Dan

< Note 1053.6 by AKOV75::EATOND "He who toys with the most wins, dies." >
                             -< keep it comin'... >-


5. Is the unit temperature sensitive? Does it work ok when first turned on
   but then "flake out" later on? Is it flaky when first turned on, but
   then ok after it warms up?

	We didn't have it on longer than a half hour, was that enough time?

>> Usually about an hour is enough time to reach stable operating temperature.
>> What was the approximate environmental temperature? 60-70 70-80?
>> Does this unit have MIDI? If so, use extreme caution not to connect two
>> MIDI outs or two MIDI ins together. The hardware may or may not forgive you.
>> Is there any optional outboard gear such as a programmer, other MIDI device,
>> etc., if so disconnect and try again. Did turning the unit off for 30 secs.
>> and then back on clear up the problem? Does the unit run (BIST) Built-in
>> Self Tests when powered on? If so is there any indication to the user as to
>> whether the tests passed or failed? Is there a possible source of power line
>> noise such as lighting rheostat, power tools, etc.? Is there a possible
>> source of static electricity such as carpeting, stocking feet, nylon
>> clothing, etc.? Is the power supply self-contained in the keyboard, or is
>> it one of those power pack 9v adapters?

Dave