[sdiy]Roland Sh-2000 schematics

[Bob Weigel]

I recall asking ROland now and I think they've lost track of the SH-2000 
diagrams which is why they aren't on line also.  They were only able to 
send me hard copy of the SH-1000 that would probably be close to the 
same design.

Ok the 1000 also has the 'random note' feature I see.  Here's how it works.

There is a dpdt switch whose common poles are

common 1) a little filtering and between it and the pin 3 of a 741 op 
amp (IC10 in the SH1000) AND a 2.2K resistor that connects the common to 
the pole of the switch that goes to the keyboard (so that the key CV is 
leaked across to give some interactive effect on the 'random note' 
setting I assume...otherwise if keyboard is selected this resistor is 
shorted out and meaningless of course provided the switch is working :-) ) 

common 2) The cathode of a diode whose anode attaches to and FET gate.A 
2SK30A.  It is used to actually just turn on/off gate control of another 
FET by the portamento pot/switch (when the port switch is closed it 
simply shorts out the portamento potentiometer ) which is driven by the 
output of IC10 above (Ic10 is wired with a100K feedback resistor and 
paralell .01uF cap to give a low frequency response unity gain amp as 
there is also a 100K resistor in line with the input filtering from the 
'random note' switch I mentioned above.

    Anyway, so the other pole of common 1) goes to a line labelled 
"Noise".  The poles of common 2) go to a Square wave which I assume 
symbolizes the 'gate' signal.  The pole associated with the 'random 
note' side of that one goes to a string of pulses symbol...which I 
assume is probably an 'auto gating' signal generated somewhere...don't 
have time to look right now...

But anyway, it says you should have 5.6V on the 'top' of the keyboard 
'resistor ladder'.  This voltage is likely not there.  If it isn't there 
either there is no 13V or whatever supplying the circuit which adjusts 
the span and all composed of two pots, two transistors, a diode and a 
few resistors/caps... OR one of the transistors there probably failed 
open.  Or one of the variable resistors got so dirty that it's not 
conducting maybe.  Anyway just do a general check for solder and stuff 
if it's not any of that... and I think you'll find the problem. -Bob

Diogo Melo wrote:

>hi bob!
>
>i'de appreciate much if you got those schematics. i've managed to get
>the sh 2000 running. It makes sound but only if you turn "Random key"
>mode on. The keyboard doesn't seem to be working...
>
>
>
>Thanks
>
>
>Diogo
>
>On 19/01/06, Bob Weigel <sounddoctorin at imt.net> wrote:
>  
>
>>There seems to be a lot of interest in getting these up.  I'll ask Terry
>>Wall when I talk to him if it's ok to post them.  Since it's...like
>>their first I wouldn't think they'd mind but I've sworn a solemn oath
>>and all that kind of stuff ya know :).  But any Roland service center
>>should be able to get to them.  -Bob
>>
>>Brett Maddaford wrote:
>>
>>    
>>
>>>Hi Bob
>>>
>>>What service site were u looking at? I'd like to get my hands on the
>>>1000 schems and you mention u saw it there ;)
>>>
>>>Cya
>>>Brett
>>>
>>>-----Original Message-----
>>>From: Bob Weigel [mailto:sounddoctorin at imt.net]
>>>Sent: Thursday, 19 January 2006 2:33 PM
>>>To: Diogo Melo
>>>Cc: synth-diy at dropmix.xs4all.nl
>>>Subject: Re: [sdiy]Roland Sh-2000 schematics
>>>
>>>
>>>That's a tough one as Roland doesn't even have it on the service site
>>>when I went through them all a while back.  The 1000 is there.  The
>>>technology used in all those things is fairly predictable but when
>>>funcitons are missing it's good the have the ROM codes which are listed
>>>in the service manuals.  I'll bet they used the same chips as the SH1000
>>>
>>>though and just wired them different probably.
>>>
>>>However checking my trusty web page, looks like Mark Glinsky (Manual
>>>Manor ) has it -Bob
>>>
>>>Diogo Melo wrote:
>>>
>>>
>>>
>>>      
>>>
>>>>Hi! I was wondering if anyone has the schematics for the roland sh
>>>>2000. A friend of mine has one in poor condition and asked me if i
>>>>could fix it up for him.
>>>>
>>>>
>>>>i tried the web and there were no schematics there
>>>>
>>>>
>>>>thanks
>>>>
>>>>
>>>>diogo
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>        
>>>>
>>>
>>>
>>>      
>>>
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>  
>