Vintage Synth Repair

I just started work on a Roland SH1000, and I'm looking for service 
documents or schematics - unsuccesfully so far. 

What I would need in specifics is a 
- Connection diagram for the top panel 
- The full name/characteristics on the transistors marked "C373" 
and "A733/Q265"
- An educated guess on where to start when it did produce sounds 
recently, but now sports a dead (replaced to no avail) fuse and 
absolute silence

Hope you can help - I seem unable to track down anything with Google 
these days, and I couldn't find much in the list archives.


-Mu

On Monday 17 September 2007 17:19, Mu wrote:
> I just started work on a Roland SH1000, and I'm looking for service
> documents or schematics - unsuccesfully so far.
>
> What I would need in specifics is a
> - Connection diagram for the top panel
> - The full name/characteristics on the transistors marked "C373"
> and "A733/Q265"

The full part number for those would be "2SC373" and "2SA733",  which is 
typical for Japanese transistor numbering,  they leave the "2S" off.  You can 
find datasheets through here:

http://www.classiccmp.org/rtellason/parts-index.html

and yeah,  that's my doing.  :-)

> - An educated guess on where to start when it did produce sounds
> recently, but now sports a dead (replaced to no avail) fuse and
> absolute silence

Fuse is blown and you replaced it but no change?  I'd start with checking the 
power supplies,  filter cap voltage ratings should give you some rough idea 
of what you want to see there.


-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

Thanks a million.

Happily. I have a spare one available for comparing measures - and I 
presume it just might have been a regulator giving up. But still - 
the specs on these will come in handy. 

Thanks for your effort with the parts site. It's excellent.


-Mu


--- In vintagesynthrepair@yahoogroups.com, "Roy J. Tellason" 
<rtellason@...> wrote:
>
> On Monday 17 September 2007 17:19, Mu wrote:
> > I just started work on a Roland SH1000, and I'm looking for 
service
> > documents or schematics - unsuccesfully so far.
> >
> > What I would need in specifics is a
> > - Connection diagram for the top panel
> > - The full name/characteristics on the transistors marked "C373"
> > and "A733/Q265"
> 
> The full part number for those would be "2SC373" and "2SA733",  
which is 
> typical for Japanese transistor numbering,  they leave the "2S" 
off.  You can 
> find datasheets through here:
> 
> http://www.classiccmp.org/rtellason/parts-index.html
> 
> and yeah,  that's my doing.  :-)
> 
> > - An educated guess on where to start when it did produce sounds
> > recently, but now sports a dead (replaced to no avail) fuse and
> > absolute silence
> 
> Fuse is blown and you replaced it but no change?  I'd start with 
checking the 
> power supplies,  filter cap voltage ratings should give you some 
rough idea 
> of what you want to see there.
> 
> 
> -- 
> Member of the toughest, meanest, deadliest, most unrelenting -- and
> ablest -- form of life in this section of space,  a critter that can
> be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet 
Masters"
> -
> Information is more dangerous than cannon to a society ruled by 
lies. --James 
> M Dakin
>

So - here's the mess for today -

The power supply seems fine. I get an even 17 AC in and +/- 15 where 
desired. I've replaced some tantal coupling caps and when playing I 
now get a very, very faint signal. It keeps in tune and follows the 
settings on the control panel when it comes to glide and randomized 
notes. It does not react noticably to volume, ADSR, or any change in 
presets/sounds/VCF settings, but brightens a bit following the octave 
switch.

I find nothing that explains the blown fuse - and there is no bad 
smell. I've located no shorts or odd voltages. (Compared with a 
working unit.)

I'm at my witts end. Anyone got an idea what this could be? Or a 
service manual, of course. Or both.

As an extra challenge, this SH1000 is scheduled for live use - in 
concert - tomorrow night. I might just be screw'd..


-Mu

Got the manual - 

Tossed all tantalyts and tested the cards one by one in a working unit -
 as it is now, I've got all cards running as they should, all pots, 
sliders and switches working, the power supply seems good and the 
wiring does seem to connect as it should - and yet -

not a sound. I'm quite baffled. Any hidden mojo I should know about? 
Some ghost that need secret tuning?


-Mu

After testing each and every component, trace and wire, the fault 
proved to be wear on the cable-to-board connectors. The metal was 
simply worn past breaking point. Took 30 hours to find that one loose 
bastard.. And his friends proved capable of all the instability of the 
unit.

(Connector 11 and co, at the "pulse sheet" - according to the 1976 
service notes.)


-Mu