[sdiy] Roland 80017 findings

[Nicholas Gregorich]

If you're short a scope you can narrow the broken voice down by using the synth's test mode.

http://machines.hyperreal.org/manufacturers/Roland/Juno/info/roland.Juno-106.test-mode.txt

Boot into test mode and put it into rotary voicing by pushing Poly1 and Poly2.  Let it sit until it starts acting funny.  Then slowly push keys one at a time until you find the broken voice.  The LED will have a voice number on it which will correspond to a label on the PCB.

This method isn't quite as conclusive as probing with a scope but I've been able to repair Junos in the past using it.

Nick.
  
On Wednesday, April 12, 2006, at 11:17AM, Tom Arnold <xyzzy at sysabend.org> wrote:

>On Wed, Apr 12, 2006 at 01:46:10PM +0100, Heitor Alves wrote:
>>    First, congrats for what you are doing ;o) very usefull (at least to
>>    me). I have also a Juno with a "broken" voice, but its acting very
>>    strange... sometimes it works (some patchs) but others it fails. I've
>>    looked in to the service manual trying to figure how to find the bad
>>    chip, but i cant understand very well the manual... can you tip me off
>>    ;o) ?
>
>Finding a bad filter voice is easy.
>
>Get the Service Manual :
>http://www.hinzen.de/midi/juno-106/manual/index.html
>
>Look at page 12 of the service manual and also page 13.
>Now, looking at the Module board, the front left corner you'll see two 6pin
>connectors labeled TP8-TP13 and TP14-TP19
>
>On page 12 in the bottom table you will which testpoint pair corresponds to
>which channel.  Looking at channel 1, TP8 is the output of the VCA ( you can
>see this in the schematic if you look carefully enough on page 13 ).  TP19
>is the output of the filter Before the VCA.
>
>In my case all I had to do was wait for it to make noise, then scope each
>test point until I found it.  Then confirmed that I only saw the noise on
>the VCA testpoint and not the VCF testpoint.
>
>-- 
> -----------------------------------------------------------------
> - Tom Arnold       -  Free Synth DIY webspace http://www.sdiy.org 
> - SynthGeek        -
> - BBD Fanatic      -  "...is it a virus, a drug, or a religion?" 
> - echo evho wjxo   -    Juanita Shrugs. "What's the difference?" 
> --------------------  
>
>
>