[sdiy] Akai AX80 weird PWM behaviour on Voice 8 when Saw wave enabled

Adam Inglis 21pointy at tpg.com.au
Fri Jul 13 07:15:51 CEST 2012

Sounds like your battery needed changing, before your power supply  
blew. Well, you wanted a learning experience!
Hopefully no big deal in the long run though, should be  
straightforward to fix.... (famous last words!)

On 13/07/2012, at 6:31 AM, james meagher wrote:
> I noticed when I got the board that the last ten patches on bank B
> were silent. I didn't think too much of it at the time. Today I was
> looking for a spot to save a patch and decided to check these blank
> ones out further. I suspected that some levels had been set to zero or
> no oscillators activated in either voice, or any of the other many
> reasons a patch would be silent. What I found as I scrolled through
> the parameters was that some said A1 or A2 instead of having a number
> value, and still others had values that looked like numbers missing
> some of their parts. I started making some notes of which parameters
> in which patch locations had these anomalies to see if there was a
> pattern between the patch locations. I also wanted to see if I fixed
> the incorrect values and then turned on/off the board if they would
> hold the newly inputted correct values or return to their previous odd
> states. All was going well and the patches were holding with the
> changes and making sound as they should. Then I got the final patch in
> Bank B (patch 32) and was surprised that it made sound right off the
> bat. This was especially surprising because as I cycled through the
> settings in each parameters, some had the A1 and A2 values that the
> other silent patches had had . . .
> Then, right in the middle of a note the entire machine died. No sound
> . . . no lights . . . dead. I'm feeling a tad Sisyphusian now and am
> going to spend the rest of the evening playing with synths that work.
> On the plus side, I was just thinking earlier this morning as I
> flipped from the Voice Block Diagram to the Voice Board Schematic to
> the Voice Board PCB image and made a nice little list of parts to
> order to fix my Voice 8 and Voice 4 issues, "Wow, I've really learned
> a lot in the past week".
> James  :P
> --
> C'est La Guerre Moving Pictures Inc.
> 364 Home Street
> Winnipeg, Manitoba
> R3G 1X4
> (204) 918 9317

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