[sdiy] Diagnosing Fatman problem

[Gabriel Lindeborg]

I had a similar problem when I built mine and the eprom was the cause...
I reburnt it and then everything worked.

//Gabbe of Sweden

James Howe wrote:

> I've just completed building a Paia Fatman synthesizer as my first DIY  
> synth.  Unfortunately it's not completely working.  It powers on just  
> fine, no overheating or smoking.  The MIDI input works just fine (the 
> MIDI  light flashes as expected in response to keyboard input), as does 
> the MIDI  thru.  My current problem is that the Gate LED does not light 
> up when a  key is struck on the keyboard.  Since I am fairly new to 
> doing electronics  work I fully expected that I might have some bad 
> solder joints, but I've  looked and have yet to find one that might be 
> causing a problem.
> 
> Based on some tips from Paia, I checked voltages on various IC's (1, 2, 
> 3  and 4) and the values seem to be consistent with the schematic (e.g. 
> I'm  not finding a voltage on Pin X of IC1 and no voltage on the related 
> pins  on the other IC's)  I know that the Gate LED will in fact light up 
> since  it lit up on me when I accidentally shorted out pins 4 and 5 (I 
> think it  was those two) on IC1, when I was trying to get a meter 
> reading for one of  the pins.
> 
> I'm also fairly confident that the keyboard is transmitting on channel 
> 1,  and that is how my DIP switches are configured.  I'm hoping that 
> someone  out there has some suggestions for ways that I can diagnose 
> this problem.   Unfortunately I don't have access to scope, only a 
> digital multimeter.   Are there specific places that I should be seeing 
> certain voltages (or not  seeing voltages) that would help me locate 
> places where I may have a bad  solder joint?
> 
> Any tips would be appreciated.
> 
> Thanks.
>