[sdiy] fun with KBD2e

[David Moylan]

I put one of these together, and I also found some discrepencies, but 
nothing that prevented me from getting it working correctly.  I believe 
you should have a high frequency clock being fed into U3 and on the 
output, but the associated diodes/cap on the output should be 
rectifying/smoothing this into DC.  Check the signal input to U2 and see 
what you have there.  Maybe check the polarities on your diodes, D2, D1?

Dave

Schierl, Dan wrote:

> hi list--
> has anybody had any experience with TomG's keyboard converter, the 
> kbd2e? I recently put one of these together, and am getting some 
> strange results.
>  
> documentation is here:
> http://www.ele4music.com/pdfs/kbd2e.pdf
>  
> I noticed 4 or 5 discrepancies between the schematic and the pcb, and 
> i believe I have corrected these. also, i noticed 2 discrepancies 
> between the parts list and the schematic, and I think I got those 
> right as well. the pitch CV out seems to be working fine, but the Gate 
> out is acting weird--with key up I see about 14 volts, and with key 
> down I'm getting a ~4volt p-p square wave centered around 12v, and 
> from what i can see it has a frequency of around 50 KHz. tracing back 
> a bit i'm reading a 30V p-p square wave on pin 5 of U3 (a 13600) at 
> the same frequency.
>  
> any thoughts as to what i should check next?


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