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Incorrect Sawtooth VCO output shape / Sawtooth modified by PW control. #9

Closed fuzzbass closed 6 years ago

fuzzbass commented 6 years ago

Sawtooth output waveshape appeared to have have 50% duty cycle, which may be reduced to 10% duty cycle via VCO Pulse Width control. This was consistent across all 16 VCOs.

fuzzbass commented 6 years ago

Root cause was identified as substitute (and datasheet equivalent) 74LS74 flip flop ICs (in this instance Renesas/Hitachi branded HD74LS74). These were purchased new from a trusted seller and are believed to be genuine. The 74LS74 units were replaced with the BOM listed Texas Instruments 74LS74, resolving the problem and producing the correct sawtooth wave shape.