Archive of the former Yahoo!Groups mailing list: Discussion about the Korg PolySix synthesizer

Not sure why my text is always bold.   Silly Yahoo mail program.

In most cases, we would assume that the pc bd is good, and just check
the components.   Diodes should have ~0.6V across them when forward biased using the diode scale that most DMM's have.  In the other direction they should be open, although if in-circuit, you may not see that due to other components in the circuit.   Of course, on the 367 bd, we need to check for connectivity as well as component values.  So, for instance, don't use the gnd end of D9 when checking D9.  Use a known ground elsewhere on the board.  That way if D9 is not connected to Gnd, you will see that.  The same applies to the 4.7K pullup.
You should measure 4.7K from pin 1 of the CPU to +5V on any of the digital IC's on the board, except one or two that have the battery voltage instead.   Of course power should be off when you are making any diode or resistance measurements.  Sounds like you are closing in on it.   Maybe your DAC is OK.