[comp.sys.mac.hardware] Sid Troubleshooting

Don.Rose@f444.n161.z1.FIDONET.ORG (Don Rose) (08/25/90)

I have just put together a SID (Sound Input Device) from the schematics from 
the SID Trio.  Using an external power supply, the SID looks great: low pass 
filters work, output signal is right, etc.  However, when I hook it up to the 
serial port and run the test utility, I get "SID not responding."  The V+ and 
V- voltages within the SID are both positive (which may be due to the 
tristate output of the 26LS30 chip of the serial port) and the current drawn 
by the SID is microamps.  Hooking the serial port up to the scope shows no 
change in voltage while running the test utility.  Could the software not be 
enabling the transmit lines of the
 port?  Has anyone built one of these SID's and got it to work?? Thanks in 
advance for any help.

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