[1UP]

I got my DMM today and want to learn how to measure various outputs from the RCA SPDIF socket from my DVD player - can someone tell me what exactly I can test (and how I should set my meter to test them)? e.g. impedance, current, resistance....

Ditto the input minijack on my T-amp.

 

[Fresno Bob]

http://www.powermanagementdesignline.com/howto/60402482
http://www.technology.niagarac.on.ca...iles/Lab10.pdf
http://www.physics.montana.edu/class...20Computer.pdf

 

[1UP]

Thanks, I was more looking for something like:
to test DC offset - do this, place test leads, here and here
to test DC voltage - do that, place test leads, there and there

 

[mono]

To test DC offset, put the meter on "DC" (mV to low whole digit volt) range and put the probes across the analog ground and L or R pin(s). That IS the DC voltage. The analog signal you want is an AC voltage (so set the meter to low volts AC range to test, again between ground and L or R). You should not have any reason to test SPDIF at this point.

 

[1UP]

Thanks, Mono - what about testing the 75 ohm impedance of the SPDIF?

 

[mono]

What do you mean, "what about testing it"?
I don't understand the question. Are you not wanting to use normal cable? To check it, measure with the Ohm scale that covers (75), IE- with the cable plugged into the destination, IIRC.

 

[1UP]

I read somewhere that some SPDIF output sockets are not "true 75ohm"; that's what I wanted to verify - I think your reply answers the question, though.

 

[Glassman]

measuring impedance is a way more complicated task, not just a 'place test leads between this and this' kind of thing.. you'd have to measure the differential impedance of the output driving pins of the S/PDIF transmitter IC, loading them with different loads and observing the voltage difference it makes, but this is not really possible to do using just DMM, because you can't force the transmitter to stay at steady output value, it's a serial stream and on top of that manchester encoded, that means the average level is always the same, you'd have to observe this on oscilloscope..

 

[1UP]

OK, G, well now I know!