I don't have a schematic here at work, so my instructions may be a bit
fuzzy. Also, I don't know your technical level, so I apologise if I
inadvertantly insult you...
Can you read a schematic well enough to find the opamp (triangle symbol with
inputs marked + and -) that the B input feeds? If so, you want to listen to
the output pin of the opamp to see if there is signal there. There will be 2
amps on the same chip, so the output pin will probably be either pin 1 or
pin 7. The easiest thing to do for me is to take a spare jack and solder a
couple of wires to it. Tack the ground wire to ground someplace (another
jack's ground is convenient), plug some headphones in and power the module
up. Then VERY CAREFULLY touch the hot wire to the correct opamp output pin
and listen for signal. Don't touch anything else!
If you have a signal there, we'll have to dig further. I suspect you won't.
If you don't have a signal, then something is messed up in your input
circuit. It could be a short in the coax cable, or a bad opamp chip.
If you have a multimeter, desolder the hot wire of the B input from the
circuit board, unplug the B input jack, and test for resistance between the
hot and ground wires of the B input coax. I have had shorts occur there.
Dave Bradley
Principal Software Engineer
Engineering Animation, Inc.
daveb@... >
> From: telepath@...
>
> >From: "Dave Bradley" <daveb@...>
> >
> >If you put an audio signal into the B input and turn up the
> input knob, can
> >you hear it at the output?
>
> No, I can't.
>
> >
> >Dave Bradley
> >Principal Software Engineer
> >Engineering Animation, Inc.
> >daveb@...
> >
> >> From: telepath@...
> >>
> >> Finished putting together my first MOTM module, the 120 Sub-Octave
> >> Multiplexer and power supply.
> >>
> >> Input A works fine, no problems.
> >>
> >> Input B doesn't seem to work in Cross Mode. I've checked the
> wires to the
> >> jack and there is continuity to the board.
> >>
> >> Since Input B doesn't work when in Cross Mode I'm wondering if
> anyone has
> >> any advice on further troubleshooting this problem.
> >
> >
> >------------------------------------------------------------------------
> >Why wait for a credit decision? Get one instantly! Apply for
> >the Capital One 9.9% Fixed APR Visa Platinum!
> >http://click.egroups.com/1/1895/2/_/529958/_/951924206/
> >------------------------------------------------------------------------
>
>
>
> ------------------------------------------------------------------------
> Why wait for a credit decision? Get one instantly! Apply for
> the Capital One 9.9% Fixed APR Visa Platinum!
> http://click.egroups.com/1/1895/2/_/529958/_/951926918/
> ------------------------------------------------------------------------
>
>