Chances are greater than 50% that your problem is something simple
like a bad solder joint, or IC in backwards. I had two modules that
had completely dead outputs when I finished them. The problem? Too
much heat had caused the coax insulation to melt just enough to short
the output cable. I had to learn to modify my coax installation
technique!
Moe
--- In motm@y..., bruce@s... wrote:
> I have a question about the troubleshooting guide in the back of
the
> MOTM 300 instructions.
>
> The third check box has several lettered steps. Step (b) says to
> check the VX voltage, and make sure it is close to +4.8V, and
mentions
> the right side of R3.
>
> Looking at the schematics, it looks like R3 is involved in the fine
> tune voltage, whereas R37 is closer to where one might find VX.
>
> Comments?
>
> Oh yeah, I have an MOTM-300 that is not playing nice at the
moment.
> All of the voltages seem to check correctly (with the exception of
VX
> as noted above), now it is down to verifying that all of the
> components are in the right spot...
>
> Part of me is wondering about O-Scopes and if that might help me
find
> the trouble sooner. There is no sound at all out of the module,
> except from the pulse jack, if I turn the coarse tune knob to just
the
> right spot, it outputs noise that can be changed by moving the PWM
> pot. 8-)
>
> Wahoo! (translation: this should keep me occupied for the next
couple
> of nights)
>
> Bruce