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Question about MOTM-300 Troubleshooting guide

2001-02-22 by bruce@sigalarm.com

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

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