Suggestions:
1) Look for open traces or cold solder joints (hazy looking solder).
2) Check power and ground going to all 4 chips with PCB powered. Also
verify 9 volts from the 7809.
3) Check the IC socket connections with the ICs inserted and PCB
unpowered. Do the IC pins really connect to the PCB trace underneath?
4) Beyond this, an oscilloscope starts becoming real handy. You could
try comparing each op amp stage output between the working and
nonworking modules with your multimeter. Use DC volts mode first, then
AC mode for a rough computation of whether any pulses are coming out of
that stage. This might let you narrow it down to the broken section.
I hope this helps.
John Loffink
jloffink@...
1) Look for open traces or cold solder joints (hazy looking solder).
2) Check power and ground going to all 4 chips with PCB powered. Also
verify 9 volts from the 7809.
3) Check the IC socket connections with the ICs inserted and PCB
unpowered. Do the IC pins really connect to the PCB trace underneath?
4) Beyond this, an oscilloscope starts becoming real handy. You could
try comparing each op amp stage output between the working and
nonworking modules with your multimeter. Use DC volts mode first, then
AC mode for a rough computation of whether any pulses are coming out of
that stage. This might let you narrow it down to the broken section.
I hope this helps.
John Loffink
jloffink@...
> I have 2 vc dividers. The first I put together worked right off. Thetrimming
> second one refuses to respond. That is, when I start on Ken's
> instructions there is no output from HO. I've checked that I'mgetting
> the correct voltage into the pcb, I switched the 4024 and 40106 fromthe
> working divider to the nonworking divider, I've compared the two tomatch
> up every component (and orientation), and triple-checked solderingthat
> connections - no improvement. Any suggestions? Please keep in mind
> I'm extremely poor at electronics troubleshooting - just using my
> multimeter correctly gives me a sense of accomplishment :-).
> Jeff
>