No Tone control on FA-1 Preamp ??

[bluelagoon]

Have this FA-1 Preamp circuit, it is only partially working, it boosts the signal, but the tone controls don't work, are not boosting or cutting , just flat, and on account of no tone control boost, there is overall less amplification.
Just wondering if someone here could point me in the most obvious direction to pinpoint where the fault might lie or where to best begin to trouble shoot the fault.
I'm thinking possibly something amiss with IC2 op amp not working right?? but not too sure.
Thanks.

[ElectricDruid]

The tone control circuit *looks* ok, so it must be a build error, no?

[antonis]

Possible IC1B inverting input open..
(no connection to R9/R10 joint..)

[drdn0]

Have this FA-1 Preamp circuit, it is only partially working, it boosts the signal, but the tone controls don't work, are not boosting or cutting , just flat, and on account of no tone control boost, there is overall less amplification.
Just wondering if someone here could point me in the most obvious direction to pinpoint where the fault might lie or where to best begin to trouble shoot the fault.
I'm thinking possibly something amiss with IC2 op amp not working right?? but not too sure.
Thanks.

Check you have 4.5v @ pin 5, and pin 6 is connected to the junction of the 33/10k resistors.

[bluelagoon]

Yeah It may well be a build error, might have to get the signal injector tracer out to track it down,
I build quite a few of these, that include a selectable relay switched Baxandall out option that cuts the Bax tone stack out. That switch works okay on this board, but somehow when Bax in is selected, it changes state noticeably, but somehow doesn't engage the Tone controls. I know the PCB's work successfully when put together right, but alas, there is a small percentage disappointing failure rate after assembly.
Wish it weren't so, as they are so time consuming putting together, then to track a fault takes a whole lot more time, sometimes seems easier to just write them off and reclaim the parts for the next build.
Any how, thanks for the feedback responses from those that contributed here.
Happy New Year to all the good folk of Diystomboxes.
Cheers.

[bluelagoon]

Possible IC1B inverting input open..
(no connection to R9/R10 joint..)

That sounds plausable antonis, might be worth a look at first up,
Hopefully something that simple would be an easy fix.
Cheers