Aion Lab Series L5 issues

[slacker775]

I finally managed to get all of the components together to complete my L5 and I seem to be having two issues.   The most critical one is that I'm getting a high pitched squeal out of IC8.  The other is that the compressor might not be doing much/anything but I haven't gotten to calibrating the trimmer just yet due to the squeal problem.

When I first plugged it in to try it out, once I raised the master volume up at all, the thing squealed like hell.  Bypass was perfectly fine.  Using a signal tracer, I tracked it down to IC8 which was a JRC 4558 that I got from BYOC.  I pulled out IC8 and no squeal, all is good.  I put in a "JRC 4558" from Tayda and same squeal.  This is suggesting to me that the ICs aren't the problem, it's probably something new the surrounding componentry.   I'm going to do a deep dive inspection around that area once I clear the cobwebs, but if anyone has any thoughts as to what might induce that squeal, that may help to narrow down the problem.

As for the compressor, I've noticed that the LED stays on all the time, wether compressor is enabled or not, or if any signal is going through or not. I'm not sure if that's normal, or perhaps tied to it not yet being calibrated.  I can't really tell if it's doing much of anything if I fiddle with the knobs, though again, I should probably get the thing calibrated before I worry too much on that front. 

[bcalla]

Regarding the compressor, mine was on all the time until I calibrated it.  However, once calibrated to the provided spec it doesn't come on at all.  I need to get it back on the bench to see if I can find a happy medium.

[Droogie]

Did you try with the multifiliter all the way counterclockwise? IC8 is the upper two frequency levels of the multifilter. Check  values for C10, C26–29, R49–54, and maybe even IC13.

[bcalla]

Did you try with the multifiliter all the way counterclockwise? IC8 is the upper two frequency levels of the multifilter. Check  values for C10, C26–29, R49–54, and maybe even IC13.

I will do this.  Thanks.

[Droogie]

That was more for Slacker775. Bad reply nesting on my part!

[bcalla]

Oops, my bad.  I hijacked his thread.  Carry on.   

[slacker775]

No worries.  We're potentially having similar issues with the compressor so whatever fixes one may fix the other.