GSSL (Rev. 11) from PCB-Grinder noise issue with chassis ground connection

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bxt403

Well-known member
Joined
Jan 9, 2009
Messages
65
Location
Calgary, AB Canada
I have a PCB Grinder GSSL board that seems to be working (the metering is responding) but the compression seems to be subtle (if non-existent); the LED doesn't seem to turn on all the time either. The problem is that the circuit board isn't connect to chassis (the 3 holes that are grounded with the stand-offs have paper washers over them).

It seems like the circuit is working (i.e. the metering is responding to the front controls) WITH the chassis ground connected BUT there seems to be a ground loop somewhere as the sound is distorted and at a lower volume. When I disconnect the circuit board's 0V cable that comes from the BAL IN section: I get audible sound but there seems to be hum and the compression isn't as drastic (especially the bypass) when the chassis ground is disconnected.

I've been searching through the forums but have to look through close to 400 posts so would rather just hope if some one out there might know where a ground loop on the PCB Grinder board might exist- as I'm certain I need to connect the main board to chassis ground. Furthermore- it seems like consolidating (and deciphering  the different revisions of the GSSL) seems prudent: given that I have the latest (at the time of this writing) version (so all the prior issues were likely resolved while some other ones have likely cropped up).

I've resoldered most (if not all) the points (albeit I'll probably be doing it again) but I first want to find out if there are any possible trouble areas that might need fixing (especially if there are any traces that might need to be broken). 

I've read trying out the CRCRC filter (albeit a schematic would be helpful), along with placing the bridge rectifier off the circuit board (keep in mind that those are non-PCB Grinder versions).  I'll have to get a porto-board but (from what I've looked up thus far) : it seems to be a possible cure (despite the fact that I don't see how it'll fix what seems to be a ground loop).

Any advice from anyone who has a working Rev. 11 GSSL would be appreciated- especially w.r.t. any (if not all) trouble areas (for conciseness sake).

The biggest point of contention I'm having is why I can't connect the main circuit board to chassis ground (and why the compressor seems to work "better" with it connected- albeit with distorted/low sound).

Just noticed that there's an entire separate thread for the GSSL from PCB-Grinder so I'm reposting this and hoping a moderator can delete this post.

Thanks.
 
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