GSSL HELP THREAD!!!

[richtrix]

Ok I've made progress!!! I looked over the PCB and don't know how I missed it before but I missed a tie next to the 47k resistor by the left vca... Plugged that hole and viola!!! It passes audio now!!! Woohoo!

All still is not good though. When I put the compressor button in the signal noticeably distorts and doesn't seem to respond to Threshold nor makeup gain. The only response from front panel (other than bypass button) I get is when I move the ratio to 10:1 the signal audibly lessens and the meter deflects to about 8db and just sits there. The meter does this whether there is signal or not. I can audibly hear the drop though. I verified all the ICs and caps are in the right place and orientation. I have the tie in on the control board that Jakob mentions everyone forgets next to meter output. I'm pretty good with soldering iron so no globs. I guess just start checking the resistors?? Would be nice for some additional voltage test points if anyone has any. THANKS

 

[gyraf]

just go systematically through this thread's variety of already-known errors fitting your symptoms

..like bypass wireing, the link where SC HPF can be inserted, and such

 

[TimKR]

Hey all,

would be nice if someone could take a look at the latest post of the Addon Thread (https://groupdiy.com/index.php?topic=65232.140) im got some trouble with the SSC.

Thank you

 

[HyprDrivr]

For your CoolAudio V2181, you'd need the 51R resistor as the shunt part of the 150K voltage divider in order to adjust the SYM-port for a max.range of [ +/-15V / (150000R+51R) * 51R = +/-0.005V = +/-5mV ]. You fed the VCA's SYM-port with +/-15V instead.

I have been staring at this post for about two hours to try to understand what it really means. Is there any chance you can give me some more info?
As far as i understand it the 1meg (purple on Matts scheme) is replaced by the 150k, but i dont get where the 51R should go. Is it on the blue position on Matts scheme?
http://diy.fischerworks.com/gssl_vca.shtml

I think it wold be great to have a really clear path to using the Coolaudio VCAs since it seems like the THAT ics will be gone for at least six months more.

 

[Harpo]

..., but i dont get where the 51R should go. Is it on the blue position on Matts scheme?
http://diy.fischerworks.com/gssl_vca.shtml

Yepp, the blue position.
You could have figured it out yourself by comparing the That2181 datasheet with the grandiose V2181 "datasheet" (probably a close relative to a DBX2150 with a 6mV/dB control law, but the datasheet is missing nearly every relevant information, such as pin parameters or parts max.ratings) in context with the GSSL schematic.

 

[HyprDrivr]

Yepp, the blue position.
You could have figured it out yourself by comparing the That2181 datasheet with the grandiose V2181 "datasheet" (probably a close relative to a DBX2150 with a 6mV/dB control law, but the datasheet is missing nearly every relevant information, such as pin parameters or parts max.ratings) in context with the GSSL schematic.

That is how I did figure it out, just wanted confirmation
Many thanks!

 

[TimKR]

Hi,

im using THAT 2180B VCAs and the output level becomes is slightly uneven L/R So im thinking about to modify the THAT circuits related to http://diy.fischerworks.com/gssl_vca.shtml.

At the moment i got all resistors and the trimmers installed like "Original Value"! i also noticed cracking and  distortion...

 

[gyraf]

"slightly uneven" meaning how much? Don't worry too much about differences under 1dB or so..

/Jakob E.

 

[mhbunch]

Recently finished this - the HEAVIEST GSSL EVER!  ;D ..thanks to the gigantic Onan branded ADC transformers. Still need to finish the front panel and clean up some wiring.

 

[mhbunch]

from the front (still using pencil marks at the moment)

 

[craigmorris74]

Hi,

I just wired up a GSSL Rev 7 board with Expat CRC and turbo boards.  Upon powering up the two resistors on the positive side of the capacitors on the CRC start smoking.  When the CRC isn't connected to the board, it's putting out + and - 24V, as I'd expect.

Reading through this thread, from previous posts, it sounds like I have a short on the main board to ground.  Does anyone have any advice for searching for that short?  Any areas on the board that are notorious for this?

Thanks,
Craig

 

[Script]

Isn't the stock version 18V power transformer? Regulated down to 15 and 12 ?

Also pull all ICs out of their sockets and measure for correct voltages at corresponding pins.

 

[craigmorris74]

Isn't the stock version 18V power transformer? Regulated down to 15 and 12 ?

Also pull all ICs out of their sockets and measure for correct voltages at corresponding pins.

The +-24V is after the CRC, but before the regulators.

Won't the regulators shut down without the opamps in?

 

[Script]

I'd pull all ICs out and disconnect the CRC for now. Also it sounds like there's no way around checking all solder joints for shorts using the board overlay from Gyraf's website. Shorts can easily hide anywhere on these boards. I'd start by checking all power pins first (V+ and V- on all regulators and all ICs). Also check for correct orientation of all regulators and ICs.

As for the CRCRC board -- which is an add-on, although a very simple circuit -- make sure the caps are oriented correctly. Also it'd be best to replace the four smoked resistors before inserting again. Pictures might help.

 

[craigmorris74]

I'd pull all ICs out and disconnect the CRC for now. Also it sounds like there's no way around checking all solder joints for shorts using the board overlay from Gyraf's website. Shorts can easily hide anywhere on these boards. I'd start by checking all power pins first (V+ and V- on all regulators and all ICs). Also check for correct orientation of all regulators and ICs.

As for the CRCRC board -- which is an add-on, although a very simple circuit -- make sure the caps are oriented correctly. Also it'd be best to replace the four smoked resistors before inserting again. Pictures might help.

I'll give this a whirl this weekend.  I could probably find the old layout of I searched hard enough.

 

[Script]

Also check power rectifier(s) for orientation.

Pic of CRC board is here: https://groupdiy.com/index.php?topic=65232.msg987868#msg987868

 

[craigmorris74]

Also check power rectifier(s) for orientation.

Pic of CRC board is here: https://groupdiy.com/index.php?topic=65232.msg987868#msg987868

I've double and triple checked all the components and orientation of components and tried to find shorts on the PCB, but I've still got problems.  At this point, I'm going to start from scratch with a new rev 11 board, and make sure I do crazy neat job soldering.

 

[Script]

Of course, that's another way of doing it... Just asking, you sure your power transformer is hooked up correctly ?

[add]Component layout and traces are the same on Rev 7 and Rev 9, as far as I remember. [/add]

 

[craigmorris74]

Of course, that's another way of doing it... Just asking, you sure your power transformer is hooked up correctly ?

[add]Component layout and traces are the same on Rev 7 and Rev 9, as far as I remember. [/add]

The power transformer is hooked up correctly.  I'm getting the right voltages out of it. Until the new boards arrive, I'll try a couple of more things.  Thanks for the layout, and all of your suggestions.

 

[craigmorris74]

Just looked at the CRC board parts list.  Could the resistors on that board be smoking because they are 1/4 watt instead of 1/2 watt?