Re: GSSL HELP THREAD!!!
« Reply #8380 on: March 18, 2021, 12:05:36 AM »
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

Re: GSSL HELP THREAD!!!
« Reply #8381 on: March 18, 2021, 03:55:10 AM »
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
..note to self: don't let Harman run your company..

TimKR

Re: GSSL HELP THREAD!!!
« Reply #8382 on: March 18, 2021, 12:37:14 PM »
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

Re: GSSL HELP THREAD!!!
« Reply #8383 on: March 20, 2021, 10:13:46 PM »
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

Re: GSSL HELP THREAD!!!
« Reply #8384 on: March 21, 2021, 06:30:16 AM »
..., 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.
A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.  -Douglas Adams

Re: GSSL HELP THREAD!!!
« Reply #8385 on: March 21, 2021, 07:08:24 AM »
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

Re: GSSL HELP THREAD!!!
« Reply #8386 on: March 22, 2021, 11:19:39 AM »
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...

« Last Edit: March 22, 2021, 12:05:37 PM by TimKR »

gyraf

Re: GSSL HELP THREAD!!!
« Reply #8387 on: March 23, 2021, 05:09:26 AM »
"slightly uneven" meaning how much? Don't worry too much about differences under 1dB or so..

/Jakob E.
..note to self: don't let Harman run your company..

Re: GSSL HELP THREAD!!!
« Reply #8388 on: April 14, 2021, 12:18:26 PM »
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.

Re: GSSL HELP THREAD!!!
« Reply #8389 on: April 14, 2021, 12:20:26 PM »
from the front (still using pencil marks at the moment)


 

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