GSSL HELP THREAD!!!

[signalflow]

i'm not sure
my 79L12  voltages are:

Out:     0,64  (and this is the voltage on all my -12v rail)
In:     -20,3
Com:    0

while my 78L12 volts are:

In:     19,7
Con:   0
Out:   11,91

i don't think this is normal. is it?

replace the 79L12

 

[Harpo]

i'm not sure
my 79L12  voltages are:

Out:     0,64  (and this is the voltage on all my -12v rail)
In:     -20,3
Com:    0

while my 78L12 volts are:

In:     19,7
Con:   0
Out:   11,91

i don't think this is normal. is it?

replace the 79L12

... or better remove the regulator following short or broken part first.
Pull the TL074, TL072 and sidechain VCA out of their hopefully fitted socket and measure again. Follow the -12V trace with magnifying glass and check for shorts. At some spots its a little tight. If the -12V rail now comes alife, the regulator only was in short circuit protection mode and one of the prementioned ICs is probably broken. Case not, you still can replace the regulator.

 

[pietro_moog]

i'm not sure
my 79L12  voltages are:

Out:     0,64  (and this is the voltage on all my -12v rail)
In:     -20,3
Com:    0

while my 78L12 volts are:

In:     19,7
Con:   0
Out:   11,91

i don't think this is normal. is it?

replace the 79L12

... or better remove the regulator following short or broken part first.
Pull the TL074, TL072 and sidechain VCA out of their hopefully fitted socket and measure again. Follow the -12V trace with magnifying glass and check for shorts. At some spots its a little tight. If the -12V rail now comes alife, the regulator only was in short circuit protection mode and one of the prementioned ICs is probably broken. Case not, you still can replace the regulator.

i'm not sure, but i'm gonna check it.
actually, there's a little scratch on the -12v rail. i put some solder on it, it toke it, now it seems good.
do you think this could be the short? i tried 4 vca and 2 tl074 (got a turbo board to install after standard mode is working),
and the voltages are the same ( now i don't have another tl072)
thanks, i'm gonna report soon

 

[Harpo]

i'm not sure, but i'm gonna check it.
actually, there's a little scratch on the -12v rail. i put some solder on it, it toke it, now it seems good.
do you think this could be the short? i tried 4 vca and 2 tl074 (got a turbo board to install after standard mode is working),
and the voltages are the same ( now i don't have another tl072)
thanks, i'm gonna report soon

That scratch could (unlikely) cause a broken trace, not a short. Mend it with a piece of wire/cutoff for a more reliable fix.
You already double checked the correct orientation of both 22uF polarized caps after the -12V regulator (next to TL072 and below label 'sidecHAin')?
Measure for -12V with prementioned chips pulled out. After this fails, the 79L12 regulator is probably broken. Your Opamps and sidechain-VCAs should still be OK when always fitted in the correct orientation.
good luck

 

[pietro_moog]

thanks harpo.
capacitors are well oriented,and -12v doesn't re-apperar without tl072, 74, 2180.
i'm gonna change the 79l12, and see what happens.

 

[bassculture]

hi everybody

i got a working GSSL with the turbo & supersidechain board.

my problem >
in turbo mode, the turbo side compress two times more than the gssl side.
in normal mode, compression is the same as gssl side in turbo mode...

i got two sidechain boards, wired as in the turbo board .pdf.

they output the same level, i also visaulize with my oscilloscope... no noise, same levels & signal on both super sidechain boards output...

i also double check my resistors values around the sidechain VCA & turbo board... found no mistakes...

is that issue known ?

when i mesured both VCA on pin 1, i got on the turbo more than two time the voltage i mesured on the gssl side...
where should i look more closely ? eventually resistor i should try to change ?

any idea ?

 

[stereokillah]

perhpas your problem come from the ratio turbo wiring, have linked it on the same place of the controle boad or like it's describe on turbo pdf?

 

[Holger]

bassculture, I would suggest to disconnect the sidechain boards and try to get turbo and regular mode running well first. Don't forget that the compression in both modes is program pending (ist your test signal mono?)
My next assumption is that you'd probably made a wiring mistake at the 2x 47k summing point that feeds the GSSL and the turbo sidechain. Just a remote diagnosis...

 

[audiophreak]

Hi,
      I've done several searches, but can't seem to find the post about lowering some distortion by wiring the bypass switch in a certain way.  Could someone point me in the right direction ?
    Thanks

 

[Silvas]

Hi,
      I've done several searches, but can't seem to find the post about lowering some distortion by wiring the bypass switch in a certain way.  Could someone point me in the right direction ?
    Thanks

You mean this thread?

http://www.groupdiy.com/index.php?topic=34219.msg418719#msg418719

Luckily, i saved the link on my hard disk, otherwise....

 

[audiophreak]

That's the one !!!  - THANKS 

 

[bassculture]

hi everybody,

yes my test signal is mono - i feed 2 input with a y cable.
i've allready bypassed the sidechain cards & checked with a scope (no noise or strange stuff).

my compressor is runnig ok, i just got the side with turbo wich is compressing 6db (average) more than the gssl side...
voltage at pin 1 of the VCA is higher on the turbo than on the gssl...

i've made the connection exactly as described on the turbo .pdf

i guess i'll continue there http://www.groupdiy.com/index.php?topic=28113.msg339348#msg339348

there's a procedure to troobleshoot that kind of problems (thanks keith)

thanks for troubleshooting suggestions (and are still welcome )

 

[mikerisha]

happy holidays everyone.

i just finished my 3rd gssl, and everything is working fine up until the make up gain.  Its only working for the left channel.  Right Channel stays the same.

I have already switched out my entire main pcb with another, and still have the same problem, so I am guessing it has something to do with the control pcb. 

any trouble shooting suggestions?

thanks.

 

[radiance]

happy holidays everyone.

i just finished my 3rd gssl, and everything is working fine up until the make up gain.  Its only working for the left channel.  Right Channel stays the same.

I have already switched out my entire main pcb with another, and still have the same problem, so I am guessing it has something to do with the control pcb. 

any trouble shooting suggestions?

thanks.

Seems unlikely since it's 1 pot controlling two vca's. More specific...if there was anything wrong with the control pcb you would not have been able to controll only the left channel.
Did you swap VCA's as well?

 

[mikerisha]

happy holidays everyone.

i just finished my 3rd gssl, and everything is working fine up until the make up gain.  Its only working for the left channel.  Right Channel stays the same.

I have already switched out my entire main pcb with another, and still have the same problem, so I am guessing it has something to do with the control pcb.  

any trouble shooting suggestions?

thanks.

Seems unlikely since it's 1 pot controlling two vca's. More specific...if there was anything wrong with the control pcb you would not have been able to controll only the left channel.
Did you swap VCA's as well?

yeah i changed out the entire main pcb with another complete one that i just finished.  still the same prob.  im getting correct voltages on the pot as well.

my signal is balanced with the unit in bypass though.  could it be something with that?

EDIT.  (big edit!)

wow so i just realized only the left side is compressing as well.. right channel stays balanced thruout the whole chain.. so entire left channel is doign what it should from top to bottom, and right channel stays the same regardless of any knob movements.. WTF.

help.

 

[radiance]

my signal is balanced with the unit in bypass though.  could it be something with that?

What you mean with "my signal is balanced"?

 

[mikerisha]

my signal is balanced with the unit in bypass though.  could it be something with that?

What you mean with "my signal is balanced"?

sorry.. it stays the same. its like its bypassed. nothing i do with any knobs affects the right channel. same level going in that is coming out.

 

[radiance]

Maybe a mix up between the 1K & 1M resistors on the side of the pcb?

 

[Harpo]

wow so i just realized only the left side is compressing as well.. right channel stays balanced thruout the whole chain.. so entire left channel is doign what it should from top to bottom, and right channel stays the same regardless of any knob movements..

You already double checked resistor values around your audio VCAs and have the wire link right next to the 1K of the left audio VCA block fitted?
If you swap the audio VCAs and the fault follows the swap, this VCA is probably broken.
If you swap the NE5534 from the DBX202 substitution circuit and the fault follows the swap, this opamp is probably broken.
Otherwise compare identical spots from working chanel. Start measuring at the 1K resistors where the control voltage is split, going to left and right substitution circuit, labled 'CV TO VCA'S' from schematic.

 

[mikerisha]

wow so i just realized only the left side is compressing as well.. right channel stays balanced thruout the whole chain.. so entire left channel is doign what it should from top to bottom, and right channel stays the same regardless of any knob movements..

You already double checked resistor values around your audio VCAs and have the wire link right next to the 1K of the left audio VCA block fitted?
If you swap the audio VCAs and the fault follows the swap, this VCA is probably broken.
If you swap the NE5534 from the DBX202 substitution circuit and the fault follows the swap, this opamp is probably broken.
Otherwise compare identical spots from working chanel. Start measuring at the 1K resistors where the control voltage is split, going to left and right substitution circuit, labled 'CV TO VCA'S' from schematic.

opamps swapped and vcas swapped as well.. same problem for the right channel. 
resistors checked and matched.

could it be something on the control pcb?