GSSL HELP THREAD!!!

[peteys]

Thank you.  I'll try pushing them in a little harder. 

 

[peteys]

Are you guys using the MIL Max sockets for the VCA's.  Digikey ED60002-ND?  I'm really worried about bending the pins on the 2180's?  They are not going in easily.

 

[audiophreak]

Hi,
  I built a couple of these and ran in to the same situation, I ended up using something like this from Digikey - A24815-ND - I couldn't find the actual part number I used, so double check the pin spacing, Expat audio uses these in their Turbo kits.

 

[JayDIY]

Hi everybody,
I've just finished my gssl and verified all the voltages on ICs, the possible shorts on the 10 pin connector, bypass wired as it should and working, everything is correct.
But i have an almost continuous signal at the vu meter, increasing when i lower the threshold sensitivity (as it should do with an audio signal).
Last thing, when audio applied into the XLRs it seems to work correctly, adding the compressed audio above the continuous signal.
Can someone help me about that?
Cheers

Jerome

 

[radiance]

But i have an almost continuous signal at the vu meter, increasing when i lower the threshold sensitivity

Would be easy to track if you have an osciloscoop. Just follow the side chain pat, and see where the signal appears. If you don't have a osciloscoop start by checking for solder shorts around both tl74 and tl72 in the side chain  path.
Do you also have this continuous signal when the bypass in engaged? Did you look at the schematic?

 

[JayDIY]

But i have an almost continuous signal at the vu meter, increasing when i lower the threshold sensitivity

Would be easy to track if you have an osciloscoop. Just follow the side chain pat, and see where the signal appears. If you don't have a osciloscoop start by checking for solder shorts around both tl74 and tl72 in the side chain  path.
Do you also have this continuous signal when the bypass in engaged? Did you look at the schematic?

The signal stops when in bypass...
And yes i looked at the schematic, everything goes where it should...
The only thing i didn't check is all the pins of all ICs, i only checked +- 12V and +- 15V on each and of course when i remove the tl074 in the sidechain detection circuit the continuous signal stops...
And no oscilloscope at all... :-/

 

[peteys]

Thanks Audiofreak,  I'm gonna try those out.  It looks like the same lead spacing.

 

[radiance]

The signal stops when in bypass...
And yes i looked at the schematic, everything goes where it should...
The only thing i didn't check is all the pins of all ICs, i only checked +- 12V and +- 15V on each and of course when i remove the tl074 in the sidechain detection circuit the continuous signal stops...
And no oscilloscope at all... :-/

Signal still there when removing the side chain VCA?

 

[peteys]

Does anybody know whether Mouser Part # 512-LM7915CT by Fairchild  could be a correct substitute for the 7915 regulators?  It's only rated at 1amp.  The Digikey 7915 Part in Greg's BOM is out stock, which is rated at 1.5 amps.

 

[livingnote]

Don't worry, you could probably string 4 GSSLs on one of those 1 Amp regs.

 

[JayDIY]

Signal still there when removing the side chain VCA?

Yes signal still there...
Any clue?

 

[radiance]

Yes signal still there...
Any clue?

removing tl74?

removing tl72?

 

[JayDIY]

removing tl74?

removing tl72?

Well what's happening is :
  - removing TL074 : No more signal
  - removing TL072 : Still signal but 2 dB vu weaker, and very small effect actioning the thres pot (0,1dB vu from fully CCW to CW)
  - removing VCA : Still signal
  - removing TL072 and VCA : Very low signal (2 subdivision of the meter), and no longer effect actioning the thresh. pot

That's it

 

[radiance]

My guess is...either a solder short or a wrong value part somewhere around the tl74....or both 

 

[JayDIY]

My guess is...either a solder short or a wrong value part somewhere around the tl74....or both  

Many thx for this little troubleshooting Radiance
Gonna check that on tomorrow afternoon, and tell you more about this issue...
Cheers

 

[Autophase]

Just rdering the final bits for my comp.
I'm opting for jacks rather than XLR, I've come across 2 pole and 3 pole jacks, which do i need for the GSSL?
Does 2 pole simply mean mono and 3 pole refer to stereo?

 

[livingnote]

3 Pole because it's mono balanced - tip and ring are the same mono signal but ring is
180° phase reversed, and sleeve is ground. That's why XLRs are 3 pin, too - it's not for
stereo.

 

[Autophase]

Stressing out a bit here guys.
Got all the components on my board, apart from the IC's
I've just done a continuity test on the main board, now I'm getting continuity on many of the output connections on the bottom of the board, but not on the input.
Is this right, I would have assumed they should be the same, or am I completely wrong?

 

[_casio]

Howdy,

I've been trying to dig up trouble shooting info on my particular problem for several hours, and so far no luck. The issue I'm having is as follows:

When the GSSL is powered on, I get no sound output at all, and the meter shows no activity. When it is powered off, I get audio pass through at a very low level, and it is completely distorted - like a fuzz box/distortion pedal.

I get proper voltage at all of the IC terminals.


Can anyone point me in the right direction or (even better) tell me where I should start trouble shooting?


Thanks so much,

-Drew

 

[peteys]

I hate to bother you guys here.  Great forum.  I've completed the board and hooked everything up.   But I have no compression.  Audio passes fine and all my voltages seem to be correct but the only pot that does anything is the makeup gain pot.


I do not have dc varying with signal on pin8 of the tl074 and I am not getting any voltage at pin 8.

Pin 1 is not changing with threshold variations on the tl072..

I'm really confused because all voltages seem correct.

Sidechain Vca Pin 3 is .15v(should be 5.5v) I'm not sure if this is ok.

Helpppppppppppppppp! ???


EDIT:  Problem solved.  Had to resolder some loose joints on board.