GSSL HELP THREAD!!!

[Gustav]

Lorlin end-stop washer set to position 5 ?

again, can you elaborate? I followed the build guide instructions pretty faithfully, maybe I missed something?

JohnnyScotch, did this end up being the problem with your crunchy auto-release? I'm experiencing the same thing in that position. I'm going to take a look at my pins again this week.

Its fairly easy to check. Just turn the switch until you can't turn it no more, then turn the other way while you count the number of times you can switch it. If the number is 5,  your second to last step is actually the auto-release, while the last step is just a nonsensical setting in context of the circuit. 

Gustav

 

[jsscalet]

Hey guys, so I just assembled my GSSL kit, no sidechain and no mods.

I powered everything up and I'm getting signal to the board, but I'm not getting any signal out. The switches and pots are working. I've triple checked the wiring on the outputs and I know those are correct.

I had a friend walk me through some trouble shooting but couldnt quite track down the issue.

Some readings we found were
Ground to +12 read 0
pin 1 of the 7812 regulator read 11.92 then scrambled and then would read 0.
pin 3 of the 7812 regulator read 22.8, scrambled around then went to 0. Pin 3 occasionally sparked while reading
positive pin of Cap 1 read 0
+ rectifier read 0
- rectifier read -.01 but then would read - 0

5532
Pin 4: -14.79                  Pin 4: -14.75
Pin 8: 15.18                    Pin 8: 15.13

TL074
Pin 4: 12.10
Pin 11: 0

TL072
Pin 4: -11.89
Pin 8: 12.10

His thought is "its possible you may need to change the rectifier. it thats not putting out DC voltage with some consistency then that would be an issue"

I would love some other insight and see what else I should check. Thank you

 

[gyraf]

TL074
Pin 4: 12.10
Pin 11: 0

..you somehow lost the connection to 074 pin11..

 

[synthetic]

Hi, I have a GSSL compressor which is passing audio but not compressing. All power measurements look correct (+/- 15 and +/- 12).

Point C does not seem to be acting correctly. With input or not, it is -11V at min threshold. As I bring the threshold up, it hits 0V at 12:00 and stays at 0V all the way to the top. The audio output jumps 13dB when this voltage jumps to 0V. I read elsewhere that it should go from 0V with no signal and get negative as input increases.

The threshold pot itself seems to be working, sweeping from -12V to +12V. The sidechain VCA at pin 8, with threshold minimum, goes from 0V to -0.7V to -0.2V as input increases. If threshold is max, this stays at 0V with any input signal.

TL074 pin 7 ranges from 11V to 0.3V as input increases. TL074 pin 1 goes from -0.2V to 4V as input increases.

I have spent a few hours checking for shorts and parts facing the wrong way but everything looks correct. My next move was going to be replacing the sidechain VCA and/or TL074, but I figured I would check in here first. Thank you for your help!

[edit:] Bypass is wired correctly, 202 VCAs, no mods/sidechain yet.

 

[Harpo]

What mods did you do to make a DBX202 (a lot different to a 202C) work ?

 

[synthetic]

I bought the VCAs from someone on this board. I think they were actually taken out of an SSL, I bought them in 2009. Pic:

https://dl.dropboxusercontent.com/u/35205491/ssl_vca.jpg

 

[jsscalet]

TL074
Pin 4: 12.10
Pin 11: 0

..you somehow lost the connection to 074 pin11..

TL074
Pin 4: 12.10
Pin 11: 0

..you somehow lost the connection to 074 pin11..

I spent some more time with it and its reading -11.89. I also got a consistent reading of 11.98 on the regulator pin 1. And the +12 is also reading 11.98. Also when poking around with my multimeter I accidentally touched the green and yellow connection under the board and I heard the audio I was running through the comp, but it had a ton of noise and sounded thin

So my updated readings are

Ground to +12 read 11.98 DC
pin 1 of the 7812 regulator read 11.98 DC
pin 3 of the 7812 regulator read 23.1 DC
positive pin of Cap 1 read .1 AC
+ rectifier read .1 AC
- rectifier read 0 AC

5532
Pin 4: -14.79 DC              Pin 4: -14.75 DC
Pin 8: 15.18  DC              Pin 8: 15.13 DC

TL074
Pin 4: 12.10 DC
Pin 11: -11.89 DC

TL072
Pin 4: -11.89 DC
Pin 8: 12.10 DC

 

[synthetic]

I replaced the sidechain VCA and it is compressing now. But not acting well.

If the Threshold is set between minimum and 11:00, very little audio output. The meter is pegged all the way to the right with any input signal.

From around 11:00 to 12:00 I can get it to compress. It is like all of the control over the signal is in a very small amount of travel here.  The meter acts as expected.

If the Threshold is turned beyond 12:00, I no longer hear any compression. Output signal is much higher. Meter is all the way to the left.

The threshold pot is a 50K linear and is wired correctly. I guess I'll start looking at that TL072 next.

 

[JoelCoteBergevin]

I just finished building my GSSL and when I powered it for the first time, smoke arised coming from the 7812 area (burnt 10ohm resistor I guess). Meter's leds light up just fine, audio was passing.

Already checked for shorts to ground in the power section, also reflowed a couple joints to be sure but nothing apparent. I tried to power it another time, same thing happened, except this time I heard a ''pop'' (the cap near 7815 popped). Turned my unit off immediately. Since I dont want to damage anything I dont want to power it up again to check voltage..  I use the toroid supplied from gustav (15v/15V) wired for 110V. I already have some 7812 and 7815 replacement parts that I ordered two days ago in case of... what happened today.  Should I just swap them and try again ?

Anything else I can check for/or test ? Here's a photo of my build if this can help. 

UPDATE: replaced the 22uf popped cap, replaced 7815, removed the clip heatsink I put on the V regs, reflowed some other pads, removed all IC's and VCA and now the unit powers up without any smoke and my pushbutton lights light up (it didnt at first) so I think I'm in the right direction.

UPDATE: Just put the IC's and VCA's back in. Audio passes but it's heavily compressed. Controls work but the threshold is acting super weird.. Whenever I get past ''+10'', the compressor turn in bypass mode and my pushbuttons leds light off. I have the turbo board too.  Seems like I have the same problem that synthetic has..

 

[gyraf]

synthetic,

Seems like your threshold is far too sensitive. Try following the schematic/description to understand it's way of working.

Check the value of the (220K) resistor in series with threshold pot wiper - or the (56K) feedback resistor across the related opamp. These two sets the DC gain of the threshold control. Also re-check values around the sidechain VCA circuit.

Jakob E.

 

[JoelCoteBergevin]

Just checked my threshold pot and it doesnt wipe. It stays around 12.21V then suddenly goes down to around -2.01V at 3 o'clock. My make-up pot however wipes from 12v to 0v correctly. Reflowed all the threshold pot's connections, same result. Is this behaviour only related to a faulty pot or the issue could come from somewhere else ? (sidechain VCA and/or TL074/TL072)

Checked all the R's value already and also didnt notice any solder bridge or cold solder joints.

I'm using 50k linear pots as well. 1/2W.

UPDATE: I tried another 50k pot I had and same behavior.

 

[Harpo]

I bought the VCAs from someone on this board. I think they were actually taken out of an SSL, I bought them in 2009. Pic:

https://dl.dropboxusercontent.com/u/35205491/ssl_vca.jpg

: Your answer is like >'What's the type and model of your car?' , 'Its a red car!'.
You want to know what type of VCA you've got. Maybe have a look at http://www.thatcorp.com/datashts/dn127.pdf, in your case especially pg.4, to identify your part and in order to know if it comes with a 50mV/dB or a 6mV/dB control law. (Your messy threshold behaviour might be related if it has a 6mV/dB control law...). This is not a DBX202C, so there will be more to change, hence my request what mods you have done to make it work (IE the 27K in front of the VCA now is a ..., the 15K feedback resistor at the current_to_voltage converter now is a ..., its corresponding 100pF compensation cap now is ..., the 1M at the sym-adj.port now is a ..., etc.).

 

[synthetic]

Thanks Gyraf. I had the same idea about the 220k and it was indeed the wrong value. Everything is mostly working now, except the ratio is acting backwards. Raising the ratio makes the output go up (but only a dB or two). I've already poked around those surrounding resistor values, will keep searching. 

Edit, maybe it's working properly?

 

[JoelCoteBergevin]

I started troubleshooting for the non-responsive threshold but with no success. It's stuck around 12VDC and suddenly comes down to -2V past 3'o clock. It's compression at maximum range all the time.

Here's what I did/tried:

- TL072 pin 4 read -11.67VDC, pin 8 reads +12VDC.
- TL074 pin 4 reads 12VDC, pin 11 reads -11.55VDC.
- Swapped TL074, same issue.
- Swapped sidechain THAT2180 VCA, same issue.
- Reflowed most pads in the sidechain section (especially point ''F'' on both boards).
- Triple checked R values and component polarity in the sidechain section.
- Detached turbo board completely, same issue.
- Tried new 50K pot, same issue.
-Tested for continuity with the pot and everything's fine also..

If I vary the makeup gain pot, the voltage on pin 7 of TL072 changes and it stays constant at pin 1 (this is correct). However,
If I vary the threshold pot, the voltage stays constant on both pin 7 and pin 1. While it sould change on pin 1. (It actually changes but really abruptly around the end of the CW rotation of the pot.

Otherwise, everything's working as it should. Attack, release, ratio, makeup, meter, audio are all fine, with no distorsion, and sound level is even on both sides.

My last guess is a faulty TL072, which I doubt.. I'll get one tomorrow and see. But is there anything else I could check for ? All resistors in the pot path and in the sidechain section have the correct values. I've been through the help thread about a thousand times for this particular issues and tried all the possible solutions.. I'm lost right now.  :-\

 

[jsscalet]

So just an update of where I'm at now. I'm getting input and output from the Right channel, but input and NO output from the left channel. All my IC values are good and I've went in and reflowed the connections in the output section. I've probably quadruple checked my wiring to the xlr.

I'm not sure, what else should I be checking to troubleshoot?

 

[Gustav]

So just an update of where I'm at now. I'm getting input and output from the Right channel, but input and NO output from the left channel. All my IC values are good and I've went in and reflowed the connections in the output section. I've probably quadruple checked my wiring to the xlr.

I'm not sure, what else should I be checking to troubleshoot?

Since you have a working channel, you have the chance to compare the channels/Swap ICs from left to right etc.

Gustav

 

[jsscalet]

[/quote]

Since you have a working channel, you have the chance to compare the channels/Swap ICs from left to right etc.

Gustav
[/quote]

Thanks for the response, I've only swapped the IC's of the left/right outputs. Is there a reason to try and swap the IC's from the inputs as well?

 

[eqp1a]

I'm trying to fix my friends non working GSSL. Already sorted the audio path, but the sidechain is still acting weird. All controls seem to function as they should, except that the compression is far too aggressive, with clicking sounds on the attack (even at slowest settings) and far too much gain reduction, even at what is metering as reasonable amounts. Also, there is far too much make up gain. He went with the detented pot, and only the first two clicks are useable; after that the signal distorts and is too hot for any input source you'd put it in to.

Obviously I've checked and rechecked all wiring, component values and orientations, etc. but everything seems to be right. Anyone seen or heard of this before?

Edit: can post some sound samples tonight.

 

[JoelCoteBergevin]

So I ordered new TL074, TL072, 78L12 and 79L12 and same issue.. Threshold is not responsive. Maximum compression all the time . After new pots, new IC's and reflowing all the sidechain section, I dont know what else to do, kinda desperate right now..

 

[tzman]

I'm trying to fix my friends non working GSSL. Already sorted the audio path, but the sidechain is still acting weird. All controls seem to function as they should, except that the compression is far too aggressive, with clicking sounds on the attack (even at slowest settings) and far too much gain reduction, even at what is metering as reasonable amounts. Also, there is far too much make up gain. He went with the detented pot, and only the first two clicks are useable; after that the signal distorts and is too hot for any input source you'd put it in to.

Obviously I've checked and rechecked all wiring, component values and orientations, etc. but everything seems to be right. Anyone seen or heard of this before?

Edit: can post some sound samples tonight.

I've seen this exact behavior with a wrong value resistor where there should be a 120R resistor in the audio VCA sections.