GSSL HELP THREAD!!!

Pusch3l · Jan 30, 2016

I finished my built of this nice piece including a switchable Turbo PCB from Expat Audio but no Sidechain Boards.
Its a Rev.7 PCB with That2181 and the omitted and changed Resistors that Jakob puts on the actual Rev12 Silkscreen.

Played around yesterday with the unit and noticed some (strange?) behaviour:
When Unit is in Bypass mode it still boosts the sound around 3db.
i tested this with a sine generator (1Khz) at -18dB and i got an output after the bypassed GSSL from -15.1dB (Left) and 15.9dB (Right). So the boosting is not even equal on both channels
I already checked the wiring to the Bypass switch and the Voltages on the 15v/12v rails and on the Turbo PCB like the Manual said.

The Other thing is the behaviour of the Meter that the needle rests between 4 and 8dB reduction with Threshold pot turned fully CCW.

milanvdmeer17 · Jan 30, 2016

Hi,
Im trying to install the super sidechain board on my gssl, no succes. Built the 'standard' GSSL (pcb grinder, gyraf) while ago and it's working perfect. However, when i install the sc board only audio is passing. No compression and make-up.
Where should i start?

thanks in advance,
Milan

edit

pamps used: ne5532ap
followed these instructions: https://picasaweb.google.com/108309409331755720628/GSSLSuperSidechainPCB

Pusch3l · Jan 31, 2016

milanvdmeer17 said:
Hi,
Im trying to install the super sidechain board on my gssl, no succes. Built the 'standard' GSSL (pcb grinder, gyraf) while ago and it's working perfect. However, when i install the sc board only audio is passing. No compression and make-up.
Where should i start?

thanks in advance,
Milan

editpamps used: ne5532ap
followed these instructions: https://picasaweb.google.com/108309409331755720628/GSSLSuperSidechainPCB

Hi Milan,
Dont know if its important (i dont have SC boards) but if i look at your pic and at one from your link:
https://lh3.googleusercontent.com/-zkH6q-7EASY/SBI98D2eXtI/AAAAAAAAAu0/qVyGzyDyijY/s642-Ic42/PCB%252520connections.jpg
I see you have a missing connection on "SND" Pad

Greets

Gustav · Jan 31, 2016

Pusch3l said:
I see you have a missing connection on "SND" Pad

Yes, if you are on the first step of the switch, and you dont have the external SC connected, the side chain will be broken off.

Gustav

Gustav · Jan 31, 2016

tylergarcia said:
Black probe on center tap and red probe on one of the sides yields ~18v with the transformer unattached.

Gustav said:

tylergarcia said:

Thanks, Gustav. I should have specified the 12v was from the meter light wires. After re-measuring I may have the correct amount of Ac coming in but noticed that one of my 22R are burned up. Am I correct in thinking that if my 12v rails are okay but my 15v rails are reading 40v+ that there could also be a regulator issue?

Click to expand...

For the sake of easier trouble shooting, make sure to specify when you are referring to the transformer AC output (going to the board), and the rectified DC (after the bridge/in the circuit).

A burned 22R would suggest a short somewhere, a misplaced IC, too much voltage on he trafo secondaries, or faulty wiring.

If you did not place your ICs before trying to power the circuit (recommended), I would boil the first suspects down to a short, faulty wiring or too much voltage on the trafo secondaries.

The 12V rails are tapped off of the 15V rails, so if you are getting 40V on the 15V rail, I would suspect the 12V regulator would shut down, or at least get enormously hot, if you are actually getting 12V off of it.

Step 1. Disconnect the trafo from the circuit, check that the secondaries are 2 x 15V. If they are higher, come back and let us know.

Step 2. Measure the center tap to the sides without connecting the trafo to the circuit to verify its wired up correctly. Should be about 15V on each side (It varies with a load on the trafo, but you can get a ballpark figure).

Gustav

Click to expand...

Converting from AC to DC gives you a factor of about 1.4, so 18V will be around 25V. I suspect that will be a little high for filter resistors in the input. I would try jumping them (or if you have some, add a 22R in parallel), then try connecting the power and see if your regulators put out expected voltages.

Gustav

milanvdmeer17 · Jan 31, 2016

Gustav said:
Pusch3l said:

I see you have a missing connection on "SND" Pad

Click to expand...

Yes, if you are on the first step of the switch, and you dont have the external SC connected, the side chain will be broken off.

Gustav

I can just leave the sidechain signal out (snd), open right, if im not sending to an external? There is no compression for all steps of the switch.
The led isn't lighting up also. The supply voltage seems to be right.

Milan

tzman · Jan 31, 2016

Your description sounds like the GSSL is in bypass: it passes audio, but there isn't compression or makeup gain. I would triple check the wiring to/from the control board.
Also check your 12V rails on the control board and report back.

bogus · Jan 31, 2016

Hi ! After searching this thread, I decided to ask a simple question

The left output is 0.2-0.3db lower than the right. It also measures 0,2-0,3volts less between the output connectorson left than the right (TRS plugs).

I found some posts with 0,5++ db differences, but since I'm somewhat a novice in eletronics, I thougt I'd dare to ask

Gustav · Feb 1, 2016

bogus said:
Hi ! After searching this thread, I decided to ask a simple question

The left output is 0.2-0.3db lower than the right. It also measures 0,2-0,3volts less between the output connectorson left than the right (TRS plugs).

I found some posts with 0,5++ db differences, but since I'm somewhat a novice in eletronics, I thougt I'd dare to ask

And what is the question?

Gustav

milanvdmeer17 · Feb 1, 2016

tzman said:
Your description sounds like the GSSL is in bypass: it passes audio, but there isn't compression or makeup gain. I would triple check the wiring to/from the control board.
Also check your 12V rails on the control board and report back.

- 12 and 12 at both sides of the threshold pot. Make-up pot: 12v at pin 3, 1mV at pin 1. Moving the washer results in 0 to 12 v, reaching pot B input on de sidechain board. Pot A on the sc board is around 2.5mV regardless of the threshold or make-up position.

bogus · Feb 1, 2016

After asking, and reading about I ordered some 50k trimmers to exchange the 27k resistors with
Guess my post was unnecessary and without the question

Thanks tzman

Gustav said:
bogus said:

Hi ! After searching this thread, I decided to ask a simple question

The left output is 0.2-0.3db lower than the right. It also measures 0,2-0,3volts less between the output connectorson left than the right (TRS plugs).

I found some posts with 0,5++ db differences, but since I'm somewhat a novice in eletronics, I thougt I'd dare to ask

Click to expand...

And what is the question?

Gustav

cray · Feb 5, 2016

Hello guys.
first time i hear this sound / noise when switching off the unit.

audo file: http://www40.zippyshare.com/v/7tklN6Hk/file.html

the unit works perfect , but never seen this before on other units.

always i use these wimp caps :
https://www.google.es/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0ahUKEwiLusnMo-HKAhUFPxoKHUJKCIUQjRwIBw&url=http%3A%2F%2Fuk.farnell.com%2Fwima%2Fmks2c031001a00kssd%2Fcap-film-pet-100nf-63v-rad%2Fdp%2F1006030&psig=AFQjCNFQODWde-FY36OjuQlaWrTn_6KdZQ&ust=1454784197206142

this time i used :
http://i.ebayimg.com/images/i/181722375261-0-1/s-l1000.jpg

(both are 0.1uf )

but don't think thats the problem. any suggestion please?

thanks in advance.

Gustav · Feb 5, 2016

cray said:
Hello guys.
first time i hear this sound / noise when switching off the unit.

audo file: http://www40.zippyshare.com/v/7tklN6Hk/file.html

the unit works perfect , but never seen this before on other units.

always i use these wimp caps :
http://i.ebayimg.com/00/s/MTIwMFgxMjAw/z/nkoAAOSw8lBTnoCV/$_35.JPG

this time i used :
http://i.ebayimg.com/images/i/181722375261-0-1/s-l1000.jpg

(both are 0.1uf )

but don't think thats the problem. any suggestion please?

thanks in advance.

I am getting an image holder frame thing on the first and a picture of a 1.0uF Wima on the second of your links.

That sounds is awesome...

Gustav

cray · Feb 5, 2016

Gustav said:
cray said:

Hello guys.
first time i hear this sound / noise when switching off the unit.

audo file: http://www40.zippyshare.com/v/7tklN6Hk/file.html

the unit works perfect , but never seen this before on other units.

always i use these wimp caps :
http://i.ebayimg.com/00/s/MTIwMFgxMjAw/z/nkoAAOSw8lBTnoCV/$_35.JPG

this time i used :
http://i.ebayimg.com/images/i/181722375261-0-1/s-l1000.jpg

(both are 0.1uf )

but don't think thats the problem. any suggestion please?

thanks in advance.

Click to expand...

I am getting an image holder frame thing on the first and a picture of a 1.0uF Wima on the second of your links.

That sounds is awesome...

Gustav

What i meant is the wima caps on board are bigger than usually .
( but same values 0,1uf) , other times i used same wimp caps but smaller shape ,

any suggestion about that noise?

cray · Feb 5, 2016

cray said:
Gustav said:

cray said:

Hello guys.
first time i hear this sound / noise when switching off the unit.

audo file: http://www40.zippyshare.com/v/7tklN6Hk/file.html

the unit works perfect , but never seen this before on other units.

always i use these wimp caps :
http://i.ebayimg.com/00/s/MTIwMFgxMjAw/z/nkoAAOSw8lBTnoCV/$_35.JPG

this time i used :
http://i.ebayimg.com/images/i/181722375261-0-1/s-l1000.jpg

(both are 0.1uf )

but don't think thats the problem. any suggestion please?

thanks in advance.

Click to expand...

I am getting an image holder frame thing on the first and a picture of a 1.0uF Wima on the second of your links.

That sounds is awesome...

Gustav

Click to expand...

What i meant is the wima caps on board are bigger than usually .
( but same values 0,1uf) , other times i used same wimp caps but smaller shape ,

any suggestion about that noise?

OMG.
all Wima caps are 1.uf on board !!! :O

the unit works fine.. i think im lucky if nothing is burned.

seems to be ok.
newbie fault :/

tylergarcia · Feb 5, 2016

Alright, thanks to some awesome help by Gustav and others, I found out that my issue was a faulty regulator. I went ahead and replaced them all, and my voltages measured excellent at all test points on the ICs. I noticed that the meter was pointing around 16 db GR with no audio connected. Flipping bypass caused it to spike all the way to 20 db GR. Found that when turning the makeup gain pot clockwise, the meter began to fluctuate wildly and the 22R in the power section that feeds the 12v rails ( I think?) burnt. This particular resistor has burnt multiple times. I noticed that when turning the makeup pot more caused arcing inside the pot itself. I took a measurement at the 15v jumpers and now they measure 55v! Nothing changed besides turning the makeup gain pot. I know I'm likely looking for some shorted solder pads but I can't find any. Any ideas on what section I can start looking in? Thanks again everyone.

Gustav · Feb 6, 2016

tylergarcia said:
Alright, thanks to some awesome help by Gustav and others, I found out that my issue was a faulty regulator. I went ahead and replaced them all, and my voltages measured excellent at all test points on the ICs. I noticed that the meter was pointing around 16 db GR with no audio connected. Flipping bypass caused it to spike all the way to 20 db GR. Found that when turning the makeup gain pot clockwise, the meter began to fluctuate wildly and the 22R in the power section that feeds the 12v rails ( I think?) burnt. This particular resistor has burnt multiple times. I noticed that when turning the makeup pot more caused arcing inside the pot itself. I took a measurement at the 15v jumpers and now they measure 55v! Nothing changed besides turning the makeup gain pot. I know I'm likely looking for some shorted solder pads but I can't find any. Any ideas on what section I can start looking in? Thanks again everyone.

Its been a while since you posted, but you measured 18V from center tap to sides of the trafo, right?

It sounds really odd that you are getting 55V - I would not rule out a problem in the PSU section, and regulators getting hot/shutting down.

Please measure voltage on the input pins of the regulators instead of the output pins.

Also, check direction of the round bridge. (+ should be on the square solder pad).

And, of course, as you mention, check for shorts (Not seeing where the 55V would come from without a basic PSU problem, though).

Gustav

Harpo · Feb 6, 2016

tylergarcia said:
Flipping bypass caused it to spike all the way to 20 db GR. Found that when turning the makeup gain pot clockwise, the meter began to fluctuate wildly and the 22R in the power section that feeds the 12v rails ( I think?) burnt. This particular resistor has burnt multiple times. I noticed that when turning the makeup pot more caused arcing inside the pot itself.

Your bypass switch (whatever type it might be) is wired incorrect. Switch pole and throw position is exchanged in improved circuit, that would be shorting out the +12VDC rail in the pots CW position, if hookup would not be corrected.

I took a measurement at the 15v jumpers and now they measure 55v!

They won't measure 55v (and assuming 55VDC). If this number was read correctly, either your multimeters battery is low, giving you silly readouts, or you picked a wrong circuit node (probably and wrongly 'safety ground') as point of reference for your idea of "ground". (using the word "ground" without qualifier is asking for trouble as there are so many different and unrelated "grounds", like safety ground, supply ground, signal ground, shield...)

I know I'm likely looking for some shorted solder pads

Probably only bypass switch is wired incorrectly. Assume the makeup pot being damaged by now from excessive current flowing with pots wiper thru the switch wrongly tied to 0V refrence voltage and dialed towards its CW position.

earthsled · Feb 6, 2016

Hi all!
I'm a newbie to this project, so forgive me if this has been addressed before. I've searched, but I can't find an answer to my specific question(s).

I have PCB rev. #11 and schematic rev. #9. [hopefully these are the most up-to-date versions]

- The PCB clearly has places for 4x 1000uF capacitors in the PSU.

- The components list at gyraf.dk indicates "2pcs" for 1000uF caps.

- Schematic #11 has 2x 1000uF caps marked, and 2x unmarked. (?)

- An older schematic (rev. #7) shows 2x 1000uF, and 2x 100nF caps in this position.

Does the PSU circuit need a total of 4x 1000uF caps, or should it be 2x 1000uF and 2x 100nF?

Thanks for your help!

Gustav · Feb 6, 2016

earthsled said:
- The PCB clearly has places for 4x 1000uF capacitors in the PSU.

When in doubt, go with the PCB.

Gustav

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