GSSL HELP THREAD!!!

[Script]

What reading do you get when measuring across the individual pins of the makeup gain pot ? Especially from pot wiper pin. You should get between 0VDC to 12VDC when rotating the knob. And this same DC voltage should go directly thru your switch to the 620K. (--Could also check for connectivity with beeper--).

If it DOES show across the pot pins but NOT at the 620K resistor, your bypass switching is wrong.

If it DOES show across pot wiper pin to other pot pin but does NOT show between pot wiper pin and chassis ground, you are missing the connection between signal ground and chassis ground.

And if it does NOT show across the pot pins, your pot either doesn't connect properly to 12VDC and/or GND, or the unit is not switched on, or you are measuring wrong.

(I never implemented the bypass there. I hardwired that connection to constantly "in". I think switching there is a useless feature. Instead I use relays for hard bypassing the unit )

 

[atticus1872]

What reading do you get when measuring across the individual pins of the makeup gain pot ? Especially from pot wiper pin. You should get between 0VDC to 12VDC when rotating the knob. And this same DC voltage should go directly thru your switch to the 620K. (--Could also check for connectivity with beeper--).

If it DOES show across the pot pins but NOT at the 620K resistor, your bypass switching is wrong.

If it DOES show across pot wiper pin to other pot pin but does NOT show between pot wiper pin and chassis ground, you are missing the connection between signal ground and chassis ground.

And if it does NOT show across the pot pins, your pot either doesn't connect properly to 12VDC and/or GND, or the unit is not switched on, or you are measuring wrong.

(I never implemented the bypass there. I hardwired that connection to constantly "in". I think switching there is a useless feature. Instead I use relays for hard bypassing the unit )

Going from wiper to ground I get .007-.068 same measurement at 620K resistor. I checked resistance and I get a beep with a reading of 1.30 ohms from the wiper to the pot and .15 ohms from the wiper resistor 620K but only when turned all the way CCW or CW when I turn it to the middle the meter goes to OL it’s the same on the threshold though which is odd to me. I checked between pot wiper pin and chassis ground and it goes OL so like you said I’m missing a connection between signal ground and chassis ground.

Like you said though Relays would be a great way to bypass the unit wish I had thought of that myself.

Any recommendations on where to look now for the open between signal ground and chassis ground?

 

[atticus1872]

What reading do you get when measuring across the individual pins of the makeup gain pot ? Especially from pot wiper pin. You should get between 0VDC to 12VDC when rotating the knob. And this same DC voltage should go directly thru your switch to the 620K. (--Could also check for connectivity with beeper--).

If it DOES show across the pot pins but NOT at the 620K resistor, your bypass switching is wrong.

If it DOES show across pot wiper pin to other pot pin but does NOT show between pot wiper pin and chassis ground, you are missing the connection between signal ground and chassis ground.

And if it does NOT show across the pot pins, your pot either doesn't connect properly to 12VDC and/or GND, or the unit is not switched on, or you are measuring wrong.

(I never implemented the bypass there. I hardwired that connection to constantly "in". I think switching there is a useless feature. Instead I use relays for hard bypassing the unit )

Any recommendations on where to check for wiper to chassis ground? I believe that’s my issue at this point.

 

[Script]

The middle pin of the 5-pin input/output header is easy-to-reach signal ground.

 

[cluelessbloke]

Hi there, I am maybe 30% through my GSSL build and all has gone well so far, however I have a question about the bridge rectifier component. The one I purchased seems to be overkill for this project as well as the fact I don't know if it is the correct type as in the component list is states a "round" bridge rectifier is required. I have had a trawl through the forum and surprisingly found very little about rectifier sourcing.

https://www.mouser.co.uk/ProductDet...StlT9s1MErw==&countryCode=GB&currencyCode=GBP
This is the one I have at the moment, yes I know its overkill but will it work? Or is it not the correct type?

Thanks!

 

[gyraf]

it's overkill at 8Amp, where a ½Amp would do fine. But will work, providing there's room for it and it fits PCB holes..

The intended one is like https://www.mouser.co.uk/ProductDet...ductor/W10G-E4-51?qs=D6r9GjgEnNMZn/TpjmZOHQ==

/Jakob E.

 

[cluelessbloke]

it's overkill at 8Amp, where a ½Amp would do fine. But will work, providing there's room for it and it fits PCB holes..

The intended one is like https://www.mouser.co.uk/ProductDet...ductor/W10G-E4-51?qs=D6r9GjgEnNMZn/TpjmZOHQ==

/Jakob E.

Thanks for your response! I really appreciate the time everyone here puts in to helping randoms on the internet

Just to add for anyone here for future reference, the component i got does fit, it’s just a little too big but can fit fine albeit slightly higher above the PCB than normal.

 

[morob]

I just finished building the GSSL now, with THAT 2159 VCAs. I'm getting sound through, but I'm not hearing any compression effects what so ever. The only knob that seems to have any sort of effect is the gain knob. The threshold pot, and ratio, attack and release rotary switches seems to do nothing to the sound at all. I have not put any trimmer resistors in the circuit yet. I'm unsure if the 2159s are trimless (pre-trimmed) or if I need trimmers. I think it might need trimmers since the datasheet of the 2159s shows a 50k trim resistor to through a 150k resistor to pin 4. And a 51 ohm resistor between pin 4 and 2. But looking at this schematic and component placement guide, there seems to be no resistors of those values anywhere in the circuit. Can someone confirm that the % symbols are trim resistors? If that's the case, then there seems to be 4 different places for trim resistors in the vicinity of each of the main VCAs. When the trimmers are left out, should I still be hearing some effects of the compression, or could the lack of trimmers be the reason why I'm not hearing any compression at all? I'm having a hard time finding any information about doing this build with the 2159s, but pcbgrinder is currently selling these along with the PCBs.

 

[Script]

Search function is amazing !

Found this when searching for "THAT2159":

https://groupdiy.com/threads/that-vca-high-2nd-order-distortion.72442/#post-917856
According to that post, and that unit, might not need the trimmer (there is only one per VCA) but benefits from it when implemented just like a 2181. And if even the datasheet says so...

Ergo, something else is wrong in your build

 

[Script]

On how to implement different VCAs, could look here:

https://groupdiy.com/threads/gssl-help-thread.47/post-1029346

 

[atticus1872]

The middle pin of the 5-pin input/output header is easy-to-reach signal ground.

I’ve got continuity going from the output to signal ground but not on the input going to signal ground. Which is odd considering I wired it up per the instructions with the middle input pin going to the two inputs then the two outputs. It said to cut the middle pin wire from the output and not use them.

 

[Ricardus]

I just finished building the GSSL now, with THAT 2159 VCAs. I'm getting sound through, but I'm not hearing any compression effects what so ever. The only knob that seems to have any sort of effect is the gain knob. The threshold pot, and ratio, attack and release rotary switches seems to do nothing to the sound at all. I have not put any trimmer resistors in the circuit yet. I'm unsure if the 2159s are trimless (pre-trimmed) or if I need trimmers. I think it might need trimmers since the datasheet of the 2159s shows a 50k trim resistor to through a 150k resistor to pin 4. And a 51 ohm resistor between pin 4 and 2. But looking at this schematic and component placement guide, there seems to be no resistors of those values anywhere in the circuit. Can someone confirm that the % symbols are trim resistors? If that's the case, then there seems to be 4 different places for trim resistors in the vicinity of each of the main VCAs. When the trimmers are left out, should I still be hearing some effects of the compression, or could the lack of trimmers be the reason why I'm not hearing any compression at all? I'm having a hard time finding any information about doing this build with the 2159s, but pcbgrinder is currently selling these along with the PCBs.

Have you tried it with 2180s just to see if it will work? It might be worth it.

 

[Script]

I’ve got

Err...

Middle pin on 5-pin header is 'signal ground' and good as reference (black probe) to measure DC on your makeup pot.

If signal ground is not connected to chassis (at one point, and one point only), then chassis does not work as a reference for measuring anything. Either way, it does not explain a non-working makeup pot, nor a non-working bypass switch.

And I assume you checked your bypass switch with beeper for correct connectivity (i.e., from 'source' [component] to 'destination' [component]). in both ON and OFF positions by now as per schematics.

 

[morob]

Search function is amazing !

Not exactly a GSSL build, so I've missed that in the search. I have been searching the compiled GSSL help thread
Darn it. I will have to go through this thing in the weekend then. Might order some pretrimmed 2180As anyways, since people seem to really like those

 

[morob]

Thanks for the replies guys. Back to the soldering station and oscilloscope then

 

[atticus1872]

Err...

Middle pin on 5-pin header is 'signal ground' and good as reference (black probe) to measure DC on your makeup pot.

If signal ground is not connected to chassis (at one point, and one point only), then chassis does not work as a reference for measuring anything. Either way, it does not explain a non-working makeup pot, nor a non-working bypass switch.

And I assume you checked your bypass switch with beeper for correct connectivity (i.e., from 'source' [component] to 'destination' [component]). in both ON and OFF positions by now as per schematics.

Thats correct I've checked the bypass switch for correct connectivity and everything there is working correctly!

 

[Harpo]

Thats correct I've checked the bypass switch for correct connectivity and everything there is working correctly!

The hookup of your bypass switch from your post#8660 differs from schematic. It has wire connections "E" and pot-wiper exchanged for optimized performance (see thread "Improve your GSSL... for free!"). From your pics, you seem to have a super-sidechain-board within your build, that differs in this respect. If so and you have hooked up both in parallel, they are shorting out each other. Your check starts with all (+15VDC, -15VDC, +12VDC, -12VDC, maybe additional aux+12VDC, all in respect to 0V reference voltage) supply rails working. From your measurements, one or both of the +/-12VDC rails might be failing because of prementioned conflicting hookup.

 

[atticus1872]

The hookup of your bypass switch from your post#8660 differs from schematic. It has wire connections "E" and pot-wiper exchanged for optimized performance (see thread "Improve your GSSL... for free!"). From your pics, you seem to have a super-sidechain-board within your build, that differs in this respect. If so and you have hooked up both in parallel, they are shorting out each other. Your check starts with all (+15VDC, -15VDC, +12VDC, -12VDC, maybe additional aux-12VDC, all in respect to 0V reference voltage) supply rails working. From your measurements, one or both of the +/-12VDC rails might be failing because of prementioned conflicting hookup.

That makes perfect sense. So checking the board I've got 0V on both +15VDC and -15VDC Sorry to sound ignorant but where do I check the +/- 12VDC rails?

 

[Harpo]

That makes perfect sense. So checking the board I've got 0V on both +15VDC and -15VDC Sorry to sound ignorant but where do I check the +/- 12VDC rails?

Having your gssl switched to On and a not blown fuse in between, you could measure your local AC mains voltage arriving in between the mains transformer primary winding ends. Nada, replace broken fuse and/or switch the unit to On. Now switch your multimeter for measuring DC voltage, have your black wire probe plugged into the meters Com-terminal and probe tip to a 0V spot on pcb. Measure FI for +15V at NE5534-pin 7, for - 15V at NE5534-pin 4, for +12V at TL072-pin 8 and - 12V at TL072-pin 4.

 

[atticus1872]

Having your gssl switched to On and a not blown fuse in between, you could measure your local AC mains voltage arriving in between the mains transformer primary winding ends. Nada, replace broken fuse and/or switch the unit to On. Now switch your multimeter for measuring DC voltage, have your black wire probe plugged into the meters Com-terminal and probe tip to a 0V spot on pcb. Measure FI for +15V at NE5534-pin 7, for - 15V at NE5534-pin 4, for +12V at TL072-pin 8 and - 12V at TL072-pin 4.

So I measured FI for +15V at NE5534 Pin 7 and I'v got -.013V at pin 4 I've got -14.99V Checking TL072 at pin 8 I've got 12.14V and at pin 4 I've got -12.03V