GSSL HELP THREAD!!!

[gyraf]

You don't happen to have something electrically noisy near-by? Fluorscent light, switchmode supplies, CRT-screen stuff or such?

Can you replicate the problem in a entirely different environment?

Jakob E.

 

[alisomay]

Hey people, sorry for cutting in and probably repeating a reported issue.
I have built a gssl which works great and happy with it.
There is only one thing that i wonder, i think i saw someone else mentioned it somewhere in the forum but i can’t seem to find it now,


“When I power it up for the first time after a while, no audio passes the device and the meter stays fix at 0,2 mA. When I power it off,  the meter goes all the way down, as far as possible, and then swings back to zero. When I turn it on the second time, everything works fine and the meter goes back to zero normally when turning off.”

This is a quote from my friend who i made the compressor for.

I remember somebody mentioned this behaviour.
It doesn’t cause a problem but would you technically explain what causes this behavior and why?

Thank you very much,

 

[gyraf]

what you see is probably power supply latch-up, where one power rail comes on much before the others, preventing the others from turning on. Unproblematic, really - once it is on, it won't fail until turned off again.

but if you really want to fix it, measure your +/-15V and +/-12V to find what voltage you are missing, then replace that regulator to different type/brand. I've had the error often with "TS" brand 7915's


Jakob E.

 

[alisomay]

Thanks! It is now clear.

 

[Potato Cakes]

I've had a similar latching issue with the 78L12 and 79L12. For these I would recommend Texas Instruments or ON Semiconductor brands. I believe the ones I had issues with in the past were STMicroelectronics.

Thanks!

Paul

 

[alisomay]

I will keep that in mind thank you.

 

[weiss]

I completed an unfinished GSSL by another member with the Rev 7 boards. Voltages from the toroid power transformer are correct, +/-15V is getting through the main pcb. Audio is passing but compression doesn't seem to be present. Makeup gain control works fine, threshold doesn't. VU Meter won't zero.. I am using the Nissei TR57 (http://www.mableaudio.com/en/productview.asp?sid=6667).
Is there any errata i need to keep in mind? Components to change, jumpers to make apart from the things marked on the pcb? Can't see any info on the schematic.

There is also a SC HPF board by Steffen/Greg connected to the 47k resistor positions. Is this wiring correct?

Thank you

Ansgar

 

[Potato Cakes]

Unfortunately, you're probably going to have to return it to stock and see if you still have issues. This is the only way to know if it's something with the GSSL board or the mod. If the GSSL board if fine then you should head over to the GSSL add-on page to have the external SC card questions be better served.

Thanks!

Paul

 

[weiss]

Unfortunately, you're probably going to have to return it to stock and see if you still have issues. This is the only way to know if it's something with the GSSL board or the mod. If the GSSL board if fine then you should head over to the GSSL add-on page to have the external SC card questions be better served.

Thanks!

Paul

Thanks Paul,

I followed your advice, inserted the two 47k resistors back again and nothing changed.
The device is using 3x THAT2180LB.

This is what the 100Hz hum looks like..

 

[Potato Cakes]

Thanks Paul,

I followed your advice, inserted the two 47k resistors back again and nothing changed.
The device is using 3x THAT2180LB.

This is what the 100Hz hum looks like..

Let's start with your grounding. Remove the 0V connection from the PSU input and also from your output header. The only ground connection to the board should be at the input header. All of your XLRs Pin 1 should be tied together and then to the star ground. Which power transformer are you using? How far away from the board is it? How much of the board was built before you received it? Does this still produce the 100Hz with the compressor disengaged?

On a side note, I would recommend using an a separate PSU that has good filtering. Pretty much any board that can be found here that has +/-rails will work great. I've used them for everyone I've built and they've all been really quiet. Unless I messed up something in the build, of course.

Thanks!

Paul

 

[weiss]

Let's start with your grounding. Remove the 0V connection from the PSU input and also from your output header. The only ground connection to the board should be at the input header. All of your XLRs Pin 1 should be tied together and then to the star ground. Which power transformer are you using? How far away from the board is it? How much of the board was built before you received it? Does this still produce the 100Hz with the compressor disengaged?

On a side note, I would recommend using an a separate PSU that has good filtering. Pretty much any board that can be found here that has +/-rails will work great. I've used them for everyone I've built and they've all been really quiet. Unless I messed up something in the build, of course.

Thanks!

Paul

Appreciate your help!

1. I'm using a Talema 2x15V 1A toroidal transformer and onboard PSU. Which 0V connection has to be removed from the PSU? Had no problem with that in my earlier versions..
2. They are on the opposite side of the case, about 30cm apart.
3. It came pretty much populated only the wiring had to be done and i mounted an onboard rectifier to use the external toroid. I made the wiring and grounding.
4. Yes, 100Hz hum is always there no matter which settings used.

My bigger problem is that it's not compressing. Maybe if i find the error, the noise will solve itself..  ???

Thank you!


The 2x 2 cables from the 15V rails are each supplying the HPF board and the vu meter.

 

[Harpo]

Remove the 2nd rectifier next to the on board transformer provision. Audio-Vcas and sidechain-Vca are not oriented in the same direction. The once powered Vca with wrong orientation will be blown.

 

[weiss]

Remove the 2nd rectifier next to the on board transformer provision. Audio-Vcas and sidechain-Vca are not oriented in the same direction. The once powered Vca with wrong orientation will be blown.

oh man.. you were right. this board was printed wrong...
i replaced the VCA's and removed the rectifier, it's compressing perfectly fine now and also most of the hum is gone.
Thank you so much harpo!

There is one error left:

The release switch seems not to do anything. i mounted it directly on the board, unlike the other controls.. may it be oriented wrong?

Question: If i want the makeup to be disabled when in bypass mode, how do i have to wire the bypass toggle switch?

 

[Potato Cakes]

Since it was mostly populated and the silkscreen was printed wrong, you'll probably have to go over the solder joints and placement with a fine tooth comb and make comparisons to the original schematic to solve your release control issue. It may suck.

For the question about the makeup gain, do a search for "GSSL make up gain defeat." Near the make up gain pot connections and above the bypass switch connections (I think, it's been a while), there are two unmarked solder pads that when shorted takes the make up gain out of circuit. You'll just have to figure out how you want to accomplish this (relay, toggle switch with more poles, etc).

All the 0V/ground connections are/should be connected to one another via the copper traces, so only one connection from the board to the star ground should be made. For my GSSL builds I would use the ground connection point on the input header for this task and I would always use an off board PSU. Any one of those points would be fine I suppose, I just chose the one I did as it was generally closer to the star ground. Since the 0V connections for the power transformer is connected to all the other ground points, you can leave that off the board and tie that to the star ground as well unless there is some mystical electron property that I don't know about, which sometimes is the case. Look up Ian Thompson Bell's Grounding 101 paper that is on his site (http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/SimpleMixer/grounding101v2.pdf). I apply this to all of my builds when I can with great results in the noise floor.

Also, if someone else made the board other than Gustav you might have to also compare all the traces to the ones on Gryaf's site. There may be an connection taking place that is not supposed to be which is contributing to your noise.

Let us know when you find the culprit.

Thanks!

Paul

 

[Harpo]

There is one error left:

Opinions vary, but I can see at least 4 wrong resistor values in the VCA substitution blocks (the 3K9's current setting resistors for the +/-15V supplied VCAs would better be 5K1. The 68R's for the DBX2150 type VCAs should be removed/left out for your THAT2180 type VCAs.)

The release switch seems not to do anything. i mounted it directly on the board, unlike the other controls.. may it be oriented wrong?

You -in this order- removed the nut, the washer and the indexing ring below the nut, turned the rotary switch full CCW and put back the indexing ring to the full CW position 5 for the release switch?

 

[weiss]

Paul, Harpo,

thank you for the great advice.

Opinions vary, but I can see at least 4 wrong resistor values in the VCA substitution blocks (the 3K9's current setting resistors for the +/-15V supplied VCAs would better be 5K1. The 68R's for the DBX2150 type VCAs should be removed/left out for your THAT2180 type VCAs.)
You -in this order- removed the nut, the washer and the indexing ring below the nut, turned the rotary switch full CCW and put back the indexing ring to the full CW position 5 for the release switch?

Absolutely right, i need to change the values of the resistors.
I thought i had done that but will check it again. Might be it!

thanks again

 

[salomonander]

hey,
just finishing up my gssl with some add ons i installed. everything is fine except for one thing: my meter seems to fall past zero (further to the left) after showing heavy compression. this makes it behave very hectic. i use the cheap hairball meter - and i guess thats the issue? but if there is anything i can do to tame this - please let me know. cheers!

 

[weiss]

hey,
just finishing up my gssl with some add ons i installed. everything is fine except for one thing: my meter seems to fall past zero (further to the left) after showing heavy compression. this makes it behave very hectic. i use the cheap hairball meter - and i guess thats the issue? but if there is anything i can do to tame this - please let me know. cheers!

Which meter exactly?

 

[salomonander]

Which meter exactly?

thanks, its the 8027-B. 1mA DC. 600 ohms reistance.

 

[weiss]

Thats weird. Should actually work fine. But otherwise everything is working?