GSSL HELP THREAD!!!

[bobtheninja]

Thanks for your reply! I took off the bottom casing and took a look, comparing it to the general wire guide by Gustav, but I couldn’t see what was wrong from my wiring to his guide. This is what I have:

XLR out 1
Pin1 red
Pin 2 orange
Pin 3 yellow

XLR out 2:
Pin 1 red
Pin 2 brown
Pin 3 black

XLR in 1:
Pin 1 red
Pin 2 yellow
Pin 3 orange

XLR in 2:
Pin 1 red
Pin 2 black
Pin 3 brown

Red goes to chassis earth.

And a picture:



Is this incorrectly wired? If so that makes me very happy (and slightly embarassed). Thanks again!

 

[Gustav]

Is this incorrectly wired? If so that makes me very happy (and slightly embarassed). Thanks again!

Its impossible to tell by your description/colors. For example. the connector on the PCB can be turned 180 degrees.

Go back and check the wire guide, ignore the colors, read the markings and connections. That will probably solve your problem.

Gustav

 

[dannyc123]

Hi everyone,

I have searched this thread and read most of it in the process but I am completely at a loss as to how to even begin fixing the problems I am having! Hopefully someone might be able to help.

Have recently finished my GSSL and this forum has been a great help. It powers on and passes audio on the left channel with no compression but the makeup gain works when switched in. Doesn't even pass audio on the right channel but makes a nice scratchy sound (like a bad pot) when the makeup gain is switched in and turned. I don't know where to start!

I have checked all the voltages, swapped ICs for each channel over and nothing changes.

Any ideas on a good place to start? I would imagine that somebody has had similar problems but I've struggled to find it on this thread.

Many thanks in advance,
Danny.

 

[Olegarich]

Hi! I’m not a pro in electronics but Maybe I’ll try my best.
The scope would be handy here. Do you have one?
Well, I would start from the input. First of all I’m checking do all the opamps are not swaped? ( ones I’ve put 33 where 5534 had to be) is their orientation is good, do they get right voltages to right pins? If all is good then with scope I check if I’m getting signal on input xlr,  if all good then I move to the pcb input, then opamp in, opamp out. First I would check if sound is getting to the VCA’s. Just before 27k. If you don’t have scope, maybe you could measure with meter.  If  I remeber 0 dbu is  0.775 volts so try measure ac in input section. Don’t know if that will help

 

[dannyc123]

Hi there, thanks for your help. Unfortunately I don't have a scope, though I am getting close to buying one if it will help me work this out!

Have checked voltages just before the 27ks on both channels. Left channel is 0 regardless of signal, right channel is 7.6(?!) regardless of signal.

I'm a bit lost, I don't understand enough about circuits at this point I think.

 

[Gustav]

Hi there, thanks for your help. Unfortunately I don't have a scope, though I am getting close to buying one if it will help me work this out!

Have checked voltages just before the 27ks on both channels. Left channel is 0 regardless of signal, right channel is 7.6(?!) regardless of signal.

I'm a bit lost, I don't understand enough about circuits at this point I think.

Voltage the same on both sides of the 27K?

Gustav

 

[dannyc123]

Hi Gustav,

0 volts on both sides of the resistor on the left channel, 7.6 volts before the resistor on the right channel, 0 volts after.

I have just noticed that the value before the right channel 27k resistor increases as the circuit is powered up. It does not start at 7.6 volts but settles around there.

EDIT : I have somehow fixed this problem. Went through chasing the rogue voltage and testing/resoldering all the components between the input and that 27k resistor. Both channels are now passing audio but no compression and the makeup gain has stopped working when switched in. The meter sits at about 4dB when bypassed and jumps to 8dB when switched in. I will keep troubleshooting, appreciate the help so far!

 

[Gustav]

Hi Gustav,

0 volts on both sides of the resistor on the left channel, 7.6 volts before the resistor on the right channel, 0 volts after.

I have just noticed that the value before the right channel 27k resistor increases as the circuit is powered up. It does not start at 7.6 volts but settles around there.

EDIT : I have somehow fixed this problem. Went through chasing the rogue voltage and testing/resoldering all the components between the input and that 27k resistor. Both channels are now passing audio but no compression and the makeup gain has stopped working when switched in. The meter sits at about 4dB when bypassed and jumps to 8dB when switched in. I will keep troubleshooting, appreciate the help so far!

I wanted to see if I could deduce which side the short was on.

It sounds like you have general problems with shorted out and/or cold solder joints.

May also have a problem with the wiring of the bypass switch, or a missing jumper/SC switch on the main bord SCHP connection (3 pin connection)

Could you post a picture of the board - solder side?

Gustav

 

[dannyc123]

Thanks for the reply. I have attached photos of both the underside of the main board and the bypass switch.

I keep seeing the SC switch thing popping up so have checked that and have a switched cap in its place.

I have also attached a picture of the bypass switch just to be sure.

https://www.dropbox.com/sh/9qp15tcz7a03k50/AACGlqQkeViDtuVwo9Pgav3Fa?dl=0

I currently have signal passing on both channels and makeup gain effecting both equally when the compression circuit is switched in, but no compression etc. The meter needle seems to have stopped misbehaving also.

 

[Gustav]

Thanks for the reply. I have attached photos of both the underside of the main board and the bypass switch.

I keep seeing the SC switch thing popping up so have checked that and have a switched cap in its place.

I have also attached a picture of the bypass switch just to be sure.

https://www.dropbox.com/sh/9qp15tcz7a03k50/AACGlqQkeViDtuVwo9Pgav3Fa?dl=0

I currently have signal passing on both channels and makeup gain effecting both equally when the compression circuit is switched in, but no compression etc. The meter needle seems to have stopped misbehaving also.

Soldering looks ok - some joints I would definitely go over, but seems "ok", and certainly not a bloody mess. (Theres one joint I would do before proceeding - one side of the AC input seems like trouble)

Up some more pics, backside of the control board etc.

The SC is split off from the audio path and summed, and the pots are responsible for control voltages sent to the VCAs. Sounds like the main path/VCAs are fine, and your side chain has some issues. Since they have come and gone on the make-up, I would look at the soldering, but as they are now gone, and completely gone on the meter as well, I would also look at the 12V supplies, the control board,  and the area around the TL074 carefully.

Gustav

 

[dannyc123]

Thanks Gustav.

I will spend this evening going over all of the solder joints that look anything other than perfect. I will also focus some more attention on the control board but so far all of the testing I have done there has seemed to be working as expected, altering voltages at the ICs etc. I will focus on all the components around the SC first.

I have uploaded pictures of the tops of both boards and the bottom of the control board also so if you could spot anything there that would be great.

I really appreciate your help, it feels a lot easier trying to fix this when you have someone else's eyes looking at what could be up too!

EDIT : The resistor before pin5 on the SC 2180 is marked on the schematic as a 3K9 and on the board as a 5K1. I have looked through this thread and this doesn't seem to have been addressed directly (though it has been mentioned a few times, or maybe my ability to search is deteriorating!). It is clear from a lot of peoples responses that this should indeed be a 3K9. Could this be the problem as I have a 5K1 in there, as per the markings on the PCB?

 

[Olegarich]

5K1 resistor there is OK, It should be 5K1 if you're using THAT2180 VCA

 

[dannyc123]

5K1 resistor there is OK, It should be 5K1 if you're using THAT2180 VCA

Okay thanks, just wanted to check as the schematic says 3k9! Back to it!

 

[Olegarich]

There will be some more resistors on schematics but not on board, don't worry that's ok. It because of different VCA.

 

[bobtheninja]

Its impossible to tell by your description/colors. For example. the connector on the PCB can be turned 180 degrees.

Go back and check the wire guide, ignore the colors, read the markings and connections. That will probably solve your problem.

Gustav

So, it turned out that I am indeed stupid and had swapped the opamps between the VCA stage and the output stage. So the moral of this whole thing is: use your head and eyes and don't make assumptions just because the four identical opamps looked good in a line from top to bottom on the pcb. Thanks for an amazing kit and an amazing compressor. Will start mixing my second record through the GSSL immediately after posting this. Excited!

 

[dannyc123]

Turns out I had a tiny solder bridge that was giving me continuity in the circuit after the sidechain vca. All I needed was to come back to it with some fresh eyes!

Many thanks to everyone who pointed me in the right direction and helped me rule out everything it wasn't so that I could find it. It's a great community here and I'm happy to finally not just be a lurker

Looking forward to getting it plugged in in the studio in the next few days and running it through its paces!

 

[Miguel Cohen]

Hi, I'm having a problem where my "power on" led shuts down  when the make up gain pot is turned all the way to zero make up. The moment I turn it approx. 20 degrees CW, the led  slowly lights up again.
Test points show that the -12v goes away to the whole board, so if you could help me that would be great.

Thank you

 

[gyraf]

Short of pot center to ground? Maybe at the connecting wires between the psb's?

Jakob E.

 

[Miguel Cohen]

Short of pot center to ground? Maybe at the connecting wires between the psb's?

Jakob E.

Jesus! How do you do that? I'm gonna try that right now and post the results, but it seems like the only problem I might have. 

 

[Miguel Cohen]

Jesus! How do you do that? I'm gonna try that right now and post the results, but it seems like the only problem I might have. 

Well that did it, now I have another problem where the middle leg of the 7915 (neg voltage regulator) is at -30V and the left leg is at the correct -15V...