GSSL add-on help thread

[weiss]

Here is a video of my problem. The compressor reacts weird:

http://sendvid.com/8tmy9378

 

[Potato Cakes]

I can see you that your return from your board is going to the wrong 47k pad. It should be returning back to the one that is closer to the sidechain section. Are you also getting the proper VDC to your SC board?

Thanks!

Paul

 

[weiss]

I can see you that your return from your board is going to the wrong 47k pad. It should be returning back to the one that is closer to the sidechain section. Are you also getting the proper VDC to your SC board?

Thanks!

Paul

Thank you!
I think the pads from the resistors are bridged.. Either was I tried it both ways as I found two different wiring guides but none of them works. voltages are spot on.

 

[Potato Cakes]

If the schematics from the old and new GSSL boards are mostly the same then that is correct regarding the 47k. The thing that makes troubleshooting as a third party difficult is that I don't know how many people are familiar with this particular SC board you are using. If the circuit is indeed without problems then there has to be a build error involved somewhere provided you do indeed have a working GSSL without the mod board. You may have to contact the designer directly.

In the meantime, since you aren't using a thrust type circuit and just putting a HPF on the side chain, you should be able to do this passively as that is how it is done on the newer GSSL boards. You would have to look at the current schematic to see where the capacitor for the HPF is connected and just insert a switch with the caps you want to use. I believe you can passively add the external sidechain source as well with the appropriate resistors/caps in line.

Thanks!

Paul

 

[weiss]

If the schematics from the old and new GSSL boards are mostly the same then that is correct regarding the 47k. The thing that makes troubleshooting as a third party difficult is that I don't know how many people are familiar with this particular SC board you are using. If the circuit is indeed without problems then there has to be a build error involved somewhere provided you do indeed have a working GSSL without the mod board. You may have to contact the designer directly.

In the meantime, since you aren't using a thrust type circuit and just putting a HPF on the side chain, you should be able to do this passively as that is how it is done on the newer GSSL boards. You would have to look at the current schematic to see where the capacitor for the HPF is connected and just insert a switch with the caps you want to use. I believe you can passively add the external sidechain source as well with the appropriate resistors/caps in line.

Thanks!

Paul

i contacted steffen but waiting for reply. although like you said i am not sure if the board is the problem. I am replacing it with a super sidechain board now to see if the problem remains...

thank you

 

[Olegarich]

Hey! Don't know if you solved it already, but i had absolutely same problem. Same acting of meter, absolutely same.

In my case problem was in turbo mode board.  Just a bad connection, i started moving cables and found that problem dissapears sometimes, so i resoldered these connections and made new cables to connect and problem was gone.
Sometimes i think it's better to solder in those cables when you checked and all working fine. Had this issue in two gssl with turbo mode.

 

[weiss]

Hey! Don't know if you solved it already, but i had absolutely same problem. Same acting of meter, absolutely same.

In my case problem was in turbo mode board.  Just a bad connection, i started moving cables and found that problem dissapears sometimes, so i resoldered these connections and made new cables to connect and problem was gone.
Sometimes i think it's better to solder in those cables when you checked and all working fine. Had this issue in two gssl with turbo mode.

oh, thanks for the explanation!
i replaced the board by a super SC board and everything turned out to work fine. no idea what the problem was in the end.. 

 

[aaronmcphee]

Hey Matt. Did you ever get an answer to your question?  I am in a similar pickle and I suspect its a wiring issue.
I have added the two SSC boards and the Turbo using the Don Audio wiring diagram above but absolutely nothing, no compression and no functioning ratio/Attack/Release...only makeup working.  Hope you had more success?

Hi Everyone,

I'm trying to figure out how to properly wire up a few things on my GSSL/Turbo/2 Super Sidechain project.

My question is whether or not I need to connect both Super Sidechain boards "Com/On/Off/Pot A/PotB" connections to the back of the control board or if I can just connect the left SSC board connections and leave the right SSC ("Com/On/Off/Pot A/PotB") disconnected?

Also wondering if I use the "In SW "to" and Ret" and LED connections on just the left side SSC board to connect to my "Compression" on/off front panel illuminated switch or do I take it from the control panel and leave these disconnected?

I know a lot of this has been discussed but I haven't found any definitive way of wiring these connections and I'm a bit confused (clearly...

My front panel has 2 illuminated switches. TURBO and COMPRESSOR. Each has a DPDT switch and LED "+ and -". I'm trying to wrap my head around wiring them up with all the boards. Any help would be greatly appreciated.

Thanks!
Matt

I'm basing my wiring on these:

 

[Gustav]

Hey Matt. Did you ever get an answer to your question?  I am in a similar pickle and I suspect its a wiring issue.
I have added the two SSC boards and the Turbo using the Don Audio wiring diagram above but absolutely nothing, no compression and no functioning ratio/Attack/Release...only makeup working.  Hope you had more success?

Did it work before adding the mods?

Gustav

 

[aaronmcphee]

Hi Y'all.
I trawled through several threads but could not find an answer to this one.

I recently built and installed the Turbo PCB from Expat Audio following their very clear and easy to follow manual (Thanks Expat team), however what I am finding when I power up the GSSL and feed audio through it, I get no VU activity and no front panel functionality with the exception of the makeup gain. EXCEPT when I unplug the Ratio header from the Turbo PCB, then my GSSL comes to life and behaves as a regular GSSL.

I have checked all my wiring and all checks out as per the Expat install manual, I have checked the Turbo PCB for shorts, traces and any bad joints but all is clean and looks good. I also checked component orientation but again all looks good. (Image link https://ibb.co/XxtJ3dr) I did plan on making the Turbo switchable but for now the "S/C Input" is just soldered to the lifted leg on the 47k on the GSSL PCB.  The VCA is a 2180c and the op amp is TL0748CN, the manual doesn't specify any suffix for this so I'm assuming a CN is fine?

The only cockup I made to was to order a top mounting DIL socket for the VCA but it soldered perfectly fine from the top side and the solder has fed through to the underside no problem (I checked for continuity) .

So I'm not sure where to proceed, I am hoping somebody has encountered this and found a fix...but any help would be gratefully received.

 

[Harpo]

...EXCEPT when I unplug the Ratio header from the Turbo PCB, then my GSSL comes to life and behaves as a regular GSSL.

and the other end of your ratio wires connect to the unused switch terminals (pole C, throw 7,8,9) of the ratio switch on control pcb ?

Else every fix starts with the check of supply voltages. All 5 supply rails (+15VDC, -15VDC, +12VDC, -12VDC and aux +12VDC, all in respect to 0V reference voltage) operating ? ...and with turbo ratio header connected ?

 

[aaronmcphee]

Hi Harpo.

Yes the wires from the turbo board ratio header were connected to the corresponding pins on the control PCB in the correct order, this was one of the first things I checked, as I mentioned the header being connected was in fact the issue, it was once I disconnected the header that I got any compression.

However the plot deepens, turns out the Turbo board was the only thing giving me compression (albeit without the ration), I removed the turbo and put the GSSL back to stock.... Nada!!,  my on-board side-chain seems to have taken a long vacation.

I fitted a new 47k in case that had gone but still nothing, double checked continuity/connections on all headers and switches etc but all seems to be in order, and just to rub salt into my already gaping wound my multi-meter started playing sill buggers so I've had to order a new one....some tedious fault finding awaits...sigh :-(

 

[aaronmcphee]

and the other end of your ratio wires connect to the unused switch terminals (pole C, throw 7,8,9) of the ratio switch on control pcb ?

Else every fix starts with the check of supply voltages. All 5 supply rails (+15VDC, -15VDC, +12VDC, -12VDC and aux +12VDC, all in respect to 0V reference voltage) operating ? ...and with turbo ratio header connected ?

Hi Harpo.

Got my new meter and set to work taking readings, I know there several posts of others posting their results but there seems to be quite some variation so I hope you don't mind but I have posted my results below (god you must be sick of seeing these!)

If you would be so kind as to run your expert eyes over them I would appreciate it, the only voltages that seem to conflict with others I have seen on this form are the input NE5534's and output NE5532's, the rest seem ok...sorry I have put every pin but I just wanted to be belt and braces. I have just put 0 for any pins that read very negligible voltages.

Trafo: 18v 18v 36v (As expected)

Input 5534 (1)
Pins
1 =12.72v
2=0v
3=0v
4=15v
5=0v
6=0v
7=15v
8=-12.75V

Input 5534 (2)
1=-12.7v
2=0v
3=0v
4=15v
5=0v
6=0v
7=-15v
8=-12.67v

Output NE5532 (1)

1=0
2=0v
3=0v
4=-15.14
5=0v
6=0v
7=0v
8=15.23v

Output NE5532 (2)
1=0v
2=0v
3=0v
4=-15.15v
5=0v
6=0v
7=0v
8=15.23v

VCA Right
NE5534
1=2.66v
2=0v
3=0v
4=-15.41v
5=0v
6=0v
7=15.24v
8=12.62v

THAT1280 Right
1=0v
2=0v
3=0v
4 (Lifted)
5=-2.90v
6=0v
7=15.24v
8=0v

VCA Left
NE5534
1=12.6v
2=0v
3=0v
4=15.4v
5=0v
6=0v
7=15.23v
8=12.64v

THAT1280:
1=0v
2=0v
3=0v
4 (Lifted)
5=2.86v
6=0v
7=15.23
8=0v

Sidechain VCA
1=0v
2=0v
3=0v
4 (Lifted)
5=2.90v
6=0v
7=12v
8=0v

TL072
1=3.02v
2=0v
3=0v
4=2.08v
5=0v
6=0v
7=1.84v
8=11.96v

7915 in=23.7v/Out=15.17v

7812 In=23v/Out15.4v

7815 In=23.8v/Out=12.2

Many thanks for any feedback you can offer.

 

[Harpo]

....
7915 in=23.7v/Out=15.17v

7812 In=23v/Out15.4v

7815 In=23.8v/Out=12.2

As already said, "Else every fix starts with the check of supply voltages. All 5 supply rails (+15VDC, -15VDC, +12VDC, -12VDC and aux +12VDC, all in respect to 0V reference voltage) operating ?"
For any more meaningful advice, please be more correct with part numbers and signs matter.
A 7915 type voltage regulator is for a -15VDC negative supply rail. Your measured result reads a positive number.
A 7812 type voltage regulator is for a +12VDC positive auxiliary supply rail. Your measured result reads a positive number expected for a 7815 type Vreg.
A 7815 type voltage regulator is for a +15VDC positive supply rail. Your measured result reads a positive number expected for a 7812 or 78L12 type Vreg.
Supply rail voltages from 78L12 and 79L12 Vregs are missing. From your TL072 measurement, at least the -12VDC rail is faulty (your pin 4 measurement was +2,08VDC).

 

[aaronmcphee]

As already said, "Else every fix starts with the check of supply voltages. All 5 supply rails (+15VDC, -15VDC, +12VDC, -12VDC and aux +12VDC, all in respect to 0V reference voltage) operating ?"
For any more meaningful advice, please be more correct with part numbers and signs matter.
A 7915 type voltage regulator is for a -15VDC negative supply rail. Your measured result reads a positive number.
A 7812 type voltage regulator is for a +12VDC positive auxiliary supply rail. Your measured result reads a positive number expected for a 7815 type Vreg.
A 7815 type voltage regulator is for a +15VDC positive supply rail. Your measured result reads a positive number expected for a 7812 or 78L12 type Vreg.
Supply rail voltages from 78L12 and 79L12 Vregs are missing. From your TL072 measurement, at least the -12VDC rail is faulty (your pin 4 measurement was +2,08VDC).

Thanks for replying so quickly Harpo.

Yeah well spotted, I transposed the 7812 and 7815 voltages when typing.

The 7915 does indeed read -15v and the TL075 does have -12v at pin 4...another typo!

Well I was hoping there would be a genuine ambiguous reading but all seems to be ok as far as voltages go, im gonna try replacing the .01uf cap on the Sidechain switch, see if that could be duff?

 

[Harpo]

...and the TL075 does have -12v at pin 4...

Typo again, or you have a problem when using this existend but different pinout quad opamp instead of a TL074.

 

[aaronmcphee]

Typo again, or you have a problem when using this existend but different pinout quad opamp instead of a TL074.

OMG! I need to go back to school I think...or get Grammarly which fixes everything apparently

Yes Typo.

Thanks.

 

[aaronmcphee]

Hi Harpo.

Yes the wires from the turbo board ratio header were connected to the corresponding pins on the control PCB in the correct order, this was one of the first things I checked, as I mentioned the header being connected was in fact the issue, it was once I disconnected the header that I got any compression.

However the plot deepens, turns out the Turbo board was the only thing giving me compression (albeit without the ration), I removed the turbo and put the GSSL back to stock.... Nada!!,  my on-board side-chain seems to have taken a long vacation.

I fitted a new 47k in case that had gone but still nothing, double checked continuity/connections on all headers and switches etc but all seems to be in order, and just to rub salt into my already gaping wound my multi-meter started playing sill buggers so I've had to order a new one....some tedious fault finding awaits...sigh :-(

Hi Harpo.

Yes the wires from the turbo board ratio header were connected to the corresponding pins on the control PCB in the correct order, this was one of the first things I checked, as I mentioned the header being connected was in fact the issue, it was once I disconnected the header that I got any compression.

However the plot deepens, turns out the Turbo board was the only thing giving me compression (albeit without the ration), I removed the turbo and put the GSSL back to stock.... Nada!!,  my on-board side-chain seems to have taken a long vacation.

I fitted a new 47k in case that had gone but still nothing, double checked continuity/connections on all headers and switches etc but all seems to be in order, and just to rub salt into my already gaping wound my multi-meter started playing sill buggers so I've had to order a new one....some tedious fault finding awaits...sigh :-(

Hey Harpo....or anybody that might know what this issue is!

Ok so as mentioned above I attached my newly built turbo board and got no compression except when I removed the ratio header from the turbo board, then after removing the turbo and putting the GSSL to standard build, I found my GSSL wasn't compressing anymore!! :-(

So after checking all voltages as Harpo suggested I found all were reading as they should be (with acceptable tolerances) So all I could think to do was start changing out all of the IC's...and BINGO! my sidechain TL074 was dead. So I replaced it with the one from the Turbo board and my GSSL lived again.

Not being deterred I ordered a few spare TL074's and tried again with the turbo board, this time I decided to take one baby step at a time.

Connected only the +12/0v/-12v to the main PCB and powered up....no issues and compressor still worked as standard.

Next connected the ratio header to the corresponding pins on the control board ration switch...no change and compressor still worked as standard.

Now with the "Signal connector" header I decided to try one pin at a time, connected "Point C" to the mainboard and powered up....VU Meter slammed hard right and I go no audio pass through and no front panel switches did anything.

So thinking that perhaps this might be a side effect of not having connected the  other two pins, I then connected the "S/C C.V" & S/C input headers. And now I'm back to square one again....no compression and no functioning dials (except makeup)

I have check the Turbo PCB thoroughly with my meter and found no shorts, continuity tested underside pads to make sure they were getting to the topside where applicable, checked all tracks for continuity where applicable, checked continuity between the flying leads from the headers and the corresponding underside pads, checked component orientation etc.

Now the only thing I'm not sure is which critical voltages I should check for on the Turbo PCB? perhaps this would be the next place tom start?

I also wondered if it matters that I am using THAT2180c's on my mainboard? I know there resistor changes depending if you use 2181/2150/2180, but I don't think that applies to my build as I am using rev12.

My front panel switches are still wired as the standard GSSL build (see attached|) and I have left the External sidechain header connected to the mainboard (Nothing on the Turbo manual suggests I should remove or bridge this), and I have left the bypass pads bridged on the control PCB.

I would be grateful if anybody has nay further suggestions as to what else I might try?

Aaron.

 

[aaronmcphee]

Hey Harpo....or anybody that might know what this issue is!

Ok so as mentioned above I attached my newly built turbo board and got no compression except when I removed the ratio header from the turbo board, then after removing the turbo and putting the GSSL to standard build, I found my GSSL wasn't compressing anymore!! :-(

So after checking all voltages as Harpo suggested I found all were reading as they should be (with acceptable tolerances) So all I could think to do was start changing out all of the IC's...and BINGO! my sidechain TL074 was dead. So I replaced it with the one from the Turbo board and my GSSL lived again.

Not being deterred I ordered a few spare TL074's and tried again with the turbo board, this time I decided to take one baby step at a time.

Connected only the +12/0v/-12v to the main PCB and powered up....no issues and compressor still worked as standard.

Next connected the ratio header to the corresponding pins on the control board ration switch...no change and compressor still worked as standard.

Now with the "Signal connector" header I decided to try one pin at a time, connected "Point C" to the mainboard and powered up....VU Meter slammed hard right and I go no audio pass through and no front panel switches did anything.

So thinking that perhaps this might be a side effect of not having connected the  other two pins, I then connected the "S/C C.V" & S/C input headers. And now I'm back to square one again....no compression and no functioning dials (except makeup)

I have check the Turbo PCB thoroughly with my meter and found no shorts, continuity tested underside pads to make sure they were getting to the topside where applicable, checked all tracks for continuity where applicable, checked continuity between the flying leads from the headers and the corresponding underside pads, checked component orientation etc.

Now the only thing I'm not sure is which critical voltages I should check for on the Turbo PCB? perhaps this would be the next place tom start?

I also wondered if it matters that I am using THAT2180c's on my mainboard? I know there resistor changes depending if you use 2181/2150/2180, but I don't think that applies to my build as I am using rev12.

My front panel switches are still wired as the standard GSSL build (see attached|) and I have left the External sidechain header connected to the mainboard (Nothing on the Turbo manual suggests I should remove or bridge this), and I have left the bypass pads bridged on the control PCB.

I would be grateful if anybody has nay further suggestions as to what else I might try?

Aaron.

GOOD NEWS, well sort of!

After trying a few things I found that the Turbo board works as long as I do not connect the 10:1 ratio wire to the ratio switch, 2:1 and 4:1 work and I get great compression.

Thinking this might be a short or a bad solder joint on the Control PCB I checked everything,  but nothing revealed itself, so I double checked I had set the locking ring to the correct amount of clicks on the rotary switch and that seems fine (Start fully CCW  and count 2 clicks CW, then set ring until it cannot turn CW beyond that point??) I would appreciate at it is somebody can confirm is this is correct?? (all rotary's are the Lorlin type and I have set the attack and release this way and they are functioning fine)

So my only other thought  is, I either have a faulty rotary, or some aspect of the Turbo board that controls the 10:1 ratio is faulty, I have again checked the Turbo PCB but cannot find anything obvious......had anybody experienced something similar? what might be the best starting place to fault find this?

Thanks in advance.

 

[aaronmcphee]

GOOD NEWS, well sort of!

After trying a few things I found that the Turbo board works as long as I do not connect the 10:1 ratio wire to the ratio switch, 2:1 and 4:1 work and I get great compression.

Thinking this might be a short or a bad solder joint on the Control PCB I checked everything,  but nothing revealed itself, so I double checked I had set the locking ring to the correct amount of clicks on the rotary switch and that seems fine (Start fully CCW  and count 2 clicks CW, then set ring until it cannot turn CW beyond that point??) I would appreciate at it is somebody can confirm is this is correct?? (all rotary's are the Lorlin type and I have set the attack and release this way and they are functioning fine)

So my only other thought  is, I either have a faulty rotary, or some aspect of the Turbo board that controls the 10:1 ratio is faulty, I have again checked the Turbo PCB but cannot find anything obvious......had anybody experienced something similar? what might be the best starting place to fault find this?

Thanks in advance.

Ok so l got to the bottom of my problem, and i had bugger all to do with the operation of the Turbo PCB....It was me...or to be more specific "The stupid balanced signal I have been feeding my GSSL from my mobile phone all this time" FACE PALM!!

Since my soldering/projects desk is some distance from my computer...and Cubase, I was playing audio from my mobile via a small Stereo jack going to two large jacks...just for convenience. so I decide to check my meter calibration whilst I was fault finding the turbo issue, so I hooked everything to Cubase, suddenly my feeble meter readings became hefty meter readings! another FACE PALM! hooked up the Turbo again and the needle is wiggling away nicely.

Now just to button up this sexy beast and put it to work.

I was going to remove this rather long winded post but it does end with a rather poignant "What not to do" so I will leave it for other GSSL builders.

And thanks again to Harpo for his help.