GSSL HELP THREAD!!!

[pstcho]

Hi again, after spending hour to replace almost everything on the PCB i arrived to another situation ( unlucky build )

The unit powers up, the sounds is super low, ( like -40dB compreswsion doesnt work, makeup gain doesnt work, i tried to reaplce again and again every that, tlo, Ne555, no difference, verified again and again every value or resistor and if there was no short circuit but i cant find anything

i checked all voltages and compared all i could on my other units and i cant find difference,

so i need ehlp understand on the chain what could affect the signal for neither the compression ( threshold ratio att release  ) neither make up  have any effect

 

[innercityman]

Ok  Gustav. In fact I don't really mind, it's just that I've finished installing a crush N' blend mod into my unit, there's a led on the board and I was surprised by the fact that it lights up much more brighter than the one in the GSSL for the vumeter. Beside of that I tested my unit today with the Crush N' Blend installed, and I got an issue, but that's another problem and I'l post on the right thread for that.

Thanks anyway.

Pierrick

 

[pstcho]

Hello, nobody could try to help me please?

the only differences  i managed to find between my units :

not voltage coming  "CV to SC" point

i have no voltage at resistors 100k and 220k going to the TLO72

no voltage either  at the resistors 100r ( out of TLO72 ) and 470r ( input of the THAT 2081 )

the unit fires up

I have very very low signal going though

The volume know doesnt  play any role, even if i can see it changing  the voltage at R620K

By passed or not, i have the same volume coming out ( -50dB more or elss )

The compression works properly threshold attack release ratio ( according to what the VU meter tells me )

 

[pstcho]

Still nobody ?

One last info and i give up

By mistake while doing some mesurement i did a shortcut between PIN 6 and 7 of the input NE5534 the sound dropped for a while then the channel was was working perfetly for a while ( 15-20 seconds ) i tried many times on both channels and everytime it works ... still no suggestions ?

but if the NE5534 is here or not, there is no difference ( if i remove it or not i mean )

 

[Gustav]

Still nobody ?

One last info and i give up

By mistake while doing some mesurement i did a shortcut between PIN 6 and 7 of the input NE5534 the sound dropped for a while then the channel was was working perfetly for a while ( 15-20 seconds ) i tried many times on both channels and everytime it works ... still no suggestions ?

but if the NE5534 is here or not, there is no difference ( if i remove it or not i mean )

Dont you have a working unit?

Perfect for comparison.

Gustav

 

[pstcho]

I even have 2, i compared all i could, but cant get the differencem rebuild the whole thing a second time just to be sure

I dont have an oscilloscope unfortunately, it would help

 

[gyraf]

Basically, it's a matter of finding the error(s).

Yes, there is an error somewhere in there if the unit does not work.

Usual suspects (in order of popularity in this thread) are:

- wrong component
- trace shorts (solder blobs)
- wrong wiring
- wrong orientation

Read the previous posts in this thread for help and inspiration: What works is checking and rechecking until error is found.  No magic involved.

We simply can't do the error tracing from here.

When you find and correct the fault, the unit will work.

Jakob E.

 

[pstcho]

Hi Jakob ( the almighty for me that gave us access to so great stuff, i made 6 G9 4 1176 and 3 SSl so far <3 )

thanks for your reply

About the components, i rebuilt it cause i have problems with some resistors that were not well labeled and i didnt mesure each one of them ( mistake ) at first, so i just replaces every resistors, all the capacitors also, all the circuits also to be sure i didnt fry any of them, so about the components, i am pretty sure

about the orioentation, i compared a lot with the other boards i have ( they are all n the same rack so it is pretty easy to compare ) and i dont think there is a mistake here either

about the wiring, i am pretty sure again cause when i replace then mother board with another unit it works perfectly ( so front plate and all connections are good )

about trace shot, i checked 10000 times but i am not sure cause .... i am just a human, i wish i could understand better the role of each components in order to be able to debug it alone but i see now i am at the limits of my limited knowledge

i dont really see where to search about the problem

first of all, what can cause the make up gain not to work, generally? i guess that must surround the main problem

in by pass the volume is super low and in working settings, the make up gain does not work and the volume stays low

 

[pstcho]

Hello guys, after a night of crazyness i managed to make it work perfectly except one detail

I have un bypass -16.8dB of difference between a working unit and the new one

In compression mode with the same setting i manage to have exactly the same compression except that i need to put the threshold around -17dB and the make up gain FULL: if i send a sinusoid inside i get perfect phase cancellation while using the phase out function

 

[tglsnell]

Hi guys,

Currently still troubleshooting my GSSL. I've worked out its an issue with either the side chain or the channel VCAs as audio passes in and out and but the compressor doesn't engage.

I've noticed on my board there are a lot of % signs, now in the PCB grinder build guide (https://pcbgrinder.com/download/GssL/FullKitAssemblyGssL_rev1.pdf) it has these left blank but in the official schematics and on this website (http://diy.fischerworks.com/gssl_vca.shtml) it sees to suggest that these should be filled with resistors.

So my question is, should I place resistors in these gaps or leave them blank as shown in the PCB grinder build guide?

Thanks
Tom

 

[Gustav]

Hi guys,

Currently still troubleshooting my GSSL. I've worked out its an issue with either the side chain or the channel VCAs as audio passes in and out and but the compressor doesn't engage.

Could be lots of things - even an error in the wiring of the SCHP or the bypass switch.

I've noticed on my board there are a lot of % signs, now in the PCB grinder build guide (https://pcbgrinder.com/download/GssL/FullKitAssemblyGssL_rev1.pdf) it has these left blank but in the official schematics and on this website (http://diy.fischerworks.com/gssl_vca.shtml) it sees to suggest that these should be filled with resistors.

So my question is, should I place resistors in these gaps or leave them blank as shown in the PCB grinder build guide?

Leave them blank, unless you are using alternative VCAs.

Gustav

 

[pstcho]

Check out also if you didnt buy cheap ICs on ebay, all my problems were from there

NE5532 34  TLO  .....

i got a very similar problem ( on both channels though )

 

[tglsnell]

Could be lots of things - even an error in the wiring of the SCHP or the bypass switch.

Leave them blank, unless you are using alternative VCAs.

Gustav

I'm using the standard 2180 but in the schematics pin 4 is connected with a 47ohm resistor, this is omitted from the PCB. So is this pin not meant to be connected at all?

I haven't connected the side chain switch yet as I'm doing the mod. I've assumed that it'll function properly without this rigged up as it is hard bypassed? or do I need this switch in order to trigger the side chain.

I've not cheaped out on any components and have bought and tried spares of all of them.

 

[Majestic12]

I'm using the standard 2180 but in the schematics pin 4 is connected with a 47ohm resistor, this is omitted from the PCB. So is this pin not meant to be connected at all?

I haven't connected the side chain switch yet as I'm doing the mod. I've assumed that it'll function properly without this rigged up as it is hard bypassed? or do I need this switch in order to trigger the side chain.

I've not cheaped out on any components and have bought and tried spares of all of them.

Pin 4 is for distortion trimming purposes of the THAT 2181 VCAs and not needed with the pre-trimmed 2180 version.

Without a proper connection of the sidechain signal through a switch or wire jumpers you won't get a working compressor. Without any switch you will have audio signal going through the unit but neither compression nor make up gain

 

[tglsnell]

Pin 4 is for distortion trimming purposes of the THAT 2181 VCAs and not needed with the pre-trimmed 2180 version.

Without a proper connection of the sidechain signal through a switch or wire jumpers you won't get a working compressor. Without any switch you will have audio signal going through the unit but neither compressor nor make up gain

Ah that sounds like its my problem. I assumed (wrongly) that the side chain was hard bypassed unless wire up. I left it unwired as I was going to do the SuperSide Chain Mod. I do have functional makeup gain but obviously no compression. I'll try wiring up a temporary switch and see if that gets it working. Thank you for the advice!

 

[frazzman]

Hey folks, 
I have an issue here with a build where the right channel has a high pass filter like frequency response - see attached.

Apart from that everything works as it should.

My gut instinct was that it may be related to a wrong cap or resistor value in the input or output stages but thus far I haven't found any anomalies. Also gone through all the usual diagnostics like swapping opamps etc..

Frequency response is the same in both bypass and circuit in.

Anyone ever encountered a problem like this ?

 

[gyraf]

..could also look as a factor 10 reduction of a resistor value?

Jakob E.

 

[Harpo]

most likely a 10uF instead of a 100uF fitted at output stage.
(a 2u2 instead of 22uF fitted at the debalancing input stage would have the same effect, but is lesser likely).
A change of resistor value will change the gain setting as well, so not a likely cause.

 

[justinheronmusic]

Hey! I'm about to make my wires for the molex headers. Would these crimp terminals pins work?

http://www.mouser.com/ProductDetail/Molex/08-50-0114/?qs=sGAEpiMZZMs%252bGHln7q6pm%252bS0pk2Wo0Xxo6Bf1atdX88%3d

 

[hugo]

Hey! I'm about to make my wires for the molex headers. Would these crimp terminals pins work?

http://www.mouser.com/ProductDetail/Molex/08-50-0114/?qs=sGAEpiMZZMs%252bGHln7q6pm%252bS0pk2Wo0Xxo6Bf1atdX88%3d

Yes it fits..you also can take pre wired... shielded cables are not so important in that build..it is dead quiet even without them..
https://www.banzaimusic.com/PCB-Connector-25-5G.html