GSSL HELP THREAD!!!

[vertiges]

[quote author="3nity"]I think you sould break the 0V to Ground only at the Input or the Output.... but not both at the same time?

not really sure.

Thanks.[/quote]

Unless, as Matta, you have a wire from "the center tap" to the star ground.
(the center tap=the 0V from the PSU=the center pin of the 3pins connector on the PCB)

My understanding is : if you link your PCB by two different paths to the star ground you've got a "ground loop"

eD)))

 

[udenjoe]

I know many are using metal chassis. Is this a requirement for the gssl? Could I add some sheet metal to a plastic chassis and connect the ground from the power cord to the sheet metal? I ordered some from here without noticing "plastic" in the description:
http://www.rackmount-devices.com/021-7086.html

Idiot am i.

All I need is a new soldering tip and I can finish these things...

 

[king-rb]

hi all yaaa... ive got some problems with my mixbus comp...

and in bypass mode

if i play with make-up or threshold it change the volume.
i also recaped it but thane thing...
coult it be the sidechain filter board=?

thank you

 

[roginator]

whell..I cant find info how fix a problem on one of my 2 new GSSLs.. so I need a help

Using THAT 2181LB..sound in sound out OK, Bypas ok...so I found there is a problem in SIDE chain ( or not?????? )

whell..make up gain is working!! on VU meter I can see difference when Im using TRESHOLD BUT..no audiable diference when mooving TRESHOLD

As far as I see everyting elese is working BUT TRESHOLD is not afecting in AUDIO signal..

I read all meta mta...but cand find solution how to fix it...

HELP!!!!

 

[vertiges]

Roginator,

Check at the TL074 pin8 if you have DC varying with signal at the output of the sidechain.

Check at the TL074 pin 1 and 7 if you have DC varying with signal level as well as a superimposed DC signal from threshold (TL072 pin1) and makeup (TL072 pin7). These two are your VCA control voltages.


eD

 

[vertiges]

king-rb,

Could you give us more infos ?

You mean you've got a hum ?
How did you make your grounding wiring ?

Check, and rechech and re-re-check for bad components orientations, values, cold solder, short.

eD)))

 

[guavatone]

[quote author="3nity"]What matta did with his wiring is that he took the 0V from an outboard PSU and send it to Star Ground and i think that his star ground now becomes his 0V but if you use the On board regulation, you only go to star ground by the XLR pins 1, This seems clear to me.

See carefully at this pic. Greg only has his center tap to the board and no star ground.....but look at the XLR!

[/quote]

How did this work for you 3?

-I have CT to chassis then to the unit, but I have problems which I'll list when I am sure I can't figure it out.

 

[Nadege]

Hello

I've build 3 GSSL now, All of them are working pretty good except for one thing.

One the 3 of them I have exactly the same problem, HUM. Loud enough to be annoying.

A friend of mine which is teacher in electronic and work as a maintenance ingeneer in the audio world, came to help me because I couldn't find what was going wrong.

It's a clear 50Hz humm variing whith the gain compensation control.

I measured the ripple on the power supply, I have between 0.02 and 0.03 volt ripple on both + and - power rail.

When I bypass the VCA just to listen to the input and output stage (by adding a link from pin 1 to pin 8 of the That 2181, it's clear, no hum.

When I bypass the sidechain section by putting the CV to VCA's to ground pin 7 of the TLo72 to ground, signal is clean.

So for me the hum is comming from the DBX202 emulation circuit. But cannot find anything wrong in there....

And it's clear, it's a 50Hz Buzz, maybee induction noise????

Does anybody here had this problem and solve it?

I don't have any idea anymore, and my electronician friend neither.

As I have the exact same problem on the 3 unit I've buils at different time, And that except for this buzz, all of them are working properly, What should I suspect....

You can have picture of my first unit on http://www.twin-x.com/groupdiy/thumbnails.php?album=90


Thanks for the help

 

[gyraf]

check cleanliness and integrity of your +/-12V lines?

 

[Nadege]

I have, it's clean

 

[mikeyB]

Anybody advise?
Just trying to simplify circuit. Each of the release settings has it's own tant capacitor - is there a reason or can it be simplified by putting just 1 tant in the pole of the switch?
I'm maybe doing a CAD of modded SSL with ultimate oxford and sidechains in new year - time permitting :!:

Thanx and big up xmas to everyone :wink:

 

[vertiges]

Nadege,

Are you sure about the wiring of you PSU transformer ?
In my first GSSL, I made it wrong even if it worked and I got the good voltages everywhere. (But I had a hum.)
Shouldn't you have to wires tied together on the secondary ? (Maybe it's normal as you don't have the same current there in Belgium)

Have you isolate the Main PCB from the scews of the stands ? (Nylon washers)

Have you scratched off the paint of the chassis at the star ground ?


eD)

 

[Stentor Productions]

My buddy and I are trying to place an order with Mouser and they are asking for an excel file but all we've found so far is pdf.

Any suggestions?

I've been pulling my hair out cutting and pasting and invariably making part# and other errors.

Dammit, I'm a guitarist not a secretary Jim!

 

[Nadege]

Vertiges,

thanks for your answer,


(Shouldn't you have to wires tied together on the secondary ? )I don't think I understand this question? (Bad english)

The pcb is isolated from the chassis and I'm Using an aluminum enclosure, not painted.

 

[vertiges]

Nadege,

Could you give me the reference for the PSU transformer you use ?
(The brand, etc. or a web link...)

Sorry for using the french :wink: :

Pour le secondary à la sortie de transformateur, tu as quatres fils : rouge, noir, orange, jaune. Ma question était de savoir si deux d'entre eux ne devaient pas être reliés ensemble pour te donner le 0V de référence. Mais après avoir vérifié sur le PCB qu'il me reste je vois que l'orange et le noir sont liés par le PCB. Vérifie que tu ne t'es pas trompée dans les couleurs.

You wrote you used a unpainted aluminium enclosure, but on the pics you posted, the chassis is definitely paint in black :shock:

Vérifie aussi que toutes les "plaques" qui forment le chassis sont reliées à la terre. QQ fois à cause de la peinture dans les pas de vis, le contact ne se fait pas.

Did you try to move the transfo ?

By the way, how high is the hum ?


There is something I don't understand on your pic :

Is there a contact here between the chassis and the black wires ?


eD

 

[Bluzzi]

[quote author="Stentor Productions"]My buddy and I are trying to place an order with Mouser and they are asking for an excel file but all we've found so far is pdf.

Any suggestions?

I've been pulling my hair out cutting and pasting and invariably making part# and other errors.

Dammit, I'm a guitarist not a secretary Jim![/quote]

You will have to do it by hand. Some part numbers may have to be sub'd.
What problems are you having?

jim

 

[Nadege]

Hello Vertiges,

I'm damn sure of my tranformer wiring, as you said both 0v are linked together at the PCB.

I've to check for the transformer part number, but I bought it at Farnell.

On the pictures of my first unit, it is a black painted stell enclosure, but the other unit are fitted into a aluminium anclosures by Schroff, the multipac series.

The picture with the black wire is something I changed, I made a mistake and wire both input and output XLR ground to the star ground, I've removed those links and only put one wire from one input XLR pin 1 to chassis with the Earth ground.

The volume of the hum is not really Loud, but clearly audible. Not a poblem for compressing rock and roll guitar, but impossible to use for acoustic music.

Sorry for french.

Merci d'avoir répondu en partie en français, c'est plus clair... Je continue quand même en anglais au cas ou qqu d'autre avais ce problème et pourrais le résoudre via notre discussion.

Thanks for the help

 

[vertiges]

Nadege,

If your PSU transformer is a Multicomp, your wiring is correct.

The strange thing is you have the same problem on the 3 units you build.
So it's probably the same "mistake" on the 3 units. Maybe you built the 2nd and the 3rd one by refering to the first one.

There is a post in this (loooong) thread, on the page 102, from the member DQ who had a hum :

"I have moved the trasformer and the W04 from the middle of the PCB to the edge of the PCB, near the 1000uF caps , on the other connector (the one that was supposed to be right..))
The noise has come down a lot , almost completely!"

Your W04 is on the middle of the PCB... It's maybe that.

And there is another interesting thread from Mnats :

http://www.groupdiy.com/index.php?topic=18855&postdays=0&postorder=asc&highlight=difference&start=0

I've got the same problem on my first GSSL. I know how it can be frustrating ! (I have a second one to build, but I put it on standby until I solve the problem of the first one.)
I have a hum too, a 60 Hz (it's electromagnetic, no static) it's very low but audible on soft sources. After many many many hours of chasing this hum, checking and re-checking everything, replacing some of the components, reading hundred pages in the forums, I've decided to build an external PSU and see if that solves the problem. I've ordered the PSU PCBs from Mnats. I'm too busy right now, but I will try it around mid january.

I hope you'll find the solution,

eD)))

PS : congratulations for your "new" government :wink:

 

[Bluzzi]

Nadege - This is a long shot but I noticed you have a grey wire from Xfr that is not being used and taped in a loop. I would try and shorten that wire as much as possible and cut and tape straight not looped. Make all your AC wires as short as possible.

I also noticed on photo that some components are not close to the PCB. If you look at transistors the leads are sticking out. I would try and get them to be as flush to PCB as possible.

Your rectifier is also not flush with PCB and I would resolder.

2 Questions that I'm curious about as I am finishing one of these. I noticed a black wire jumping from one end of the switch PCB to the other. I don't have that on mine and was wondering what that was for? The other is I noticed your bypass switch is SPDT, isn't it supposed to be DPDT?

This may be nothing but every little bit helps and it will not hurt. At least you will eliminate that as potential problem.

I'm about to hook mine up (number 1) so stick around, I may need your help soon!

At least its only a hum. Had one on my LA2A and solved by moving 1 wire! Sometimes its the little things.


jim

 

[vertiges]

Jim,

About the black wire of nadege, these two points are linked on the PCB. Maybe she "repaired" a broken trace. And about her bypass, maybe she only bypassed the VCA and not the GAIN Make up... She'll tell us !

About the fact some of the components are not flush flush with the PCB, are you sure it could be a source of hum ?
I think I read something somewhere ( :wink: ) tha t for example, about the polarised caps that it was a good idea to let some space "under them" when soldering. Maybe it's totally wrong !

You made a good point about the grey wire. I was wondering if the two unused wires of the primary (because of the 220 volts) hadn't to be tied together. I'm not sure.

:evil: These hum problems drive me crazy !!!

eD