GSSL HELP THREAD!!!

[Harpo]

Ok, I'll change the switch.

??? Not what I said, and fixing a faulty unit, you want to measure other spots (FI supply voltage rails) anyway.

 

[fingercarlos]

i need some help I build a GSSl and im having a problem with the threshold pot,  it works but when i turn it all the way CW there is sparkle from the inside and after that it burns the potentiometer.  what could be causing the problem?  i replaced that pot twice.

Thanks 

 

[Industrial Waves]

Pfff my build of the GSSL is a catastrophe.

I switch on the GSSL and the db meter goes instantly to 20 db. No signal come out, the led don't light.
Now comes the problem because I don't know how to find mistakes. I follow the enembling guide provided by PCB Grinder carefully and I think is everything in the place. <---- obviously not

 

[gyraf]

Industrial Waves,

An useful approach to error-tracing is reading this thread, looking for someone with similar or related symptoms, and checking your work for common errors.

We have talked numerous people through basic fault-finding - you have a good chance of fixing your GSSL if you follow the same procedures..

Jakob E.

 

[blackartmixing]

Hi All, my first post here and a total noob so apologises.  please can someone help?  i have really tinny harsh high frequency only sound out of the left side of the compressor.  the right side is fine.  any ideas or help where i can start to troubleshoot it?  sorry it would take weeks to read 312 pages of this thread although i did try.

 

[Greg S.]

First of all,
Signalgenerator at the Input (used one is all right)

Second,

trace the SignalPath using an Oszilloscope! (used one is all righti too)

GSSL is Stereo, so you may compare!!!

 

[jicama]

Something weird happened, I ordered resistors from farnell to build my second gssl, but the size of them are half of normal 1/4W resistors and I don't know if there's a mistake here is the link of the resistor example

http://uk.farnell.com/te-connectivity/lr0204f27k/resistor-metal-27k-0-25w-1/dp/2329909?Ntt=2329909

And here is a picture of both 1/4W resistors for comparing. Is this normal??

 

[Harpo]

Something weird happened, I ordered resistors from farnell to build my second gssl, but the size of them are half of normal 1/4W resistors and I don't know if there's a mistake here is the link of the resistor example

http://uk.farnell.com/te-connectivity/lr0204f27k/resistor-metal-27k-0-25w-1/dp/2329909?Ntt=2329909

And here is a picture of both 1/4W resistors for comparing. Is this normal??

The smaller ones are only rated for 200V. As the GSSL operates at +/-15VDC and below, this will not cause any trouble.
Your 27K resistor worst case has to dissipate 15V^2/27000R=0.0083W, so doubling up the min.required rating in order to keep temperature down, the 0.250W rating is ample for this 27K parts value.

If you would ignore these partly wrong, outdated or missing important parameter BOMs (IMHO BOMs should be banned) and look up the parts datasheets, you probably could answer these questions on your own and learn a lot along the way.

 

[micah421]

Im starting to stuff my SuperSide Chain board, the diode leads are too large for the PCB holes, any suggestions? Can I drill the holes larger?

Thanks

 

[jicama]

Something weird happened, I ordered resistors from farnell to build my second gssl, but the size of them are half of normal 1/4W resistors and I don't know if there's a mistake here is the link of the resistor example

http://uk.farnell.com/te-connectivity/lr0204f27k/resistor-metal-27k-0-25w-1/dp/2329909?Ntt=2329909

And here is a picture of both 1/4W resistors for comparing. Is this normal??

The smaller ones are only rated for 200V. As the GSSL operates at +/-15VDC and below, this will not cause any trouble.
Your 27K resistor worst case has to dissipate 15V^2/27000R=0.0083W, so doubling up the min.required rating in order to keep temperature down, the 0.250W rating is ample for this 27K parts value.

If you would ignore these partly wrong, outdated or missing important parameter BOMs (IMHO BOMs should be banned) and look up the parts datasheets, you probably could answer these questions on your own and learn a lot along the way.

7

Thanks for the info Harpo,

I´m sure it will be very important and useful  to take a electronic course, hopefully some day will find the time to make it happened until then, thanks for the help. 

 

[late]

What is the best 12V regulator for rev #11? Got the problem that +12v not get powered always.

 

[jicama]

What is the best 12V regulator for rev #11? Got the problem that +12v not get powered always.

Yeah I used to have 7815 but changed it to LM317 following the instructions here http://diyaudioprojects.com/Technical/Voltage-Regulator/

 

[late]

What is the best 12V regulator for rev #11? Got the problem that +12v not get powered always.

Yeah I used to have 7815 but changed it to LM317 following the instructions here http://diyaudioprojects.com/Technical/Voltage-Regulator/

I mean 78L12 and 79L12 regs. There is some latching problem with those.

 

[noiseattitude]

Hi Guys,
I'm a newbie from Sicily. I have some problems with my Gssl.
I'll try to explain, i need a help:

My Gssl is the new gssl from Gustav (Pcb Grinder), without sidechain.
After the complete assembly, i had a latch-up. I checked the voltage regulator (in latch-up status) and I found the cause: 7815 latch-up. I changed it. So I tried to pass the audio. Bypass work, Makeup work .....but no meter, no compression, no treshold.

After this, i noticed that when i move the makeup gain pot my voltage on + 15 e - 15 rail change a lot (the + 15 goes at 16,8 and the -15 goes at -13).... after these measurements happens a new problem: now i have the right channel with serious distortion  ....and no affect by the makeup (only on the right - the left is affected).

I noticed also that the latch-up of 7815 returns when my makeup is not on zero .....obviously I don't have the latch-up when bypass is inserted.

So i tried to change both linear 50k pots ..... but nothing.

I double and triple checked all the diodes, talantum, elcos .....solderings; and I read all this big thread a few times .... I don't know now what I have to do.
I hope someone could help me.
Excuse me for my bad english.
Thank U in advance.

Giovanni.

 

[noiseattitude]

Do you think i have to change the tl74 and tl72 ? (the others ....i tried to swap them)
Somebody could help me ?
Excuse me for the reminder

Giovanni

 

[Harpo]

My Gssl is the new gssl from Gustav (Pcb Grinder), without sidechain.

probably ment 'without 2nd.sidechain (turbo)' or 'without sidechainfilter'...

After the complete assembly, i had a latch-up. I checked the voltage regulator (in latch-up status) and I found the cause: 7815 latch-up.

7815 latching on startup, giving out an about -0.3V negative DC voltage in respect to 0V reference voltage ?

Bypass work, Makeup work .....but no meter, no compression, no treshold.

Maybe only missing the 'HPF' jumper on main board ...

After this, i noticed that when i move the makeup gain pot my voltage on + 15 e - 15 rail change a lot (the + 15 goes at 16,8 and the -15 goes at -13)....

Highly unlikely. Missing mains transformer center tap connection ? What type is your mains transformer and how does it connect to pcb ?

I noticed also that the latch-up of 7815 returns when my makeup is not on zero .....obviously I don't have the latch-up when bypass is inserted.
So i tried to change both linear 50k pots ..... but nothing.

Probably/maybe latching 78L12 (supply for the sidechain is powered by 78L12 and 79L12 regulators for the +/-12V rails). Nothing to do with the +/-15V audio supply rails and probably nothing wrong with your TL074 and TL072 opamp. 4 additional 1N4004 diodes should fix this latching for both +/-12V and +/-15V rails. (cost for all 4 diodes in single quantities incl.vat below 0.10€. Experimenting with different brands of voltage regulators and uncertain outcome will cost a LOT more.)

It gets a little boaring when an answer for this fix comes up over and over again (11 times within the last 12 pages of this thread, not counting the others)...

 

[noiseattitude]

Hi Harpo, many thanks for your help.
I try to reply point to point to you:

1) "7815 latching on startup, giving out an about -0.3V negative DC voltage in respect to 0V reference voltage ?"

Now i'm at work ...but in 2 hours i'll check this and reply !!

2) "Maybe only missing the 'HPF' jumper on main board ..."

YESSSSSS .... so I have to solder a jump from the first hole to the third ....right??? Very stupid ...on the pcb  I have not seen a straight line on the HPF ....but now i see it on the schema....


3) "Highly unlikely. Missing mains transformer center tap connection ? What type is your mains transformer and how does it connect to pcb ?"

I have a toroidal 230 primary and 2 x 15 secondary. I have joined the end of the first secondary with the start of the second secondary ....and put it on the center ..... The remainings wires on the sides (respectively). But I Repeat, on a first time this "unlikely" condition don't happens   ..... I had good sounds without hum or noises.... .... but while I was checking the voltage of the ICs and pot, suddenly ..... the left channel goes into distortion. Do you think I have to desolder and resolder the toroid?

4) "Probably/maybe latching 78L12 (supply for the sidechain is powered by 78L12 and 79L12 regulators for the +/-12V rails). Nothing to do with the +/-15V audio supply rails and probably nothing wrong with your TL074 and TL072 opamp. 4 additional 1N4004 diodes should fix this latching for both +/-12V and +/-15V rails. (cost for all 4 diodes in single quantities incl.vat below 0.10€. Experimenting with different brands of voltage regulators and uncertain outcome will cost a LOT more.)"

I read it some days ago. I have now 2 brands of regulator .....I changed the 7815 because on first latch up i noticed that was it the problmes. Do you think i have to change also the 7812


I want to give you again my thanks !!! And sorry for my "newbism"

 

[Harpo]

2) "Maybe only missing the 'HPF' jumper on main board ..."
YESSSSSS .... so I have to solder a jump from the first hole to the third ....right??? Very stupid ...on the pcb  I have not seen a straight line on the HPF ....but now i see it on the schema....

You could place a cap with appropriate value here for a HPF at desired cutoff and a switch could short out this cap for HPF disable.

3) "Highly unlikely. Missing mains transformer center tap connection ? What type is your mains transformer and how does it connect to pcb ?"
I have a toroidal 230 primary and 2 x 15 secondary. I have joined the end of the first secondary with the start of the second secondary ....and put it on the center ..... The remainings wires on the sides (respectively).

Wiring seems correct. Your symptoms seem to describe a missing voltage reference from the transformers center tap. If so, look out for a broken trace, most likely close to/at this center tap connection to pcb. A magnifying glass might help to spot it. Moving these connection wires with wire ends directly soldered to pcb traces might easily break these traces.

But I Repeat, on a first time this "unlikely" condition don't happens   ..... I had good sounds without hum or noises.... .... but while I was checking the voltage of the ICs and pot, suddenly ..... the left channel goes into distortion.

You might have shorted out IC pins with the tip of your probe. Sh*t happens.

I read it some days ago. I have now 2 brands of regulator .....I changed the 7815 because on first latch up i noticed that was it the problmes. Do you think i have to change also the 7812

This latching on startup doesn't happen consistantly and might come back again. I'd use the diodes for a permanent fix and save the cost and hassle, but YMMV.

 

[noiseattitude]

Hey Harpo .... i tried to resolder the toroid.....but i think i have a strange thing: if i put the black of my voltmeter on + of the bridge circular regulator....and red on - of the 3 tips of the toroid i have: -22v on the left, -22 on the center and 0 on the right .......could be broken the traces? If yes.....where i can solder in right way these ?. Thanks a lot ! (on hpf , for the moment I put a simple bridge)

 

[noiseattitude]

about the shorted out ic pins: i try to swap, without success, all ics except tl74 an 72 obviously .....do you think these are broken ?