GSSL HELP THREAD!!!

[MartyMart]

I'm having a hard time following that photo, it's all cream covered wires and
what's all that "twisted pairs" wiring !! ( looks like too many wires there )

Sorry, the Amveco data seems pretty direct, if you are following that then
you should have an AC voltage on the secondaries of about 21V - as there's
no loading on it yet.
Secondaries are red&brown tied together for "0" volts and the green and blue
wires should have about 21v AC each, on them.
Do you have a good "ground" to the case on the primary side from the IEC socket?

Another check, Primary side wires are much thicker than the secondary wires on all
the toroids that I have .... ?? could that amveco colour code be reversed and therefore
you're getting no voltage reading ?

MM.

 

[vertiges]

From AMVECO :

For 230V operation, connect primaries in series by connecting black and red lead wires together and apply 230V across yellow and violet leads wires. For 115V operation, connect primaries in parallel by connecting yellow and red lead wires together and black and violet leads wires. To parallel the secondaries, connect green and brown wires and red and blue together. To put the secondaries in series, the red and brown wires are connected together.

About the primaries : the Violet should be connected to the Live Pin, not the Neutral. And the Yellow to the Neutral. You did the contrary.

I don't understand the way you connected the wires of the secondary.
The red & brown should be connected together : that the C.T. (Center Tap). That goes to "the middle" of the 3-pins Molex.
The two other wires will give you the two V+. (Left and Right of the Molex)

If you test the toroidal alone, you should link the center tap to ground before measuring. If you don't, you will a floating 0V and you'll risk to read crazy voltages...

eD)))

 

[FreelY]

looks like too many wires there

yes primaries ground and secondaries red & brown (0) are doubled (stupid HiFi...)

Do you have a good "ground" to the case on the primary side from the IEC socket?

I use screw hole for the moment. This is not very good but 'work' on every parts of the case without paint.

About the primaries : the Violet should be connected to the Live Pin, not the Neutral. And the Yellow to the Neutral. You did the contrary

.
I reversed the wires here because it does not work in the other direction. They are reattached correctly now.

If you test the toroidal alone, you should link the center tap to ground before measuring. If you don't, you will a floating 0V and you'll risk to read crazy voltages...

I had forgotten that. Unfortunately no changes linked to the ground

 

[vertiges]

That's weird...

Are you sure that your voltmeter is in AC mode ? (AC= courant alternatif / DC= courant continu) The current is not rectified yet, it's sill AC...

Have you tested the fuse ? :roll:

eD)))

 

[Harpo]

with disconnected line voltage your meter should read about 0 ohm between yellow and violet transformer wires, also between green and blue, otherwise you have no connection between black/red and/or red/brown. These transformer wires have an hard to see isolation paint applied that needs to be scrapped off at the wire ends for a working connection.

 

[MartyMart]

Do you have a good "ground" to the case on the primary side from the IEC socket?

I use screw hole for the moment. This is not very good but 'work' on every parts of the case without paint.

NOT good !!
You MUST solder the mains earth to a metal lug and bolt that to the case
after scrapping off some paint, use a serrated washer also for a proper earth
contact !!
Just poking the earth in the hole is going to be unstable and potentially
LETHAL

Almost there ... :!:

 

[FreelY]

These transformer wires have an hard to see isolation paint applied that needs to be scrapped off at the wire ends for a working connection.

That's good!

The red protection on the secondaries between the red & black wires still block the contact!
next step: A real big star for the ground :wink:
Thanks to all for this very effective international help ! !
:thumb: :thumb: :thumb: :thumb:



PS: I'm not Claude François :razz: (french joke..sorry)

 

[vertiges]

[quote author="FreelY"]PS: I'm not Claude François :razz: (french joke..sorry)[/quote]

You're not building your GSSL in your bath !!! Are you ? :grin:

 

[FreelY]

lol No, but not far: in my bedroom :green:

other little question:
where is the best place for take the + power for the led of my meter. Here after the rectifier, before the regulators?

I have one led of 3.5V 30mA. So I have to use one 400ohms resistor true? (15-3.5)÷0.030=383.33

 

[Harpo]

No. The spot to take your LED +power is ok, but the voltage is different. This is raw DC before regulation. This voltage is calculated AC voltage * 1,1 (to allow for 10% line overvoltage) * 1,414 for rectification - 2*0,7V Diode drop in your rectifier, so for a 15VAC transformer your LED will see about 22V DC in this spot. 30mA is the LED's limit, for usual 10-15mA draw is sufficient, so I'd try (22V-3,5V)/0,015A=1,2k / 0,5W.

 

[FreelY]

Ok! I see better now
thank you Harpo

 

[karl j]

Had time last night to try calibrating the SC. Nothing changes when I adjust VR1.

I guess I have some other trouble shooting to do. I've got good voltage on the 5532s in the SC, and I'm pretty sure I'm getting signal at the L,R input. Unfortunately I won't have more time until tomorrow to do any more work on it.

 

[MartyMart]

[quote author="FreelY"]

other little question:
where is the best place for take the + power for the led of my meter. Here after the rectifier, before the regulators?
[/quote]

I took mine from the small "link" lead mid board which is +15vDC there's a
-15vDC right next to it ! ( it's the point that feeds all the IC's with +15v )
Used a 10k r to my Behringer meter LED + point and it's all OK.
( of course there's a ground connection needed too )

MM.

 

[Harpo]

[quote author="karl j"]Had time last night to try calibrating the SC. Nothing changes when I adjust VR1.

I guess I have some other trouble shooting to do. I've got good voltage on the 5532s in the SC, and I'm pretty sure I'm getting signal at the L,R input. Unfortunately I won't have more time until tomorrow to do any more work on it.[/quote]
Skip the addon sidechain part for now (place the two 47k summing resistors back in their original spot) and get the compressor working as designed by Jakob in the first place. This is easy to change back when you know, the essential part is running to your needs. What type of 202 are you using? DBX built the 202 'black can', 202R, 202X, 202XT, 202XTC, 202C 'gold can', 2001 'silver can', 2002 'blue can', 2002R, 2002N, 2002T. Some came with different parameters like input impedances or -6mV/dB to -50mV/dB control voltage. Have a look at at design note dn127 from That may help to identify your parts.

 

[karl j]

I have 202c gold can VCAs. I think I have some XTs around here somewhere too. But currently I have the 202c in my GSSL.

 

[karl j]

And I have a dbx 2151 in the sidechain.

 

[Harpo]

your VCAs should behave as designed by Jakob.
Check point 'F' varying +/-12VDC with reference to gnd when moving your threshold pot. (case you have a 47k offset resistor on the outer leg of the 50k pot, this will vary from +12V to -0,5V or -10V with 4,7k offset resistor) Case else, your pot is probably faulty.
Check resistor value 220k connected to this 'F'. With 56k in the feedback loop of this opamp, the control voltage, adjusted by the threshold pot is reduced by *-0,25, so at the opamp output (pin 1 of TL072 on pcb, pin 7 on schematic) you will measure -3V to +3V by moving the threshold pot.

 

[karl j]

WTF!

It looks like the 10k vari-resistors Digikey sent me for the sidechain (vr1 & vr3) ARE 10 ohm. NOT 10k ohm.

That might make a difference.

 

[Harpo]

shure it will make a difference, but as these are in the feedback loop of the opamps, the signal will increase when resistance increases, resulting in even more compression. Doublecheck your other resistor values.

 

[karl j]

Well, I had time last night to make a few changes.

I found a suspect threshold solder joint/trace on the "-" hole on the control pcb. So I wired a jumper on the backside of the board.

Also went to Radio Shack and got some cheap 10k vari-resistors. They're not quite the right package style, but I got them in there. It was late by that time, so I didn't put the VOM to it (I couldn't focus my eyes on those little points anymore), so I just ran some music through it. It was behaving much better. Much less GR and seemingly normal thresh control.

I'll check it out more today.

Harpo, as far as this...

shure it will make a difference, but as these are in the feedback loop of the opamps, the signal will increase when resistance increases, resulting in even more compression.

.... well, I'll take your word for it. Lots of this stuff still doesn't make sense to me. But, I'm little by little I am learning a few things by doing this project. I can remove/replace and install parts really well (I have a bunch of old MCI gear :razz: ), but what they're doing in the circuit I generally have no clue.

Thanks for taking the time to offer your advice! I appreciate it very, very much.

I'll update again later.