GSSL HELP THREAD!!!

[melomane]

Hi Gustav,
Thank you for your reply
I have put the 1k regarding this document for pushbutton switch: http://www.frontpanels.de/app/download/8067320385/SSL_switch_wiring.pdf?t=1393932105
Is it right?

 

[Harpo]

I have put the 1k regarding this document for pushbutton switch: http://www.frontpanels.de/app/download/8067320385/SSL_switch_wiring.pdf?t=1393932105

will depend on the type of illumination inside the switches and is betting your luck on the current drive ability of the 78L12. The link between the two dots next to the makeup pot and 750K (makeup gain always operating, no matter if switched to bypass) is missing as well.

 

[salomonander]

hey
is it possible to use 202 (black can) vcas in the gssl? would it even make sense sonically? id like to get as close to an authentic sound as possible. cheers

 

[beatnik]

sure you can, i don't know if that's what the console compressor used

i know the rack version (g384 if im not wrong) uses the 202xt

there are some resistor changes you need to make it's well documented over the forum

 

[salomonander]

great thanx

i do have another question...
do i need a turbo mode for the oxford mode? or only if i want to be able to switch between the two. is it possible to build gustavs pcb in the oxford fashion straight away?

cheers

 

[beatnik]

you need the add on board fof modding to the original sidechain, then if you also add the switch you can bypass and keep the gssl style sidechain as well

 

[Greg S.]

Good Morning,

Short question, short answer!
My GSSL runs! (with Thats 2180 LB)

Got 2 Super Sidechain Boards(Rev A from J.Backhaus) and a Turbo Board from Expat Audio!

Question:
Which kind of 2181 should I use for the Expat?

THX and have a nice Easter WE.

gr

 

[beatnik]

both 2150 and 2180 series will work

 

[Harpo]

Which kind of 2181 should I use for the Expat?

The same type 218x or 215x VCA as populated in the GSSL sidechain, except you want the L/R channels behave slightly different.

 

[Greg S.]

So I have to find some Thats 2180LB's,

Thx Guys!
Appreciate your Help

 

[Dissler89]

I've ran into some problems.

After soldering all the parts on to the pcb and running a test. All voltages seem correct.

But after placing my chips and powering the unit up the +15 Volt rail seems to drop dramatically down. Every other voltage seems fine.

After looking through the forum I've come to the conclusion that the 7815 regulator is at fault (ordered a replacement and currently waiting).

But I am uncertain about this conclusion, if I remove all the chips the +15 Volt rail seems to go back to normal.

Does anybody have any suggestions?

 

[Harpo]

I've come to the conclusion that the 7815 regulator is at fault

unlikely.
Double check all +/-15VDC supplied ICs are in their corresponding socket (single opamps NE5534, dual opamps NE5532 and the audio-VCAs) with correct orientation. Expect any chip fitted reversed or in the wrong socket to be faulty, once powered on.

 

[dirtyhanfri]

Just made my forth GSSL, Internal C´n´B and homebrew Sidechain HPF

https://www.dropbox.com/s/37bix9fj33dexx6/P1010006.JPG

https://www.dropbox.com/s/6lbs5xbx0b0z9t1/P1010010.JPG

Working nicely from first run

 

[main repairman]

Can replace polyester capacitors - ceramic capacitor? 

 

[gyraf]

Can replace polyester capacitors - ceramic capacitor?

no

 

[Jamie1234]

Hi,

I'm just trying to troubleshoot my gssl which I made a right mess of last year and I've only just got round to looking at.

Here's what I know I did wrong:

-Put one of the NE5532 chips in backwards
-Forgot to use a jumper on the sidechain

I replaced the chip, put the jumper in and was just about to fire it up when I spotted that the two 10R resistors in the power supply are totally burnt to a crisp. Any guesses what might have caused this? The wiring all looks right and the capacitors are all the right way round. Dodgy transformer? dodgy regulator? I'd be surprised if it was anything other than a cock up on my part but I can't work out what..

The power transformer is 30VA, obviously overkill but would that cause a problem??

 

[Harpo]

I replaced the chip, put the jumper in and was just about to fire it up when I spotted that the two 10R resistors in the power supply are totally burnt to a crisp. Any guesses what might have caused this?

'-Put one of the NE5532 chips in backwards' this, underrated 10R resistors (what watt?) and shorts at the +/-15VDC rails as the most likely cause.

The power transformer is 30VA, obviously overkill but would that cause a problem??

The rectifying diodes will have a harder time for the inrush current and your mains fuse rating will be different, but transformers VA rating is not the cause of the problem of these fried resistors. Too high secondary voltages of your kept a secret mains transformer might be.

 

[main repairman]

Can replace polyester capacitors - ceramic capacitor?

no

Why not? Ceramic capacitors have better properties than polyester.

 

[Jamie1234]

I replaced the chip, put the jumper in and was just about to fire it up when I spotted that the two 10R resistors in the power supply are totally burnt to a crisp. Any guesses what might have caused this?

'-Put one of the NE5532 chips in backwards' this, underrated 10R resistors (what watt?) and shorts at the +/-15VDC rails as the most likely cause.

The power transformer is 30VA, obviously overkill but would that cause a problem??

The rectifying diodes will have a harder time for the inrush current and your mains fuse rating will be different, but transformers VA rating is not the cause of the problem of these fried resistors. Too high secondary voltages of your kept a secret mains transformer might be.

Thanks Harpo. I'll have a really good check around for shorts on the power rails.

The transformer secondaries are 18v. I know it says 15v on the schematic but from what I've read 18v works fine. Not sure of the rating of the 10r resistors, I bought the whole lot as a kit from pcb grinder. What watt rating should I replace them with?

Thanks

 

[Harpo]

The power transformer is 30VA, obviously overkill but would that cause a problem??
The transformer secondaries are 18v. I know it says 15v on the schematic but from what I've read 18v works fine.

30VA / (18V+18V) = 0.833A AC max. Mains voltage isn't a constant and is allowed to (and actually does, depending on location and/or time of day) vary by +/-10%. These 2*18VAC are secondary voltages at rated load, that will be higher by 10-20% unloaded, depending on type of transformer. These (18VAC+18VAC)*1,1*1,2=worst case 47.52VAC get rectified to 47.52*SQRT(2)-2*0.7V diode drop=65.8Vpk=+32.9Vpk/-32.9Vpk, so the 35V rating of the 1000uF caps are sufficient.
The 30VA/(18V+18V)=0.833A is AC current / form factor 1.8 from full wave bridge rectification=0.463A DC current= 0.23ADC for the sum of all negative voltage rails and 0.23ADC for the sum of all positive voltage rails that the 30VA transformer could deliver. With 10% high AC mains voltage this will further drop to 0.42A, 0.21ADC per sign rails.
If you add a turbo board and/or sidechain filterboard(s) and/or illuminated gizmos/switches/.. one day, a 30VA transformer isn't overkill, considering a single illuminated switch might draw more current than the complete rest of the GSSL circuit, but YMMV.
For the latest pcb revision (sidechain jumper, 78L12/79L12 fed from 7815/7915, aux.7812) no problem expected with a dual 18VAC or 36VAC center tapped transformer. Previous pcb revisions would be betting your luck with a 2*18VAC transformer in front that the 78L12/79L12 could deliver sufficient current for the sidechain section, considering these TO92 parts have a 0.75W rating and from previous Vpk numbers would transfer 63.5%max.to heat, leaving only 36.5%worst case (=23mA) for the +/-12V rails (the power on LED alone draws 10mA from this worst case 23mA).