GSSL HELP THREAD!!!

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Alain said:
.. found some short because I put the 7815 and 7915 on the chassis to avoid heating the pcb
  got a short from this ..
Click to expand...
Hi Alain,

the 7815 and 7915 have different potential connected to their metal sheet/heatsink. You will need an isolation kit to mount these to your case ground (else the 7815 will cause a ground loop, the 7915 will short out the rectifier). For the original gssl build you don't need additional heatsinking the 7815 or 7915. Just place the regulators on pcb and take care that the metal sheets of these regulators don't touch eachother. From your 1st experiment you also might have blown the bridge rectifier (in the upper left pcb corner where your external transformer connects).

should I replace all the chips (that 2181, the tl 074 and ne 5534 and so on)
when I got the short the jumpers nexs  the bridge rectifier  and beheind the 7915 were not in place!
Click to expand...
op-amps and VCAs should be alife.
The wire link behind the 7915 should be fitted, the link next to the unused spot for the on board transformer bridge rectifier is not needed. Your (maybe blown) bridge rectifier is in the upper left pcb corner.

I got it right now
I also got the 15 v (13.9)
and the 12 v (11.3)
Click to expand...
there are 4 different DC voltage potentials compared to 0V. +15V, +12V, -15V, -12V and your 15V (13.9) @ whatever sign is out of spec, so there is still something to fix.
Check all 4 DC voltages and make sure, your supply is working before connecting other gear.

 
Harpo said:
If wired as drawn wrong, exchanging the 'COM' and 'ON' wires to your relais will stop shorting the op-amp around the ratio circuit to gnd. This might also fix your ratio problems.
This relais is at least missing a flyback diode (kathode to gnd/pin-16, anode to relais pin-1), but your 78L12 might have survived a possible reverse current until now.
I don't like the idea of powering this relais (@ whatever current this draws) and bypass LED (@20mA) from the +12V rail, but YMMV.
Click to expand...

I just tried to exchange the COM and ON wires to my relais (wich is not powered from the +12v rail like in that picture) but nothing changed, and I still have the meter showing different amounts of gain reduction as I change the ratio switch...when I bypass, the meter shows 0, right as it should be. could my 78L12 be broken? my relais seems to be ok...that's what I deduce by a continuity test...
 
Hi Guys! Well i've read some post about calibrating the Ratio using different That VCA's, Kambo sended me the links that i've actually read before, but i'm still having hard time understanding why my Ratio is acting backwards, i mean i understand that calibration is for fine tuning the 2:1 4:1 etc... to a more accurate db value at the output, but i've checked the tant caps on the control board and the resistors, and nothing weird here, right values in the right place, with the right polarity, and when i send Sine wave at 1Khz , and let's say i put the threshold to about 6dB GR, in 2:1, then i hit 4:1, and it will drop to 2db of GR or so etc...., and i'm using 2180 pretrimmed, i've swapped most of the resistors around the VCA as mentionned in some topics 3.9K for 5.1K etc...., resistors around TL074 and diodes are also correct.... Any body that had the same prob before that can help? Besides that GSSL works properly all voltages correct Make-up gain etc.... all good. Thanks for helping me out
 
Hi Every one and thank you Harpo for your support.

So,

I did insert new bridge rectifier ,
new radial electrolytic 1000 uf (both)
new dc regulators,

an then I did chek the voltage pointing at the 0v link

the +15 and thew +12 is ok

but the -15 and -12 is much too low, alomost nothing

is this cause by the radial electrolytic 22uf-25v?

on the front should I have all plastic potentiometer (isolated)?

thank you

Alain .
 
Alain said:
Hi Every one and thank you Harpo for your support.

So,

I did insert new bridge rectifier ,
new radial electrolytic 1000 uf (both)
new dc regulators,

an then I did chek the voltage pointing at the 0v link

the +15 and thew +12 is ok

but the -15 and -12 is much too low, alomost nothing

is this cause by the radial electrolytic 22uf-25v?

on the front should I have all plastic potentiometer (isolated)?

thank you

Alain .
Click to expand...
Close up pics from your build might help to narrow it down a little more easy.

You now have both 7815/7915 regulators back on pcb or isolated the regulators from case ground before switching the unit on ? or you might have blown your rectifier again.
You already checked the correct orientation of all polarized caps ?
Your 22uF/25V caps in front of the regulators are rated close to the edge or already a step bejond (the schematic calls for 22uF/35V). With a 2x15V transformer and ignoring voltage drop in the rectifier they might see 15VAC * 1,1 (for 10% high mains voltage) * 1,2 (for transformer regulation) * sqr(2), giving 28V raw DC. 

Pull all chips out of their socket in case a blown one is shorting out a negative voltage rail.
Power up your gssl.
Check if your transformer is delivering 30V-36V AC at the rectifier AC leads.
Check if you have about 42V-50V unregulated/raw DC in front of your regulators (between rectifier DC leads, between 7915 center pin and 7815 leftmost pin or at the unused spot for the bridge rectifier for on board transformer - whatever is easier to probe for you).
Check for correct +15V and -15V DC voltages at empty IC sockets NE5532 pin 4/8 (Some 79xx regulators might measure a higher DC voltage without connected min.load).
Check for correct +12V and -12V DC voltages at IC sockets TL072 pin 4/8.
If any of previous steps fail, mend the broken trace, fix the broken part or remove the short before continuing.
Now put the chips back in their sockets. Watch out for different parts orientation.
Check DC voltages again.
 
zayance said:
Hi Guys! Well i've read some post about calibrating the Ratio using different That VCA's, Kambo sended me the links that i've actually read before, but i'm still having hard time understanding why my Ratio is acting backwards, i mean i understand that calibration is for fine tuning the 2:1 4:1 etc... to a more accurate db value at the output, but i've checked the tant caps on the control board and the resistors, and nothing weird here, right values in the right place, with the right polarity, and when i send Sine wave at 1Khz , and let's say i put the threshold to about 6dB GR, in 2:1, then i hit 4:1, and it will drop to 2db of GR or so etc...., and i'm using 2180 pretrimmed, i've swapped most of the resistors around the VCA as mentionned in some topics 3.9K for 5.1K etc...., resistors around TL074 and diodes are also correct.... Any body that had the same prob before that can help? Besides that GSSL works properly all voltages correct Make-up gain etc.... all good. Thanks for helping me out
Click to expand...

Your ratio is not backwards.  THe circuit is designed to keep a constant output level when changing ratios.  The threshold, although independantly adjustable is also tied to the ratio control.  So when you increase the ratio you also raise the threshold, thereby reducing Gain Reduction.  If your compressor is not properly calibrated for the VCA's you're using you will actually get more GR on lower ratios.  This doesn't mean your ratios are backwards, it just means you haven't calibrated the compressor properly.  I'd bet you money that if you test your ratios with an oscillator you'll see that they're correct (10:1 needs a 10dB increase in input level for a 1 dB output increase, and 2:1 needs a 2dB increase in input level for a 1dB increase in output.).  
Check out http://homepage.mac.com/marten.thielges/gssl/calibration.html for info on how to calibrate your gssl.  You need to remove 2 resistors from the sidechain VCA circuit, and also remove some resistors, change some resistors, and replace some resistors with wire jumpers in the audio VCA circuits.
 
Ok i get the picture, thanks, i had removed some of the res. around the VCA's but not in the sidechain area, thanks a lot, i'll try all that, keep in touch...
 
You now have both 7815/7915 regulators back on pcb or isolated the regulators from case ground before switching the unit on ? or you might have blown your rectifier again.
You already checked the correct orientation of all polarized caps ?
Your 22uF/25V caps in front of the regulators are rated close to the edge or already a step bejond (the schematic calls for 22uF/35V). With a 2x15V transformer and ignoring voltage drop in the rectifier they might see 15VAC * 1,1 (for 10% high mains voltage) * 1,2 (for transformer regulation) * sqr(2), giving 28V raw DC. 

Pull all chips out of their socket in case a blown one is shorting out a negative voltage rail.
Power up your gssl.
Check if your transformer is delivering 30V-36V AC at the rectifier AC leads.
Check if you have about 42V-50V unregulated/raw DC in front of your regulators (between rectifier DC leads, between 7915 center pin and 7815 leftmost pin or at the unused spot for the bridge rectifier for on board transformer - whatever is easier to probe for you).
Check for correct +15V and -15V DC voltages at empty IC sockets NE5532 pin 4/8 (Some 79xx regulators might measure a higher DC voltage without connected min.load).
Check for correct +12V and -12V DC voltages at IC sockets TL072 pin 4/8.
If any of previous steps fail, mend the broken trace, fix the broken part or remove the short before continuing.
Now put the chips back in their sockets. Watch out for different parts orientation.
Check DC voltages again.

[/quote]

Thank you so much again Harpo,

I did all the cheking you said
and finally there was no good reading on -12 v  or -15 v anywhere,
so I decided to change the bridge rectifier again
an then they all appears , the - 15v, the - 12v are all good now

but I took away all the chips and waiting to reinsert thems(5532 5542 tl072 ect.)

so my question is now  1-  are thy responsable for blowing the bridge rectifier?

                                2- I noticed ,cheking everywhere ,that I forgot to put in some parts (1k resistor on the VCA next to 55340
                                                                                                  (100p ceramic capacitor  on the right output betwen the radial elctrolytic)
could it be the reason why I blew the rectifier?

thank you so much
Alain,.

I will get a picture of my mess tomorrow!
 
Alain said:
I did all the cheking you said
and finally there was no good reading on -12 v  or -15 v anywhere,
so I decided to change the bridge rectifier again
an then they all appears , the - 15v, the - 12v are all good now

but I took away all the chips and waiting to reinsert thems(5532 5542 tl072 ect.)

so my question is now  1-  are thy responsable for blowing the bridge rectifier?

                                2- I noticed ,cheking everywhere ,that I forgot to put in some parts (1k resistor on the VCA next to 55340
                                                                                                  (100p ceramic capacitor  on the right output betwen the radial elctrolytic)
could it be the reason why I blew the rectifier?
Click to expand...

Your op-amps or VCAs won't blow your rectifier if it is sufficiently rated. As I told you in a previous post, mounting the 7915 to your case ground without insulation kit most probably was the reason why. Have a look at the regulators datasheet. The 7915 has a different pinout than the 7815 and input voltage connected to its center pin and the chips heatsink surface. Mounting both unisolated to the same conducting surface will cause a short. (The 7815 alone mounted unisolated might only cause a ground loop if you have another connection between 0V and case ground).

You also changed the 22uF/25V elcos in front of the 78L12/79L12 regulators for 35V rated caps ?

Leaving out the 1K resistor(s) will only have a 'gssl not compressing' effect because of missing VCA control voltage.
The missing 100pF lead compensation cap won't matter that much for a unity gain stable op-amp with this -0.5 or -1 voltage gain setting.

Reinsert your op-amps and VCAs into their sockets, turn the unit on and check all supply voltages again.
You're close to finish.

Good luck
 
Hi All,

  I now have three GSSL main boards working, meaning: they compress,make up gain works, ratios work but I dont know if they are correct, and side chain works.
I have found two different posts on calibration/optimizizing for that THAT VCAs, but the ones I used dont seem to be listed ( just my luck  ::)  ) 

I used the THAT 2181BL08U , was wondering if someone could shed some light on what changes I need to make to the 10Ks,3k9s,68Rs,1Ms, 1Ks and others that may need to be removed or jumpered to calibrate / optimize for this set up.

here are the posts I am referring to :

http://diy.fischerworks.com/gssl_vca.shtml

http://homepage.mac.com/marten.thielges/gssl/calibration.html

  I think I have done pretty well, with a LOT of help from this thread, but am still very much a  newbee and paint by numbers kind of DIY'er and need a little guidance in this matter.

  Thanks in advance,
                          Chip
 
regularjohn said:
ytsestef said:
Hello again. Today I finally collected everything I needed. I'm going to start soldering tomorrow!
I have a consideration though:
While the 1000uF, 0.47uF, 22pF and 0.1uF caps snap perfectly into place, there seems to be a slight lead spacing mismatch between the caps that were sent to me (I made sure I followed faithfully jakob's BOM) and the holes in the PCB. The values and voltages are correct though. My question is: Is it too important to ignore or should I start soldering anyway? The radial caps need to be ever-so-slightly stretched outwards to be able to solder them 2mm above the pcb surface, while the other ones need to be stretched inwards, again, for a 2mm distance-from-pcb goal.
Is it supposed to be like this? Or do they have to touch the PCB?
PS: The 22uF fits perfectly in the turbo board while stretches out a bit on the main gssl board.  ???
Click to expand...

It's fine.  That's what component leg benders are for.

Though I actually typically use higher uF values.  1800-2200uF for the power caps and double of the others...but that's ONLY for electrolytics.  The ceramics and film caps need to remain what they are.  Upping electrolytic values gives the active components in the circuit a larger reservoir of current to draw from.  Although if you go too large, you can introduce problems into the circuit.
Click to expand...

Well, thanks a lot for your answer!
I finished soldering the pcbs, wired the thing as well.
Is there some table containing the ideal voltage readings on the ic sockets?

My build powers up succesfully and I get pretty stable +/- 0.15 volts everywhere, but I would like to make sure.

However, I have a slight problem:

1 out of 4 times the unit fails to power up, and the meter needle goes up mid-way, and the power led doesn't work.
As soon as I switch it off the meter needle goes crazy over-the-top (hits the plastic), and quickly backs off at its resting position while at the same time (just when I turn it off) the power led blinks for a millisecond or something. When I turn it back on, everything is normal. This happens ONLY WITH THE ICs SOCKETED. When powering up the unit without ICs, it powers up every time.

Any ideas on what is wrong?

Note: I havent listened to it yet.

UPDATE: In bypass mode, when this happens, meter needle does not move (well it does a tiny bit).  ??? ???
UPDATE2: Listened to it, definately sounds like an ssl. Very nice! Haven't tested ratio values yet, but there is another problem here:

Right channel is way lower in level and very bright, like something is out of phase. The reason I mention this is because I don't know how to track if the problem is on the input or the output, BUT I noticed that when I put the jack at the input half-way in (so that the tip becomes the - (minus) signal and the + is left unconnected) it does sound right, only it is unbalanced. (Yeah, I use 1/4" instead of XLRs). No hum or buzz whatsoever. How can I check and correct this??

I am getting close!!
 
Hy Harpo and everybody,

I di a lot of work on my gssl but still not working properly

I finally get some soud ou of it (instead of super loud noise)
I realisez that the vca (that 2181) was burn on one side
sor I trade for a 2180 and got some sound.
I dont get any sing of compreswsion and the needle dont move at all
exept some time on ingnition it goes on tjhe middle and stay there.

Also when I touch the board one chanel stop playing and if I retouch
somewhere it comes back

I am just wondering if it next thing to do is to by another
pcb and restart a new board??

Alain .
 
hi alain,
I'm not an expert, but I had similar problems with my unit and I just fixed them checking all the connections on the pcb.. maybe some bad wiring or soldering...

angelo2979 said:
Harpo said:
If wired as drawn wrong, exchanging the 'COM' and 'ON' wires to your relais will stop shorting the op-amp around the ratio circuit to gnd. This might also fix your ratio problems.
This relais is at least missing a flyback diode (kathode to gnd/pin-16, anode to relais pin-1), but your 78L12 might have survived a possible reverse current until now.
I don't like the idea of powering this relais (@ whatever current this draws) and bypass LED (@20mA) from the +12V rail, but YMMV.
Click to expand...

I just tried to exchange the COM and ON wires to my relais (wich is not powered from the +12v rail like in that picture) but nothing changed, and I still have the meter showing different amounts of gain reduction as I change the ratio switch...when I bypass, the meter shows 0, right as it should be. could my 78L12 be broken? my relais seems to be ok...that's what I deduce by a continuity test...
Click to expand...

any help?

thanks...
 
Sorry for posting again, I don't want to be a PITA but, does anyone else has this problem?

When powering up, 1 out of 4 times (most likely when it has cooled down) the meter needle goes up halfway (~12dB reduction) the power led doesn't work. When I switch it off the meter needle slaps its way on the resting position and the power led blinks for 20ms or something. When I turn it on again, everything is back to normal?

Just the basic setup with led plus turbo board (although this happens even without the turbo board).

Do I need bigger 1000μF caps? Like, 1800μF?
Where do I start?
 
ytsestef said:
Sorry for posting again, I don't want to be a PITA but, does anyone else has this problem?

When powering up, 1 out of 4 times (most likely when it has cooled down) the meter needle goes up halfway (~12dB reduction) the power led doesn't work. When I switch it off the meter needle slaps its way on the resting position and the power led blinks for 20ms or something. When I turn it on again, everything is back to normal?

Just the basic setup with led plus turbo board (although this happens even without the turbo board).

Do I need bigger 1000μF caps? Like, 1800μF?
Where do I start?
Click to expand...

hi,
i don't know if you have already modded the original scheme to power up your clone correctly... so here's a link to an italian forum where Massimo Sutera has made the mod: http://www.proaudioteam.com/forum/index.php?topic=4.0

yes I know it's in italian but you can understand it anyways..he uses two 100nf/50v caps and a 1N4007 diode...

I hope it can help...
 

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