GSSL HELP THREAD!!!

[ptron]

hello i made a thread regarding my build but been told better to post all here so here it goes!!
thanks in advance for any help.

1- first of all... all the wiring i think i get it now. i just want to know really what should i measure before i connect my jacks into my soundcard or my desk i dont want to blow anything !!  like ... the power lines should be near 15 and 12 volts as i have read 10% tolerance is within measure.. but something else i should be aware of? i dont wanna burn my adaptors. and i am, as u can see, completely unexperienced.

i have another question and its regarding my design.. my power switch well nothing i can do bout it now. i drilled  the holes in the left  and then realized the power line from the transformer is going to go from far right (from transformer) to front left (power swithc) and back again to fuse( far right)... is this going to bring any noise??
actually i got other problem.. mouser sent the wrong vcas... 2180A instead of 2181A... i got a couple of 2181B spare i could use for the vca to try it out but is there anything i got do other than bend the leg 4 of that 2180A for it to work on my 2181A setup?..

well it looked all good in the forum seemed that only one leg had to be bended and all would be good ... i pluged the VCA`s.. cool nice colour leds working except bypass .. i thought might be i twisted polarity so i switch... suddenly it dont turn on... i think the fuse is gone so i get another one..

ok its on again.. checked polarity on the bypass switch led and its correct.. still not on.. i try passing some audio thru to see if by aaaaaany chance it would be mercyful.. it is kinda passing audio but its really distorted and every now and then a really loud thump appears.. maybe some broken vca or short somewhere?.. i really am in the dark here with measurments or troubleshooting.. i see the 2 leds working and looks like a big improvement from yesterday. and makes me think not all is lost!

any more info that i need to give u ill be here waiting for your replys thanks in advance!!

btw i just turned it off and tried to turn on again and wont ... its the same thing been happening... first time i got it fired up i turned it on and off a few times and .... then just started doing this

Im not sure whats wrong with it.. The fuses break when i turn the machine OFF weird... Only thing i could measure is iec connector and measured 16-17v in one leg and 117v on the other... My fuses were 1/4A 250v.

(just to b clear... For measuring voltages on pins and power lines i should place the black(com) on my multimiter on to the ground and the red one to the place i wanna measure?

EDIT: (i got .5A 250V fuses in the end... im not sure why it was blowing the fuses maybe the short)
Thanks a lot any help will b greatly apreciated.

well thanks to kevin for the quick reply and lot of help now we are up and running ! went for a bigger fuse just for testing and comp is passing audio!! yay

.5A 250V not sure if they are slo blo but its working!!

WOHoooooooooo!!!!

.. all switches are working or so it seems.. but few issues..
first .. pretty loud hum/ hiss / noise ..

(when its off its really noisy!! )

AAa while measuring i found a short somewhere
DAMN it sounds nice! i need to keep troubleshooting will post more while i go

- voltages measure -14.75
                           14.54
                            11.80
                           -11.81
- also if i touch the frontplate or the switches it buzzes louder.. it doesnt when i touch anything else of the box... (not anymore.. only when shorted on the connector to the ctrl board)

thanks a lot !! everyone kevin dude thanks so much for your help it was a terrible day before those .5A fuses came along

wohoo adrenalin rush
-haha  weird.. maybe this tells u something too it still passes audio while in OFF ???!! much lower than on bypass mode or compressing... but ... passes audio when its off..
weird and it still is noisy as hell! any ideas on the noise issue?

i htink i found the problem.. or at least the one i was on about the header from gssl to ctrl board ... maybe some weirdness there.. it was very hard to connect to its other part.. and possibly broke something underneath. is there a way of fixing this kind of issues? it still works fine but if the noise could be coming from there it is a problem innit

the short makes also the power on LED to change its polarity if thats of any help... but just touching the board will swap it back and will be compressing.. touching the board again will make it really dodgy and no control works..

 

[ptron]

well ive narrowed the main fault to that header i hope i didnt break the pcb traces when trying to insert it..

the only thing is this really loud hum and buzzing sound when its off. and not so loud but very audible hum when its off.. it has to be related one to the other i guess but i hope someone has an idea.. still passes audio when unit is off altho very very quietly.

im going to try and resolder the header see if i have any luck or get a new header in there if the traces arent broken.

any ideas ?

thanks!

 

[bbben]

Hi there !!
Here is another GSSL builder SOS... Actually, the thing is that the compressor works fine !! Good news, why are you posting here then ? However, when I power it on, most of the time, I have a trouble with my 7815 which doesn't start everytime (sometimes yes, sometimes not)... I tried to change it to another model, but same thing happens... It might be a ridiculous thing to fix, but I am stuck here !!
Have anyone experienced the same problem ?!
Thanks,
Ben

 

[ilfungo]

Ciao bbben
I do not know if this is your problem, but long ago I found on an Italian website, this mod to the power of SSL.....
http://www.groupdiy.com/index.php?topic=47.4400

 

[bbben]

Hi ilfungo,
Yes that is exactely this latch-up problem... Thanks a lot !!
Actually, i noticed that the 7815 starts when I just short circuit (really quickly) 2 "legs" of my 7815... Just to make it start !! And then, no problem with my -15V...
I will try other brands of 7815 like reported in this thread (http://www.groupdiy.com/index.php?topic=440.0), and if nothing works, will try this cap/diode mod... (There is also some information on page 177/178 of this thread)
Here is the link to the original site in italian (I think it is, isn't it?) : http://www.proaudioteam.com/forum/index.php?topic=4.0 !!!

Thanks... I will keep trying !!! =)

 

[ptron]

coool so i fixed the short circuit the header did break the solder pad .. but i resoldered it very dodgy behaviour but it is working now and no short circuits or anything! ... just few things...

-the hum very loud .. and ocational buzzing... very quiet buzzing sound.  when i touch the outputs where its connected from xlr to trs it buzzes louder and it doesnt on the inputs..

-buzzing when i touch the faceplate or any of the switches or pots that are in contact with it. EDIT : but not anymore... maybe something related to the shortage but not sure..
the buzz /hum makes it compress slightly on -15treshold (with the thrust filters it compresses much much more...) calibrated somewhat them thrust filters with that noise

-no more LEDs going berserk..

-its still passing audio while in off but very low volume, not distorted anymore but its very noisy when off. (more hum and lot of buzzing..)-when off, noise seems to be about -30db when i plug the input jacks.. when they are unplugged goes up to -20db
when it is on, noise is a bit lower than that

-for the rest i think its great!! working like a champ! with .5mA fuses.. ill go tomorow downtown see if i can get them smaller ones.. but if it was blowing up the 1/4A fuses.. would that be because of the previous bad header connection and u think it wont be doing it anymore? just to know maybe something wrong with something im not aware of
(of course im not aware of anything but success!! ;D)

-its also making a weird sound when powering off.. like pitch down 303 kinda thing.. sometimes it does it sometimes it doesnt.. when meter tells me it is compressing the sound appears when i power off, if not it doesnt... i guess kinda normal.. its almost the same sound my synth does when it powers down


new power measurments:
15v = 14.71
-15v = -14.93
12v = 11.93
-12v = -11.90
thanks!

ps... how come it still pass audio while off??? im not understanding that... hum goes away when i unplug the machine obviously but it keeps passin audio.. hrmm

got it snorted now... cable from star ground to positive pin of the meter made it.. not sure why how .. but cool silent

 

[ej_whyte]

I'm having problems fitting my turbo board.

Previous to installing it, everything was working fine. Now i have added the turbo board but IC the voltages are all over the place! I have checked the voltages going to the board, all checks out at a steady +/-12v. Here are the voltages (all taken with silence on the inputs):

VCA:
pin 1: -11.88
pin 2: -0.32
pin 3: -0.32
pin 4: -0.32
pin 5: -0.22
pin 6: -0.32
pin 7: 0.53
pin 8: started around 9.50, but exponentially dropping (i waited until it hit 8.70 but it took a loooong time)

TL074
pin 1: 10.51
pin 2: 10.90
pin 3: -0.32
pin 4: 0.53
pin 5: -0.32
pin 6: started around 9.50, but exponentially dropping
pin 7: started around 9.50, but exponentially dropping
pin 8: 11.54
pin 9: 11.09
pin 10: -0.32
pin 11: -0.18
pin 12: 0.00
pin 13: -0.32
pin 14: -0.32

As i have said, i have checked the power supply voltages and they are all ok. I then checked all the resistors and caps. Caps are all good. However, i think i must have had a duff batch of resistors. Although the colour codes are right, some of the resistors are waaay out. For example, all of the ''20K'' resistors are actually only 14K, the "3M9" resistor is actually only 800k, and the "1M8" resistor is only 670k. Now obviously the main priority is to change these out for the right values, but could this be what is causing my wierd voltages, or is it something else totally unrelated?

Cheers

 

[ej_whyte]

O yeh and i've checked the polarity of all diodes + the electrolytic, and had a thorough check for solder shorts.

Cheers

 

[Harpo]

...As i have said, i have checked the power supply voltages and they are all ok.

obviously not. Turbo pcb supply TL074 pin4 should read +12VDC and pin11 should read -12VDC in respect to reference voltage 0V that should be connected to turbo pcb as well. Read the TurboInstallationManual.pdf again and double check wire connections.

...However, i think i must have had a duff batch of resistors. Although the colour codes are right, some of the resistors are waaay out. For example, all of the ''20K'' resistors are actually only 14K, the "3M9" resistor is actually only 800k, and the "1M8" resistor is only 670k. Now obviously the main priority is to change these out for the right values, ..

These values obviously are measured in circuit (with other parts being in parallel and/or series, F.I. your 20k on turbo pcb has at least the series string (20k+10k+20k)=50k in parallel, giving 14k29). You'd have to lift one parts end to get it out of circuit and have to measure again. This will be your least priority to double check and probably not neccessary at all if the unit was working before.

 

[ej_whyte]

...As i have said, i have checked the power supply voltages and they are all ok.

obviously not. Turbo pcb supply TL074 pin4 should read +12VDC and pin11 should read -12VDC in respect to reference voltage 0V that should be connected to turbo pcb as well. Read the TurboInstallationManual.pdf again and double check wire connections.

...However, i think i must have had a duff batch of resistors. Although the colour codes are right, some of the resistors are waaay out. For example, all of the ''20K'' resistors are actually only 14K, the "3M9" resistor is actually only 800k, and the "1M8" resistor is only 670k. Now obviously the main priority is to change these out for the right values, ..

These values obviously are measured in circuit (with other parts being in parallel and/or series, F.I. your 20k on turbo pcb has at least the series string (20k+10k+20k)=50k in parallel, giving 14k29). You'd have to lift one parts end to get it out of circuit and have to measure again. This will be your least priority to double check and probably not neccessary at all if the unit was working before.

Ok thanks for the info on the resistors, school-boy error on the measurements!

What I meant when I said I had checked the voltages going to the board was literally that, I checked the voltages arriving at the +12/0/-12 header connector. I knew the TL074 should be showing the +/-12v on the appropriate pins, but couldn't understand why it wasn't if the supply to the board was good, hence posting here for some help. I'll give all the connections another check though.

From my understanding of the schematic, the +/-12v goes directly to the TL074, and the only components related are the 100n caps, so I guess I should recheck those again? Or is there something else it could be?

Thanks again,

 

[ej_whyte]

Ok its all sorted, it was just down to a major school boy error on my part. I'm so embarrassed about it im not gona tell you what was wrong, just suffice to say it was one of the stupidest mistakes I have ever made!

Thanks for the help Harpo

Cheers

 

[Harpo]

You'll need a little luck that your turbo VCA has survived the reversed signal/power connectors.

 

[ej_whyte]

Yeh, luckily though I wasn't that stupid to put them in without checking the voltages

 

[Bob1991]

I'm very close to the fault in my not working GSSL.. which was/is not compressing..
After hours of checking for shorts, and nothing, I got a oscilloscope which I used to measure the signalpath.
I removed all THAT's (and bridged pin 1-8 with a piece of wire), and checked the audio VCA control voltage input (pin 3) on a scope, and saw a moving line depending on the volume of the music, and the beat of the music.. The speed and amplitude of this movement was working in relation with the ratio/attack/release knobs..

So I put back in the sidechain VCA, but gone was the control voltage for the audio VCA's.. So I removed only the sidechain again(and bridged it), and now the audio VCA's are controlled with that control voltage.. And muting/compressing my audio depending on the volume of the audio.. My knobs are working too, and the GR meter is working as it should work.. Only the threshold isn't working

But still, there has to be something wrong with the sidechain circuit, since the audio is passing through with no problems, the knobs work, the meter's working, but it all stops working when I put in a sidechain VCA (which isn't broken).. Somebody any tips where to specifically search for errors in the circuit?  Can I assume that the TL074 and 072 stages are all working fine? (because of the working knobs) Oh, bypass is working too btw.. Really no shorts somewhere, checked continuity, resistors, diodes.. it drives me crazy

 

[ptron]

damn sounds like hell man :/ i hope u find that fault soon!

myself have been for days testing it with no dodgy behaviour it has passed every test.. tried it vs thermionix culture phoenix mastering edition  and still much less noise from GSSL (couldnt beat STC-8 but that was a long shot) really fine piece of work thanks a lot yall involved in the development of this great comp!!! ssc board is awsome !!! great tool for electronic music. turbo well what can i say 

if anything the distortion on high ratio and low treshold and some of the thumping i think i could use a quad vca circuit .. and some transformers for output agrrr!!

i dont know where else or how to look for this information..

1- i think there is an upgrade to use 4 paralell 218X and different driving amps like opa or something else that is more precise than tl and ne ??. i think i remember livingnote or kingston saying something about this.
i seen threads about paralell vca but nothing concrete.. even if i was to veroboard it or etch the pcbs  i got lots of fun doing that!

2-- a way of getting it all in the regular gssl is my problem i dont know what id need to take in or out. If i could see an schematic of it paralell vca inside the whole circuit would help tons!!! ive seen THAT shcematic i got it somewhere but never seen that schematic inside the dbx emulation circuit or how to set up on GSSL :/

3-do i have to change anything if i was using 2180A? i guess the trimmer parts would go away ..

4 -other question.. anyone could say if 2180 are better than the trimmable ones? can i get a cleaner sound with 2181A or 2180 are absolutely the lowest distortion i can get?

5- also .. now that the circuit is working i added the mod for second RC loop.. i sorta like it but i think i want one really fast position on that release .. i would like to know more or less how many ms would be the shortest release possible  on tl074 ? is the 180K*0.47U the fastest it can release? could i go 91 or 100k ? (those are just the ones i got spare here..)

thanks !!

 

[Siegfried Meier]

Hey guys,

Just built up my 10th GSSL, and I've been very successful with these-I check all resistors with a meter as I can't see/read the colours very well.  On this 10th unit, audio is passing, clean as a whistle (with that CRC power board), but I cannot get any compression to happen.  The bypass switch appears to work correctly as I can hear the makeup gain drop when out, but not a shred of compression or reading on the meter.  I've gone back and checked the resistors with a second unit I've built (readings don't always show accurately in circuit, but they match across to the other unit), swapped chips, checked for shorts and faults but cannot find a single thing wrong with it...

Any advice on where to look when there's no compression happening?

Much appreciated,
Sig

 

[Bob1991]

Siegfried, your GSSL appears to have the same problem as mine  ???

Remove the sidechain vca, and bypass it by linking pins 1 and 8 with a piece of wire.. Do you get a strange kind of compression/gain reduction (and a moving GR meter) then?

It won't solve your issue, but maybe you have exactly the same wrong thing as mine.. I can't find any faults either..

 

[Siegfried Meier]

Nope, no compression, no weird sound, no meter, nothing is different when I do this...

Anyone else have any ideas?

Is it possible to wire up the bypass where it affects the makeup gain, but does not compress?  Curious if something is wrong there with the wiring...

 

[Siegfried Meier]

OK, found a short in the sidechain section.  First short I've had in 10 units!!!!  Damn boards are so tight, I think this might be the last GSSL I'll do - I had a bunch of extra boards and this is the last one.  Check for shorts man, I went over and over and over and still missed it.

I have ratio, attack, release and makeup working, but my threshold does nothing...only thing left...

Thanks!
Sig

 

[Siegfried Meier]

Been over this thing for hours...does anyone know what can cause the threshold pot to not function?  It's a high quality alpha 50k.  I've measured the pot across the terminals, seem to be ok.  What can cause this?

Thanks,
Sig