GSSL HELP THREAD!!!

[artosaudio]

unfortunately, the replacement makes no difference or whatsover. maybe my tl074 is faulty then...

 

[artosaudio]

:-[ can somebody help me, I'm lost here.... ???

 

[migidee]

I was trying to order some  110n polypropylene capacitors from digikey and they dont carry them anymore(p4593-nd)  and when i asked for a replacement the new capcitor uses a stack metalized plastic film dielectric.  in the BOM  it specifically states to use polyester capacitors, so will the replacement part not be up to grade for the gssl?  is there somewhere i can still find 1oon polyester capacitor?

 

[regularjohn]

I've used metal film before.  No problems, just a little bit different sound.  BOM's are only guides, not set-in-stone mandates.
You can get 100n WIMA film caps from Mouser.

 

[migidee]

does it sound different like better or worse? 

I realize that technically they are both capacitors with the same rating and the circuit will work with both, but i would like to make it sound as close to the ssl as possible so different doesn't sound that great to me. i wouldn't have asked but the tech i talked with at digikey gave me a replacement part with different a dielectric, and i see that its used in the audio path so i figured it mike make it difference in the "sound" 

Does anyone know where to find 50v 110n polyester caps at?  the tech at digikey told me that they still make them, but they wont carry them.  ???

 

[ken_bless]

On the electrolytics, does upping the voltage rating do any harm, assuming they still fit on the board?  Thanks.

 

[artosaudio]

Afters a couple of more hours still the same,

distorted signal on the left and clean an the right, no compression and the only working control is make-up (in compressor IN that is)
anyone?

 

[johnmellor]

Afters a couple of more hours still the same,

distorted signal on the left and clean an the right, no compression and the only working control is make-up (in compressor IN that is)
anyone?

vca's in the right way? checked solder joints from control board to main board?

 

[artosaudio]

yes solder joints double checked, vca's also in the right way, with pin 4 bended...

thanx

 

[mac]

Hey Ken,
generally higher v rating is not a problem, but as you say - physical size is often a problem.
You might want to think about vertical height too. Often the bigger caps wont fit in a 1RU case.


I am trying to trouble shoot my build. 78L12 is still giving me grief (i have tried three brands now), and swapped out the resistors for 100r (thanks Mark).  I have just done the diode mod (thanks harpo)....
Time will tell if this has now been resolved, as it was only intermittently latchining.



Mac

 

[artosaudio]

After swapping vca's left and right are reversed, meaning right channel distorted, other clean. Does this mean i blew up my vca's or something? Still no compression though, on neither channel

hmmm ???

 

[johnmellor]

After swapping vca's left and right are reversed, meaning right channel distorted, other clean. Does this mean i blew up my vca's or something? Still no compression though, on neither channel

hmmm ???

make sure its the same way as this http://www.groupdiy.com/index.php?topic=35352.msg433433#msg433433
nice clear photo's, unison build

 

[artosaudio]

it is, as far as i can see, it really is...

after swapping the sidechain vca for the right (faulty i suppose) one, I get in compressor IN a huge compression on my meter but no signal at all on the left and just clean signal on the right. Oh and the make-up doesn't work anymore. What's going on? I'm going insane :-\

 

[artosaudio]

ok i've noticed something else happening. When I turn the threshold knob, the meter reacts so it seems quit accurate however it immediately goes down again, en then when I turn it back my meter throws itself to maximum gr and goes back again. Also when I power up while sending audio to the input it takes a while before one channel is audible, is this something anybody encountered before. Oh and I allready swapped the 074 and 072 so those should be fine

 

[artosaudio]

Sorry for stalking all off you but....

Here are my tl074 measurements

tl074 geen input
pin 1 0.17
pin 2 0
pin 3 0
pin 4 -12.09
pin 5 -0.01
pin 6 0
pin 7 0.78
pin 8 0
pin 9 0.14
pin 10 0
pin 11 12.18
pin 12 0
pin 13 0
pin 14 0.19 (ratio 1:2) 0.34 (tatio 1:4) 0.38(tatio 1:10)

If I remember correct pin 1 & 7 are suppose to read 0v right?
Is this some kind of indication

 

[regularjohn]

Artosaudio, if your meter reacts while turning the threshold knob and you've got no audio running through the comp, or if it overreacts while you have audio running through the comp, you likely have a problem with one of your power rails shorting to ground.

The ONLY voltage measurements that matter on any of the opamps are the voltage rails (+/-15 and +/-12) on the appropriate pins.  All other pins are subject to change depending on the audio (or lack of audio) running through the comp.

 

[artosaudio]

That indeed is probably the case. I've shorting it on purpose and it's indeed the same effect. What would be the best way troubleshooting this as i've stairing at the board for hous now! Any ideas? Thanx alot!

 

[regularjohn]

Really the only way that I know to find it is with your eyes.  You can figure out which rail is shorting by using a continuity meter.  That might help narrow it down.  But finding the exact spot can really only be done visually. 

Do you only have a gssl pcb, or do you also have a supersidechain or turbo as well?

Your exact problem happened to me one time when I mistakenly attached the ground of a supersidechain to the +15V on the gssl pcb.  I used those larger solder pads around the audio vca's to tap the rails for the supersidechain, and between flipping the pcb over I apparently got mixed up which hole was which.  It took me a couple hours of just visually tracing through the circuit to find my mistake.

 

[mac]

Hey guys,
mine is up and running and sounding great straight off.

The diode seems to have done the trick on my 12v rail (20 or so startups now and no latching up!!)....

Now for the add on bits, SSC illuminated switches, extra relays etc...

thanks for the advice!! ( I love this place)...

Mac

 

[migidee]

so i did a little research and mouser carries polypropylene caps at 100v ratings that are small enough to fit.  they are alittle more expensive(.56 us dol. if you buy ten) im guessing from the upsized voltage rating, but  if anyone wants them the part # it is 505-mkp20.1/100/5