GSSL HELP THREAD!!!

[Pri]

Hi guys,
I just came around to thank all of you. I just got the transformer, hook it all up and it work right away and it sounds great. I'll post some pictures when i have the case
thanx again jakob, gustav, jaydee and all of you

Niklas

 

[gyraf]

:thumb:

 

[5meo-geo]

ello folks
i have a small question to ask (maybe its been discussed earlier but i couldnt find it in this topic)

what changes i need to make to use 0.2 mA meter coil???

thanks in advance

 

[mathflan]

put a 2K trimmer instead of the 2 K meter resistor, see schematics.
CAlibrate your meter like this :

FRom a previous jakob's post

Put in a signal, threshold at max (no gain reduction)

Adjust output level to 0dB (or 1V AC)

Turn threshold downwards untill level drops to -6dB (or ½V AC)

Check that your meter reads 6dB GR.

If it reads more, use larger series resistor.

If it reads less, use smaller series resistor.

You could possibly use a trimmer in series with the meter for final finetuning.

Don't expect the dB scale on the B* meter to show anything linear - it's some homebrew scale. You need a linear meter with a linear scale to read accurately.

Jakob E.

 

[mathflan]

HI,

My SSL worked good some days ago but Now I have a big trouble on It.

In fact I put a 0db signal 1Khz into the SSL so as to See how that THe SSL threat the signal.

with the SSL bypass , I have 0dB, GOOD.

I turn the THRESHOLD at 0, so NO compression, with Make up at 0.


I read

RATIO 2:1

- 24,5 dB

RATIO 4:1

- 31,5

RATIO 10:1

-34

with Make up at MAX,+20.

I read


RATIO 2:1

- 8,2 dB

RATIO 4:1

- 15,2

RATIO 10:1

-17,6


Before, When I turn the threshold to have a defeat of -10db for example, I could Recover the volume with the make up, now I can't...
SO I don't think It's good, do You know What can I check on the board to find the trouble?

thanks

 

[5meo-geo]

10x man
it was easy one

 

[Dor]

hello, would someone be so kind as to post the part number for the IC socket for the vcas? I ordered from the PDF but am missing the correct part # for this particular socket

Thanks in advance!

D

 

[BladeSG]

I don't know if there is a correct part for this. You can cut a 16 pin IC socket in half or just cut down some IC socket strips like this:

 

[fucanay]

I just got my second GSSL up and running last night and there is something very screwing going on. I've read all 100 pages of this thread today and one person asked about the same thing, but it just died there.

What's happening is the meter goes crazy when the threshold pot is turned. I've compared everything with the first unit I built and everything is the same except the voltages I'm getting on the TL072 and TL074.

Here is what I'm getting:

First Unit
----------
TL072
1. -3.06 through +3.08 when thresh is turned
2. 0
3. 0
4. -12.16
5. 0
6. 0
7. 0 through -1.95 when thresh is turned
8. 12.17

Second Unit
----------
TL072
1. -3.06 through +3.10 when thresh is turned
2. 0
3. 0
4. -12.26
5. 0
6. 0
7. 0 through -1.95 when thresh is turned and voltages go crazy when thresh is turned
8. 12.20

First Unit
----------
TL074
1. -.10 through .19 when thresh is turned
2. 0
3. 0
4. 12.17
5. 0
6. 0
7. 0
8. 0
9. 0
10. 0
11. -12.15
12. 0
13. 0
14. .38

Second Unit
----------
TL074
1. .21 and spike wildly when thresh is turned
2. 0
3. 0
4. 12.20
5. 0
6. 0
7. 0
8. 0
9. 0
10. 0
11. -12.26
12. 0
13. 0
14. .14 and spike wildly when thresh is turned

What I've done so far is to change all of the chips in that area (072/074/2181LB), compared and traced wiring on both units and changed the voltage regulators. None of this helped. I also went back and searched for solder bridges and check the wires going to and from the front panel PCB.

I feel like the problem is right under my nose, but I'm lost at this point.

Any ideas?

Matt

 

[fucanay]

This is becoming a habit for me in this thread. I figured the problem out before anyone had the chance to help. It was the standard problem of "check for solder bridges"! I found one in a place I didn't expect and it fixed everything. It was between pins 5 and 6 on the 5534 in one of the emulation circuits. If anyone else has this problem, this might be a place to check. I found it when I discovered that the chip was getting a little bit warmer than the other one.

So thanks to Jakobs standard reply, I found the issue. Is it me or is trouble shooting fun when you actually find the problem?

Thanks Again

Matt

 

[fenderfred]

Hello!
I need some help
I can't get +15v out of 7815

on power section:
7915 : in-22.8v / out -14.9v (good)
7815 : in 22.5v / out -0.06v (???)
78L12: in 22.3v / out 11.9v (good)
79L12: in -22.7v / out -11.9v good)

i used reg TS7815 that i replaced with a new one but no change (-0.06v)

i'm going mad!!!

 

[fenderfred]

Sorry !
not -0.06v but -0.6v

 

[gyraf]

As always, look for the shorts..

 

[Greg]

[quote author="fucanay"]Is it me or is trouble shooting fun when you actually find the problem?[/quote]
I'd have to disagree with you on this one. I think troubleshooting is a royal pain in the ass. Just today I was checking a PLC panel and found a short at one of the breakers... :roll: Took me two hours to find the problem. But fixing things is always rewarding, so I'd agree with you there :thumb: .

 

[OffChip]

Hi,

I need some advice for my SSL clone.
I bought a 1U schroff rack case, and I noticed the useable height of the case is only about 34mm. The power transformer I bought has a height of 39mm, so obviously it won't fit in the Schroff case. :?
So I was looking for another transformer and found one from Farnell: 9532161. But I'm a bit confused because in the specs a bolt length of 40mm is mentioned. And this is larger than the height of my rack case.
Can somebody confirm it will fit in my box, because I don't want to risk buying another part which I can't use.

Thank you very much!

 

[fucanay]

[quote author="Greg"][quote author="fucanay"]Is it me or is trouble shooting fun when you actually find the problem?[/quote]
I'd have to disagree with you on this one. I think troubleshooting is a royal pain in the ass. Just today I was checking a PLC panel and found a short at one of the breakers... :roll: Took me two hours to find the problem. But fixing things is always rewarding, so I'd agree with you there :thumb: .[/quote]

Don't get me wrong. I would prefer to have everything work on first power up, but I also wouldn't be learning anything. I've only been at this a couple of months and this time period is critical to learning to read schematics and trace components on the boards. Every little error corrected is a new thing learned. Very exciting to me.

Someday, I would like to be able to look at a schematic and build something, so this trouble shooting is very useful to my overall knowledge.

Matt

 

[fenderfred]

Thanks Gyraf
I'm looking for...
I read a topic where you talk about problems you had with 78XX.
Mine are marked TS7815-5C4CZ.
Do you believe they're in fault?

 

[Ozzie]

Hi!
I finished putting together my first GSSL two weeks ago, but ran into problems...
First, it was a faulty VCA (2159's from a behringer ultramix, I guess I "cooked" some while desoldering them with a heat gun). After solving that (and two shorts), I have another problem:

- I input a +6dBu (1.54V), 1kHz sine wave
- In bypass, I get appr. +11dBu (2.8V) on the output
- With Attack and Release set to Fast and Makeup to zero, the meter shows gain reduction while turning the Threshold.
- However, with Threshold fully turned I get these numbers:

Ratio 2 - GR 4.7dB (1.67V out)
Ratio 4 - GR 5.9dB (1.45V out)
Ratio 10 - GR 6.4dB (1.36V out)

It seems that it's not compressing "enough".
I also tried lowering the input to -25dBu (-19dBu out), and at Ratio 10 with the Threshold fully turned, it showed a GR of 3dB (-22dBu out).
Also, the Makeup pot only adds 1.5dB at any setting.

I have tried swapping the VCA's around with no change. The meter is slammed to the right while the Threshold is fully turned, but it's not really calibrated (300uA meter with a 6.7k resistor in series instead of the 2k), so I guess it's not really trustworthy (5.6V at the meter terminals without the meter hooked up).

My voltages all seem ok.

Does anyone have any idea as to what the problem might be?
Grateful for any help I can get!

 

[udenjoe]

[quote author="Ian MacGregor"]Carbon resistors are fine. 5% is probably just fine as well. I would, however, buy 1/4 watt resistors and NOT 1/2 watt resistors. The PCB layout is a little cramped as it is.
Ian[/quote]

Well, I finally found the question, page 26. How about an index? Anyway... :wink:

Ok, I bought some 1/2w 1% resistors from Mouser. I didn't order them all, just about $20 worth I could afford. I needed some to finish my Mini Synth.

Would it be ok to use the ones I got 1/2w while ordering 1/4w, to fit better? How about mixing tolerances? Does it really matter if or what you mix (wattage and tolerance of course) the resistors in the GSSL? If carbon is fine can you mix in metal too?

 

[gyraf]

..the ssl is happy with just about any resistor you can fit on the pcb's..

Jakob E.