GSSL HELP THREAD!!!

[djob]

Hi everyone,
first off, thanks very much for all of your helpful content on GroupDIY. I have completed my GSSL build - audio kitchen pcb + expat CRC and Turbo boards.

Unfortunately something is wrong. The unit was passing audio but not compressing at all, and no light on the meter. So I began testing.

Output to controller and turbo boards showed no voltage.

Voltage pins on the audio input and output ICs, VCAs and NE5534s  looked healthy.

+/- 15v jumpers by the VCAs showed +/- 15v

7815 voltage regulator readings looked healthy also.
however the 7915 showed -6.3v at input and 0v output, and very hot to the touch!

Then suddenly while testing some of the resistors on the CRC board started smoking so I turned the thing off! Then disconnected CRC from main PCB turned on and it showed +/- 24v at output with no more smoke.

Anyone got an idea about this? Would really appreciate it, not so keen on the smell of smoke!
Cheers

 

[gyraf]

-15V-line shorted to ground somewhere
the burnt crc-board capacitors oriented wrong or too low a rated voltage (these are the only real reasons for burnt-out capacitors)

Try looking up similar problems earlier in this thread, you're not alone

Jakob E.

 

[djob]

Thanks for the support Jacob! I'll hunt for that. Btw I now realise it was a resistor smoking not a capacitor.

 

[Gufi]

Hi everyone,

I'm from Poland and I'm new here. I'm a musican and I want to start build some diy stuff for my studio.
This is my first project so I think I will be need some help. My first problem is an board. I buy all elements from Gustav's list but later I saw that the PCB is different than the one posted on the Jacob site in gerber's file format (rev.7). Does anyone have Gerber files to the new version GSSL? Near my house is a company that can quickly complete single board for not much money. I don't have software for coversion new Jacob's PDF to Gerber.

Thanks for help

Artur

 

[Neko Neko]

Sigh we'll having some problems with transformer. It's this one http://uk.farnell.com/jsp/search/productdetail.jsp?id=9530312&Ntt=9530312

I'm getting 38v before the bridge reflector & 26 on the + & - 15v rails respectively. Secondaries are wired in series. I have. Heckled I have been given the correct transformer & wiring is correct. It's dual primary & double checked there wired right I'm in the uk.

Any ideas what would cause this?

Just realised my voltage meter battery is dying so will test again with new one. This strange thing has happened before when battery dies.

 

[Neko Neko]

It was the battery in my multimeter. Voltages are fine

 

[Stratman]

Hi All,

I have been looking through my parts box and looking to get all the bits for a GSSL. I have a pile of Panasonic ECQ-B polyester caps 100nf and they are 50v. Is the voltage rating on these going to be an issue if I wanted to use them? (Yes I have searched the thread, it looks like this has been asked before, but I can't see an answer)

Stratman

 

[Harpo]

I have been looking through my parts box and looking to get all the bits for a GSSL. I have a pile of Panasonic ECQ-B polyester caps 100nf and they are 50v. Is the voltage rating on these going to be an issue if I wanted to use them? (Yes I have searched the thread, it looks like this has been asked before, but I can't see an answer)

50V rating is ample for these parts.

 

[Bassmann]

Hi DIY'ers

I'm pretty new to DIY and has finally gotten my act together and started out building my GSSL kit (from pcbgrinder).

Got a couple of questions. I bourght the case from Purusha (white with G-series written on it) and it seems to be prepared for a Sifam-type meter. I don't want to drill the frontplate out and use one of Gustavs (pure aestethics) fine looking meters so what should I use instead? I would really like a reliable meter for this build so it doesn't have to be the cheapest possible.

Another question. I bourght the kit and it came with the rev.7 pcb. So far I've carefully mounted all the resistors I was left though with a 130 Kohm res (and a 100 kohm blank spot in the meter sen. area) and a 47 Kohm res. which I did find in the schematics on the RAR board but without drillings for it? Should I mount this resistor?

On the pcb there's to res. around the VCA running the same trace rated 15K in the drawings it says 22K. The kit supplied components to fit resistors according to the drawings so that's what I did. Was I right in doing so?

What does the "Mangler 22R -> lus v.15V" mean?

This is a really interesting project (personally) and I feel I'm learning a lot though I have a pretty steep learning-curve going.

Thanks guys

Sebastian

 

[Bassmann]

http://gyraf.dk/gy_pd/ssl/ssl.htm

Well it seems every answer I'm seeking at the moment are right here...Sorry 'bout that I'm going to try to keep posts relevant.

Cheers!

 

[djob]

Just want to say thanks for your reply Jakob. Took a while but found that the 7915 was shorting to its ground pin. Swapped it out then no more of that issue. Then found that one channel was distorting heavily with massive gain. Turned out to be a defective 2181 VCA, swapped that out then no more distortion. Then found the machine was compressing like hell fury, turned out to be a defective TL074, swapped it out and now all is beautiful. Wow only wondering now whether these parts were bad to start with or that they were damaged somehow during the build? Cheers again

 

[Neko Neko]

Need a little bit of help with my gssl build. Have been debugging it for a few days but not really getting anywhere.

Symptoms are passes audio fine but no compression no meter ( well few millimeters of movement, meter is 500uA ) make up gain works.

I thought it was the side chain part of the circuit so I have checked there following info in the thread. Pin 1 & 14 look good on tl074 can see voltage affected by threshold & ratio & expected volts at 12 13 2 & 3. can also see volts dc & ac volts at pin 7. Can see very low volts dc at pin 8. Tl072 constant dc voltage at pin 1 & 7 & 100r res after.

I have taken out the bypass switch for now to eradicate that & make gain is jumper end on the board. I have changed the tl072 & tl074 no difference. One thing I noticed is that when the d wire affects the attack voltages after the resisters. Without the wire I get the bypass voltage (ie pin 14) before resisters & similar v after resisters, which I expect is correct function. With the d wire connected I get the same before resisters but 0v after. I have checked for shorts on main board in this path but nothing & it leads to pin 10 of tl074. This seems strange to me but searched & couldn't find correct voltage refs in thread. The release voltages seem low too 0.7v.

I am trying my best to learn the circuit & have experience debugging but just can't see the problem here. Any help much appreciated or list of correct voltage list.

Thanks

Gray

 

[Orchid0]

Hi, Building my First GSSL today.

Finally plugging it in I got audio passing through without power on from both sides which was nice (No IC's or VCA's connected)
I put my IC's and VCA's in, power on the unit and get a hum. Upon power off the LED flickers and speakers crackle. upon second power up the LED lights and  audio passes and is clear and audibly different then the original signal in a pleasing way. Turning knobs or bypass doesn't work... after awhile the 7815 regulator starts to get warm enough that you can feel heat off of it (but stays consistently warm. could be normal could not be). Meter isn't working either. -replaced regulators.. Doesn't latch anymore

I also don't understand what to short for the *HPF on the TL074 -still no compression

I used the 8027 1MA meter off of hairball audio. I tried shunting it as well.. Diode check still shows meter working.

Im reading correct voltages at the +/- 15v Rails. I double checked all the IC's based on PG 302 and they are all reading what they should be



I tried to find answers. thats how I stumbled upon the *HPF and some power latching problems but I can't find an answer Thanks!

 

[Orchid0]

Anybody?
Audio Played out of my laptop into it comes back into my pre's quieter but the tone is Fine.
Non of my knobs are operational. I double checked my bypass and its wired correct.

Input
Right

Pin 4- 14.97V
Pin 7- 14.9 V

Input left

Pin4- 14.9 V
Pin7- 14.89v

Output Right

Pin4-14.99V
Pin8-14.88V

Output left
Pin4- 14.98V
Pin8- 14.89V


VCA Right

Pin 4-15V
Pin 7-12.3V

VCA left

Pin4- 15V
Pin7- 12.4 v

Tl072

Pin4- 12.31V
Pin5- 0V
Pin8- 11.61V

 

[gyraf]

Voltages seem correct. Time for error tracing. Many examples in this thread.

Jakob E.

 

[leafcutter]

I picked up a set of boards a while ago (says rev 7 on the back) the guy that I bought them from said that some of the resistor markings on the board are incorrect. I'm wondering if this is true or is it that he had to change something because he was not using 2150's?

I'm going to use DBX 2150's, a picture of the boards is attached.

Can someone who is sure please let me know if the markings are correct?

Many thanks,

John.

 

[Gustav]

I picked up a set of boards a while ago (says rev 7 on the back) the guy that I bought them from said that some of the resistor markings on the board are incorrect. I'm wondering if this is true or is it that he had to change something because he was not using 2150's?

I'm going to use DBX 2150's, a picture of the boards is attached.

Can someone who is sure please let me know if the markings are correct?

Many thanks,

John.

http://gyraf.dk/gy_pd/ssl/ssl.htm

Check the last line of errata...

And this - http://diy.fischerworks.com/gssl_vca.shtml

I think that covers everything.

Gustav

 

[leafcutter]

Ah thanks Gustav!

I completely missed the errata.

Cheers.

 

[djob]

GSSL working awesome, thanks all! Only issue now is regarding the  8027-B 1mA 0 - 20 Hairball meter and have searched other posts on meter calibration extensively to correct it. Without calibrating the meter with adjustment to the 2K** resistor value the meter accurately reflects the db of compression at points 0db and 20db however at say 10db compression it reads well above 12db compression. Also if I calibrate 2K** resistor value to set the meter correctly reference the 10db compression point, points below 10db will be accurate but above 10db not, it will display 15db compression at approx. 20db actual compression and 20db at approx. 30db compression Is this an issue with the $25 sifam meter copy being inaccurate?, or must i calibrate something else. Make up gain and ratio resistor calibration makes no difference to this issue either. Failing all else do I just have to make a new backplate for the meter with values spaced in a non linear fashion from 0 thru 20. Anyone? Cheers!

 

[gyraf]

In my opinion, absolute meter precision is not a thing I'd worry about at all - specially not when you're knocking 10dB off.

Use your ears Always.

The GSSL is running at linear V/dB sidechain, meaning it's meter voltage output is close to absolute precision. Which means it's probably the meter who's not very linear (but certainly good enough for this purpose)

Jakob E.