GSSL HELP THREAD!!!

[gyraf]

..check for shorts and component values. Use a magnifier and a beepophone (sp?).

read earlier in this thread - we have MANY posts about raw error-tracing

Jakob E.

 

[Graph]

..check for shorts and component values. Use a magnifier and a beepophone (sp?).

read earlier in this thread - we have MANY posts about raw error-tracing

Jakob E.

Edit: Some cold solder was missing... but the beeper worked anyways, i just apply some more solder in some pads that beeped, but needed more solder, and worked out!

Thanks everyone I have my GSSL working, Thanks Jakob for the great project, Gustav for the Kits and Frank for the Front Panel(Which says Compresso instead of compressor )

 

[cray]

Hello guys.
After a log reading , I have not clear if i can connect the lamp of a berhinger meter on the "Power on Led pcb control board".

I have decided not use a led on the front panel , just the meter shows if its powered on .

thanks in advance.!

 

[gyraf]

Don't use the 12V-led-supply on the control board - we don't want to load the 12V reference lines unnecessarily.

Some users report that their 78L12 overheats and shuts down the +12V reference line when a high-consuming LED is mounted.

Take 12V to LED from the aux. 7812 regulator (if you have that mounted) or from the +15V line

Jakob E.

 

[cray]

Don't use the 12V-led-supply on the control board - we don't want to load the 12V reference lines unnecessarily.

Some users report that their 78L12 overheats and shuts down the +12V reference line when a high-consuming LED is mounted.

Take 12V to LED from the aux. 7812 regulator (if you have that mounted) or from the +15V line

Jakob E.

Thanks  Jakob.

no 7812 mounted .
Do you mean . directly from the secondaries , ?  thats make sense 

 

[dissonantdissident]

Alrighty,

Finally got a chance to get back to mine.  Went poking around, today, and noticed that the chips I got were the pre-trimmed 2180s, not the 2181s that were in the schematic.  Totally my bad for not reading the silkscreening.  So, looking back at the thread, I saw folks would bend or remove the 4th pin, which makes sense(I'd assume I was basically at double the proper trim value).  Did that to all three 2180 chips and reinstalled.  No change, still distorting, when compressing.  It seems to be less distorted, but I haven't tested it, in a couple weeks, so I'd be a poor judge.

So,(while I think the answer would be no) would having had installed the 2180s, without bending the pin have spoiled the ICs?  Looking through the thread, it would seem that It shouldn't matter, whether or not I bent the pin, but I'd love for an order to mouser to be the answer. 

Also, there is a thread about using 2180 chips and certain resistors(though there didn't seem to be a concensus) that should be removed, but the thread is quite old, and I don't know if that is still true, seeing as I have the newest board revision.

glenn

ps- could someone point me to the page number containing the info about checking the circuit with a "beepophone".  Never heard of one of those.  I've gone through tons of pages of tips, but haven't found this.  Alternately, would a normal circuit tester work?  Like this?

http://www.harborfreight.com/circuit-tester-30779.html

 

[Gustav]

Alrighty,

Finally got a chance to get back to mine.  Went poking around, today, and noticed that the chips I got were the pre-trimmed 2180s, not the 2181s that were in the schematic.  Totally my bad for not reading the silkscreening.  So, looking back at the thread, I saw folks would bend or remove the 4th pin, which makes sense(I'd assume I was basically at double the proper trim value).  Did that to all three 2180 chips and reinstalled.  No change, still distorting, when compressing.  It seems to be less distorted, but I haven't tested it, in a couple weeks, so I'd be a poor judge.

So,(while I think the answer would be no) would having had installed the 2180s, without bending the pin have spoiled the ICs?  Looking through the thread, it would seem that It shouldn't matter, whether or not I bent the pin, but I'd love for an order to mouser to be the answer. 

Also, there is a thread about using 2180 chips and certain resistors(though there didn't seem to be a concensus) that should be removed, but the thread is quite old, and I don't know if that is still true, seeing as I have the newest board revision.

glenn

ps- could someone point me to the page number containing the info about checking the circuit with a "beepophone".  Never heard of one of those.  I've gone through tons of pages of tips, but haven't found this.  Alternately, would a normal circuit tester work?  Like this?

http://www.harborfreight.com/circuit-tester-30779.html

Are you using the latest revision PCB with the % signs at some component slots? In that case, all you have to do is leave those out to adjust the circuit for use with the pre-trimmed VCAs.

Im doing to guess and say a beepophone is a meter set to continuity. It will beep when continuity is measured.  (usually a speaker-like symbol on the meter). I have a small gadget at work that does nothing but this also. Just a box with small speaker and two probes sticking out.

Gustav

 

[gyraf]

Distortion while compressing, but not while not-compressing points exclusively to a sidechain error: Somehow you must have too large an AC component in the control voltage going to the VCA's.

You are aware that fast timing will always distort low frequencies to some degree?

Do you see release times that are approximately correct (meter reading should reflect this)? Otherwise you should look at the attack/release timing circuit/switches on the frontpanel-board.

The usual reason for overall-distortion-when-compressing is forgetting to mount the small wire link on the frontpanel-board, just above where the meter connects. But I think we've mentioned this earlier?

Do you have access to a scope? If so, look at the raw sidechain CV at the meter output.

Jakob E.

 

[dissonantdissident]

Thanks for all of the info, Gusatv!  Turns out that I just didn't understand the comment about the wire on the frontpanel PCB.  I thought you were talking about the main board and didn't even check there.  Soldered in some resistor lead, and bingo, GSSL's awesome "glue" came right out.  Goodbye distortion!

Onward, to ordering the second sidechain board!

Thanks so much, to everyone that helped.

glenn

 

[mike76]

Okay, parts arrived an just started. A noob question: what is the smallest  resistor wattage I can solder in the PCB? I accidently ordered a few  mini resistors with 1/3 Watt  an some "bumble bee" with 2w is that relevant or could I use them? Thanks.

 

[Potato Cakes]

Unless it's specifically labelled on the BOM, the resistors being used are usually 1/4W.

 

[mike76]

Unless it's specifically labelled on the BOM, the resistors being used are usually 1/4W.

Thank you!

 

[Potato Cakes]

If anyone is about to finish or mod their GSSL, could you measure the voltage you are getting on Pin 5 of the sidechain VCA? I know that hundreds of people probably have built this with the new BOM and PCB layout with no issues on the first go, but I keep getting hung up on the resistor values that seem to differ on the schematic (3k9) and what is printed on the PCB (5k1) for the resistor that is in series with the -12V rail and pin 5.

So far, I've gone through and removed and resoldered the connections on the sidechain and VCA sections on the main PCB and selector switch area. I've double checked my resistors (I had to do it by color since on some of the higher values it won't read it's actual resistance while in place) and put in new TL072, TL074, and THAT2180B's with pin 4 removed. I did have a bad solder joint on the input section that caused one side to be down 6dB and now that has been corrected. It passes audio cleanly and the make up gain works properly. The threshold knob seems to be soldered as the assembly guide shows. I saw about halfway through this thread one guy had the same problem and it turned out to be a tiny solder bridge, so I have been looking very carefully for any unintended connections, but none so far.  Capacitors on the main and rotary switch PCBs seem to be oriented correctly. I still believe it is some silly error on my part. I have been able to troubleshoot various other builds and eventually figure it out yet the answer to this mystery has hidden itself very well.

I would appreciate it if anyone could either let me know their voltage on pin 5 of the sidechain VCA or if they could point me in the right direction that would be super great.

Thanks!

Paul

 

[Harpo]

...the voltage you are getting on Pin 5 of the sidechain VCA?

The VCAs pin5 is a current source pin. This current is measured in mA (not in V).

I keep getting hung up on the resistor values that seem to differ on the schematic (3k9) and what is printed on the PCB (5k1) for the resistor that is in series with the -12V rail and pin 5.

3K9 is setting the current for the +/-12VDC supplied THAT218x sidechain VCA.
5K1 is setting the current for the +/-15VDC supplied THAT218x audio VCAs.

 

[Potato Cakes]

Thanks Harpo,

I put the resistor back to the values as printed on the circuit board and will try changing out some capacitors. I'm going to order another kit next week and try building one fresh. I'll still try to keep seeing if I can get this to work, but this may wind up just being the cost of learning.


Thanks!

Paul

 

[krm76]

Hi there,

I'm about to start this GSSL project. I wonder if on the PSU section you guys have used 1000uF/35v or 1000uF/63v?
I have a couple bom lists and on both they show up 1000/63v caps, since on GUSTAV board says 1000/35 I'm just curious.

Thank you

 

[mike76]

I am waiting for the last resistors to get the party started I've got another question regarding the power-led: it is a standard red led. What Kind oft resistor should I use? Any kind  of help, especially hints to calculate the resistor, are very welcome.

 

[gyraf]

KRM: 35V is fine, anything higher, like 63V, is fine too.

Mike: Plenty of instructions available on how to dimension a led resistor. Search.

But don't load the +12V line too much - some 2-5mA is ok, not much more.

Most LED's are bright enough at 2mA.

If you need more light/current, use the +15V line in stead (or the on-board aux. 12V from the extra 7812 regulator) These are not overly sensitive to loads like the +12V reference.

Jakob E.

 

[cray]

Hello , some questions :

1- my gssl works with rev 7 pcb. 
vcas are "that2180lb"  & sidechain vca is  "that2150"

Acording the image attached , for this #7 rev.  i have to modify everything except on the sidechain section. right?  unless you have another 2180lb installed this area. please tell me if im right.

2- That2180lb  are pre timmered , when are installed on sidechain section pin 4 also must be disconnected or bend?  or just on vca section?

Thanks in advance !

 

[mike76]

Mike: Plenty of instructions available on how to dimension a led resistor. Search.

But don't load the +12V line too much - some 2-5mA is ok, not much more.

Most LED's are bright enough at 2mA.

If you need more light/current, use the +15V line in stead (or the on-board aux. 12V from the extra 7812 regulator) These are not overly sensitive to loads like the +12V reference.

Jakob E.

Thank you, Jakob.