GSSL HELP THREAD!!!

[Harpo]

It measures +/- 37mm in thickness, I've ordered but havent received the chassis yet. It looks like its going to fit (Just measured it with one of my other 1 HE units). Knowing my luck it wont fit at all, if thats the case I'll order a smaller one and put it down to school fees.

Boxes inner dimensions are not standarized, so these might vary depending on manufacturer.
This might be useful information as well.
For your higher VA rated transformer you want a bridge rectifier rated for this higher inrush current, so maybe use a B80R type instead of a W04 type FWB.

 

[Olegarich]

my gssl works with the same 50VA power transformer, everything works well.

 

[Rockitdog]

It measures +/- 37mm in thickness, I've ordered but havent received the chassis yet. It looks like its going to fit (Just measured it with one of my other 1 HE units). Knowing my luck it wont fit at all, if thats the case I'll order a smaller one and put it down to school fees.

Boxes inner dimensions are not standarized, so these might vary depending on manufacturer.
This might be useful information as well.
For your higher VA rated transformer you want a bridge rectifier rated for this higher inrush current, so maybe use a B80R type instead of a W04 type FWB.

Yeah, ok thanks. Will change them out.

my gssl works with the same 50VA power transformer, everything works well.

Is that with the standard 1A/50V recommended bridge rectifier? 

The transformer is rated at 1,66A so Im not going to risk it, Ill up the bridge rectifier spec. Thanks Harpo.

 

[Olegarich]

defenitely up bridge rectifier

 

[main repairman]

Harpo please can you tell me how you measured the values ​​that are in your manuals page 210 DMM? Scope?
1.problem :-[:
I replaced TL074, all the diodes and the voltage at the junction 20K, Kat.1N4148, 10K is always 0.08VAC. (Correct 0.14VAC)??
Why?

2.problem  :-[:
TL 074 pin14 ratio
2:1 = 0.66VAC  (correct 4.8VAC) ?
4:1 = 0.802VAC (correct 0.83VAC)
10:1 = 0.452VAC

Why is the measured voltage is low (2:1)?
I measured DMM more picture.(board is test version)
Harpo please help 

 

[Nanitlig]

Hello, looking for some GSSL help.  After the unit is on for a little while the LED's in the meter go out and the GR meter hovers around -8dB.  If I turn the threshold control full CCW to -20, the LED's slowly come back on and the unit works again.  Then, if I put the threshold back around 0dB or higher, the meter dims again then quits working.  Could this be a problem with the +/-12V supply to the control board/meter?  When the meter goes out, the VCA's still reduce gain and the in/out amps pass signal, so the +/-15V supply seems to be unaffected.  I haven't gone probing around yet, I thought I would see if anyone else had a similar problem or had some ideas on what to start poking at first.

 

[gyraf]

Check for shorts around your front-panel pcb and wireing - specially to the return line for the threshold voltage. Probably fail here.

Else:

Verify that it's your +12V that goes away (measure while it's failing).

possible solutions to 12V shutdown if nothing shorted:
- use a larger LED resistor ->less current in the LED
- take LED voltage from somewhere else - e.g. the +15V
- heatsink the 78L12 to removing some heat, preventing it from thermal shutdown.

Jakob E.

 

[Nanitlig]

Jakob,

Thanks for your help!  I moved two LED's from the front board to a dedicated aux 12V supply that I added to run two relays that I installed.  I also drilled a hole in the top cover above the 78L12/79L12 to vent heat.  I've been running signal through it all day and so far it hasn't shut down.

Danny

 

[Harpo]

2.problem  :-[:
TL 074 pin14 ratio
2:1 = 0.66VAC  (correct 4.8VAC) ?
4:1 = 0.802VAC (correct 0.83VAC)
10:1 = 0.452VAC

Why is the measured voltage is low (2:1)?

No readable parts values from your distant component side pic, but at 1st. sight obviously one diode between TL074-pin13/14, further going to 'A' and ratio switch is missing. (there might be more parts/jumpers missing...).
I already answered your 1st. question twice.

Just to add, your multimeters specifications are 'frequency range 40 - 400Hz and displayed RMS value relates to pure sine signal.' Signal at junction 20K, Kat.1N4148, 10K is no more a sine signal with half of the waveshape at 0V, so the value your UNI-T UT70A displays might/will not be the real world value.

 

[main repairman]

2.problem  :-[:
TL 074 pin14 ratio
2:1 = 0.66VAC  (correct 4.8VAC) ?
4:1 = 0.802VAC (correct 0.83VAC)
10:1 = 0.452VAC

Why is the measured voltage is low (2:1)?

No readable parts values from your distant component side pic, but at 1st. sight obviously one diode between TL074-pin13/14, further going to 'A' and ratio switch is missing. (there might be more parts/jumpers missing...).
I already answered your 1st. question twice.

Just to add, your multimeters specifications are 'frequency range 40 - 400Hz and displayed RMS value relates to pure sine signal.' Signal at junction 20K, Kat.1N4148, 10K is no more a sine signal with half of the waveshape at 0V, so the value your UNI-T UT70A displays might/will not be the real world value.

Harpo YES my UNIT 70A  measured RMS it was a problem. Measured values ​​scope are correct but the voltage ratio of 2:1 is less than 4.8VAC. As I measure so I measure (DMM, scope) the voltage is still low. Voltage 4.8VAC is real value???

Diode between TL074-pin13/14 is the PCB bottom.

 

[frazzman]

Hi Guys, i'm still trying to work out an issue with my GSSL. Everything is working now except I have difference in output levels between channels. Channel R is about 6db less in volume than L. I have checked for shorts around all opamps and have found none.

Following the follow advice from Harpo in another thread:

'([/quote]
Most probably a wrong part or broken trace in the audio path.
Feed both inputs with the same AC signal. (maybe 1V @ 1kHz, doesn't matter that much)
1) Your NE5534 input op-amps should show the same value at pin-6 when comparing left and right ch. (possible fault: wrong resistor value or broken trace)
2) Your NE5532s for current to voltage conversion after the audio-VCAs should show the same value at pin-1 when comparing left and right ch. (possible fault: wrong resistor values 15k / 27k or 30k)
3) Your NE5532s inverting buffers after previous stage should show the same value at pin-7 when comparing left and right ch. (most porobably fault: wrong resistor value, short between pin 6 and 7 or short in XLR-cable)

If any of the previous steps fails, fix the problem in that stage before going further.
[/quote]

I have checked AC voltage on all pins of opamps, they are exactly the same on both sides
1) NE5534 in op-amps are showing the same value at pin 6 between L & R
2) NE5532s are showing same value at pin 1 between L & R
3) NE5532s are showing same value at pin 7 between L & R

given this is there anything that could explain the apparent drop in level on the R channel?

 

[frazzman]

Hi Guys, i'm still trying to work out an issue with my GSSL. Everything is working now except I have difference in output levels between channels. Channel R is about 6db less in volume than L. I have checked for shorts around all opamps and have found none.

Following the follow advice from Harpo in another thread:

Most probably a wrong part or broken trace in the audio path.
Feed both inputs with the same AC signal. (maybe 1V @ 1kHz, doesn't matter that much)
1) Your NE5534 input op-amps should show the same value at pin-6 when comparing left and right ch. (possible fault: wrong resistor value or broken trace)
2) Your NE5532s for current to voltage conversion after the audio-VCAs should show the same value at pin-1 when comparing left and right ch. (possible fault: wrong resistor values 15k / 27k or 30k)
3) Your NE5532s inverting buffers after previous stage should show the same value at pin-7 when comparing left and right ch. (most porobably fault: wrong resistor value, short between pin 6 and 7 or short in XLR-cable)

If any of the previous steps fails, fix the problem in that stage before going further.
[/quote]

I have checked AC voltage on all pins of opamps, they are exactly the same on both sides
1) NE5534 in op-amps are showing the same value at pin 6 between L & R
2) NE5532s are showing same value at pin 1 between L & R
3) NE5532s are showing same value at pin 7 between L & R

given this is there anything that could explain the apparent drop in level on the R channel?
[/quote]

 

[Harpo]

Hi Guys, i'm still trying to work out an issue with my GSSL. Everything is working now except I have difference in output levels between channels. Channel R is about 6db less in volume than L. I have checked for shorts around all opamps and have found none.

I have checked AC voltage on all pins of opamps, they are exactly the same on both sides
1) NE5534 in op-amps are showing the same value at pin 6 between L & R
2) NE5532s are showing same value at pin 1 between L & R
3) NE5532s are showing same value at pin 7 between L & R

given this is there anything that could explain the apparent drop in level on the R channel?

Signal connecting to right side output XLR-pin3 is interrupted. Could be broken trace, bad solder or more likely the molex-connection doesn't connect for whatever reason (bad crimp contact, contact inside molex housing pushed out,not connecting to pin, ...)

 

[ilfungo]

Hi
I'm building another GSSL with DBX202 vca ( main board)
If I ad a turbo board there is a different vca...
Can work?
I must do some adjustment?
Thanks

 

[Harpo]

I'm building another GSSL with DBX202 vca ( main board)

Black can DBX202 VCAs (comming with a 6mV/dB control law) or is this a typo?
Are these VCAs known working at all?

If I ad a turbo board there is a different vca...
Can work?

Make both sidechain VCAs (probably THAT218x on main board and turbo board) the same for same behaviour. Nothing to do with your audio VCAs.

I must do some adjustment?

Some adjustment for the DBX202 type VCAs needed. Lots of ways to skin the cat, but following changes should get it working.
Change the 27Ks in front of the DBX202 VCAs to 75K to not exceed the less allowed input current,
change the 15K feedback resistors at the NE5532 current_to_voltage converters to 37K5 (2*75K in parallel=37K5) and change the 100pF caps in parallel to this resistors to 47pF caps,
change the 100K feedback resistor between TL072-pins6/7 to 12K to adapt for the differing 6mV/dB audio-VCA control law and change the 100pF cap in parallel to this resistor to a 680pF cap,
don't fit parts for the DBX202C substitution circuits.
Good luck.

 

[ilfungo]

Thanks Harpo!

The vca's are DBX 202C gold can....
There is a way to use the same vca on turbo board?
Thanks

 

[Harpo]

The vca's are DBX 202C gold can....

: Why did you ask for the DBX202 ?

There is a way to use the same vca on turbo board?

Sure, and for the main boards sidechain VCA as well. Nothing a Dremel, a piece of perfboard and some gaffa tape couldn't fix, but I'm no going to reply to this nonsense.

 

[ilfungo]

sorry, I badly explained
I have 2 dbx 202c Gold for main board,
I want to add turbo board that I think does not include this type of VCA
how can I use DBX202c Gold  also on Turbo Board?
Sorry for my English.
Thanks

 

[Harpo]

I want to add turbo board that I think does not include this type of VCA
how can I use DBX202c Gold  also on Turbo Board?

Why would you want to do so ? I might be wrong, but it seems you have no idea what the use of the turbo board is.

 

[MeToo2]

sorry, I badly explained
I have 2 dbx 202c Gold for main board,
I want to add turbo board that I think does not include this type of VCA
how can I use DBX202c Gold  also on Turbo Board?
Sorry for my English.
Thanks

No. You can't easily. And it would almost certainly not be sensible anyway. On the main board, the DBX202c does NOT sit in the side chain path. The side chain on the main board is based on the That 2180. As is the duplicate side chain on the turbo board.