GSSL HELP THREAD!!!

[bluebird]

Just putting this out there again....

I've fixed the high roll off problem with my SSL.

I still have a hum.
Re reading this whole thread I've noticed I have the same exact problem Nele had. less hum with the unit in bypass. and the hum gets louder when turning up the make up gain pot

I think it has to do with the switching panel. if I put my finger by where the bypass switch wires go to the PCB the hum gets louder.

Its weird because everything works perfectly. So what gives? Could I have wired something wrong with the bypass and have it still work perfectly?

 

[tubejay]

Okay, so I fired up my GSSL today, and it works...SORT OF! Hopefully you wonderful people here can help me. Here's the situation:

It passes signal equally on both channels, and sounds normal. The makeup gain knob works perfectly. My problem, NO COMPRESSION! Well...sort of anyway.

I think the problem is in my bypass switch. If I put my fingers on certain pins, while putting my fingers on the pins with the two outer switch wires on them, it will do a super compression, almost as though I had the threshold WAY WAY down. So I cut the wires to the two outer pins of the connector and tried just connecting them to the center wire on the knob. Then I got an infinite compression, meaning no sound. It attacks, releases, and sounds like the ratio is correct. It seems weird, and the threshold control just seems to have no effect on the signal, regardless of my fingers touching etc. I guess the problem could be there too.

Any ideas?

Thanks,

Jay

 

[tubejay]

Anyone? If I need to supply more info, please let me know. I don't see any lifted traces etc...

 

[gyraf]

Try tracing the DC CV voltages through the sidechain rectifier, the timing, to the ½TL072 that also carries makeup gain, and the other½ that carries threshold..

Jakob E.

 

[tubejay]

Thanks for the help Jakob! You'll have to excuse me, most of this is new to me, so I may not understand everything you're telling me. Unfotunately I'm not sure I understand how to trace the DC CV voltage. I don't understand where to get that?? Which pins on the 072 should I be looking at?

If this helps, I'm getting +12 on wiper one of the threshold pot, and variable voltage at the middle pot (depending on where I turn it) and -12 on the last wiper.

When the compressor is not bypassed (ie the com and on holes on the pcb are jumpered) the meter needle slams all the way to the right, showing infinite compression. Also, I can FAINTLY hear sound when it's jumpered, and turning the makup gain all the way up turns it up a little more, though it's still REALLY quiet. I checked all of my resistors and all of the solder points around the 072, and all looks good, with no touching traces.

On the 072 here's the voltages I'm getting when not bypassed:

Pin 1 - 6v (actually variable depending on where I have the threshold from 6v to 0v)

Pin 2 - 0v
Pin 3 - 0v
Pin 4 - -12v
Pin 5 - 0v
Pin 6 - 0v
Pin 7 - 5v
Pin 8 - 12v

Thanks again for your help, I'm pretty lost here!!

 

[gyraf]

Jay,

- At point "C" (going to the control board) you should have a DC voltage that is zero for no input signal, and going gradually more and more negative with higher input levels. When the unit is working properly, the threshold pot will also vary the negative voltage here (when there is input signal present)

- This DC signal should also be present at point "D" (providing that the unit is "IN", not bypassed) - now the DC voltage's A/R timing has been set by the A/R switches.

- An exact replica of this signal should now be present at pin8 of the TL074 - this is the DC voltage driving the meter through the 2K resistor.

- This DC signal is added to the voltage dialed in with the threshold and makeup gain pots, and is found at pins 1 and 7 on the TL072

Double-check orientation of your diodes, specially the one at point "C" ...also check that all your IC's are getting the right supply voltages, and that none of them run hot

Jakob E.

 

[tubejay]

Thanks Jakob, well I think we're getting closer.

At pin C I am constantly getting -10v, no matter what. At point D I get -10v when not bypassed, and 0v when bypassed.

I checked all of the diodes and they are in correctly. I also checked them with my diode checker and they all measure 667, whatever that means. I assume that means that they are operating normally.

It looks like whatever the problem is, is related to this. As always, your help is most appreciated!!

Thanks,

Jay

 

[Guest]

stupid question....


how do the attack, ratio, and release switches mount on the pcb. It seems they could fit a couple ways. Do the numbers on the back (1-12) mean something?

Thanks,
Brandon

 

[Aharon]

Yes,the #s mean something.Check also the letters,A,B,C,D in the center and compare to the layout.
Aharon

 

[Jonathan Hayward]

Frist, the numbers on the back indicate the number of ways the switch can be made to go. For each switch, check the number of ways it needs to go on the schematic (for example the ratio goes 3 ways) and then put the little washer with the perpendicular spike on it with the spike in the hole by the number three on the switch's body (and make sure it stays there until you've fixed the switch board to the frontpanel).

 

[tubejay]

Does it matter which direction they go in? For instance, there's two potential ways each switch could go in (on Gustav's PCB's, which is Gyraf's 7th rev). My understanding was that it doesn't make a difference which way you put them in. However, that might be why I can't get mine to work properly! :wink:

 

[tubejay]

[quote author="tubejay"]Thanks Jakob, well I think we're getting closer.

At pin C I am constantly getting -10v, no matter what. At point D I get -10v when not bypassed, and 0v when bypassed.

I checked all of the diodes and they are in correctly. I also checked them with my diode checker and they all measure 667, whatever that means. I assume that means that they are operating normally.

It looks like whatever the problem is, is related to this. As always, your help is most appreciated!!

Thanks,

Jay[/quote]

Also, to add to this, the threshold control has no impact on the voltage present and point C or D. C is always -10v and D is either -10v when engaged, or 0v when bypassed. Something must be shorted?? Is there a trick to mounting the switches that I'm screwing up possibly??

 

[gyraf]

The switches are symmetrical, so it dosen't matter what way they are mounted. Only you need to adjust the "end-stop" for the release switch to five positions.

Jay - If you have constant -10V at point "C", then your problem probably is in the rectifier section or in the ratio switching.

- First lift the two wires at points "A" and "B" and see if the -10V goes away (with no input signal). If so, then there's a short or a wrong resistor value around the ratio switch.

- If that dosen't do it, then check for shorts and correct components at the rectifier around TL074 pins 1-2-3 and 12-13-14. Possibly exchange the TL074 for a new one. Check orientation of ALL diodes. Measure DC voltage at TL074 pins 1, 2, 13, 14.

- make sure that your sidechain VCA is orientated the right way around. It is mounted opposite of the two audio VCA's!

Jakob E.

 

[HappyTom]

I'm getting done with my clone just one thing missing.. Juice for the light in the behringermeter (BE-46). Anyone knows where to get that? I know it's been up in a thread somewhere but i can't find it.

 

[tubejay]

OH - MY - LORD!!!! I can't believe it, I had the sidechain VCA in the WRONG WAY!!! DOH!! I had read not to do that, probably in 10 different places, and somehow I still managed to screw it up!

Jakob, as Bette Midler would say, "did you ever know that you're my HEEEEE-ROOOOOOO??" Thank you so much for your help, hopefully if someone else has this problem I can help them out. I can't say it enough, THANK YOU THANK YOU THANK YOU!!

DIY SUCCESS!!! I ran a drum machine through it this morning, and it sounded very nice indeed! I have a mix session next week, and I can't wait to try it out! I'll post results.

Now, I'm with HappyTom, I need to get that light going in the Behringer meter. Has anyone done this?

Thanks again Jakob, your patience is truly a virtue!


:guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :thumb: :thumb: :thumb: :thumb: :thumb: :thumb: :thumb: :guinness: :guinness:

 

[Jonathan Hayward]

Tom What's the voltage rating on the Behringers.

Over-keen boy here popped his Chips into the board last night (having care fully checked the supply voltages). Inserted the two 5534s in the vca circuits round the wrong way; much heat in the 2181s and now massive distortion with new 5534s in the right way. No compression either (but the sidechain and meter are behaving correctly).

I'm assuming the 2181s are cooked, does this tally with anyone's experience?

 

[tubejay]

Jonathan, is it distorted even when it's bypassed? I'm not sure if the channel VCA's are bypassed when the unit is in bypass, but I don't think they are.

The sidechain might be the only thing being bypassed then. In that case, the unit will still operate in bypass if there's no 2181 in the sidechain vca slot. If that's the case, you could take the 2181 out of your sidechain and put it in one of the channels to see if it's the 2181's that are fried, or the 5534's. If it's still distorted with the sidechain 2181 moved to one of the distorted channels, it's either the 5534's or something else.

I'm not certain this is all correct, but from my experience with having the vca in the sidechain in backwards, this is how I expect bypass works. It would at least allow you to check and see if it's the 5534's or the 2181's.

Jakob, let me know if I'm wrong here.

 

[gyraf]

Jay,

Good that you got that fixed! :guinness:


Jonathan,

Audio passes the VCA's even when bypassed. The bypass simply cuts of the sidechain signal path (right before the timing circuit)

To check if it's your audio VCA's that are fried, try substituting one of them with the one from sidechain (if you're sure there's no other component problems now) Note orientation! :razz:

The unit will pass signal with no sidechain VCA, but will not compress. So at least you should be able to check if your VCA's are allright.

Jakob E.

 

[Guest]

I'm looking to have two buttons with LED's for the power and bypass. There is one take-off for an LED on the control pcb, can I come off that same spot for both LED's?

Thanks,
Brandon

 

[gyraf]

Brandon,

You could, but it's preferable to use individual dropper resistors for each LED. Just tap off the +12V on the control board where the LED dropper resistor already sits...

Jakob E.