GSSL HELP THREAD!!!

[Greg]

On the output, don't connect pins 1 and 3 together. Leave pin 1 open and measure across pins 2 (+) and 3 (-). I did the same thing when testing my first clone.

Not sure what to say about the crosstalk... Gyraf should be around soon and he should be able to give some direction.

 

[gyraf]

You'll need to find the place in the circuit where the crosstalk is introduced, by tracing the signal through the unit. Then look closely around that part to see if you can find any shorts...

Jakob E.

 

[fum]

[quote author="Greg"]On the output, don't connect pins 1 and 3 together. Leave pin 1 open and measure across pins 2 (+) and 3 (-). I did the same thing when testing my first clone.

Not sure what to say about the crosstalk... Gyraf should be around soon and he should be able to give some direction.[/quote]

Sorry, should have been clearer, tied 1 & 3 on the input.

Define across =). My scope probe has a ground clip, and a probe point. Two definitions of across arise.

1. Leave the ground clip on ground, and probe both 2 and 3 at same time.

2. Ground clip to 3, probe pin 2.

I'm finding the more that I think I know, the more I know nothing =)

As to the crosstalk, let the tracing begin =)

ju

 

[tmbg]

measurements are always referenced to some voltage. Usually, it's referenced to ground, which would be equivalent of scoping pin 2 or 3 with pin 1 clipped to ground. You can call that measuring "At 2". Measuring "across" something means using one side as a reference and measuring the value of the other as referenced to the 'virtual' ground, SO across 2 and 3 would be ground clip on 2 and probe tip on 3 (or vice versa)

 

[fum]

thanks for the clarification.

Here's what we got:

Pin 1&3 on input tied, signal to pin 2,

Scope ground clip pin 3, probe pin 2.

Still no disco.

Connect it to the mixer, hear the happy sine wave.

yes, I've been having bad electronics karma lately.

ju

 

[j.hall]

[quote author="lictme"]hmmm...If you build an ssl with the 215x circuit in lieu of the 202, can you insert a 202 over the 215x circuit (assuming you pull the 215x and 5532 out of the circuit)?

-james[/quote]

no one ever answered this.....i'd like to know as i got my hands on some 202's

also, i assume i need to trim the 202's.....is this true?

 

[fum]

I'm usin 202's on mine, I left the trimmers in there. I think I asked at one point, and no one said anything to the contrary, so I assumed I was good

But don't listen to me, I'm gettin wrung through the electronics wringer these days.

ju

 

[gyraf]

I'm not sure I understand the question - but yes, you can build the circuit with two 202's and one 2150 (2151/2155/2180/2181) for the sidechain.

The pcb is laid out to directly accept 202's - simply leave out all components "beneath" these. Which also means: keep the trimmers. If in doubt, check the original ssl schematics for reference..

Jakob E.

 

[j.hall]

thanks!!! that answers my question.

a new problem.....

my first unit is up and running without a single problem.

i finished up the second, put power to it. i checked power throughout the unit and everything looked great. i put all the chips in and hooked up the daughter board and the 12 volt rail dropped. the power on LED isn't lighting up. and the meter is up reading 3 db of gain reduction.

i checked the 12 volt regulators and they have 24 volts into them and noting out. they are SUPER hot as well. did i burn them up some how?

the wierd part is that i still have 12 volts on pin 4 and 7 of the 5534 in the emulation circuit.

 

[gyraf]

check for psu rail shorts on the front panel board.

the wierd part is that i still have 12 volts on pin 4 and 7 of the 5534 in the emulation circuit.

Naa. There should be +/-15V here..

Jakob E.

 

[j.hall]

[quote author="gyraf"]
Naa. There should be +/-15V here..

Jakob E.[/quote]

not according to your schematic

http://www.gyraf.dk/gy_pd/ssl/ssl_sch.gif

 

[j.hall]

problem solved

i landed the TL074 socket on the PCB the wrong way....so i plugged the chip in backwards.

power wise everything is working now.....i have to pass audio through it to full test it

i hope that chip isn't blown.

 

[gyraf]

[quote author="j.hall"] ]not according to your schematic[/quote]

You're right - but look at the pcb - the 12V's are only for sidechain.

[quote author="j.hall"] i hope that chip isn't blown.[/quote]

It is with 99% certainty - when you reverse a TL074, you reverse + and - supplies. It shouldn't survive that.

Jakob E.

 

[j.hall]

[quote author="gyraf"]
It is with 99% certainty - when you reverse a TL074, you reverse + and - supplies. It shouldn't survive that.

Jakob E.[/quote]

that would explain why it powers up now, but is not working well at all.

meter movement is backwards, audio is awful.....i need a new chip!!

 

[j.hall]

ok...i put a new tl074 in there. the left channel is great. the right channel is barely passing audio.

i checked all the xlr connections, the molex connectors....all that stuff.

could the flipped tl074 have blown a component in the input/ouput stages?

seems unlikely to me as that's all on the 15v rail. anyway.....

all the chips are fine i swapped them all out and traded positions and such....problem remains constant.

any ideas of where to start looking from here?

thanks,
j.hall

 

[BladeSG]

Hi guys, I got a question for you:

Do the shafts of the switches and pots need to be cut down?

The reason I ask is they look a little long to me (like they will stick to far out once mounted on the front panel) and I'd prefer to cut them before I solder them.

Thanks in advance.

 

[Ian MacGregor]

yes... I ended up filing the switch shafts down a little. Some switches are longer than others, check the datasheets.

Ian

 

[BladeSG]

Thanks Ian. Do you remember what length the shafts need to be or how much you took of them?

 

[Ian MacGregor]

I just measured the length of the pot shafts and made the switches the same. The length will completely depend on the knob you are using and how close you want the knob skirt to be to the front panel.

Ian

 

[BladeSG]

Thanks again. :grin: