GSSL HELP THREAD!!!

[gerardmanvuca]

I have a real dumb question, I'm trying to figure out how to measure the DC before I put in the chips,
mine is 15v and - 12v but I just have no clue
on how to do it.

I basically would like do the same as Roland with his multimeter at the bottom of th page.
http://www.geocities.com/cruzeman2001/english/2.html


Sorry, I know this is probably gonna be classified
under the top ten most dumb question.

I would really appreciate the help.

Thanks !!!!!!!!!!!!!

 

[gyraf]

As mentioned before, it dosen't make sense to measure supply voltages before putting in IC's, as the regulators usually don't regulate before there is a current draw..

Jakob E.

 

[nemisis633]

I just fired up my first GSSL clone and I'm having some problems. Initially when i powered up the unit I had accidently installed an NE5532 in the place of a NE5534 (In the left emulation circuit...)I did power it up once like this but switched the part out. (just a bit of preface).

Basicly.. i can get the right channel to pass audio, but it wont compress... the left channel will not pass audio.

the only response i get from any of the controls is if the makeup gain is turned all the way up. At that point I get massive distortion from the output, and the meter pegs.

I checked my voltages. +15 reads 14.69 and -15 14.89
the +12 is reading +12.01.

I'm using the pre trimmed 2180's so I have pin 4 removed on all 3 VCA's...

This is my first DIY project so I'm at a loss here. Any thoughts?

thanks,
Jon

 

[gyraf]

Hi Jon,

Check the usual problems, as mentioned earlier..

Jakob E.

 

[nemisis633]

I managed to get both channels passing audio and the make up gain is working now as well. I still cant seem to get the threshold knob to have any effect on anything. (IE im getting absolutely no compression...) Any area's I can check for this specific problem? I'm assuming its somewhere in the sidechain section?

thanks in advance,
Jon

 

[gerardmanvuca]

Hey everyone,
I've condensed the SSL HELP THREAD to 4 pages, if anybody
has hard time searching through the whole post, this might
make your life a little easier.

enjoy.

http://www.buythebeats.com/SSL%20HELP%20THREAD%204%20pages.rar


peace.

 

[littlenemo]

Hi, it's my first DIY project and I have a problem with my GSSL clone. If I look correctly at the schematic, I should read +12v and -12v at pins 7 and 4 of the NE5534 above the 2180 VCAs from the emulation circuit, but in my clone, I read +15v and -15v... I have correct voltages everywhere else and I don't understand this problem. Is the schematic wrong or am I wrong ??

 

[gyraf]

Been there before..

Look at the pcb layout: there are 15V lines going directly there, so 15V is alright.

Will fix the schematic on a future update.

Jakob E.

 

[littlenemo]

cool, I was getting nuts about it it seemed o be completely unlogical :shock:

 

[gerardmanvuca]

I have been debugging all week and still I'm in the same situation it's really getting to me.

This is what I did so far.

- powered up the gssl = 10R resistor on the negative rail smokes. The reason why was because
I wired the yellow and black wire on my toroid the wrong way. (thanks Sintech's pic I was able to
rectify this mistake)

- After wiring it correctly, there was no smoke. The knobs don't work and there is no compression.
The audio is coming through.

- Readings are good for 15+/-v but cannot get -12v, can only read +12v in one location.

- I replaced the 12v regs, the tl072,tl074 = still the same thing.

- If I take out the tl072, the audio gets louder (what would this mean?)

- All the VCA s are workin, the led on control panel works fine but none of the knobs work.

- i am gettin voltage changes with both pots on the control board...i can trace the threshold
to the motherboard to pin 2 on the tl072 and i get a voltage change......but when checking the
make up gain at pin 5 or 6 i get no reading changes.........so the control panel is defin working
but yet theres no compression or change in sound when i turn them??

- i have a strong feeling that the problem lies around the tl072/4 chips but i have no idea what?

- I have realised that i have got bad 12vdc readings, my 15vdc+/- readings are perfect but on the
12v rails I get reading of 3.4V ??????

- All caps, resistors(10R), 12v regulators in the power supply and i'm still getting the same
reading, no shorts or bad soldering. All solders are good.

- My control panel works because I get volt changes when I turn the knobs, just no
change in sound.

- The audio is losing about 12-14 db in volume after the tl072, I know this because
when I pull that chip out the sound goes to full volume.


- I've checked for ages (scanned the PCP) and no shorts, no blobs


these are the measurement I get from;


- tl074

in 6 = -1.29
in 5 = 0
in 3 = 0
in 13 = -2.1
in 12 = 0

tl072

in 3 = 0
in 8 = -3.22


I really don't know what to do at this point, I am thinking of desoldering everything
and starting from scratch or even get a new PCB and start again, but it's really
frustrating because I don't know what is causing the problem, arghhhhhhhh.



thanks for the help.

 

[Harpo]

Did you replace your smoked 10R for the -12V rail?
It won't work properly if eighter of the +/-12V is faulty or shorted, so any readings at other op-amp pins don't make much sense for now.

Pull TL074, TL072 and sidechain VCA.
Measure for -12V at TL072-Pin 4, TL074-Pin 11 and cw end of threshold pot.
Case not, check for short, replace faulty 79L12 or bad 22uF cap after the reg.
Measure for +12V at TL072-Pin 8, TL074-Pin 4, VCA-Pin7 and ccw end of threshold pot. Case not, check for short, replace faulty 78L12 or bad 22uF cap.
Put TL074 back in circuit and measure +/-rails again. Same to TL072 and VCA. If a rail voltage goes down, this chip is probably broken.

Hope, this is of any help.

 

[nemisis633]

After many hours of troubleshooting.. I almost have my clone 100% working. A few notes...

Everything is great except I absolutely can't get my threshold knob to have any effect on the audio. (The pot is working however.. Voltage varies on the center pole)

For some reason.. (I've tried 3 different resistors) Anytime I add the resistor to the bottom leg of the threshold knob.. (to reduce sensitivity) the 12 volts no longer can be measured at that pole. Is that normal? When I use straight wire.. I measure 12.11 volts..

Also I'm using 2180LA VCA's.. (Pre trimmed) but I am using the 3k9 resistor in the VCA emulation circuit still.. Instead of the 5k1 suggested for this VCA. (I just haven't received the replacements yet..)

All that said.. Would these items be having an effect on my threshold knob? Everything else works great.....

I'm planning on building a couple more of these and have come into a few 202C VCA's, the pins seem to be to big to fit through the holes in the PCB. How do you suggest I make these fit?

Thanks once again,
Jon

 

[gerardmanvuca]

hey guyz......having some problems with the volume of the compression......its very low and when i have the make up gain on full and turn the threshold right up the unit goes extremly quiet....if i then switch into bypass mode it goes back to full volume and louder if the make up is high...its definitly compressing just need to get the volume louder.........can anyone help on this? as i cant find anything on the forum.......cheers

 

[dinesh]

Hi,

I think you are over compressing by turning your threshold up, slowly turn it other way & see any diffrence in sound?

 

[gerardmanvuca]

when i turn the other way the unit does get louder but at the sacrifice of less compression and i like the amount of compression when its a higher thresh level......i just want to get the gain louder because i'm pretty sure its to low compared to the bypassed signal(i.e if i turn the compressed signal up and hit bypass the audio is a hell of alot louder)......i have wired the bypass link on the ctrl pcb where Jacob sais (link on pcb-defeat makeup when out-) maybe i should take it out? or is there a way to boost the gain of compression?

 

[nemisis633]

bump for some help with my threshold issues .....

see up!

:grin:

 

[gyraf]

nemisis,

Check for shorts and inter-pcb cabling.

Jakob E.

 

[kryckmeister]

[quote author="Harpo"][quote author="kryckmeister"]Yup, it's all there...[/quote]
If troublefree in bypass, the fault comes from the sidechain part or it's powersupply. Assuming, you already checked the diodes orientation, you may have a bad TL072, TL074 or VCA chip or bad 78L12/79L12 regulator. First check for stable +/- 12V voltages on TL072+TL074.
If you have a lamp for the meter connected, from where did you power it ?[/quote]
I think you were on to something here... when checking the TL074 I had 12V at some of the pins but when I hit the second from the right closest to the top my meter started smacking. I guess I oughta change this one. Do you reckon the distortion would come from the same thing?

The 78L12 is at 23V and 79L12 shows 0V. That's gotta be wrong.

Since I suck at this, and this is my first DIY I gotta ask this stupid question, but is it supposed to be 12V on every pin on the TL072 and TL074?
Thanks, I just sensed a bit of hope here.

 

[Harpo]

[quote author="kryckmeister"]... but when I hit the second from the right closest to the top my meter started smacking. I guess I oughta change this one. Do you reckon the distortion would come from the same thing?

The 78L12 is at 23V and 79L12 shows 0V. That's gotta be wrong.

Since I suck at this, and this is my first DIY I gotta ask this stupid question, but is it supposed to be 12V on every pin on the TL072 and TL074?
Thanks, I just sensed a bit of hope here.[/quote]
Have a look 7 posts previous to this. Take care to put back in your sidechain VCA in the right direction (opposite to the audio-VCA's).
Your problem seems to look similar to this http://www.groupdiy.com/index.php?topic=23801
If this doesn't solve your problem, some pics from trace- and component side may give a clue.

 

[kryckmeister]

Here's the values with the TL072 and TL074 still inserted.

Gave with 7915, 7815 and the TL074 and 072...