GSSL HELP THREAD!!!

[gyraf]

Are you sure about the pinout of those rectifier bridges - i.e. where +, -, ac, ac goes? Pic is not clear.

pcb is made for the standard round types, always this pinout, seen from top:

~ +
-  ~

..the square types comes in all sorts of different pinouts, including:

-  +
~ ~

..which WILL be trouble if mounted in this pcb...

Other than this, try looking for shorts in power lines & gnd - before and after rectiifier - with a ohm-meter.

About checking voltages without mounted IC's, see earlier in this thread (often not possible)

Jakob E.

 

[Enchilada]

The top of the bridge rectifier has this on it

-  +
~ ~

Could this be my problem? I hope so  ;D

 

[Enchilada]

Jakob you are a legend!!! This instantly removed the hum from my trafo and now the voltages at the pins read 18V.

Now I have a different problem. I tested the voltages without ICs at the points in the pdf provided by kante1603. All of the '+' voltages are reading 0 and the '-' are reading double what they should.

Any ideas???

EDIT: Another piece of info, I recall reading that the voltage regulators should read +15V and -15V. The 7915 reads 55V and the 7815 reads 0V. I'm going to assume that's a problem? I traced it all the way back to the bridge rectifier (which I connected wired to the PCB in order to reverse the - and ~ on the left hand side). Here are the voltages I'm reading at the bridge rectifier:

-18.4V  +18.4V
~55.4V ~0V

I'm assuming I've blown the bridge rectifier. I'll get a new one tomorrow and report back  8)

Thanks a bunch for all of your help guys.

Kris

 

[Enchilada]

Also, in case anyone does notice in the pic, there was a 100pF cap missing which I have now soldered on so that isn't the issue 

 

[gyraf]

Make sure to measure from 0V/Ground - take reference from e.g. the heatsink fin on the 7815

And don't expect the power supply to act correctly without load - at least mount the TL074 or some other inexpensive IC to load it a bit before judging voltages.

Jakob E.

 

[Enchilada]

Make sure to measure from 0V/Ground - take reference from e.g. the heatsink fin on the 7815

And don9;t expect the power supply to act correctly without load - at least mount the TL074 or some other inexpensive IC to load it a bit before judging voltages.

Jakob E.

I'm measuring the voltages from the centre pin. I'm not expecting perfect voltages but surely those measurements are a sign of something wrong. I'll pop in the TL074 and see how it goes.

The heatsink fin on the 7815 was where it read 0V and the 7915 heatsink fin was 55.4V.

 

[kante1603]

The heatsink fin on the 7815 was where it read 0V and the 7915 heatsink fin was 55.4V.

I´m really confused where these 55 Volts do come from-even if the secondaries where connected in series you wouldn´t end up there...strange :-\

Btw:The heatsink surface of a 7815 is normally connected to it´s gnd,so measuring the "plate" against a 0-volts-point should be zero.The surface of 7915 is connected to it´s input!!!So you should read the rectified voltage there,i would expect something arround  MINUS(!!!) 21 volts dc (if transformer is working correct and also properly wired to the-hopefully-correctly mounted rectifier),but not 55 volts against 0V.

Oh-and yes:Jacob is totally right with giving the psu some load,so a TL074 is just some cents worth.I remember that these 78xx and 79xx behaved very strange when unloaded,especially low-cost types.

The link to the pdf was just something i found in my very first GSSL-folder long long ago.Anyway:Good points to measure when the psu is doing it´s job well.

Udo.

 

[Enchilada]

I'm equally as confused. I really think it's the bridge rectifier though because it's reading correct voltages where the secondaries connect to it and 0V/55V out the other side. I'll pop a round 400V one in today and let you guys know how out goes.

 

[Holiveira]

Hi ppl,

Good switch (from RAFI) for Gssl:

http://pt.farnell.com/rafi/1-15-108-351-0000/switch-pushbutton-latching-illum/dp/9927670

The RAFI has a few LEDs operating at 2V and they are suitable for switches 1-15-108-351-0000

http://pt.farnell.com/rafi/1-90-692-003-0000/led-yellow-base-t4-5/dp/9929754

Excellent. I used it in my Gssl w / ssc board and so did not need to walk with relays to power the lamp. The LEDs were linked to PCBs.

Hugo O.

 

[kante1603]

I'm equally as confused. I really think it's the bridge rectifier though because it's reading correct voltages where the secondaries connect to it and 0V/55V out the other side. I'll pop a round 400V one in today and let you guys know how out goes.

Hi,

yes,put in a round one so we have the right connections at this point at least.
Have you removed the other rectifier on the left btw?(If this is mounted in a wrong way it may cause trouble too I think).
So remove it if not done yet-even if it´s only for cleaning up your pcb.
These 55 v look a bit like if there was a voltage doubler/tripler or so.....hmmmmmppppffffff.......

Udo.

P.S.:And maybe it would be good to post some clear pics with a better resolution,maybe from the bottomside too.

 

[Enchilada]

Put in a round bridge rectifier with the correct pin-out, same voltage reads. Put in the TL074 and there was no change at all in the voltages. I Had removed the second rectifier. Could I have perhaps damaged the regulators by putting in the incorrect bridge rectifier?

To answer another question, the regulators are definitely not touching. I remembered reading that before soldering that in the first place.

There are definitely no shorts and no cold solder joints. I spent hours probing every single joint.

I'm fairly sure I wired the trafo correctly although I was initially surprised that each secondary was 18V from a 15V trafo. I posted details of how I wired it a page or two back.

Here are some higher-res photos of the PCB. Hopefully someone might spot something.
http://img265.imageshack.us/img265/2097/tophalf.jpg
http://img406.imageshack.us/img406/7378/bottomhalf.jpg

 

[Harpo]

Make sure to measure from 0V/Ground - take reference from e.g. the heatsink fin on the 7815

And don9;t expect the power supply to act correctly without load - at least mount the TL074 or some other inexpensive IC to load it a bit before judging voltages.

Jakob E.

I'm measuring the voltages from the centre pin. I'm not expecting perfect voltages but surely those measurements are a sign of something wrong. I'll pop in the TL074 and see how it goes.

The heatsink fin on the 7815 was where it read 0V and the 7915 heatsink fin was 55.4V.

The center pin of these regulators is internally connected to the heatsink. Keep your voltage reference probe connected to the heatsink of your 7815 regulator or the transformers center tap and measure with your multimeter set for a DC voltage reading.
For the unlikely case, your -55.4V raw DC input voltage reading at the center pin or heatsink of the 7915 was correct, expect both 7915 and 79L12 negative regulators to be blown from exceeding parts abs.max. input voltage of 35V. (More likely they were blown from reversed polarity input voltages. The negative rail 1000uF/35V and 22uF/35V el.caps might be damaged as well for the same reason).

 

[Enchilada]

Make sure to measure from 0V/Ground - take reference from e.g. the heatsink fin on the 7815

And don9;t expect the power supply to act correctly without load - at least mount the TL074 or some other inexpensive IC to load it a bit before judging voltages.

Jakob E.

I'm measuring the voltages from the centre pin. I'm not expecting perfect voltages but surely those measurements are a sign of something wrong. I'll pop in the TL074 and see how it goes.

The heatsink fin on the 7815 was where it read 0V and the 7915 heatsink fin was 55.4V.

The center pin of these regulators is internally connected to the heatsink. Keep your voltage reference probe connected to the heatsink of your 7815 regulator or the transformers center tap and measure with your multimeter set for a DC voltage reading.
For the unlikely case, your -55.4V raw DC input voltage reading at the center pin or heatsink of the 7915 was correct, expect both 7915 and 79L12 negative regulators to be blown from exceeding parts abs.max. input voltage of 35V. (More likely they were blown from reversed polarity input voltages. The negative rail 1000uF/35V and 22uF/35V el.caps might be damaged as well for the same reason).

The 55.4V reading was taken from the 0V of the transformer and the heatsink. The same voltage is observed by measuring the 0V of the transformer and the bridge rectifier. I'll test voltages at the negative rail caps and the 79L12 tomorrow and let you know what it reads. I might make a video of me measuring voltages so you guys can let me know if I'm measuring incorrectly.

Thanks again for all the help guys 

Kris

 

[artosaudio]

Does anyone know wich pin of the 24 v relais should get the voltage, I do not hear any click when turning on my gssl I read 2.30V on two pins wether it is in bypass or not, my gssl is in an eternal bypass mode so i sense a connection...
Oh this is the ssc board offcourse...

by the way is 17 volts to much for the main rail?

greetings thanx in advance!

 

[Enchilada]

OK, I've removed the regulators and still getting 55V. I'm starting to think I've wired my transformer incorrectly now. Should it actually read +18V and -18V on my multi? It reads +18V and +18V.

Could this be the problem?

 

[Holiveira]

Hi,

I'm with some problems in my Gssl (my 1st DIY). My treshold (with 47K in +) is not sensitive and slow to respond. The meter (Sifam presentor 19) ... I already placed the 4k7pot and I can not calibrate. with the "compressor in" and  the threshold at +20, the meter is at 20 dB (gain reduction). when moving slowly  the threshold to -20, the "meter" goes to 4dB quickly. That I use 2180BL.

I made the recommended changes for this VCA from this site: http://diy.fischerworks.com/gssl_vca.shtml
  and i  removed the 10k and 47R resistors from sidechain.

I looked at the boards and I see no anomaly.


Has anyone had this problem? or have suggestions?

Thanks
Hugo

 

[Harpo]

OK, I've removed the regulators and still getting 55V.

55V what. You switched your multimeter for DC voltage reading when measuring after rectification ? (More likely this might be 55mV ripple showing up in your meter set for AC voltage and you might have missed the mV).

I'm starting to think I've wired my transformer incorrectly now. Should it actually read +18V and -18V on my multi? It reads +18V and +18V.

So your multimeter was set for an AC voltage reading and your unloaded dual 15VAC transformer secondary windings are reading about 18VAC each or 36VAC between the outer winding connections with the inner connections joined for the center tap.

 

[Enchilada]

Actually I just double checked and I actually ordered an 18V trafo so the 18V are OK  :-[

Here's a video of me testing voltages. I've since removed both voltage regulators and there was no change. I think you may also be onto something in that my multimeter may not be correctly set-up.

http://www.youtube.com/watch?v=kEvx5jc2reg

 

[audiophreak]

...  is the black probe plugged into the mA feature on the DMM ? and should be in the ( COM )  ?

EDIT : measuring voltage on my DMM is black prob on COM and RED on  acv/dcv 

 

[kante1603]

EDIT : measuring voltage on my DMM is black prob on COM and RED on  acv/dcv

Same here (on Fluke).
Kris-seems you´re measuring wrong.Maybe you should have a look on the DMM´s manual first and figure out how to measure and where to plug the probes.Also how to select what you want to do (for voltages "ac" or "dc",the expected range;for current e.g. you must do this in series and so forth.... ).

Give it a try,

Udo.