GSSL HELP THREAD!!!

[gyraf]

That should be all that's needed..

Jakob E.

 

[Purusha]

OK, thanks Jakob.

 

[Greg]

Did you by sockets for them, or are you planning to just solder straight to the board?

 

[Purusha]

Well, I wasn't even thinking about the sockets yet. What do you suggest?
Is it hard to get them?

 

[BR]

Hey guys,
still working on mine here..
I got everthing where it needs to be. Using 2180LA.
I ran the unit through a anylizer and it was outputing +24db with 45% distortioin.. I bet it sounded killer.
So I started checking the power around the chips, (with the help of my good friend amorris). The rails were fine but I read ,on the 5534s, 12V on pins 1 and 8. I'm not sure if that is right. Whenever I pull the chip and measure the sockets I have no DC reading at those pins.
Is this normal or do I have a bad chip or something??
I did replace that particular chip with another one and had the same reading.

thanks
Gil

 

[Greg]

Purusha, I used sockets that are often used for socketing discrete opamp amps, but I did have to carefully drill the holes on the PCB a little bigger to get them to fit. Check in my API parts list (Fabio version) for the part number.

 

[roginator]

PAD2002TS
http://www.proaudiodesign.com/productinfo.php?ItemID=P60008
did anybody tried that VCA in GSSL instead Gold 202c ...

Pro Audio Design said that this State of the art VCA is direct replacement for old 202c...

I wonder how that sounds ....since it using 4 THAT 2181LA per VCA

 

[Greg]

With a list price of $179, I doubt that anyone tried it... but I may be wrong.

 

[Purusha]

[quote author="Greg"]Purusha, I used sockets that are often used for socketing discrete opamp amps, but I did have to carefully drill the holes on the PCB a little bigger to get them to fit. Check in my API parts list (Fabio version) for the part number.[/quote]

Sorry, can you direct me to your parts list?

 

[Greg]

Go to search... Look in the "The Lab" only and put "Greg" in the author field. It should come up on the first or second page. It's a thread called, "Greg's Parts List - All"

It'll be in there.

 

[tommypiper]

I inherited a GSSL board that was stuffed but not working. When I plugged it in one of the 5534 chips exploded.

Voltages are not healthy. I've now replaced all the parts in the power supply portion but still not getting correct voltages. Can someone steer me to a next diagnostic or idea?

I'm not getting correct voltages off the regulators. But replacing the regulators has not helped. I've also replaced the power transformer and the rectifier. Resistors test fine. Already replaced the first 1000 uF caps and 22uF caps too. Where do I look next?

This pcb board has been worked on by two people now and neither one of us can find the problem. It's REV 7 board. Is there something peculiar on this REV 7 we should know? Any ideas? Help.

 

[tommypiper]

GSSL Help?

 

[gyraf]

Piper,

Nothing to do but check, check, and double-check. And read this looong thread.

Jakob E.

 

[tommypiper]

Yep. I'm worried about lifted solder pads having broken off and then buried under new solder. And no longer connected to the trace. The regulators and caps have been replaced several times, by two people, and I also replaced several other parts and noticed at least two solder pads lifting and breaking free.

I've also been suspecting broken traces and solder bridges. Between the two of us scraping possible solder bridges I found at least one trace that got cut.

I've also been testing for continuity on traces to verify them, and to verify lack of solder bridges, but I find the components appear to spoil the continuity readings. So I'm somewhat in the dark about whether to trust these readings on a stuffed board. Will that work?

The voltage readings with new parts do not produce logical results. I'm getting irregular voltage right off the regulators.

 

[gyraf]

Don't just replace parts. Trace signals through the unit (search post about this) - that way you'll know where to look for problems.

Jakob E.

 

[tommypiper]

Thanks. Searched and read what I could find. With yet new regulators, tracing the current, I find:

-Transformer feeding 16.4 VAC from both leads of the transformer entering the board.
-Rectifier showing + / - exactly 21 VDC each side.
-Regulator 7915 showing -15.2 VDC.
-Regulator 7815 showing +12.0 VDC.
-Regulator 79L12 showing -12.2 VDC.
-Regulator 78L12 showing +12.1 VDC.
-At "-12" mark on back of board I am showing -20.8 VDC.
-At "+12" mark on back of board I am showing +12.1 VDC.
-At "-15" pad mark on back of board I am showing -15.2 VDC.
-At "+15" pad mark on back of board I am showing +12.0 VDC.
-At "-15" mark on bottom, back of board I am showing -15.2 VCD.
-At "+15" mark on bottom, back of board I am showing 0 VDC.

So many wrong voltages.
So, 7815 is suspect, apparently again? That will be regulator number 5 in that position. (I'll search for broken pads when replacing, maybe that's causing it.)

Where could the -20 V be coming from when it's supposed to be -12V?

Why is there 0 V at the bottom of the board when it's supposed to be +15?

I'm not having success corrolating components on the board with the schematic. Which cap, or point on the schematic, corrolates with the "-12" mark on the back of the board, please?

Likewise, which points on the schematic corrolate with the other pcb marked voltage test points? That would be a huge help in following the schematic pathways on the physical board.

 

[Greg]

Measure resistance from +15V to ground... see if you have a short.

 

[tommypiper]

No, thanks, but there's no short on the +15. And with the new regulator it now shows +1.01 volt. Weird as a witches whistle.

I spent the day checking every conceivable place for continuity. Thought maybe I'd be lucky today. There is one area under the sidechain VCA that is showing continuity across traces. I cannot find it exactly on the schematic - can someone help me with this? How do we locate components on the schematic? I'm struggling to do this without part numbers. I've cleared all the solder away and made many visual inspections and it still shows continuity where I don't think it should. I wonder if the continuity is passing through a cap or resistor or some other pathway? Maybe it's normal? If I could show you on the schematic it would help. How can I identify this trace?

Everything else checks out fine for continuity. The whole board is cleaned and inspected up the bloody wazoo.

I replaced reg 7815. Now getting consistent +14.86v and -15.3v. Not great, but maybe not my problem either.

12 volt regs doing fine.

But I am still getting -20.8 V on the -12v test point. It's driving me nuts.

I'm at a loss. The only possible theory I can find is that trace under the sidechain. Would that cause these issues?

Can someone tell me where the -12v test point is on the schematic? And the lower +15v test point, please?

I'm dreaming about this board in my sleep.

 

[fucanay]

Between which pins is it showing? I think there should be continuity between some of them.

Also, if you have iChat on, ping me at fucanay. It's an AOL name, not .mac.

Matt

 

[tommypiper]

Hi Matt, thanks, you've cheered me up already. Sorry, I don't have iChat, I'm on a very old Mac...

Counting from the edge of the board, it's the traces connecting to pins 2 and 3 which show continuity under the sidechain VCA.