GSSL HELP THREAD!!!

[JW]

Hey guys,

I'm all finished with the GSSL w/ turbo board and it sounds unbelievably awesome. Only thing is, I find the meter to be not reactive enough.

I know there are several things at play here, and I just need to get the (3?) resistors involved to be right.

I'm using DBX 202c's. I have a 100uA, 100mA sifam meter.

I've tried the 330R resistor across the meter like the schematic says to use with this kind of meter, but it makes the meter even less reactive. I can hear it compressing before anything even starts to show up on the meter. So I've removed it. I still need it to start showing compression earlier though.

Where the schemo says 4K7, before the meter, I actually have a 2K resistor. Should I lower this even further?

I also have the 47K threshold de sensitize between the board and threshold pot. Should I remove this one?

I'm still a little confused with which various resistor changes were in regards to using THAT chips (and so unnecessary with the 202's) and which revisions should be for all GSSL's regardless of which VCA you're using.

 

[Harpo]

If you have a 100mA meter instead of a 1mA meter or a 100uA meter, I fear you will have to exchange this part. A internaly current limited TL07x will not drive this meter to full deflection.

 

[Harpo]

Hey,

Below is the area which has the high voltage. I've measured all components and all is well to specification. Perhaps I am looking wrong at tracing the error? The left input plus and minus (hot and cold) pins receive the 6~7 volts. It has to be something. The high voltage comes from pin 7 which is the VCC+ on the chip, and the +-15v or still correct. 

//edit image removed: http://img139.imageshack.us/img139/513/gsslproblemvj0.jpg

Thanks for your help!

Right when disconnecting the XLR input Molex the voltage raise to +15 volts! I just do not know where that is coming from?

What I did is lifting one resistor leg around the whole signal path of the left input, no result. Same thing with the 100nF and 22uF, all right. Next stop was the right output channel and did the same procedure as the left channel, no result and all correct. But now you know that the high voltage is from, probably, a +15v rail!  ;D   

*Corrected to right pin from the 5534

Doublecheck for broken traces in your red marked area, including the trace to 0V molex center pin at the lowest 22K and especially check for broken traces going from pin 6 to pin 2 of your NE5534 with the 22k feedback resistor in between.

 

[feza]

Doublecheck for broken traces in your red marked area, including the trace to 0V molex center pin at the lowest 22K and especially check for broken traces going from pin 6 to pin 2 of your NE5534 with the 22k feedback resistor in between.

Will do man! Certainly will re-solder all the joints there and report back.

I really appreciate your help. 

 

[JW]

Actually, sorry, it's 100uA

 

[feza]

This is getting out of hand!

Now every pin except the -15v pin is +15 volts on the left input 5534!

I'm really getting frustrated right now, not really a surprise. What I did was re-soldering all the 22K across the marked area and some other components, no capacitors just resistors. Still the other chip voltages are good including the VCA's. What is going on? I'm looking a lot at the schematic and read this thread again and nobody else has this problem. I have to admit I do not fully understand the schematic but trying hard learning it.

Replaced the opamp by the way, still crazy readings. What's next? Anything can help right now.   

 

[Harpo]

...Will do man! Certainly will re-solder all the joints there and report back...
...What I did was re-soldering all the 22K across the marked area ...
What's next? Anything can help right now.   

Maybe reread my last post and check for broken traces . Get a magnifying glass if it helps.
If a trace is broken f.i. in the feedback loop, this would be the same as a resistor with near infinity value instead of this 22K in your case.

 

[trancedental]

[quote  Get a magnifying glass if it helps.
[/quote]

A Jewellers loupe even a cheap one will let you really see if you have any shorts or any problems

 

[feza]

Major thanks already!

If found one, I do not doubt about that, do I have to connect point "A" to "B" using wire or jumpers? And doing the bridge connection it has to be on the trace right? Any more insight is hugely appreciated!

Finally have a better feeling about solving the issues, you know.

 

[Harpo]

Whatever works best for you. Cutoffs from resistor leads f.i. come handy for these kind of jobs. Make sure to clean the broken trace from any isolating substances in order to give solid contact to your solder for the mending bridge. Keep your mending flat to avoid unisolated leads touching case ground when you put the pcb back in your housing.

 

[trancedental]

Just installed the cheapo Farnell meter (the 100uA edge meter code 143509) on my GSSL & was wondering do I change the meter sensitivity resistor from 2K to 20K AND shunt a 330R resistor across the meter?

Tried searching to confirm this but I'm not 100% sure if I need to do both of the above?

Cheers & Happy Xmas ;D

 

[feza]

Hey Harpo and the other members!

I just had the time to check the continuity of the traces around that "15 volts" area and looked for shorts, they are all giving the beep of right connection. But then I started thinking how MANY times I pulled the XLR Molex connectors and changed the 5534 opamp. I'm guessing because of the pull-outs the connection is not optimal anymore because once the left input did work correctly and the voltages of the opamp were right. Me and my father are going to visit a nice electronics shop tomorrow and certainly going to dump the Molex solution for ever! Still I will be looking for broken traces (great advice by the way) to and around the area. 

But hey. When the unit is fully working? You all deserve the "well know handshake of appreciation" !! 

 

[Harpo]

Just installed the cheapo Farnell meter (the 100uA edge meter code 143509) on my GSSL & was wondering do I change the meter sensitivity resistor from 2K to 20K AND shunt a 330R resistor across the meter?

Tried searching to confirm this but I'm not 100% sure if I need to do both of the above?

Cheers & Happy Xmas ;D

Only put a 330R shunt across your 100uA meter. A sensivity trim is easily done by replacing this 2K by a 4K7 or 5K trimmer with wiper centered for 1st. power up. Just have a look at the schematic to get the idea.

Merry Christmas

 

[trancedental]

Cheers Harpo ;D

I used the 300R resistor for the meter & a 5K for the meter sensitivity until I get a 5K trim, seems to indicate OK. I'll fine tune it later.

Meanwhile I'm trying to get rid on the hum on this unit ??? Disconnect the control PCB & most , almost all of the hum disappears so I'm assuming there might be a short in there somewhere? :

I ordered 50K pots with PCB pins by mistake doh!  ;D Nightmare to wire up compared to solder lugs :-[

 

[gyraf]

Disconnect the control PCB & most , almost all of the hum disappears

check that your +/- 12V lines are alive and well

 

[JayDIY]

Hey guys,

I'm doing a GSSL with 2 X super side-chain + Turbo ... i'm going for a 2 x 15V 30 VA like that one http://fr.farnell.com/multicomp/mcfe030-15/transformateur-30va-2x-15v/dp/9531726. is that ok?

Second question, i saw along the forum that the super side-chain and the turbo boards was functionning with 12V, how does it work to transform the 15V in 12V? or should i don't bother with that?


Any help is welcome...  and apologize for this newbie question...

 

[Eje2005]

So i have my up and running with the turbo mod, sounds great. But i wanna get rid of the hum.

Voltages are fine. Had some problems with a "hangup", works on reboot, so im gonna change the regulators.

Second plan is to make an external power supply.

Can i leave the bridge and 78/79 regulators onboard and just Hook up the +-15 coming from outside? Can i feed the Main board via the +-15v jumpers near the onboard trafo?

Cheers!

 

[RedNoise]

Hi there!
May I ask if someone could tell me if Lorlins should be MBB or BBM???
If someone got a Farnell reference , it will be very cool!!!
Thx!
T.

 

[Eje2005]

So i have my up and running with the turbo mod, sounds great. But i wanna get rid of the hum.

Voltages are fine. Had some problems with a "hangup", works on reboot, so im gonna change the regulators.

Second plan is to make an external power supply.

Can i leave the bridge and 78/79 regulators onboard and just Hook up the +-15 coming from outside? Can i feed the Main board via the +-15v jumpers near the onboard trafo?

Cheers!

okay found more info on it....

 

[Stagefright13]

Wow Rednoise you building everything! Gimme a sec I will get ya the Farnell lorins... I got mine from Mouser but have purchased from Farnell also. Give ya part numbers as soon as I check.