SB4000 Support Thread

[solderboy]

okkkaayyyy... that´s sound´s goog! thank you so much!!!
do you also know about the 50k trimmer on the quad pcb? what is he doing? do i need this one when using 2180a or b?

 

[ruckus328]

and another problem i got today...  :'(
i was trying out a different switch like the one from the bom. i still had this one:
http://www.conrad.de/ce/de/product/706170/SIGNALLAMPE-TYP-1-MAX-65-MM/?ref=detview
the switch is using a kind of mini-bulp 12v, 40 mA and it seem´s this is to much... or something is wrong in general with my power. when i connect a normal 12v led it´s working fine - mini-bulp: nothing. for controlling i did a connection from the 12v out of the psu to the switch: lamp is working. so... what´s wrong? is the 40mA to much? what kind of light is the switch from the bom using?

i would be extremly happy about any help...

You can't use a 12V bulb here, even if you resize the resistor, it will stress the regulator.  It's intended to use an LED, 10mA max per switch here.  Another 80mA on the 12V rail is too much.

If you want to use a bulb, then you should run it directly off of the diode bridge on the power supply, before the regulators.  Depending on your transformer you'll probably have somewhere around 24VDC here, so use a switch with a 24V bulb instead.  You could run it right off the transformer secondaries too for AC.

Keep in mind, illumination is just an option, you can use a simple non-illuminated toggle switch (or similar) too.

 

[ruckus328]

hello!
got the pcb from a friend and have one question... documentation is for trimmed vca´s. can someone please explain (like for dummies... ) what i have to do when i want to use pretrimmed vca´s on the pcb and also for the quad?

Which are you doing?  Single 2180 or quad 2180?

If single, just follow chart on schematic.  You leave off symmetry resistors and 50K sym pots.

Never used pretrimmed VCA's in quad config, but far as I know you should treat it like it's not pretrimmed (yes you can still trim the pretrimmed VCA's), Even if using pretrimmed VCA's - in a quad configuration you still need 50K rmagic between CV and SYM pins on the quad board to null for lowest THD, so therefore you also still need symmetry resistor and 50K sym pot's installed on the main PCB as well.  For quad arrangement, divide symmetry resistor value on the chart by 4 for for correct value.  So for A grade 680K/4 = 170K (160K is ok), B grade 220K/4 = 56K, C grade 130K/4 = 33K.

Harpo, please correct me if I'm wrong there.

 

[solderboy]

hello ruckus328!

as fist thank you for the help!!!
i mean the quad version with 2180a´s. when i get you right i have to do following things:
- vr1/vr2 change to 10k... done
- c70 & c73 change to 47uF... done
- r76/r96 change to 170k... done with 180k
- r38/r49 change to 5,1k... done
- jumper 8 & 9... done
- vr3/vr4 50k trimmer... need to buy tomorrow
- vr1 on the quad board 50k trimmer... need to buy tomorrow

anything else?

but i still dont get why i have now 2 times 50k trims for thd. one on the board and one at the quad pcb. how to adjust? or i´m just think to complicate...

 

[solderboy]

okay... thanks so far... it´s working. but i loose around 6db on the left site in the input stage. i was tryin to calibrate the unity and can see that the left site is less. also with full open pot. any ideas?

 

[ArnauTS]

okay... thanks so far... it´s working. but i loose around 6db on the left site in the input stage. i was tryin to calibrate the unity and can see that the left site is less. also with full open pot. any ideas?

Check out your xlr wiring, - 6db's might be that one of your + or - from the left input it's not connected.
Hope it helps

 

[solderboy]

no, xlr wiring is fine. but right now i saw that i forgot a 22pF cap next to the unity pot of the left side. tomorrow i can try it... hope that´s it...

 

[solderboy]

bad news... the cap wasnt the problem. no it´s in and it´s still the same... guess now i need realy help... heeeeellllpppppp.... 

 

[solderboy]

i was double checking my xlr wiring inside the comp and also the wires to my soundcard... all fine. slowly i´m running out of ideas because everything is checked and double checked.... here´s a picture... mybe someone can see it and i´m just blind...  ???

 

[MadHans]

Hi,

I have just finished the build of my unit, and everything looks good  .
I've checked the voltage at the rails(without main pcb and control board connected), and they checked out good.

Now it is time to connect the main pcb (quad vca version), and I have a couple of questions:

1) Do I check only one voltage at a time? Like this: pwr on > check +15v rail quickly > pwr off  > pwr on > check -15v rail quickly > pwr off ... etc etc. And how quick do I have to be??

2) Is it a good idea to leave the IC's and VCA's out while doing this test, and put them in after the voltage tests on the rails have checked out good? Or does it affect the voltage reading on the rails too much?
3) If it is possible to install them after the voltage test, should they be installed one by one?

4) I have read about the "47k or jump" issue on this thread, and I still don't understand what the resistor does. Many people say "jump"  but why? What is the difference?

I appreciate any help!

regards,

Hans Jacob

Anyone?

 

[sr1200]

K lemme see if i understand here... your left side is about -6db from unity with the cal pot all the way open? 
Your little SMD chips threw me for a loop for a sec...  If you swap your chips (L-> R R->L) does the problem move to the other side?

 

[solderboy]

you mean the 5534? i did a swap, same problem... 

 

[solderboy]

ah, you mean the opa... no, before i had 5532 in and had the same problem...

 

[solderboy]

also when i remove the 5534 from both input sections, the 5532 from both quads and the ne5532 from the output section i have still more level on the right side...

 

[sr1200]

Measure your signal at the input, and follow it through till you get the signal drop or increase and check to see if the component values are correct. If everything is good, keep following until you get to that pot.  If everything is good when you get to the pot, it could be a defective pot (id tend to doubt it, but ya never know)

If you've swapped out all the IC's and you're still getting the problem, you can rule out that theres a defective IC (but not a defective solder on the IC pads... check those too!)

 

[solderboy]

i don´t think it´s the pot... to change this one was the first i did... but i will check the solder points...

 

[solderboy]

it was a long way but finally it´s done!!! it was the pot. strange because i did a changing before. anyway... he´s sounding fantastic!!!

 

[sr1200]

Coold deal, enjoy it!  I love both of mine!

 

[electrisizer]

hey there,
the SB4000 is sitting for at least one year in my mix bus all the time and does a very very good job 

im noticing theres the quad vca board avaliable... i have a soundwise question: does this thing become noticeable to the overall compressor sound or would you say... better not change a running system?

 

[nickvivid]

Hey guys, I just wanted to introduce myself. Have a few questions on this project. Ordered the kit from serpent. Everything has gone very smooth so far. Soldered the boards, got the rest of the parts from digikey. The serpent kit was complete, but had some extra resistors and some wrong values (different from the markings on the board) so I put the correct values in. Everything's together. I did the first test of the power supply today, and so far, looks like it's a little off. +/- 12v is reading pretty good - around 11.8 with my digital multimeter, but the +/- 15 is only reading about 13. That normal or should i be troubleshooting before i move on to the main board? Thanks in advance

Nick