SB4000 Support Thread

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JMan

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Hey felix, I tried to upload it but it’s not going through — I think maybe the file is too big.  PM me and we’ll get it sorted.
 

Blackdawg

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felix1988 said:
would be great man! i didn‘t find it yet.
Thank you!
Here is a link to all the docs I have for this:

https://drive.google.com/drive/folders/1C5WfXIfJVefF90KV2jqWBoyQkgP4qZOr?usp=sharing

As the build guide and BOM and such.  Sorry theres a few other random docs that pertain to my own build you can ignore ha
 

jcgriggs

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May 20, 2017
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I'm trying to calibrate power on my SB4000 build and I keep frying the 10 ohm resistor at R182 on the PS board.  The first time I believe I accidentally shorted the pins with my meter probe.  I replaced the part and got the PS calibrated alone but R182 fried again as soon as I connected the main board (with the control board still disconnected) - replaced it again and it fried again when connecting the main board. 

Are there parts I should replace in the power supply  besides R182 (and its companion R183)?  I have some electronics education but mostly from many years ago, so I will have to beg your patience with me if I am being thick here.

I have looked for any obvious problems with solder bridges or component orientation and I found nothing.  One thing I notice is that the VU meter (I am using the one from Hairball) is very bright - before replacing the PS resistors the second time, I also upped of R133 (currently using 300 ohms, I  believe I originally used 260) in case that was an issue, but the meter still seems very bright - until R182 cooks, at least.

Any help is greatly appreciated.

Regards,
  John
 

critterkllr

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The dropbox links don't work for me so I can't get the build guide or BOM. I have a working SB4000 that I'd like to swap VCAs in. I'm removing a pair of Quad VCAs to a pair of DBX 202c's. Do I need to modify anything to get them to work correctly?
 

JMan

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critterkllr said:
The dropbox links don't work for me so I can't get the build guide or BOM. I have a working SB4000 that I'd like to swap VCAs in. I'm removing a pair of Quad VCAs to a pair of DBX 202c's. Do I need to modify anything to get them to work correctly?

Did you try Blackdawg’s google drive link a few posts up?  That works and has everything you need.

I think you’ll need to modify some things to make the DBXs work, but don’t quote me.  I’d take a very thorough read through this entire thread, as it was definitely discussed at some point earlier on.

Any chance you’d be willing to part with the quad VCA boards that you’re taking out?
 

Bowie

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critterkllr said:
The dropbox links don't work for me so I can't get the build guide or BOM. I have a working SB4000 that I'd like to swap VCAs in. I'm removing a pair of Quad VCAs to a pair of DBX 202c's. Do I need to modify anything to get them to work correctly?

The schematic has a chart on the left side explaining what changes to make when using the DBX cans. It's pretty simple.
If you haven't found it, then here's a link to my dropbox that should work;
https://www.dropbox.com/s/ltxznsz09y02t8j/SB4000_schematic.pdf?dl=0
 

critterkllr

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Bowie said:
The schematic has a chart on the left side explaining what changes to make when using the DBX cans. It's pretty simple.
If you haven't found it, then here's a link to my dropbox that should work;
https://www.dropbox.com/s/ltxznsz09y02t8j/SB4000_schematic.pdf?dl=0
JMan said:
Did you try Blackdawg’s google drive link a few posts up?  That works and has everything you need.

I think you’ll need to modify some things to make the DBXs work, but don’t quote me.  I’d take a very thorough read through this entire thread, as it was definitely discussed at some point earlier on.

Any chance you’d be willing to part with the quad VCA boards that you’re taking out?

Thank you both. I didn’t realize it was in the schematic at first. I’ll need to wait until I’m at a computer since it shows up pretty blurry on my phone.

Will definitely sell the quad VCA’s if I end up preferring the DBX’s more.
 

JMan

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critterkllr said:
Thank you both. I didn’t realize it was in the schematic at first. I’ll need to wait until I’m at a computer since it shows up pretty blurry on my phone.

Will definitely sell the quad VCA’s if I end up preferring the DBX’s more.

Glad you were able to find what you needed!

Let me know re: the quad VCA boards.  I’d be happy to take them off your hands if you like the dbx cans better!
 

EmptyMusicBox1

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Hello

Do you know if it's a good idea to add the VCAs trim to the front pannel for add a "Warp" compression control ?

i have see this function on this comp :

https://www.soundonsound.com/reviews/funky-junk-industries-solid-compressor



 

oscarat50

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Aug 11, 2019
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Lordward said:
Great stuff. So, I wired it all up and did the calibrations.  For some reason my Bar LED is not working.  No blink, nothing.  So I was not able to calibrate this.  Everything else went well and the unit sounds very promising so far :)

had the bar graph in upside-down.  Now it lights up.  Checked it on a mix and it's  always in the red in both input and output on a mix that has 5 db headroom.  Normal?

I'll have to wiggles some things around to see if I can get the bar meter working. 
One last question:  There are so many trim pots and I find it strange that in the calibration I did not have to touch all of them, specifically the 2 on the VCA boards...what am I missing?

DW


Hi, I'm having the exact same problem as you with the Bar Meter always running too hot, did you ever get to fix this? Thanks
 

Bowie

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oscarat50 said:
Hi, I'm having the exact same problem as you with the Bar Meter always running too hot, did you ever get to fix this? Thanks

It's not super-accurate but you should be getting constant overs addressed when calibrating. Have you fully gone through calibration?
 

charleselmi

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Oct 18, 2019
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Hi all, my first post in this forum, great place! :)

I'm trying to find which changes need to be made in order to install DBX 202X. On the chart in the schematic I can only find the values for the DBX 202 (black can) and Google is not helping much. But I've seen pictures of the SB4000 with 202X VCAs....so wondering if someone can help me out?

Thanx guys.
 

Bowie

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charleselmi said:
Hi all, my first post in this forum, great place! :)

I'm trying to find which changes need to be made in order to install DBX 202X. On the chart in the schematic I can only find the values for the DBX 202 (black can) and Google is not helping much. But I've seen pictures of the SB4000 with 202X VCAs....so wondering if someone can help me out?

Thanx guys.

It's in this schematic, on the left.
https://www.dropbox.com/s/ltxznsz09y02t8j/SB4000_schematic.pdf?dl=0
 

JMan

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Hey Everyone,

I'm thinking about building another of these for my studio.  (The first one worked almost straight away, with little troubleshooting, which always makes me paranoid. ;D I may be back with troubleshooting and/or calibration questions if this one doesn't cooperate so easily, but we'll see).

Regarding the threshold and makeup pots: Is there any reason that one couldn't use a different, panel-mounted 50k pot in these locations, skip the adapter boards, and just run the wire connections back to the appropriate pads on the control board?

Eh, I'm just musing today...
 

charleselmi

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Harpo said:

Thank you, I did my homework and let you guys have the values I managed to figure out, but a few are missing if someone wants to help out.

So for the Dbx 202x;

R76/96    = 200K
VR3/VR4  = 50K Pot
VR1/VR2  = 6K04
R38/R49  = 7K32
JMP1/4    = POP
JMP2/5    = DNP
JMP3/6    = DNP
R132      = ??? (Can’t find)
JMP8/9    = ??? Maybe POP?
R77/R121= ???
R83/R125= ???
R82/R85  = ???

If anyone could help out with the 5 missing values I would be very happy! Thanx!
 

calaverasgrande

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Couple parts clarifications if anyone is experienced with sourcing for this and can supply mouser cart or simlar?
I already own majority of the parts so I'm not buying a kit!
I can't pin down which relays to buy. The BOM doesn't specify package type or lead spacing. Just electrical characteristics for which dozens of items are possible fits. 
The 2  pots for threshold and gain are 50K, 20%, 1/2W, 6.35mm but doesn't specify lin, log or reverse. I assume linear but you know, those crazy Brits love to put funny taper pots where they don't belong.
Also looking at the build guide they appear to be specific PCB mount pots of a type I'm not familiar with.
Also these 10,22,33,100pf ceramic COG caps are all listed as 100v? I have  a ton of 50v, is 100v correct?
Not trying to blow up caps, but also trying to buy as much of this from Tayda as I can. :)
 

JMan

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calaverasgrande said:
Couple parts clarifications if anyone is experienced with sourcing for this and can supply mouser cart or simlar?
I already own majority of the parts so I'm not buying a kit!
I can't pin down which relays to buy. The BOM doesn't specify package type or lead spacing. Just electrical characteristics for which dozens of items are possible fits. 
The 2  pots for threshold and gain are 50K, 20%, 1/2W, 6.35mm but doesn't specify lin, log or reverse. I assume linear but you know, those crazy Brits love to put funny taper pots where they don't belong.
Also looking at the build guide they appear to be specific PCB mount pots of a type I'm not familiar with.
Also these 10,22,33,100pf ceramic COG caps are all listed as 100v? I have  a ton of 50v, is 100v correct?
Not trying to blow up caps, but also trying to buy as much of this from Tayda as I can. :)

Hmmm...maybe you're looking at an old version of the BOM, but my copy lists a sample part number for every component.  Even if you don't go with the exact one listed, you should be able to use it as a guide for your purchases.

Here's the part number for the relays from the BOM:
V23079A1003B301

The 50k pots that he lists are linear taper.  They also feel horrible -- just loose and flimsy, so that's one where getting a different part might be worth your while.  They are currently scheduled for obsolescence anyway.
 

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