SB4000 Support Thread

[sr1200]

:-[ :-[ :-[
I think i made a big boo boo...
I soldered the pots in.... And i didnt line up the little notches. Getting these things off is going to be rough. Is the tab orientation relative to the switch position or can i just snip the tabs off?  Also, even if i got the panel all the way down, my led meter is like a good quarter inch shy of meeting the front panel flush.

Help!

 

[Ptownkid]

Pics? I honestly have no idea what you mean, haha. What notches?

 

[sr1200]

There are little notches in the faceplate (on the back) that are supposed to line up with little tabs on the pots.  Ill try and get a pic later.  Ive bern trying to desolder them with no luck.  Need a solder vacuum for this or something.

 

[Ptownkid]

By "pots" are we talking about rotary switches? I'm pretty tired...but I'm fairly certain that the rotaries only fit the board a couple of ways and they should still be fine...the little nub just provides some resistance so that all the mechanical strain of turning the switch isn't on the pcb...but you're probably ok.

HOWEVER; Please wait for someone to verify this before powering up!

If you don't have a solder sucker or good solder wick skills, stop trying to desolder...you'll harm the pcb soon enough.

 

[sr1200]

Yeah man sorry im tired and frustrated... Its the rotary switches. I tried to get one of em out with the sucker and wick and just stopped for the night. Ugh what a mess! The board is still ok. If they have to go in a certain way im boned. Gonna have to cut em out and order new ones.

 

[Adam Smith]

Thanks for the advice. I applied a balanced signal and re-calibrated up to CV levels (I can't calibrate further, as i can't get enough GR to so so) Still having the same problem tho. I have a better set of measurements now.

Applying a balanced signal to both inputs at once and measuring the input and output with my fluke (and later scope just to confirm my fluke readings) across pins 2 and 3 of the ins and outs I got the following results.

With the input signal reading 1.23 Vacrms I couldn't get gain reduction.
With the input at 18.9dBu (6.778vacrms) here are my GR readings
Ratio 2:1
Thresh -20  | 14.9dBu (4dB of GR)
Thresh +20 | 17.8 dBu (1.1dB of GR)

Ratio 4:1
Thresh -20  | 16.71dBu (2.19dB of GR)
Thresh +20 | 18.7 dBu ( 0.2dB of GR)

Ratio 10:1
No GR in any Thresh setting.

I adjusted the threshold trimmer on the board and these readings were the most GR I could get with it set anywhere (it is set fully CC for these readings)

it should be noted that I have variable resistors in every slot that the board would take them.

So, either there is a calibration trimmer that I'm totally missing, or I'm guessing it's something in the control board. Any leads in the right direction would be great.

 

[MicDaddy]

Yeah man sorry im tired and frustrated... Its the rotary switches. I tried to get one of em out with the sucker and wick and just stopped for the night. Ugh what a mess! The board is still ok. If they have to go in a certain way im boned. Gonna have to cut em out and order new ones.

Please post a photo of your mess before you go pitching anything.  Surely we can help guide on some techniques to salvage/desolder (if it's possible)

 

[sr1200]

Its not a big deal to get new switches.  Just need to know if their position is dependent on the orientation of those tabs or if ill get a pyrotechnic show on power up (which wouldnt be until monday when the tx gets here).

 

[Ptownkid]

Unless I'm missing something, electronically it does not matter which way the switches are installed.

 

[Winetree]

Yes, the switches align with the holes drilled in the face plate.
Also turn the shaft fully counter clockwise and align with PSB diagram.
Both should align. A Hakko 808 will Do the desoldier job. Great investment.
Then you have to deal with the non aligning, impossible to keep in place,
because it doesn't fit in the cut-out, meter.
Thinking of hot-glueing it to the face plate.

 

[ruckus328]

If you have the switches in backwards it will not matter, you'll just be swapping the sets of poles but it'll work all the same - just hack the tabs off like you said.  If you have switches with flats on the shafts they will now end up on the opposite side you would want them, which would still be fine assuming you're using knobs with sets screws.

The bargraph is intended to line up with the rear of the panel.  Lots of pics in the build manual.  The cutout is intentionally a hair smaller so that you can physically press it against the rear of the panel before you solder it.  This is also why the anodize was done after the machining - so it looks nice and you're not staring at bare aluminum.  There was never an easy way to get it to line up with the front of the panel due to large height differences between it and the rest of the items - but if you want to you can surely mod it - you'll need to file the sides of the opening up a little (go slow and easy) I know of one person that has already done this with great success.  An additional 20 Pin Dip socket will probably get you in the rough ballpark of being flush with the front panel.  Alternatively just score the perforated area with a blade, break off the bargraph section and glue the sucker on there (I'd use some sort of epoxy or high strength RTV though, not hot glue).

 

[ruckus328]

Thanks for the advice. I applied a balanced signal and re-calibrated up to CV levels (I can't calibrate further, as i can't get enough GR to so so) Still having the same problem tho. I have a better set of measurements now.

Applying a balanced signal to both inputs at once and measuring the input and output with my fluke (and later scope just to confirm my fluke readings) across pins 2 and 3 of the ins and outs I got the following results.

With the input signal reading 1.23 Vacrms I couldn't get gain reduction.
With the input at 18.9dBu (6.778vacrms) here are my GR readings
Ratio 2:1
Thresh -20  | 14.9dBu (4dB of GR)
Thresh +20 | 17.8 dBu (1.1dB of GR)

Ratio 4:1
Thresh -20  | 16.71dBu (2.19dB of GR)
Thresh +20 | 18.7 dBu ( 0.2dB of GR)

Ratio 10:1
No GR in any Thresh setting.

I adjusted the threshold trimmer on the board and these readings were the most GR I could get with it set anywhere (it is set fully CC for these readings)

it should be noted that I have variable resistors in every slot that the board would take them.

So, either there is a calibration trimmer that I'm totally missing, or I'm guessing it's something in the control board. Any leads in the right direction would be great.

Adam, it sounds like your problem lies somewhere in your sidechain signal.  You're passing audio so we can check off faulty VCA's. 

Does your makeup gain work? 

Which VCA's are you using? 

You don't by chance have JMP3/JMP6 (by the audio VCA's) installed do you?

You're getting correct +/-12V rails?

Otherwise you need to just trace the signal and find out where it craps out.  Look on the schematic, start at the beginning of the sidechain.  Put the unit in Stereo Sidechain (aka Turbo Mode) and feed it a signal, just set it to 1V RMS for sanity purposes. 

Check Left sidechain - TP8 - Got 1V?

OK, move on - TP11 Still have 1V?

Next check U16 Pin 7.  Continue on down the path, let me know your findings.  You'll start to have DC voltage at U16 Pin1 and U16 Pin14 as it's a rectifier circuit.

Hey, you know what, it just dawned on me, did you install a 47K at R169 right by the threshold pot????  If so jumper him instead (you can just solder a piece of wire across the resistor to short it out, no sense in trying to remove the resistor.  Try that first before you do anything else.

 

[sr1200]

awesome! Thanks (saved me some stomach ailments!) i have an idea about the bargraph.  I also have to remember to change the resistors for the phase issue on the v4 boards.  (cant wait to do this again when i get the new boards lol)

 

[Adam Smith]

Hey, you know what, it just dawned on me, did you install a 47K at R169 right by the threshold pot????  If so jumper him instead (you can just solder a piece of wire across the resistor to short it out, no sense in trying to remove the resistor.  Try that first before you do anything else.

That did it. Stuck a jumper there and it works like a charm. I ran some mixes through it and I've gotta say this thing sounds really, really great. Seriously, everyone should own one of these. Excellent design. Many thanks to you and ptown.

 

[Ptownkid]

So happy to hear more people hitting completion! Way to go Adam!

 

[DanH]

I posted on the previous page, but here's a pic of my build. I've cleaned up the wiring and put in the ext input jacks.. Sounds awesome!

 

[sheadstedford]

Meters in, shes calibrated up, tube drive works a treat, sounding quality, (especially on drum bus wit T2)

Looks like shes fittin in nicely

 

[ruckus328]

Adam & Dan, thank you for the compliments, it's posts like yours that make it all worth it!

Dan - In answer to your questions:

- Is it criminal to use only one winding from the transformer primary? (eg, blue and grey, on the standard bom transformer). I just heat shrinked the ends of the other two and stuffed them in the corner of the chassis. If I'm crazy or if I'm going to burn my studio down, please let me know..

This is definately not advisable, you're halving the primary of your transformer, probably driving it to its max limit or even beyond, surprised it's not overheating (or possibly it is).  And unless I'm having a brain fart this morning, pretty sure bad things can happen within the unit before your fuse kicks in, you should hook up the additional wires.

- the 1mA meter shows RMS gain reduction, right?

The analog meter is not a VU meter (like you would have in say 1176, LA3A, etc), it's measuring current from the CV signal, it should be reading peak G/R (within the limits of your meter's accuracy and response).

 

[EHOFFA007]

Just need calibration! Thanks to the guys for this one!!!!

 

[Ptownkid]

Woooooot, it's spreading like wildfire!