SB4000 Support Thread

[Blackdawg]

Right tools makes a difference! Was sorting resistors and my meter wasn't confirming the color code. Picked up a Fluke 115 for 50 bucks off craigslist today. So much better!

I do have a question. Some of the resistors aren't super close to the numbers on the BOM. Is that okay?  For instance, 630k is meassured at 628k. Probably fine right?

 

[Bowie]

Right tools makes a difference! Was sorting resistors and my meter wasn't confirming the color code. Picked up a Fluke 115 for 50 bucks off craigslist today. So much better!

SB4K kit?  That big, unsorted bag-o-parts is such a joy, eh? 

 

[Blackdawg]

Right tools makes a difference! Was sorting resistors and my meter wasn't confirming the color code. Picked up a Fluke 115 for 50 bucks off craigslist today. So much better!

SB4K kit?  That big, unsorted bag-o-parts is such a joy, eh? 

Huge bag o parts!  gonna be fun!

I added this to my post above but if the resistors are off a bit is that okay?

Even the color code is not for 630k..odd..


Whoops. Supposed to be 620k. But it meassures 628k. Still okay?

 

[Bowie]

Right tools makes a difference! Was sorting resistors and my meter wasn't confirming the color code. Picked up a Fluke 115 for 50 bucks off craigslist today. So much better!

SB4K kit?  That big, unsorted bag-o-parts is such a joy, eh? 

Huge bag o parts!  gonna be fun!

I added this to my post above but if the resistors are off a bit is that okay?

Even the color code is not for 630k..odd..


Whoops. Supposed to be 620k. But it meassures 628k. Still okay?

Modern color codes give me a headache.  FWIW, I've never had an unused modern resistor test out of spec, but I still check them all.  628k is only 1% off of 620k so you're fine.  When in doubt, do the math to see how far off spec you are.

 

[Blackdawg]

Right tools makes a difference! Was sorting resistors and my meter wasn't confirming the color code. Picked up a Fluke 115 for 50 bucks off craigslist today. So much better!

SB4K kit?  That big, unsorted bag-o-parts is such a joy, eh? 

Huge bag o parts!  gonna be fun!

I added this to my post above but if the resistors are off a bit is that okay?

Even the color code is not for 630k..odd..


Whoops. Supposed to be 620k. But it meassures 628k. Still okay?

Modern color codes give me a headache.  FWIW, I've never had an unused modern resistor test out of spec, but I still check them all.  628k is only 1% off of 620k so you're fine.  When in doubt, do the match to see how far off spec you are.

Cool! Thanks.

Everythin is going good! Many more to go haha

 

[Blackdawg]

Two questions fellas:

1) I have the QUAD VCA upgrade so both have to do with that. R76, R96 on the outside of the main board are labeled 680K. Which I don't even have. But they are supposed to be changed to 5.1k from 15k. Is that still correct? Why does the board say 680k? Do I just use the 5.1k resistors that don't get used where the normal VCAs go? as in R105 and r148?

2) Says 10k pots would be better but the included 50k will work. Doesn't matter though right so long as I get them to 5K as iIunderstand it correct?

3) I'm noticing a lot of options for pots instead of solid resistors. Is it worth going to them? What's the difference with the ones not included in the kit? like VR11/12/13/14 for example.

 

[critterkllr]

The BOM has R163 listed as Mouser part # 660-MOS3CT631R100J. That is for another 10r 3W resistor. Mouser part # 684-MP915-100 is a 100r 15w resistor in a TO-126 package.

 

[Harpo]

1) ...R76, R96 on the outside of the main board are labeled 680K.

resistor value is depending on type of VCA used. 680K is ment for a THAT2181A. (have a look at the schematic to get corresponding parts values for some different types of VCAs. Corresponding values for your specific quad-VCA are listed on the Quad-VCA-BOM).

...But they are supposed to be changed to 5.1k from 15k. Is that still correct?

Neither this is correct nor is the BOM saying so. (that would be true for R38 and R49). Please read it again and sort your numbers.

Why does the board say 680k?

With limited pcb real estate you have to decide what information to place on a silkscreen. The table on schematic only lists 8 different types of VCAs. There are some more, again requiring different values for best performance.

Do I just use the 5.1k resistors that don't get used where the normal VCAs go? as in R105 and r148?

R148 isn't 5.1K but 68K and part of the ratio network. Be more exact with your numbers. Sure you can use a correct value part in a different spot when you have spares... (Bias current setting value of 5.1K is ment for THAT218x VCAs in this spot and is depending on supply voltage and type of VCA used. FI a similar NEC or DBX part might require a different value).

2) Says 10k pots would be better but the included 50k will work. Doesn't matter though right so long as I get them to 5K as iIunderstand it correct?

5K would be the trimmers initial parts value that might need further adjustment for desired performance. A 50K part has a reduced rotation angle for dialing in the target value, but should work.

 

[Blackdawg]

1) ...R76, R96 on the outside of the main board are labeled 680K.

resistor value is depending on type of VCA used. 680K is ment for a THAT2181A. (have a look at the schematic to get corresponding parts values for some different types of VCAs. Corresponding values for your specific quad-VCA are listed on the Quad-VCA-BOM).

...But they are supposed to be changed to 5.1k from 15k. Is that still correct?

Neither this is correct nor is the BOM saying so. (that would be true for R38 and R49). Please read it again and sort your numbers.

Why does the board say 680k?

With limited pcb real estate you have to decide what information to place on a silkscreen. The table on schematic only lists 8 different types of VCAs. There are some more, again requiring different values for best performance.

Do I just use the 5.1k resistors that don't get used where the normal VCAs go? as in R105 and r148?

R148 isn't 5.1K but 68K and part of the ratio network. Be more exact with your numbers. Sure you can use a correct value part in a different spot when you have spares... (Bias current setting value of 5.1K is ment for THAT218x VCAs in this spot and is depending on supply voltage and type of VCA used. FI a similar NEC or DBX part might require a different value).

2) Says 10k pots would be better but the included 50k will work. Doesn't matter though right so long as I get them to 5K as iIunderstand it correct?

5K would be the trimmers initial parts value that might need further adjustment for desired performance. A 50K part has a reduced rotation angle for dialing in the target value, but should work.

Thank you for the response.

I do not have the schematic, nor is it in the OP. Where can I get that? I know i have THAT2181Bs. So i guess i have no idea what is supposed to go in R76 and R96 without the list on the schematic. 

R38 and R49 are supposed to be 5.1k now, got it.

Sorry typo on my part, meant R146 for the 5.1K resistor. The QUAD BOM says to change the R38 and R48 15ks to 5.1ks. Since im not using the two that were meant to go in R146 and R105 I will just put them at R38 and R49.

Thanks again for your reply!

The BOM has R163 listed as Mouser part # 660-MOS3CT631R100J. That is for another 10r 3W resistor. Mouser part # 684-MP915-100 is a 100r 15w resistor in a TO-126 package.

Correct, i have the 3w 10r Resistor. Although I am struggling to find the spot for it. I know it supposed to be vertical. Going by how the PCB is laid out and numbered it should be on the faceplate PCB but i can't find it on there. Or are you saying it is better to swap to the 15w one?





and what are peoples opinions on swapping out the resistors for VR11/12/13/14 for pots? what do the pots give you that you'd need to adjust?

 

[Blackdawg]

AH HA! Found the schematic at our good friend Petersons site. I love DIYrecordingequipent

this should be added to the OP!

https://dl.dropboxusercontent.com/u/4740474/SB4000_Production/SB4000_REV4_FORUM.pdf

And look at that. Nothing goes in R76/96 for the VCA I have. Cool. Thanks guys!

 

[Harpo]

...And look at that. Nothing goes in R76/96 for the VCA I have. Cool. Thanks guys!

??? :
from your "I know i have THAT2181Bs" I told you "Corresponding values for your specific quad-VCA are listed on the Quad-VCA-BOM".
As already suggested, "Please read it again and sort your numbers."

 

[Blackdawg]

...And look at that. Nothing goes in R76/96 for the VCA I have. Cool. Thanks guys!

??? :
from your "I know i have THAT2181Bs" I told you "Corresponding values for your specific quad-VCA are listed on the Quad-VCA-BOM".
As already suggested, "Please read it again and sort your numbers."

Yea I caught that going back through the quad BOM before soldering the resistors.  :-\ but it's corrected now! 56k

 

[critterkllr]

My GR meter is sitting at -4dB instead of 0dB. It doesn't change if it's bypassed. The meter calibration trim pot is all the way down. My voltages are all correct. Meter is the Hairball 8027-B 1mA.

Any thoughts on tracking down the problem?

 

[Bowie]

My GR meter is sitting at -4dB instead of 0dB. It doesn't change if it's bypassed. The meter calibration trim pot is all the way down. My voltages are all correct. Meter is the Hairball 8027-B 1mA.

Any thoughts on tracking down the problem?

I used those meters and didn't have anything like that.  My first step would be to check the value of all the resistors in section leading up to the meter itself.

 

[critterkllr]

I used those meters and didn't have anything like that.  My first step would be to check the value of all the resistors in section leading up to the meter itself.

Making progress. I just realized it only does this when the ratio is set to 2. In 4 or 10, it goes to normal. The volume also drops when the ratio is set to 2. I'm going to pop the panel pcb off and see if R172 or R173 or the wrong values.

R129, R135, C121, R124, are all correct. Nothing is in R111. I read 0V on positive side of the meter and -.061v on the negative. At this point I'm not thinking it has anything to do with the meter circuit, but something with the ratio.

 

[critterkllr]

Found it. D24 is backwards. Thanks for chiming in.

 

[jigdagod]

Question...I'm looking to purchase a SB4000 from someone in Europe. It has a 230v transformer and I'm in the states. How difficult is swapping out the 230v for a 120v tranformer?  Is there anything else that needs to be done with the swap? Thank you in advance for any guidance.

 

[Bowie]

Question...I'm looking to purchase a SB4000 from someone in Europe. It has a 230v transformer and I'm in the states. How difficult is swapping out the 230v for a 120v tranformer?  Is there anything else that needs to be done with the swap? Thank you in advance for any guidance.

It's very easy.  It's possible that the current transformer might even have taps for 120.  It will likely say on the side of it.  Worst-case, pull the torroid and replace it with a another (around $27 + ship).  They are pretty easy to wire in, especially if terminal blocks were used instead of soldering the PSU PCB.

 

[jigdagod]

Question...I'm looking to purchase a SB4000 from someone in Europe. It has a 230v transformer and I'm in the states. How difficult is swapping out the 230v for a 120v tranformer?  Is there anything else that needs to be done with the swap? Thank you in advance for any guidance.

It's very easy.  It's possible that the current transformer might even have taps for 120.  It will likely say on the side of it.  Worst-case, pull the torroid and replace it with a another (around $27 + ship).  They are pretty easy to wire in, especially if terminal blocks were used instead of soldering the PSU PCB.

Sweet. Thanks for the help!

 

[Mmt50816]

I got the kit with the Quad VCA boards. The boards came with neat little pins. The BOM does not list the P/N for the pins. Anyone who what they are? Are you guys soldering the VCA board to the main board or are you getting sockets for the pins? Id like to order the corresponding sockets. Let me know if anyone has an idea.
Thanks