[BUILD] New FET/RACK Official Help Thread - Please read first post!

[bjohnsonaudio]

This is Pad 22?

Seems like you have no compression. 

Hard to say because your measurements are jumping around so that is either a bad solder joint, bad ground connection, or measurement error.

Your last amp stage measurements looked ok. Does it pass clean signal?

Mike

Hey Mike. I just tried passing a signal through it and I am not getting anything.

 

[Echo North]

-GR Control Amp Input
4:1- .96 VAC

I Assume you mean 0.096 here?

-GR Control Amp Threshhold

20:1 - -7.33 VDC
12:1 - -4.95 VDC
8:1 - -4.04 VDC
4:1 - -3.28 VDC

Lower seem super high.  I would triple check R58, R61-R63.  Reflow solder.

Mike

 

[Echo North]

Hey Mike. I just tried passing a signal through it and I am not getting anything.

But you were getting signal earlier. When you measured the AC.  That's what so confusing. You can measure it, but can't hear it.  You might want to check your set-up (send/returns/routing).

Mike

 

[JDport]

Thank you Mike for your response. Good to know I am not crazy!

Regards,
JD

 

[Echo North]

Is this the same post from earlier?  I answered above.

 

[bjohnsonaudio]

But you were getting signal earlier. When you measured the AC.  That's what so confusing. You can measure it, but can't hear it.  You might want to check your set-up (send/returns/routing).

Mike

Hey Mike! So I am getting clean signal through the compressor now, I wasn't routing it correctly. However when I pass the signal one thing I am noticing is that the meter switches aren't switching cleanly. I get a strong signal and when I switch over from GR off to On the signal would drop. When I tap the sides of the meter switches it seems like there is something going on there. It goes from quiet signal to loud signal and vice versa if that makes sense.

Thanks again for your patience and willingness to help!

 

[Maxwell.ravitz]

Whoops, sorry!  I thought my last comment didn't get posted for some reason, so I tried reposting.  My bad!

 

[bjohnsonaudio]

Hey Mike! So I am getting clean signal through the compressor now, I wasn't routing it correctly. However when I pass the signal one thing I am noticing is that the meter switches aren't switching cleanly. I get a strong signal and when I switch over from GR off to On the signal would drop. When I tap the sides of the meter switches it seems like there is something going on there. It goes from quiet signal to loud signal and vice versa if that makes sense.

Thanks again for your patience and willingness to help!

Yeah I am definitely getting clean signal but I am not hearing any compression. Just when I turn up the input varying degrees of saturation.

 

[Maxwell.ravitz]

I Assume you mean 0.096 here?

yes, 4:1 is .096

will reflow the resistors you suggested, but everything else seems ok?  I wasn't sure since my numbers were all a bit different from the troubleshooting guide.

 

[Maxwell.ravitz]

ok after reflowing those resistors, my numbers are definitely much closer to the proper range.  Now my last issue I'm finding is my output knob has a lot of crackling going on in the turn.  Any ideas what that could be?  I doubt it's the knob itself since the knob is new.  Thanks for all the help!

 

[bjohnsonaudio]

Yeah I am definitely getting clean signal but I am not hearing any compression. Just when I turn up the input varying degrees of saturation.

Also I went and measured my bipolar transistors between B and E and every single one reads around .59 - .63 except for my Q7 which reads 7.46 DC V ... maybe that reading helps isolate where the issue is occuring?

Also is it normal for my resistors to read different resistance now that they are put into the PCB? Because I was double checking my resistors and I am getting funny readings on some even though I double checked every single one before installing. Example would be r12 which is suppose to be a 2.2K resistor is reading -4.4 M ... I am also trying to check continuity between resistors and I a lot of them aren't reading.

I am super confused by all of this, I checked my solder joints and they all look good and I know that the resistors were right before stuffing them.

I hope that the information I have provided you with can get me going in the right direction to getting this thing up and running!

Thanks again!

 

[Echo North]

ok after reflowing those resistors, my numbers are definitely much closer to the proper range.  Now my last issue I'm finding is my output knob has a lot of crackling going on in the turn.  Any ideas what that could be?  I doubt it's the knob itself since the knob is new.  Thanks for all the help!

Do you have the active link installed? If so, there are 2 caps that need to go in backwards to fix that.  See the stereo link guide.

Mike

 

[Echo North]

Also I went and measured my bipolar transistors between B and E and every single one reads around .59 - .63 except for my Q7 which reads 7.46 DC V ... maybe that reading helps isolate where the issue is occuring?

Also is it normal for my resistors to read different resistance now that they are put into the PCB? Because I was double checking my resistors and I am getting funny readings on some even though I double checked every single one before installing. Example would be r12 which is suppose to be a 2.2K resistor is reading -4.4 M ... I am also trying to check continuity between resistors and I a lot of them aren't reading.

I am super confused by all of this, I checked my solder joints and they all look good and I know that the resistors were right before stuffing them.

I hope that the information I have provided you with can get me going in the right direction to getting this thing up and running!

Thanks again!

On your PCB the resistors are often on parallel with other components and will measure differently.  To get a true measurement you would have to desolder and lift a lead off the PCB. 

If you're not getting a proper measurements at Q7 that could certainly explain your lack of compression since that is the first active element in the GR circuit.  You get no B-E drop?

Mike

 

[bjohnsonaudio]

On your PCB the resistors are often on parallel with other components and will measure differently.  To get a true measurement you would have to desolder and lift a lead off the PCB. 

If you're not getting a proper measurements at Q7 that could certainly explain your lack of compression since that is the first active element in the GR circuit.  You get no B-E drop?

Mike

Does it matter which side I put the common on either B or E? I am noticing if I put common on E I get a -.62 and If I put common on B I get .62 except some slight variations (the .59is) except at Q7 where it reads -5.7 if common is on E and 5.7 if common is on B.

Thanks again, this is my most complex build I have done to date and it is proving a learning experience for sure!

 

[Echo North]

Does it matter which side I put the common on either B or E? I am noticing if I put common on E I get a -.62 and If I put common on B I get .62 except some slight variations (the .59is) except at Q7 where it reads -5.7 if common is on E and 5.7 if common is on B.

Thanks again, this is my most complex build I have done to date and it is proving a learning experience for sure!

You want to use your chassis as common.

 

[bjohnsonaudio]

You want to use your chassis as common.

alright I am getting 7.2 on my Q7 when I subtract the two numbers. Am I calculation the drop properly that way?

 

[Echo North]

alright I am getting 7.2 on my Q7 when I subtract the two numbers. Am I calculation the drop properly that way?

Confused. What are you Q7 voltages?

http://www.hairballaudio.com/uploads/pdf/fet_rack_a_v1.14_voltages.pdf

 

[bjohnsonaudio]

Confused. What are you Q7 voltages?

http://www.hairballaudio.com/uploads/pdf/fet_rack_a_v1.14_voltages.pdf

E = 23.22 B = 15.82 C = 27

 

[Echo North]

E = 23.22 B = 15.82 C = 27

Q7? VDC?

I have no idea. You could remove it and try the transistor diode test.

http://www.hairballaudio.com/uploads/pdf/fet_rack_a_v1.14_voltages.pdf

You may want to reflow and double check everything in the GR Amp.

 

[bjohnsonaudio]

Q7? VDC?

I have no idea. You could remove it and try the transistor diode test.

http://www.hairballaudio.com/uploads/pdf/fet_rack_a_v1.14_voltages.pdf

You may want to reflow and double check everything in the GR Amp.

Yeah that is Q7 VDC. I will go ahead and give that a shot. Thanks Mike!