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

[Diamondj421]

Are you sure your in GR OFF mode?

Unless theres a difference between GR mode aka the top button and GR OFF, I should be good to go.

 

[lackstudios]

Does the null adjust change the DC voltage?

You'll need to go through the values in the GR meter amp section, only a few parts, confirm them and reflow ant suspect joints.

Mike

Hey thanks for the help, been fooling with it all weekend, The null adjust doesn't change anything...I'm getting 0.0 from full CCW to CW.

hopefully I didn't break R71, the meter wasn't moving from -20 in GR mode, so I kept turning it and it just kept turning, turning....then I realized it had a gentle stopping point each way... 
If I push +8, +4 on the meter while theres a signal, the needle jumps way up and seems to works fine....

also, CR10 diode had 2 different length through holes, I tried both, but couldn't tell which one was right :-/ I'm in the shorter one now...

Is there a list for the GR meter amp section?

 

[Echo North]

Make sure in GR OFF mode pad 22 is shorted to the chassis (ground).

if so....

Set your unit to:
Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR OFF
Release: Full CW
Ratio: 20:1
Meter: GR
Signal: Sine 1kHz @ 0dBu

What is your AC V at pad 15 and at + output.

Mike

 

[Echo North]

Hey thanks for the help, been fooling with it all weekend, The null adjust doesn't change anything...I'm getting 0.0 from full CCW to CW.

hopefully I didn't break R71, the meter wasn't moving from -20 in GR mode, so I kept turning it and it just kept turning, turning....then I realized it had a gentle stopping point each way... 
If I push +8, +4 on the meter while theres a signal, the needle jumps way up and seems to works fine....

also, CR10 diode had 2 different length through holes, I tried both, but couldn't tell which one was right :-/ I'm in the shorter one now...

Is there a list for the GR meter amp section?

Which build do you have?  What is the PCB version you have?

 

[lackstudios]

Which build do you have?  What is the PCB version you have?

v1.12

 

[Echo North]

CR 10 only has one set of pads.  The inner hole you're seeing is a VIA. It's there to allow a trace to move from one side of the board to the other. Do not put your diode in the VIA.

The GR parts are in the section lined out and labeled GR Meter Driver Amp...or something close to that.

Thanks!

Mike

 

[lackstudios]

CR 10 only has one set of pads.  The inner hole you're seeing is a VIA. It's there to allow a trace to move from one side of the board to the other. Do not put your diode in the VIA.

The GR parts are in the section lined out and labeled GR Meter Driver Amp...or something close to that.

Thanks!

Mike

OK, so I put CR10 back in place...reflowed anything that looked even remotely weird in the meter driver amp section. same results.

 

[lackstudios]

OK, so I put CR10 back in place...reflowed anything that looked even remotely weird in the meter driver amp section. same results.

FYI, I'm not sure if I mentioned it, but I did test the ACV at the output XLR to see if the signal was getting compressed when I truned the attack up and it was working...so it looks like its just the GR meter...I think  :-\

 

[Echo North]

FYI, I'm not sure if I mentioned it, but I did test the ACV at the output XLR to see if the signal was getting compressed when I truned the attack up and it was working...so it looks like its just the GR meter...I think  :-\

1. Make sure you have all the wire harnesses in.
2. Double check your meter switch and 2-pin connector soldering.
4. Make sure the 3 pin jumper is in the right spot.
3. Check your Dc voltages in the GR meter amp section.

http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

Mike

 

[lackstudios]

1. Make sure you have all the wire harnesses in.
2. Double check your meter switch and 2-pin connector soldering.
4. Make sure the 3 pin jumper is in the right spot.
3. Check your Dc voltages in the GR meter amp section.

http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

Mike

Hey, it looks like I soldered the long side of the 3 pin jumper to the PCB : so the short side is up, it does look like its still making a connection though...

I'm embarrassed to say I'm not sure how to read the schematic  :-\ I can somewhat follow it, do you check voltages from the bottom of the PCB? I noticed some references to Q11, 12, 13 under there... keeping the black lead in the chassis?

 

[Echo North]

Hey, it looks like I soldered the long side of the 3 pin jumper to the PCB : so the short side is up, it does look like its still making a connection though...

I'm embarrassed to say I'm not sure how to read the schematic  :-\ I can somewhat follow it, do you check voltages from the bottom of the PCB? I noticed some references to Q11, 12, 13 under there... keeping the black lead in the chassis?

DC voltages using the chassis as your reference.  Doesn't matter what side just identify the leads of the transistors.  You can google the datasheet or I think they are even labeled under the PCB.

http://www.hairballaudio.com/blog/resources/diy-resources/yes-you-can-read-a-schematic

Mike

 

[lackstudios]

DC voltages using the chassis as your reference.  Doesn't matter what side just identify the leads of the transistors.  You can google the datasheet or I think they are even labeled under the PCB.

http://www.hairballaudio.com/blog/resources/diy-resources/yes-you-can-read-a-schematic

Mike

Great, starting to make more sense  but, I'm not getting the correct readings 
I started with  Q11 as it looks like one of the first components in the flow. results:
Q11  G= -.689  S= -.773  D= 16.58
Q12  E=  0.0  C= 16.61  B= -.775
Q13  E= 0.0  C= 0.0  B= -.924

 

[Echo North]

Great, starting to make more sense  but, I'm not getting the correct readings 
I started with  Q11 as it looks like one of the first components in the flow. results:
Q11  G= -.689  S= -.773  D= 16.58
Q12  E=  0.0  C= 16.61  B= -.775
Q13  E= 0.0  C= 0.0  B= -.924

Q13 or Q12 is either dead or you have bad R value or a bad joint in the GR section.  If you're confident in all the soldering and R values and confident in all the pads on the switch, you may want to try new transistors.

You have no voltage at the collector of Q13 though....which makes me think your GR push switch or 2 pin wire header isn't soldered right.

Mike

 

[lackstudios]

Q13 or Q12 is either dead or you have bad R value or a bad joint in the GR section.  If you're confident in all the soldering and R values and confident in all the pads on the switch, you may want to try new transistors.

You have no voltage at the collector of Q13 though....which makes me think your GR push switch or 2 pin wire header isn't soldered right.

Mike

the soldering at both ends of the 2 pin connector is hershey kiss heaven...and their both soldered with the gap facing the same as the silkscreen...

 

[lackstudios]

also, the voltages at TP10 & 11 are 16.5

 

[Echo North]

also, the voltages at TP10 & 11 are 16.5

TP11 is 16.5 VDC and the C of Q13 is 0 VDC?

That's impossible...they are connected.

 

[Diamondj421]

Make sure in GR OFF mode pad 22 is shorted to the chassis (ground).

if so....

Set your unit to:
Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR OFF
Release: Full CW
Ratio: 20:1
Meter: GR
Signal: Sine 1kHz @ 0dBu

What is your AC V at pad 15 and at + output.

Mike

Output + = 10.09 VAC
Pad 15 = 2.47 VAC

 

[Echo North]

Output + = 10.09 VAC
Pad 15 = 2.47 VAC

What is your VAC across output + and output -?

Same conditions.

Mike

 

[lackstudios]

TP11 is 16.5 VDC and the C of Q13 is 0 VDC?

That's impossible...they are connected.

haha, of coarse this project is impossible! JK  :'(

I triple checked and thats the reading...I'm probing all the possible spots I can reach, bottom and top...

 

[Diamondj421]

What is your VAC across output + and output -?

Same conditions.

Mike

10.38VAC