Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1060 on: February 12, 2018, 11:14:41 PM »
ok, flipped the caps and it removed the dc in the output knob.  I'm still hearing a slight click when I turn the knob completely ccw, almost like I can hear the audio click off, it's minor, but wouldn't mind figuring out what it is.  or is that normal behavior, and I'm being finnicky?  Happy to be almost done! :) . Thanks for the quick help.


Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1061 on: February 12, 2018, 11:27:20 PM »
ok, flipped the caps and it removed the dc in the output knob.  I'm still hearing a slight click when I turn the knob completely ccw, almost like I can hear the audio click off, it's minor, but wouldn't mind figuring out what it is.  or is that normal behavior, and I'm being finnicky?  Happy to be almost done! :) . Thanks for the quick help.

On the output?  Pots always have a little end of track noise.  If it's at the end that should be well out of operational range.

Mike
Hairball Audio, LLC
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Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1062 on: February 12, 2018, 11:33:36 PM »
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.

Hey Mike! So I went through and checked the DC Volts of my GR Amp part of the PCB. The resistors are the right resistors and the Diodes are in the right polarity. My transistors are not checking out at this part of the board.

My readings are

Q7 - B = 16.17 DC V
E= 23.64 DC V
C= 27.4 DC V

Q8 - B = 27.41 DC V
E= 26.91 DC V
C= 30.52 DC V

Q9 -
B = 4.97 DC V
E= 4.37 DC V
C = 5.3 DC V

Q10 - B = 5.3 DC V
E = 4.69 DC V
C = 30.53 DC V

The transistors on the rest of my board checked out great, it is just this part of the board I am trying to figure out. I went and checked my solder and did some reflow but I am still getting the same readings.

Let me know if this is clear and again I appreciate your patience and support!

Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1063 on: February 12, 2018, 11:42:33 PM »
I would guess you have something like a 4.7K, 47K, 470K mix up (there are many in the section) or one of those transistors is bad.

You could carefully pull and test them as described in that link. I would start with Q7, seems like that might be blown out.

Something is out and cascading through the circuit.

Mike
Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
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Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1064 on: February 12, 2018, 11:42:40 PM »
On the output?  Pots always have a little end of track noise.  If it's at the end that should be well out of operational range.

Mike

ok cool, then I'm up and running!   8) Thanks again for all of your guidance and quick help!

Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1065 on: February 12, 2018, 11:44:02 PM »
ok cool, then I'm up and running!   8) Thanks again for all of your guidance and quick help!

Enjoy!

Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
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http://twitter.com/HairballAudio/

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1066 on: February 13, 2018, 03:10:26 PM »
I would guess you have something like a 4.7K, 47K, 470K mix up (there are many in the section) or one of those transistors is bad.

You could carefully pull and test them as described in that link. I would start with Q7, seems like that might be blown out.

Something is out and cascading through the circuit.

Mike


Hey Mike! I figured it out, and it is working awesome! So I put in the 1k ohm and belows first. I ended up receiving 270k resistors instead of 270 ohm resistors. Since I saw 270 when measuring I must have thought nothing of it when I stuffed them.

I appreciate all of your help with this (I know it was a huge learning experience for me). Just heads up on your end, my build kit didn't have fuses and I got a wrong measurement for the 3.9 M resistors (4.2 ohm I think it was I got and I sent in a missing parts report). But after finding this I see that I was given 270k instead of 270 R. I should have caught it right away and I would have saved myself so much headache!

Also when calibrating the needle between -10 and 0 should I expect it to not be precise? I seem to be slightly off when I switch back and fourth but not by much.

Thanks again!

Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1067 on: February 13, 2018, 03:15:19 PM »
Hey Mike! I figured it out, and it is working awesome! So I put in the 1k ohm and belows first. I ended up receiving 270k resistors instead of 270 ohm resistors. Since I saw 270 when measuring I must have thought nothing of it when I stuffed them.

Ahhhh ya I thought we'd caught all those.  We had a temp guy doing kits and it's been a bit of a mess to clean up.

I appreciate all of your help with this (I know it was a huge learning experience for me). Just heads up on your end, my build kit didn't have fuses and I got a wrong measurement for the 3.9 M resistors (4.2 ohm I think it was I got and I sent in a missing parts report). But after finding this I see that I was given 270k instead of 270 R. I should have caught it right away and I would have saved myself so much headache!

Ya it's been a mess. Sorry about that.

We have been re-checking every single kit now to make sure all the kits are perfect.  Email me if you want a second one, I'll cut you as much of a deal as I can.


Also when calibrating the needle between -10 and 0 should I expect it to not be precise? I seem to be slightly off when I switch back and fourth but not by much.
Thanks again!

It takes a second to settle and it may drift a little between power ups, but it should be close.

Mike
Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
http://facebook.com/hairballaudio
http://twitter.com/HairballAudio/