Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1820 on: May 12, 2020, 11:32:02 PM »
OK - so I verified that the correct Transistor is in place, one of the J309's in Q2.  The DC voltage is:

G = 4.7
S = 8.29
D = 14.62



Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1821 on: May 12, 2020, 11:39:09 PM »
OK - so I verified that the correct Transistor is in place, one of the J309's in Q2.  The DC voltage is:

G = 4.7
S = 8.29
D = 14.62

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

Ya they're off.  However Q2 and Q3 interact off the same supply rail, so Q3 being dead could cause issues with Q2.  I would triple check all the R values and soldering. If that all looks good I would replace Q2 and Q3.  You can use the missing parts form and I'll send them to you.

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

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1822 on: May 16, 2020, 03:33:06 PM »
Ok, I just verified all the R values are correct and soldering seems good - so submitted missing parts form for Q2 and Q3. 

Hopefully it’s that easy.  :-)

Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1823 on: May 17, 2020, 08:09:58 PM »
Ok, I just verified all the R values are correct and soldering seems good - so submitted missing parts form for Q2 and Q3. 

Hopefully it’s that easy.  :-)

Sounds good.
Hairball Audio, LLC
DIY Parts and Kits
https://hairballaudio.com

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1824 on: May 21, 2020, 01:55:15 PM »
Did you receive my missing parts request?  Just checkin.... Thx.

Sounds good.

Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1825 on: May 21, 2020, 02:03:59 PM »
Did you receive my missing parts request?  Just checkin.... Thx.

I've got some requests, did you get a ship notice? I get a million emails everyday, don't know who is who and what is what.

Email me through the contact form your name, shipping address, and parts and I can see if I got it.  If not I'll ship out.

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

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1826 on: May 21, 2020, 02:10:58 PM »
No ship notice, will do the contact form. Thx, and no worries.

EmoRiot

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1827 on: May 22, 2020, 01:50:51 PM »
I'm building a Rev A and I'd like to add the red neon lamp atop the meter. I have a neon bulb, like the original, that works off  115V AC but I'm not sure where I can best tap off the  power for that.

The Meter switch bank's Off switch has solder tabs and they test for the correct behavior with a continuity tester, where the Off position breaks continuity (lamp off) but any other switch position passes continuity (lamp would be on). But is 115V passing through this switch? Or has it been stepped down or converted to DC by this point in the circuit?

Any help would be greatly appreciated!

EmoRiot

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1828 on: May 24, 2020, 12:54:19 AM »
I'm building a Rev A and I'd like to add the red neon lamp atop the meter. I have a neon bulb, like the original, that works off  115V AC but I'm not sure where I can best tap off the  power for that.

The Meter switch bank's Off switch has solder tabs and they test for the correct behavior with a continuity tester, where the Off position breaks continuity (lamp off) but any other switch position passes continuity (lamp would be on). But is 115V passing through this switch? Or has it been stepped down or converted to DC by this point in the circuit?

Any help would be greatly appreciated!

I'll come back to reply to my own comment for anyone else who might search for something similar. The answer is yes. I got my neon lamp connected to two of the switch tabs on the backside (the side which faces towards the meter). I'm running wires off the main AC input (pre-transformer). Neutral goes to one lead of the neon lamp, Live goes to the switch's 1st tab (closest to the front panel) and then a connector lead goes from the center tab of the switch to the neon lamps other lead. This setup correctly disrupts mains power from reaching the neon when the switch is in the off position but passes power to it for any of the other three positions.

If anyone reads this and notices that I've made a grave error, do let me know but it sure seems to be working as expected.

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1829 on: May 29, 2020, 08:02:36 PM »
Sounds good.

Well, I give up.  I can’t even get q2 and q3  out of their places.  I have a solder sucker but clearly I don’t have the chops to get these components out cleanly and I’m scared I’m gonna ruin something if I keep it up. 

I can’t find a contact page on your website.  How can I do the flat rate repair?  I can send it to you.  I’m just over on. Bainbridge Island. 

Thanks,

Johnny


Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1830 on: June 01, 2020, 09:45:19 AM »
Hey Mike,

Got a Rev A build I have assembled. Seems to have a muffled/ low pass filter going on with both GR on and off. Compression, attack, release and ratios work as about expected. I went through and checked the DC voltages of all the Q points and they seem to be right. I didn’t fully go through auditing the values quite yet, but checked the first stage and all the parts are correctly placed. All my solder joints look good, the few that we’re looking a mediocre I reflowed, with the exception of the transformer. Those don’t look the best, but they don’t look like they should be an issue.

I started working through the troubleshooting guide and my Q3 base is reading at about .13 instead of .05. Q2 gate and TP15 test about right.  My unit isn’t perfectly calibrated at the moment because I moved around my Qbias, etc but it’s in the neighborhood.

When I go onto the next step, in order for me to set the measurement to .200 VAC at TP17, the guide says pot should be at middle of the scale, but my output  is at -36 on output.
Is this related to input mod being done? In order to get my input to the proper level to do the step before it’s at -12, aka about 3 o clock.
TP17 and Q4 read right, but Q5 and 6 are both .105 instead of .173.

Did I burn out a component or do I maybe have a bad component somewhere? I’ll go through and audit the rest of the component values.

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1831 on: June 01, 2020, 10:20:14 AM »
Update. Just discovered I mixed up 33n and 33J capacitor  ;D. I’m assuming that’ll fix it. If it doesn’t I’ll post back!

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #1832 on: June 04, 2020, 02:01:21 PM »
I need help getting my rack unit going.  Is anyone willing and able to assist?  I need q2 and 3 replaced, then just need to make sure it’s all working.  I have the parts, and can send it your way.  Happy to pay for your time.