[BUILD] FET/500 Official Support Thread

[FarisElek]

HA! I found a Green LED in my parts drawer and it's the same size so I went for it to be over with this build. It's perfect! It ain't red but it works.
It ain't pretty on the inside near the LEDs, perfect everywhere else. Had a really hard time with some old lead cutters that I've permanently retired.

I am so unbelievably happy with this compressor now. I've already tracked drums with it on the kick. Absolutely crazy.

 

[Fuzz Face]

Man you were supposed to clip the LED leads before you solder to the board! 

 

[FarisElek]

Man you were supposed to clip the LED leads before you solder to the board! 

I know. I was building it away from my tools and I didn’t have tweezers to hold the LED’s to the board to to the pcb while soldering, so I kept one lead long enough that I could hold it bent up while soldering one side. It went wrong once but I thought I could get away with it again and it happened again . I should have just been patient and waited til I had access to my tweezers.

 

[zarndyhoff]

Hi!

Just built my two Rev Ds. (actually these are the third and fourth I've built over the years).

First unit worked perfectly, calibrated perfectly, straight away.

Second unit, everything fine during calibration until the bit where you repeat the four steps. When GR Off is engaged, nothing changes - the AC output doesn't change regardless of where the switch is positioned..

Any ideas? I've been through and re-flowed all the solder joins on the meter board, but I haven't gone over the resistors yet... dreading that part. It's pretty tidy. I'll add a photo. Can you see any issues?
Thanks!

 

[Echo North]

Hi!

Just built my two Rev Ds. (actually these are the third and fourth I've built over the years).

First unit worked perfectly, calibrated perfectly, straight away.

Second unit, everything fine during calibration until the bit where you repeat the four steps. When GR Off is engaged, nothing changes - the AC output doesn't change regardless of where the switch is positioned..

Any ideas? I've been through and re-flowed all the solder joins on the meter board, but I haven't gone over the resistors yet... dreading that part. It's pretty tidy. I'll add a photo. Can you see any issues?
Thanks!

https://help.hairballaudio.com/hc/en-us/articles/360048613813-Common-Build-Errors-and-Troubleshooting-Techniques

and

https://help.hairballaudio.com/hc/en-us/articles/360048218173-FET-500-Troubleshooting-Guide

 

[novisplit]

Having the same VR2 issue as a lot of folks. Any official fix for that? double checked all my values. rebiased 6 times now.

Meter also seems to be way hotter than VU meter in protools. Other than that it's working great.

Please help!!!

 

[FarisElek]

Does using a linear psu for the 500 series such as the CAPI floor box psu bring the 500 series unit closer to the fet rack in character?

 

[noiro]

Does using a linear psu for the 500 series such as the CAPI floor box psu bring the 500 series unit closer to the fet rack in character?

I'm buidling them both rack and 500 series, basically i don't see much of a difference but what I notice is that each of them are unique, even two rack with active link aren't exactly doing the same work, it's the beauty of the analog world, like us they are all unique in my view.

 

[noiro]

On a side note:
After calibrating "Unit#1" I put everything together. I noticed that a leg of R72 might be touching a #4 nut and/or 1/4" standoff. When I checked it with a DMM, it was so. Solved it by adding a bit of tape to the 1/4" standoff and #4 nut.

Hi man, I'm not sure if this is a good idea, it maybe suppose to touch, but it is very odd that it does that to my two last build as well REV F, not certain if i saw that before, R72 is shorting with the whole frame as well. it goes to ground, but in the schematic it does not?  any idea Mike?

 

[asstrochris]

Wondering if anyone can help with what should be a simple question? Just finished a FET/500, everything seems great, calibration mostly went fine for both, except for the VR2 "VU Trim" pot doesn't seem to adjust the lowest level. Second LED stays lit no matter of the setting on the pot. Any ideas welcomed, thanks!

Also, here's all my test measurements for the meter:

1: 1.22 VAC 10: -15.55 VDC
2: 1.52 VAC 11: 1.5 VAC
3: +7.12 VDC 12: 1.2 VAC
4: -8.02 VDC 13: +1.39 VDC
5: -.501 VDC. 14: +2.04 VDC
6: -1.115 VDC 15: +.78 VDC
7: -14.22 VDC 16: +15.38 VDC
8: -12.5 VDC 17: +2.5 VDC
9: +15.38 VDC. 18: +.05 on, +1.15 off (.7 LED1) VDC

 

[zarndyhoff]

https://help.hairballaudio.com/hc/e...n-Build-Errors-and-Troubleshooting-Techniques
and

https://help.hairballaudio.com/hc/en-us/articles/360048218173-FET-500-Troubleshooting-Guide

Thanks for this reply! I figured it out ages ago - I think I had swapped a 10 k ohm with a 10 ohm resistor. Both units have been working perfectly for a year and sound fantastic.

 

[Sweetfoot]

I built a rev D kit, got it all calibrated, and started using it for some mixes. It's been great for a week or so, but today the output suddenly got super hot. Previously, the input an output seemed to have a reasonable range across their rotation, but now the output goes from zero to completely blown out within like 5 degrees of rotation, while the input pot still functions as expected. Any Idea why this might happen? Did my q bias drift as the circuit burned in?

 

[Sweetfoot]

I built a rev D kit, got it all calibrated, and started using it for some mixes. It's been great for a week or so, but today the output suddenly got super hot. Previously, the input an output seemed to have a reasonable range across their rotation, but now the output goes from zero to completely blown out within like 5 degrees of rotation, while the input pot still functions as expected. Any Idea why this might happen? Did my q bias drift as the circuit burned in?

Update: The super loud output is intermittent. On the day I first posted, It occurred for a few minutes, then went away for a few minutes, then came back for the rest of the day. Since that day though, the unit has been sounding normal.

 

[magnusp71]

Hi all
I am in the proces of calibrating my Hairball FET/500 but have reached a dead-end before even getting started :/

Gear:
Logic Pro DAW
Apogee Duet 2 interface (Userguide)
Lindell Audio 503 lunchbox (Specs here)
Brymen 867 DMM (SPECS here)
Soundskulptor XT500 lunchbox connector extender (LINK)

Input to FET/500:
I am sending a 1kHz 0dB signal to the input from Logic Pro's Test Oscillator through my one of my Apogees balanced outputs via a mono-jack to XLR cable. By adjusting the level to approx -10dB in Logic, I measure 0.775 VAC and 1kHz on pin 2 and 3 on the XLR at the lunchbox input. So far so good.

Output from FET/500:
The knobs are set as instructed in the video. I have connected the lunchbox output to the Apogees input 1 via a XLR-cable. However, for some reason I have a zero voltage reading between the XLR pin 2 + 3 on the output of my lunchbox and thus cannot proceed with calibration.

What I have tried so far:

• As a test, I've tried to record whatever is on input 1 of the Apogee, and this is indeed a 1kHz sinus-signal (however with some "bumps" as seen on picture below").
• Measuring output between pin 1+3 and 1+2 - also 0 VAC.
• Measuring directly on the pins of the lunchbox - also 0 VAC.
• Measuring on the measuring pins of the XT500 connector (COM and OUT+) - also 0 VAC.
• Test of voltage rails as explained HERE. I have 0.18 VDC on -V Out and 14 VDC on +VR.

What I can see:

• LED1 and LED2 working.
• Green LED number 4 from bottom on Meter PCB lights up when powering on the unit and stays on.

What I can hear:

• I have attached a sound clip from a vocal signal, that I tried to send through the FET/500 while twisting the input/output knob a little. Gain is at +60dB.

I truly hope that someone is able to guide me in the right direction

Pictures:
Input cable.

Tone generated in Logic Pro.

Input on lunchbox.

Input measured.

Cable between lunchbox output and Apogee interface

Output on lunchbox:

Output measured:

FET/500 Output recorded to Apogee input in logic (signal strength can be modulated with FET/500 output knob).

The FET/500:


Thank you in advance!
Br, Magnus

 

[Echo North]

Hi,

If you have an extender you should start by working through the troubleshooting guide.

https://help.hairballaudio.com/hc/en-us/articles/360048218173-FET-500-Troubleshooting-Guide
Take care full note that the FET/500 uses a complex grounding scheme and different voltages have different reference/common points. I would start be working through the TP1/TP15/Output Tx brown wire points to isolate the particular part of the circuit where your signal is dying. 90% of my repairs are poor solder joints or misplaced parts, Working through the guide should help you isolate the area where the signal stops.

Mike

 

[magnusp71]

Hi,

If you have an extender you should start by working through the troubleshooting guide.

https://help.hairballaudio.com/hc/en-us/articles/360048218173-FET-500-Troubleshooting-Guide
Take care full note that the FET/500 uses a complex grounding scheme and different voltages have different reference/common points. I would start be working through the TP1/TP15/Output Tx brown wire points to isolate the particular part of the circuit where your signal is dying. 90% of my repairs are poor solder joints or misplaced parts, Working through the guide should help you isolate the area where the signal stops.

Mike

Hi Mike

I’ve already started Troubleshooting but noticed that my voltage rails are off. Not sure how and if to proceed from that?

“Test of voltage rails as explained HERE. I have 0.18 VDC on -V Out and 14 VDC on +VR.”

Secondly, I’m not sure I got the placements of TPs fully right based on the descriptions in your guide. Do you have a picture or an overlay where they are shown?

Thanks again

 

[sadmonkeysound]

Nevermind - it was flipped LED orientation, and the LED is in the path to the relay.

Just finished building my second FET/500 rev A. It passes audio, calibrated just fine, and sounds great (just like my first one). There are, however a few minor issues - I'm hopeful somebody can point me to particular parts of the board or components to check. I've done a few passes over the solder joints to make sure things look clean, and don't see anything obviously out of wack.

1) Neither the GR out or bypass LEDs light. I will likely try flipping them, but I'm fairly sure the orientation was correct at installation time, and I'm concerned there's a deeper issue, because...
2) The bypass switch is non-functional (the GR out switch IS functional)

Is there any reference for what I could/should expect to see at the LEDs, bypass switch pins, and/or at the relays? Alternatively, is there any earlier point I could test at that might be common to this set of issues?

 

[YoDudeRock]

This is mostly for Mike...
Have you put any HPF's on any of your own 1176's? I am trying to do a simple Cap and Resistor on a switch to cut at 60 or 130Hz before compressing. I read that it could be done by sending the output (or test point #15) through a capacitor and resistor combo, then into pin 6 on the ratio board (the one that corresponds to the white wire on the 6 pin connector that goes from the ratio board to the main board). Does this seem correct??

Thanks,
Chris Trentham

 

[marinegrau]

Hi all,
I'm in the process of building 2 Rack 1176. I finished one and also completed calibration, it should be somewhat good, although a few values are higher that they should be.

However there's a problem with the Q-Bias in the other one which I just can't find.
I compared the resistors and as far as I can see they are correct. The anode of C19/C20 is around 16V in both units, however the kathode is 9V in the (what I think) faulty one and 5.8V in the (probably) good one.

Any advice on debugging?

Thanks a lot

 

[Fet Sounds]

Hi all,
I don't know if anybody can help, i can't find any solution by myself. I have layng around a few FET/500 pcbs only, those that are sold with no components. I sourced all of the parts for the pcbs invluding the T pad but i really could not find the transformers. I'm building many units from other manufacturing and also racking myself old Studer and other console's channels and other stuff so i know very well that trannies are not very reliable on these times. Anyone could suggest an input and output transformer i can use for the 500 series FET compressor right now? Either the A, D or F is fine, i know A and D shares the same trafos, while F uses the 11148 output. I'm looking among all the supplyers i know but can't find anything in stock except Sowter, here is a list of transformers working for the rack version and could be good for the 500 (i jeed to check the dimensions) but NONE of them is in stock except Sowter.

Altran C-3837 input
Bournes B11148
Cinemag CM 3303 input all revisions
Cinemag CM-96731 output
Sowter 1260 input all revisions
Sowter 1327 output revision A and D
Sowter 1486 output revision F
UA 5002 output

Does anybody know and could maybe share some infos on a good substitution? Maybe Mike?
Thank you so much in advance, i really appreciate anybody who could help!

Marco



UA 5002 output revision A/E