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

[Deejsirois]

Does anyone know where to find the voltage chart for the Rev F?

In the absence of a response, I created my own.

 

[nbnb]

Finished a rack-Rev A and it sounds glorious; however, it seems to be out of phase.

I have checked all the connections from transformers etc - and the input/output XLR's are basically soldered straight to the board (leaving no chance to swap a hot/cold wire). Has anyone else had this issue? If I "Ping" the unit from Logic, it usually gives me a +1 sample latency, but using it as an insert, I have to put a "gain" plugin on the channel to reverse the phase as it comes back in. It's a real bummer.

Any ideas on what to trace, or should I just live with having to flip the phase every time I use the unit? (I hope this isn't the case).

 

[Deejsirois]

Finished a rack-Rev A and it sounds glorious; however, it seems to be out of phase.

I have checked all the connections from transformers etc - and the input/output XLR's are basically soldered straight to the board (leaving no chance to swap a hot/cold wire). Has anyone else had this issue? If I "Ping" the unit from Logic, it usually gives me a +1 sample latency, but using it as an insert, I have to put a "gain" plugin on the channel to reverse the phase as it comes back in. It's a real bummer.

Any ideas on what to trace, or should I just live with having to flip the phase every time I use the unit? (I hope this isn't the case).

swap your cables...been shocked how many times cables have been wired improperly. The other thing to check would be to check to make sure your audio interface doesn't have polarity switched.

And now I am wondering what exactly you mean by "out of phase". How do you know it is out of phase?

 

[nbnb]

Thanks for the advice - pretty sure it's not the cables since I used the same two cables on several other outboard units and they have no issues.

And yes, what I meant was polarity (not phase).

If I send a tone to the unit, record the returning signal, and zoom in it's very obvious that the wave forms are opposite each other (polarity). The interface is a UA Apollo and I made sure the polarity switch is off.

Any other ideas? I appreciate any thoughts.

 

[scott2000]

If you're sure the connections are right, suppose you could try to send a signal to just + or - by themselves and make sure the secondaries or whatever points are reading where they are supposed to? Maybe you got a goofy transformer?

 

[dying_star]

Hey there! I just finished a REV A build and everything seems to be working great except the 4:1 ratio setting. I have to absolutely crank the input to 6+ to get any movement of the meter and audible compression, and by then I've had to turn the preamp down so much and the input on the 1176 up so loud it's got an unusable amount of hiss and noise, or the signal becomes distorted.

Every other ratio works as expected and has been measured to be reducing db as indicated by the meter.

I have checked all of the components on the ratio sub-board and believe them to be correct. I am about 99% sure I installed the 1M R input drop mod, but I can't remember (I tried it with and without when it was still on my bench), and the unit is currently installed in my desk. I've been getting along pretty well at 8:1 but it bugs me the unit isn't working 100%.

Thanks in advance for any strategies to solve this one!

 

[scott2000]

I've been getting along pretty well at 8:1 but it bugs me the unit isn't working 100%.

Have you been through the troubleshooting guide? Looks like section 3 and on is relevant maybe.

https://help.hairballaudio.com/hc/en-us/articles/360045942974-FET-RACK-Troubleshooting-Guide

 

[Josuebeaucage]

Hey there! I just finished a REV A build and everything seems to be working great except the 4:1 ratio setting. I have to absolutely crank the input to 6+ to get any movement of the meter and audible compression, and by then I've had to turn the preamp down so much and the input on the 1176 up so loud it's got an unusable amount of hiss and noise, or the signal becomes distorted.

Every other ratio works as expected and has been measured to be reducing db as indicated by the meter.

I have checked all of the components on the ratio sub-board and believe them to be correct. I am about 99% sure I installed the 1M R input drop mod, but I can't remember (I tried it with and without when it was still on my bench), and the unit is currently installed in my desk. I've been getting along pretty well at 8:1 but it bugs me the unit isn't working 100%.

Thanks in advance for any strategies to solve this one!

You should also check all soldering on the 4:1 resistors circuit (look them up on the diagram), check for continuity and bad solder joints. Also test the all buttons in mode to see how it behaves (I think this mode bypasses all resistors directly to the fet)
Cheers !

 

[Bart_J86]

Hi all,

I've build a 1176 Rev D V2 some time ago and the unit is working fine. I would actually really like to add a (true) bypass switch, preferably on the front panel. Since I'm not good at electronics I'm in doubt whether to use a relay based switcht, or just an ordinary switch for this purpose. Which option would you choose and what are the pros/cons for either? I can't seem to find any substantive info on this topic on here.

If the choice would be to use a relay based switch, are there any pre made PCB's for this purpose, or some kind of schematic, as I'm not smart enough to come up with this stuff myself..

If the choice would be to use a non-relay switch, would it be wise to add wire just for this switch to be mounted on the front panel or would this introduce noise/hum or even degrade the overall quality of the signal?

Cheers!

 

[surtronomer]

Hello Everyone. Building my first 1176 Rev A. It’s been a blast so far.
Finished the power section build and started to test.
I’m Very happy with the build so far, it’s coming together nicely.

i had one mishap and installed the wrong diode for CR9. After realizing my mistake I pulled it out and replaced it with the one I believe is the correct one. I had a horrible time getting the first diode out and the new one in. Wasn’t able to completely clear the old solder from the through hole… Looks ****** compared to how clean everything else is.

I powered up the unit and began to test. No sparks, or smoke when turned on. I did get some sparks when metering CR8.
30VDC at CR8
-40VDC at CR9!!

Anyone have any idea what it could be? Fried CR9 diode? I don’t have a meter that tests diodes unfortunately but will order one. Something not making contact. Checked grounding at the right side of CR9 and it’s fine.

please help!
thanks in advance!!
Jeremy

 

[Deejsirois]

Hello Everyone. Building my first 1176 Rev A. It’s been a blast so far.
Finished the power section build and started to test.
I’m Very happy with the build so far, it’s coming together nicely.

i had one mishap and installed the wrong diode for CR9. After realizing my mistake I pulled it out and replaced it with the one I believe is the correct one. I had a horrible time getting the first diode out and the new one in. Wasn’t able to completely clear the old solder from the through hole… Looks ****** compared to how clean everything else is.

I powered up the unit and began to test. No sparks, or smoke when turned on. I did get some sparks when metering CR8.
30VDC at CR8
-40VDC at CR9!!

Anyone have any idea what it could be? Fried CR9 diode? I don’t have a meter that tests diodes unfortunately but will order one. Something not making contact. Checked grounding at the right side of CR9 and it’s fine.

please help!
thanks in advance!!
Jeremy

R81 and R82 are responsible for dropping that voltage down to -10, so I would assume that is the issue. Are they properly soldered?

 

[Deejsirois]

I have discovered that on the Rev F, the nuts that hold the output transformer in place if tightened too much can actually cause a short. Hopefully this saves others some time.

 

[Studawg]

Hey folks! Just finished a Hairball Rev A build and have run in to a couple of issues!

Right when we fired it up we noticed the VU meter stays all the way down. Adjusting the trim pot accessible from the front doesn’t make it budge at all. We ran a couple of tests and the circuit seems to short out at Q3. Everything before that is completely fine and tests in the expected voltage range but from there on it drops off completely. If it should measure 2.2 volts it will measure 0.022 volts. Every terminal we tested after Q3 read like that. (I don’t know if that’s relevant at all but figured I would mention it!)

We went through the troubleshoot guide and made it to the Q3 base and everything was perfect up until that point.

We’re hoping to get our hands on a continuity meter soon but any advice would be fantastic!

We also used a different Output and Input transformer (a Cinemag on the input and the UA-5002-1A Rev B for the output which we mounted to the chassis!)

This is only the second build my friend and I have done. Any sage wisdom or direction would be absolutely fantastic!

 

[SBAS]

Hello!

I recently put together a Rev A kit that I purchased a few years ago (PCB V1.12 - newer plug/play PSU) and I'm having low audio output issues.

Basically, build went fine - PSU checked out with +30VDC and -10VDC at respective points, device does input and pass signal, however, when attempting to do the very first calibration process (Qbias), I cannot output more than 1.2~VAC, not even close to the requested +11dB/2.75VAC (input set to .775VAC, Input knob set to 24). That's even with the output knob completely cranked/zeroed.

I went to the troubleshoot section of the Hairball site and started testing.

First test was for QBias Voltage - Requesting -1 VDC to -1.78 VDC at TP18 when setting QBias trim from mix to max. I did pass this with accurate voltages.

The next test requested setting the input knob to read 0.100VAC at TP1, and then check Q2 Gate, Q3 Base, and TP15. Q2-3 and TP15 were all very low voltages.

So this points me to the output circuit then? I guess my question is, where do I go and what do I look for from here? I'm currently double checking transistors and for cold joints, but nothing seems too obvious.

Lastly, unrelated, my meter does not seem to move at all. I'm assuming it's damaged? It lights up but that's it.

Thanks!

Hey all, I posted this awhile ago. I didn't get a response to this unfortunately. Hairball, or anyone, have any advice? Thank you!

 

[dbonin]

Hey all, I posted this awhile ago. I didn't get a response to this unfortunately. Hairball, or anyone, have any advice? Thank you!

For the meter, make sure you haven't over tightened the mounting screws. To test it, unplug the unit and feed an AC signal from your signal gen to the terminals of the meter - slowly increase the signal to see if it shows signs of life.

 

[john lommock]

Here's an easy one I think. My lamp PCB has the 'front' arrow pointed opposite of the build guide photo. Should I attached it as pictured to match the build guide with the arrow pointing away from the front, or flip it so that the arrow points to the front of the unit?

 

[YoDudeRock]

Here's an easy one I think. My lamp PCB has the 'front' arrow pointed opposite of the build guide photo. Should I attached it as pictured to match the build guide with the arrow pointing away from the front, or flip it so that the arrow points to the front of the unit?

That's the orientation Hairball has that little circuit board in their instructions. I think the arrow on the current 2.01 kit is a misprint. I've built approximately 90 of these units and I've always done it just the way you have in your photo. Here's the photo and link to the page...
https://www.hairballaudio.com/blog/resources/build-guides/fetrack-v2-buildbrstep-3-final-assembly

 

[john lommock]

That's the orientation Hairball has that little circuit board in their instructions. I think the arrow on the current 2.01 kit is a misprint. I've built approximately 90 of these units and I've always done it just the way you have in your photo. Here's the photo and link to the page...
https://www.hairballaudio.com/blog/resources/build-guides/fetrack-v2-buildbrstep-3-final-assemblyView attachment 92954

Thanks for the response! Just to clarify, are you saying you've built the 2.01 kits with the PCB oriented like in the guide, or you're assuming the PCB is a misprint because it seems more likely than a change to the PCB traces? The product description of the meter describes the lamp as "Lamp box w/ 12VDC fuse style lamp". Fuses are not polarized I don't think, so maybe the orientation doesn't matter?

 

[Echo North]

We switched the orientation to make replacing the lamp easier. Go with the arrow on the PCB you have.

 

[Echo North]

Though it really can go either way. Polarity isn't an issue if using a lamp.